# ECGwaves Clinical Library (/docs) A unified clinical reference migrated from ecgwaves.com. Use the section switcher in the sidebar (or search) to navigate: * **Books** — full teaching books on ECG, echocardiography, CPR and cardiovascular medicine. * **Tools** — calculators, drug manuals, reference values, guideline & treatment summaries. * **ICD-10** — fast lookup across all ICD-10 diagnosis codes. * **Quizzes** — question banks with answers and explanations. * **Clinical Q\&A** — concise answers to common questions. * **Blog** — articles and commentary. * **Pages** — about, membership and reference information. # A new ECG biomarker for sudden cardiac death (/docs/blog/a-new-ecg-biomarker-for-sudden-cardiac-death) *Published 2026-06-28* # A deep-learning ECG biomarker for sudden cardiac death: what the new Nature study shows [#a-deep-learning-ecg-biomarker-for-sudden-cardiac-death-what-the-new-nature-study-shows] Low-risk (blue) versus high-risk (red) ECG morphs in lead aVL (adapted from *Obermeyer et al*1). Representative single-beat morphs for a low-risk patient (blue) and the corresponding high-risk morph (red). Beyond the difference in R-wave amplitude, note the slurred terminal portion of the R wave in the high-risk morphology, which replaces the sharp negative S wave seen in the low-risk beat — the previously undescribed biomarker identified by the deep-learning model. ## Predicting sudden cardiac arrest [#predicting-sudden-cardiac-arrest] Sudden cardiac death (SCD) remains one of the most intractable challenges in clinical cardiology. Hundreds of thousands of arrhythmic deaths occur annually in the United States alone, yet no reliable model currently exists for the long-term prediction of sudden cardiac arrest. The constraint does not lie in therapy: implantable cardioverter-defibrillators (ICDs) are highly effective, terminating well over 99% of the ventricular arrhythmias they detect. It lies instead in patient selection. Because implantation entails appreciable cost and procedural risk, the risk-benefit balance depends almost entirely on the capacity to identify, prospectively, those individuals genuinely at risk of arrest. This predictive problem has proven persistently resistant to resolution. ## Known predictors of cardiac arrest [#known-predictors-of-cardiac-arrest] The only risk biomarker in genuinely widespread use is left ventricular ejection fraction (LVEF), measured by echocardiography. Reduced LVEF reliably identifies a high-risk group that derives a large, trial-proven survival benefit from primary-prevention ICDs. Its dominance, though, owes as much to pragmatics as to discrimination: echocardiography is ubiquitous, standardized, and cheap to interpret. The limitation, familiar to every electrophysiologist, is that LVEF is both insensitive and non-specific for SCD. Most people who die suddenly never had an ejection fraction measured before death, and among those who did, only a minority had a reduced value — the majority of sudden cardiac deaths occur in patients with preserved LVEF, for whom no practical risk-prediction tool currently exists. At the other end, roughly two-thirds of ICDs implanted for reduced LVEF never deliver an appropriate shock, so the false-positive burden is substantial. Alternative modalities — cardiac MRI, long-term ambulatory monitoring, electrophysiological study, PET, SPECT, genetic profiling — add information but are too costly or invasive to screen a population. The surface ECG is the obvious cheap, standardized, universally available alternative, and it has been mined for predictive features for decades. The problem has been that hand-engineered ECG markers have never matched LVEF, and extracting them depends on expert annotation that limits scale and generalizability. Deep learning offers a way around this: an ECG can be fed directly into a classifier with no human feature extraction, in principle delivering LVEF's practical advantages with better discrimination. The missing ingredient has been a training set large enough to link raw waveforms to reliable cause-of-death data. ## The current study [#the-current-study] This paper supplies that ingredient. The authors trained a convolutional deep-learning model on population-scale ECG data from a single Swedish region, linked to national death certificates and electronic health records, and asked whether it could isolate a clinically actionable high-risk group for SCD — one defined entirely from the ECG, without echocardiography. They then stress-tested the model against multiple outcome definitions and validated it, with no fine-tuning, in geographically and structurally distinct US and Taiwanese cohorts. Finally, and unusually, they paired the predictor with a generative model to *visualize* the waveform morphology the network had learned, converting an opaque classifier into a human-readable, hypothesis-generating biomarker. ### What they studied [#what-they-studied] The work addresses three linked questions. First, can a model trained only on raw 12-lead ECGs flag a discrete population whose annual SCD risk is high enough to justify a defibrillator? Second, is that signal specifically arrhythmic — predicting the ventricular fibrillation and ventricular tachycardia (VF/VT) that actually cause sudden death — rather than a generic marker of cardiovascular mortality? Third, what is the model actually "seeing," and does it correspond to a recognizable electrophysiological substrate? ### Study data [#study-data] The Swedish cohort comprised all 441,614 ECGs recorded between 2010 and 2016 in Region Halland (a public regional health system serving roughly 187,677 patients), sampled at 500 Hz and retrieved from a Philips IntelliSpace archive. Methodologically, the most important design choice is the data "lockbox": 40% of patients, with all their ECGs, were randomly partitioned off before any analysis and left untouched through model development and peer review, opened only after provisional acceptance. The model was initially trained and validated on the other 60% (262,554 ECGs from 75,157 patients) and then applied without modification to the lockbox (119,541 ECGs with one-year follow-up from 35,885 patients under 80; 113,072 ECGs in the defibrillator-naive subset). This is a far stronger guard against overfitting and optimistic reporting than the usual single train/test split, and reassuringly, performance improved rather than degraded when moving to the held-out data. The architecture itself is a 64-layer ResNet (32 residual blocks), trained in a multitask setup that simultaneously predicted SCD over several horizons, SCD versus other causes of death among decedents, and reduced LVEF among those with echocardiography — the last giving the network an LVEF-relevant signal without requiring LVEF at inference. External validation used two deliberately heterogeneous datasets. The US cohort (Sharp HealthCare, via Dandelion Health) contributed 251,858 ECGs from 139,613 patients under 80, recorded in 2021–2022 on GE MUSE equipment — a different vendor, format, and era from the Swedish training data. The Taiwanese dataset (National Taiwan University Hospital, via Nightingale Open Science) is a case–control ED registry of 257 cardiac arrests and 4,011 controls under 80, with detailed adjudication that classified 96 arrests (37%) as arrhythmic in origin. ### Outcomes studied [#outcomes-studied] Recognizing that no single SCD definition is fully reliable, the authors triangulated across several. The primary label was death-certificate SCD — cardiac or ill-defined cause, out-of-hospital or within the first 24 hours of admission — in the year following an ECG, using standard epidemiological criteria. To counter the known specificity problems of death certificates (which can misclassify non-arrhythmic deaths from stroke or pulmonary causes), they additionally evaluated against incident VF/VT documented in health records in both Sweden and the US, and against the detailed case-adjudicated arrhythmic arrests in Taiwan. As a fourth line of evidence, they estimated potential mortality benefit by comparing high-risk patients who did and did not receive defibrillators. ## What they discovered [#what-they-discovered] In the Swedish lockbox, the model achieved an AUC of 0.872 (95% CI 0.843–0.899) for death-certificate SCD, substantially exceeding both a generic AHA/ACC 10-year risk score (0.697) and a previously validated ECG-based deep-learning cardiovascular risk model (SEER, 0.655). Discrimination only matters clinically if it yields a usable threshold. Anchoring to the control-group event rates from six major primary-prevention defibrillator trials (median \~4.9% annual SCD — the level at which enrolment was considered ethically justified), the authors defined a preferred high-risk group of 2.2% of the sample with a **7.0% annual SCD rate** (95% CI 4.9–9.5%). For comparison, the reduced-LVEF group (≤35%) represented 1.9% of the sample with a 4.6% annual rate. Critically, **86.1% of the model's high-risk patients were not flagged by reduced LVEF** — this is not a rediscovery of the echocardiographic high-risk group but a largely net-new population. Even among patients with a *measured and normal* LVEF, for whom no risk tool currently exists, the model isolated a subgroup at 6.4% annual risk, exceeding the reduced-LVEF group. Where both biomarkers agreed, risk rose to 10.7%, indicating that LVEF carries independent information rather than being subsumed. The arrhythmia-specificity analyses are what elevate this from "another ECG risk score." Beyond the 7.0% with SCD, an additional 3.8% per year of the high-risk group had documented VF/VT. In the US cohort — where financial incentives drive more complete VF/VT coding — the zero-shot AUC for VF/VT was 0.822, and the matched 2.2% high-risk group showed a 29.1% VF/VT incidence against a 3.8% base rate. The Taiwanese case–control data provided the cleanest test of specificity: the model distinguished adjudicated arrhythmic arrests from controls with a zero-shot AUC of 0.767, while a "placebo" AUC for *non-arrhythmic* arrests (pulmonary, neurological) fell to 0.582 — close to chance, and significantly worse (P \< 0.001). The signal is arrhythmic, not a generic death predictor. On preventability, observational regressions (necessarily confounded, and presented as suggestive) found that high-risk patients with a defibrillator in place died 3.62 percentage points below their predicted 6.65% rate — a **54.4% relative reduction** in SCD (P \< 0.001). As a face-validity check, the same framework "rediscovered" the known LVEF effect (67.5% reduction, within the 50–88% range of LVEF-enrolled trials). The ECG high-risk group also showed a 12.6-point (39.0%) reduction in all-cause mortality with defibrillators, whereas the reduced-LVEF group did not reach significance for all-cause mortality — consistent with competing-cause mortality eroding benefit in the older, sicker LVEF population. The biomarker itself was made visible by coupling the predictor to a variational autoencoder generative model, then iteratively morphing a real low-risk beat along the predicted-risk gradient into its high-risk counterfactual. The morph reproduced familiar correlates of ischemic disease — left axis deviation consistent with left anterior fascicular block (LAFB), and poor R-wave progression. More interesting is a feature in lead aVL that, to the authors' knowledge, has not been described: a **slurred terminal aspect of the R wave** replacing the sharp negative S wave seen in low-risk beats. Quantified as the mean absolute first and second voltage differences from R peak to QRS end, this feature independently and significantly predicted SCD in Sweden and the US (and trended the same way in the smaller Taiwanese sample), adding signal of comparable magnitude to left axis deviation and distinct from intrinsicoid deflection, fragmented QRS, late potentials, and QRS duration. Single-lead models retained nearly the full AUC, implying a diffuse myocardial process rather than a focal one. That diffuseness motivated a mechanistic hypothesis. A slurred, progressively orthogonal terminal vector is what one would expect if randomly distributed obstacles repeatedly split the depolarization wavefront — and blinded cMRI review found that the riskiest 10% of patients had significantly more subtle, diffuse late gadolinium enhancement throughout the left ventricle, the imaging signature of myocardial fibrosis. Fibrosis plausibly unifies the biomarker, the LAFB, and the arrhythmic risk, since the left anterior fascicle is thin and vulnerable to scattered lesions. Notably, the authors found no mention of this LGE in any of the corresponding cardiologists' reports — a reminder that subtle diffuse fibrosis is easily overlooked and frequently false-negative even on MRI relative to biopsy. ## Differences and similaritites to early repolarization pattern [#differences-and-similaritites-to-early-repolarization-pattern] Early repolarization and the deep-learning–derived sudden cardiac death biomarker are both abnormalities of the terminal portion of the QRS complex, and the parallels between them are worth understanding alongside their important differences. In each, the morphological change occurs in the late, downslope region of the QRS rather than in its initial deflections, and in each the abnormality has prognostic weight for ventricular arrhythmia and sudden cardiac death. Both can be appreciated on a standard resting twelve-lead ECG without specialized acquisition, and both followed a similar historical trajectory: early repolarization was long classified as a benign normal variant before its association with idiopathic ventricular fibrillation established it as a potentially malignant entity within the J-wave syndromes, while the newer biomarker likewise identifies a high-risk waveform that had not previously been characterized. The two diverge, however, in both morphology and mechanism. Early repolarization is defined by J-point elevation manifesting as slurring or notching at the junction of the QRS and ST segments, typically in the inferior and inferolateral leads, and reflects a transmural repolarization gradient mediated by the transient outward potassium current between epicardium and endocardium. The deep-learning biomarker, by contrast, lies within the QRS itself — a slurred terminal R wave that replaces the sharp S wave, most evident in lead aVL and accompanied by left axis deviation and poor R-wave progression — and is attributed not to a repolarization gradient but to a depolarization and conduction disturbance, specifically diffuse myocardial fibrosis that fragments and scatters the activation wavefront. A practical consequence of this distinction is that early repolarization adds a discrete deflection that tends to increase the high-frequency content of the terminal QRS, whereas the new pattern represents a smoothing of the waveform, quantified as a reduction in the first and second voltage derivatives over the same interval. In summary, the two share an anatomical locus on the electrocardiogram and a common association with sudden cardiac death, yet they represent fundamentally distinct electrophysiological processes — one a transmural repolarization phenomenon, the other a conduction abnormality rooted in structural fibrosis. Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J). Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J). ## Conclusions [#conclusions] The practical message is that a single, cheap, already-ubiquitous test — the resting 12-lead ECG — can identify a large, previously unsuspected population at high, arrhythmia-specific, and plausibly preventable risk of sudden death, the great majority of whom are invisible to LVEF. Validation across Sweden, the US, and Taiwan, with no fine-tuning and across different vendors and outcome definitions, is unusually robust, and the lockbox design lends credibility to the headline numbers. The appropriate caution is equally clear. The defibrillator-benefit estimates are observational and drawn from patients already selected for implantation under current norms; they cannot establish that a *newly identified* high-risk patient would benefit. The authors are explicit that a randomized trial in this ECG-defined population is the necessary next step — and the history of SCD prediction is littered with promising markers that failed to identify patients who actually benefit from devices. Subcutaneous and wearable defibrillator technology, however, lowers the threshold for testing such groups. ## References [#references] [Obermeyer, Schubert, Ross, Mullainathan & Lingman, "An ECG biomarker for sudden cardiac death discovered with deep learning," Nature.](https://www.nature.com/articles/s41586-026-10674-6) # Answer to ECG quiz 5 (/docs/blog/answer-to-ecg-quiz-5) *Published 2018-07-16* The ECG shows AV-block III (complete heart block). P-waves are not related to QRS. PP-interval is constant, but independent of RR-interval, which is also constant. Atria and ventricles are depolarized separately. The ventricular rhythm is an escape rhythm arising in the AV-node or bundle of His. # Cardiovascular effects of COVID-19 (Coronavirus Disease 2019) (/docs/blog/cardiovascular-effects-of-covid-19-coronavirus-disease-2019) *Published 2020-03-29* ## Cardiovascular effects of COVID-19 [#cardiovascular-effects-of-covid-19] Coronavirus disease 2019 (COVID-19) has caused a global public health crisis. It is believed that the virus was transmitted from bats to humans in Wuhan, China, and it has now spread to more than 170 countries and caused unprecedented damage to humans and societies. The number of confirmed cases is approaching one million and the number of deaths is 34,000 as of March 29, 2020 (Figure 1). There are no known effective treatments, although several randomized controlled trials are underway. Figure 1. As of March 25 (2020), there have been more than 530,000 individuals with confirmed COVID-19, of whom more than 33,000 have died. *Source: Worldometer.* ## Cardiovascular implications of COVID-19 [#cardiovascular-implications-of-covid-19] Data on the natural history of COVID-19 relies on small samples of hospitalized patients. Most reports have suggested that comorbidities – *e.g. cardiovascular disease, pulmonary disease, advanced age, smoking, diabetes, hypertension, cancer, etc* – are the most important risk factors for poor outcomes. The vast majority of infections with COVID-19 result in mild disease, with symptoms similar to seasonal flu (influenza) and other viral respiratory infections. However, in some individuals the infection may be severe and deadly. Importantly, COVID-19 has caused an unprecedented number of severe and deadly infections among young and apparently healthy individuals. ### Infections and the risk of acute coronary syndromes [#infections-and-the-risk-of-acute-coronary-syndromes] It is known that the risk of developing acute coronary syndromes increases during infections, including influenza (6–9). Two mechanisms have been proposed to precipitate acute coronary events during infections: 1. An acute coronary event may be triggered by increased myocardial demand during the infection. 2. Systemic inflammation results in increased levels of circulating pro-inflammatory cytokines that may cause plaque rupture (i.e the risk of atherosclerotic plaque rupture is increased during infections). As noted by [Bonow et al](https://jamanetwork.com/journals/jamacardiology/fullarticle/2763844), it is also reasonable to believe that patients with heart failure are at increased risk of decompensation if infected with COVID-19. Moreover, there may also be an increased risk of myocarditis, given the similarities between COVID-19 and MERS (Middle East Respiratory Syndrome, coronavirus). ### Recent studies on COVID-19 and cardiovascular disease [#recent-studies-on-covid-19-and-cardiovascular-disease] Cardiovascular implications of COVID-19 have been elucidated in recent studies from China and Italy (1–5). Two recent studies published in JAMA Cardiology are summarized below. *Shi et al* present data on 416 patients hospitalized with COVID-19. In total, 82 patients (19.7%) had elevated *high-sensitivity troponin I (TnI)* levels. The mortality rate among patients with elevated troponin I was 51.2%, as compared with 4.5% among patients without evidence of myocardial injury (normal troponin I levels). Hence, troponin I was a strong predictor of survival in patients hospitalized with COVID-19 (Figure 2). Figure 2. [Shi et al, JAMA Cardiology (2020)](https://jamanetwork.com/journals/jamacardiology/fullarticle/2763524). Guo et al reported that 27.8% (52 of 187 patients) had myocardial injury, defined as elevated troponin T levels (TnT). In-hospital mortality rate was 59.6% among cases with elevated TnT levels, as compared with 8.9% among patients with normal TnT levels. Increased risk of death was noted among all patients with elevated troponin levels, although the highest risk was noted among patients with cardiovascular disease. The highest mortality rate was observed in patients with elevated TnT levels who had underlying cardiovascular disease, of which 69.4% died.  *Guo et al* also report a significant association between troponin T levels and C-reactive protein (CRP) and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP). The latter suggests that COVID-19 causes ventricular dysfunction. *Guo et al* also demonstrate that troponin T and NT-pro-BNP may be used as prognostic markers during the disease course. In summary, the risk of severe disease and death is several times higher in patients with cardiovascular disease. This suggests that every effort must be made to prevent COVID-19 transmission to individuals with cardiovascular conditions. For details, refer to the excellent editorial by [Bonow et al](https://jamanetwork.com/journals/jamacardiology/fullarticle/2763844). **References** 1. Huang  C, Wang  Y, Li  X,  et al.  Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China.  *Lancet*. 2020;395(10223):497-506. 2. Chen  N, Zhou  M, Dong  X,  et al.  Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study.  *Lancet*. 2020;395(10223):507-513. 3. Wang  D, Hu  B, Hu  C,  et al.  Clinical characteristics of 138 hospitalized patients with 2019 novel coronavirus–infected pneumonia in Wuhan, China.  *JAMA*. 2020;323(11):1061-1069. 4. Wu  Z, McGoogan  JM.  Characteristics of and important lessons from the coronavirus disease 2019 (COVID-19) outbreak in China: summary of a report of 72 314 cases from the Chinese Center for Disease Control and Prevention.  *JAMA*. 5. Guan  WJ, Ni  ZY, Hu  Y,  et al; China Medical Treatment Expert Group for Covid-19.  Clinical characteristics of coronavirus disease 2019 in China.  *N Engl J Med*. Published online February 28, 2020. 6. Madjid  M, Miller  CC, Zarubaev  VV,  et al.  Influenza epidemics and acute respiratory disease activity are associated with a surge in autopsy-confirmed coronary heart disease death: results from 8 years of autopsies in 34,892 subjects.  *Eur Heart J*. 2007;28(10):1205-1210. 7. Nguyen  JL, Yang  W, Ito  K, Matte  TD, Shaman  J, Kinney  PL.  Seasonal influenza infections and cardiovascular disease mortality.  *JAMA Cardiol*. 2016;1(3):274-281. 8. Kwong  JC, Schwartz  KL, Campitelli  MA,  et al.  Acute myocardial infarction after laboratory-confirmed influenza infection.  *N Engl J Med*. 2018;378(4):345-353. 9. Smeeth  L, Thomas  SL, Hall  AJ, Hubbard  R, Farrington  P, Vallance  P.  Risk of myocardial infarction and stroke after acute infection or vaccination.  *N Engl J Med*. 2004;351(25):2611-2618. 10. Shi  S, Qin  M, Shen  B,  et al.  Association of cardiac injury with mortality in hospitalized patients with COVID-19 in Wuhan, China.  *JAMA Cardiol*. Published online March 25, 2020. 11. Guo  T, Fan  Y, Chen  M,  et al.  Cardiovascular implications of fatal outcomes of patients with coronavirus disease 2019 (COVID-19).  *JAMA Cardiol*. Published online March 27, 2020. # Download certificates of completion (/docs/blog/download-certificates-of-completion) *Published 2019-02-16* In January of this year, we administered a poll to see whether our users were interested in obtaining certificates. The results were clear: 89% of users were interested in obtaining a certificate upon course completion. Today we are pleased to share that we have created certificates. These certificates testify that you possess the necessary ECG skills required for clinical work. You must complete the ECG course in order to obtain your certificate. New ECG test will be added in February. Continue to log in if you are already registered or register if you do not have an account yet. # The QRS complex: ECG features of the Q-wave, R-wave, S-wave & duration (/docs/blog/ecg-qrs-complex-q-r-s-wave-duration-interval) *Published 2018-05-22* # The QRS complex (ventricular complex): normal and abnormal configurations and intervals [#the-qrs-complex-ventricular-complex-normal-and-abnormal-configurations-and-intervals] A complete QRS complex consists of a Q-, R- and S-wave. However, all three waves may not be visible and there is always variation between the leads. Some leads may display all waves, whereas others might only display one of the waves. Regardless of which waves are visible, the wave(s) that reflect ventricular depolarization is always referred to as the *QRS complex*. ## Naming of the waves in the QRS complex: [#naming-of-the-waves-in-the-qrs-complex] Naming of the waves in the QRS complex is easy but frequently misunderstood. The following rules apply when naming the waves: * A deflection is only referred to as a *wave* if it passes the baseline. * If the first wave is negative then it is referred to as Q-wave. If the first wave is not negative, then the QRS complex does not possess a Q-wave, regardless of the appearance of the QRS complex. * All positive waves are referred to as R-waves. The first positive wave is simply an "R-wave" (R). The second positive wave is called "R-prime wave" (R'). If a third positive wave occurs (rare) it is referred to as "R-bis wave" (R''). * Any negative wave occurring after a positive wave is an S-wave. * Large waves are referred to by their capital letters (Q, R, S), and small waves are referred to by their lower-case letters (q, r, s). Figure 5 shows examples of naming of the QRS-complex. Figure 5. Naming of the QRS complex. Figure 5. Naming of the QRS complex. ## Net direction of the QRS complex [#net-direction-of-the-qrs-complex] The QRS complex can be classified as net positive or net negative, referring to its net direction. The QRS complex is net positive if the sum of the positive areas (above baseline) exceeds that of the negative areas (below baseline). Refer to **Figure 6**, panel A. These calculations are approximated simply by eyeballing. Panel B in **Figure 6** shows a net negative QRS complex, because the negative areas are greater than the positive area. Figure 6. Approximations of the net direction of the QRS-complex. The positive areas are yellow and the negative areas are green. Figure 6. Approximations of the net direction of the QRS-complex. The positive areas are yellow and the negative areas are green. ## Electrical vectors that engender the QRS complex [#electrical-vectors-that-engender-the-qrs-complex] Depolarization of the ventricles generate three large vectors, which explains why the QRS complex is composed of three waves. It is fundamental to understand the genesis of these waves and although it has been discussed previously a brief rehearsal is warranted. **Figure 7** illustrates the vectors in the horizontal plane. Study Figure 7 carefully, as it illustrates how the P-wave and QRS complex are generated by the electrical vectors. Figure 7. The heart's main electrical vectors seen from the horizontal plane. V1 and V5 are exploring electrodes and the reference is composed of the average of the electrodes placed on the limbs (this reference is called Wilson's central terminal). Inspired by MacFarlane et al (Springer, Comprehensive Electrocardiology, 2010). Figure 7. The heart's main electrical vectors seen from the horizontal plane. V1 and V5 are exploring electrodes and the reference is composed of the average of the electrodes placed on the limbs (this reference is called Wilson's central terminal). Inspired by MacFarlane et al (Springer, Comprehensive Electrocardiology, 2010). Note that the first vector in **Figure 7** is not discussed here as it belongs to atrial activity. ### The second vector: the ventricular (interventricular) septum [#the-secondvector-the-ventricular-interventricular-septum] The ventricular septum receives Purkinje fibers from the left bundle branch and therefore depolarization proceeds from its left side towards its right side. The vector is directed forward and to the right. The ventricular septum is relatively small, which is why V1 displays a small positive wave (r-wave) and V5 displays a small negative wave (q-wave). Thus, it is the same electrical vector that results in an r-wave in V1 and q-wave in V5. ### The third vector: the ventricular free wall [#the-thirdvector-the-ventricular-free-wall] The vectors resulting from activation of the ventricular free walls is directed to the left and downwards (**Figure 7**). The explanation for this is as follows: 1. **The vector resulting from activation of the right ventricle does not come to expression**, because it is drowned by the many times larger vector generated by the left ventricle. Thus, the vector during activation of the ventricular free walls is actually the vector generated by the left ventricle. 2. **Activation of the ventricular free wall proceeds from the endocadrium to the epicardium**. This is because the Purkinje fibers run through the endocardium, where they deliver the action potential to contractile cells. The subsequent spread of the action potential occur from one contractile cell to another, starting in the endocardium and heading towards the epicardium. As evident from **Figure 7**, the vector of the ventricular free wall is directed to the left (and downwards). Lead V5 detects a very large vector heading towards it and therefore displays a large R-wave. Lead V1 records the opposite, and therefore displays a large negative wave called S-wave. ### The fourth vector: basal parts of the ventricles [#the-fourth-vector-basal-parts-of-the-ventricles] The final vector stems from activation of the basal parts of the ventricles. The vector is directed backwards and upwards. It heads away from V5 which records a negative wave (s-wave). Lead V1 does not detect this vector. ## Implications and causes of wide (broad) QRS complex [#implications-and-causes-of-wide-broad-qrs-complex] Prolongation of QRS duration implies that ventricular depolarization is slower than normal. The QRS duration is generally \<0,10 seconds but must be \<0,12 seconds. If QRS duration is ≥ 0,12 seconds (120 milliseconds) then the QRS complex is abnormally wide (broad). This is very common and a significant finding. The reason for wide QRS complexes must always be clarified. Clinicians often perceive this as a difficult task despite the fact that the list of differential diagnoses is rather short. The following causes of wide QRS complexes must be familiar to all clinicians: * **Bundle branch block:** The left and the right bundle branch consists of Purkinje fibers which spread out into the ventricular myocardium. The Purkinje network enables  fast impulse conduction so that the action potential can be delivered to the whole myocardium at the same time (approximately). Bundle branch block occurs if a bundle branch is dysfunctional and unable to transmit the impulse. The ventricle whose bundle is blocked will have to wait for electrical impulses to spread from the other ventricle. Because spread of the impulse from the other ventricle will take place partly or entirely outside of the conduction system, it will be slow and therefore the QRS duration is prolonged. Left and right bundle branch block are discussed in separate articles. * **Hyperkalemia:** Hyperkalemia causes slow impulse transmission (in all myocardial and conduction cells) and prolongation of the QRS duration. * **Drugs:** class I antiarrhythmic drugs, tricyclic antidepressants and other medications can cause widening of the QRS complex. * **Ventricular rhythm, ventricular ectopy and pacemaker with ventricular stimulation:** * Spontaneous action potentials discharged within the ventricles may depolarize the ventricles. The cell/structure which discharges the action potential is referred to as an *ectopic focus.* Such a focus may fire a single or multiple impulses (either consecutively or intermittently). A single impulse gives rise to a *premature ventricular* beat, whereas *multiple impulses may establish a ventricular rhythm*, or even *ventricular tachycardia*. In all these instances the QRS complex will be broad because the depolarizing impulse arises and spreads outside of the normal conduction system. * *External (artificial) pacemakers* have an electrode inserted in the right ventricular apex. Electrical stimulation in the right ventricular apex will give rise to an action potential propagating from there, i.e partly or entirely outside of the conduction system (which will cause wide QRS complexes). * **Pre-excitation (Wolff-Parkinson-White syndrome):** Pre-excitation implies the existence of an accessory pathway (in addition to the atrioventricular node) between the atria and the ventricles. Such pathways virtually always insert into the ventricular myocardium, from where the action potential spreads. Again, the spread takes place outside of the conduction system which is slow and causes widening of the QRS complex. * **Aberrant ventricular conduction (aberrancy):**  Aberrant conduction is actually a bundle branch block which occurs when the length of the cardiac cycle is rapidly changed, particularly at high heart rates. The bundle branches (particularly the right bundle branch) may occasionally fail to adapt their repolarization period to the length of the cardiac cycle (which they also do). This is discussed in detail in the article on aberrant ventricular conduction. Figure 8 (below) shows examples of normal and abnormally wide QRS complexes at 25 mm/s and 50 mm/s paper speed. Figure 8. Normal and abnormal QRS durations at different paper speeds. Figure 8. Normal and abnormal QRS durations at different paper speeds. ## Amplitude of the QRS complex [#amplitude-of-the-qrs-complex] A QRS complex with large amplitudes may be explained by ventricular hypertrophy or enlargement (or a combination of both). The electrical currents generated by the ventricular myocardium are proportional to the ventricular muscle mass. Hypertrophy means that there is more muscle and hence larger electrical potentials generated. However, the distance between the heart and the electrodes may have a significant impact on amplitudes of the QRS complex. For example, slender individuals generally have a shorter distance between the heart and the electrodes, as compared with obese individuals. Therefore, the slender individual may present with much larger QRS amplitudes. Similarly, a person with chronic obstructive pulmonary disease often display diminished QRS amplitudes due to hyperinflation of thorax (increased distance to electrodes). Low amplitudes may also be caused by hypothyreosis. In the setting of circulatory collapse, low amplitudes should raise suspicion of cardiac tamponade. ### R-wave amplitude [#r-wave-amplitude] It is important to assess the amplitude of the R-waves. High amplitudes may be due to ventricular enlargement or hypertrophy. To determine whether the amplitudes are enlarged, the following references are at hand: * R-wave should be \< 26 mm in V5 and V6. * R-wave amplitude in V5 + S-wave amplitude in V1 should be \<35 mm. * R-wave amplitude in V6 + S-wave amplitude in V1 should be \<35 mm. * R-wave amplitude in aVL should be ≤ 12 mm. * R-wave amplitude in leads I, II and III should all be ≤ 20 mm. * If R-wave in V1 is larger than S-wave in V1, the R-wave should be \<5 mm. (1 mm corresponds to 0.1 mV on standard ECG grid). ### R-wave peak time [#r-wave-peak-time] R-wave peak time (**Figure 9**) is the interval from the beginning of the QRS-complex to the apex of the R-wave. This interval reflects the time elapsed for the depolarization to spread from the endocardium to the epicardium. R-wave peak time is prolonged in hypertrophy and conduction disturbances. Normal values for R-wave peak time follow: * Leads V1-V2 (right ventricle) \<0,035 seconds * Leads V5-V6 (left ventricle) \<0,045 seconds Figure 9. R-wave peak time is defined as the time interval between onset of the QRS complex to the apex of the R-wave. Figure 9. R-wave peak time is defined as the time interval between onset of the QRS complex to the apex of the R-wave. ### R-wave progression [#r-wave-progression] R-wave progression is assessed in the chest (precordial) leads. Normal R-wave progression implies that the R-wave gradually increases in amplitude from V1 to V5 and then diminishes in amplitude from V5 to V6 (**Figure 10**, left hand side). The S-wave undergoes the opposite development. Abnormal R-wave progression is a common finding which may be explained by any of the following conditions: * **Myocardial infarction**: necrotic myocardium does not generate electrical potentials and therefore there is a loss of R-wave amplitude in the ECG leads reflecting the necrotic area (**Figure 10**, right hand side). * **Cardiomyopathy** may cause either loss or gain of R-wave amplitude, depending on the type of cardiomyopathy. Amplitudes may be increased in hypertrophic cardiomyopathy, whereas they are typically diminished in late stages of dilated cardiomyopathy. * **Right and left ventricular hypertrophy** also amplifies the R-wave amplitude. Left ventricular hypertrophy causes increased R-wave amplitudes in V4–V6 and deeper S-waves in V1–V3. Right ventricular hypertrophy causes large R-waves in V1–V3 and smaller R-waves in V4–V6. * **Pre-excitation, bundle branch block and chronic obstructive pulmonary disease (COPD)** may also affect R-wave progression. These conditions are discussed in detail later on. Note that the R-wave is occassionally missing in V1 (may be due to misplacement of the electrode). This is considered a normal finding provided that an R-wave is seen in V2. Figure 10. Normal and abnormal R-wave progression. Figure 10. Normal and abnormal R-wave progression. ### Dominant R-wave in V1/V2 [#dominant-r-wave-in-v1v2] As seen in **Figure 10** (left hand side) the R-wave in V1–V2 is considerably smaller than the S-wave in V1–V2. Dominant R-wave in V1/V2 implies that the R-wave is larger than the S-wave, and this may be pathological. If the R-wave is larger than the S-wave, the R-wave should be \<5 mm, otherwise the R-wave is abnormally large. This may be explained by right bundle branch block, right ventricular hypertrophy, hypertrophic cardiomyopathy, posterolateral ischemia/infarction (if the patient experiences chest pain), pre-excitation, dextrocardia or misplacement of chest electrodes. ## The Q-wave [#the-q-wave] It is crucial to differentiate normal from pathological Q-waves, particularly because pathological Q-waves are rather firm evidence of previous myocardial infarction. However, there are numerous other causes of Q-waves, both normal and pathological and it is important to differentiate these. The amplitude (depth) and the duration (width) of the Q-wave dictates whether it is abnormal or not. Pathological Q-waves have duration ≥0,03 sec and/or amplitude ≥25% of the R-wave amplitude. Pathological Q-waves must exist in at least two anatomically contiguous leads (i.e neighbouring leads, such as aVF and III, or V4 and V5) in order to reflect an actual morphological abnormality. The existence of pathological Q-waves in two contiguous leads is sufficient for a diagnosis of Q-wave infarction. This is illustrated in **Figure 11**. Figure 11. Criteria for pathological Q-waves. Figure 11. Criteria for pathological Q-waves. ### Normal variants of Q-waves [#normal-variants-of-q-waves] **Septal q-waves** are small q-waves frequently seen in the lateral leads (V5, V6, aVL, I). They are due to the normal depolarization of the ventricular septum (see previous discussion). Two small septal q-waves can actually be seen in V5–V6 in **Figure 10** (left hand side). An isolated and often large Q-wave is occasionally seen in lead III. The amplitude of this Q-wave typically varies with ventilation and it is therefore referred to as a **respiratory Q-wave**. Note that the Q-wave must be isolated to lead III (i.e the neighbouring lead, which is aVF, must not display a pathological Q-wave). As noted above, the small r-wave in V1 is occasionally missing, which leaves a **QS-complex in V1** (a QRS complex consisting of only a Q-wave is referred to as a QS-complex). This is considered a normal finding provided that lead V2 shows an r-wave. If the R-wave is missing in lead V2 as well, then criteria for pathology is fulfilled (two QS-complexes). **Small Q-waves** (which do not fulfill criteria for pathology) may be seen in all limb leads as well as V4–V6. If these Q-waves do not fulfill criteria for pathology, then they should be accepted. Leads V1–V3, on the other hand, should never display Q-waves (regardless of their size). ### Abnormal (pathological) Q-waves [#abnormal-pathological-q-waves] The most common cause of pathological Q-waves is myocardial infarction. If myocardial infarction leaves pathological Q-waves, it is referred to as Q-wave infarction. Criteria for such Q-waves are presented in **Figure** 11. Note that pathological Q-waves must exist in two anatomically contiguous leads. Other causes of abnormal Q-waves are as follows: * Left-sided pneumothorax * Dectrocadia * Perimyocarditis * Cardiomyopathy * Amyloidosis * Bundle branch blocks, fascicular blocks * Pre-excitation (WPW syndrome) * Ventricular hypertrophy * Acute cor pulmonale To differentiate these causes of abnormal Q-waves from Q-wave infarction, the following can be advised: * If it is unlikely that the patient has coronary heart disease, other causes are more likely. It should be noted, however, that up to 20% of Q-wave infarctions may develop without symptoms (The Framingham Heart Study). * If coronary heart disease is likely, then infarction is the most probable cause of the Q-waves. * The longer the Q-wave duration, the more likely that infarction is the cause of the Q-waves. Infarction Q-waves are typically >40 ms. Examples of normal and pathological Q-waves (after acute myocardial infarction) are presented in Figure 12 below. Figure 12. Normal and pathological Q-waves. Figure 12. Normal and pathological Q-waves. **This article is part of the comprehensive chapter: How to read and interpret the normal ECG** # The electrical axis of the heart (heart axis): ECG & physiology (/docs/blog/electrical-axis-of-the-heart-ecg-physiology-definition) *Published 2018-10-22* # The electrical axis of the heart (heart axis) [#the-electrical-axis-of-the-heart-heart-axis] Although often ignored, assessment of the electrical axis is an integral part of ECG interpretation. The electrical axis reflects the average direction of ventricular depolarization during ventricular contraction. The direction of the depolarization (and thus the electrical axis) is generally alongside the hearts longitudinal axis (to the left and downwards). Figure 38 shows the coordinate system where the green area displays the range of normal heart axis. Figure 38. The electrical axis of the heart (heart axis). Figure 38. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is between –30° and 90°. If the axis is more positive than 90° it is referred to as right axis deviation. If the axis is more negative than –30° it is referred to as left axis deviation. The axis is calculated (to the nearest degree) by the ECG machine. The axis can also be approximated manually by judging the net direction of the QRS complex in leads I and II. The following rules apply: * Normal axis: Net positive QRS complex in leads I and II. * Right axis deviation: Net negative QRS complex in lead I but positive in lead II. * Left axis deviation: Net positive QRS complex in lead I but negative in lead II. * Extreme axis deviation (–90°to 180°): Net negative QRS complex in leads I and II. ## Heart axis deviation: right axis deviation (RAD) and left axis deviation (LAD) [#heart-axis-deviation-right-axis-deviation-rad-and-left-axis-deviation-lad] ### **Causes of right axis deviation** [#causes-of-right-axis-deviation] Normal in newborns. Right ventricular hypertrophy. Acute cor pulmonale (pulmonary embolism). Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). Lateral ventricular infarction. Pre-excitation. Switched arm electrodes (negative P and QRS-T in lead I). Situs inversus. Left posterior fascicular block is diagnosed when the axis is between 90° and 180° with rS complex in I and aVL as well as qR complex in III and aVF (with QRS duration \<0.12 seconds), provided that other causes of right axis deviation have been excluded. ### **Causes of left axis deviation** [#causes-of-left-axis-deviation] Left bundle branch block. Left ventricular hypertrophy. Inferior infarction. Pre-excitation. Left anterior fascicular block is diagnosed if the axis is between -45° and 90° with qR complex in aVL and QRS duration is 0,12 s, provided that other causes of left axis deviation have been excluded. ### **Causes of extreme axis deviation** [#causes-of-extreme-axis-deviation] Rare. Most likely due to misplaced limb electrodes. If the rhythm is tachycardia with wide QRS complexes, then ventricular tachycardia is the most likely cause. **This article is part of the comprehensive chapter: How to read and recognize the normal ECG** # Our friends (/docs/blog/friends) *Published 2017-09-03* ## E-resources you should bookmark [#e-resources-you-should-bookmark] [Taming the SRU](http://www.tamingthesru.com) Drs Jeffery Hill, Ryan Lafollette and Bill Hinckley run this amazing website which includes everything from ultrasound knobology and emergency procedures to practice guidelines for emergency medicine (and prehospital medicine). This is high quality medical education simply. [Life in the Fast Lane](https://litfl.com) - Australian site with one of the most impressive ECG libraries available. A must for anyone interested in ECG interpretation. Also includes vast amounts of clinically relevant discussions and articles in emergency medicine. [AnaesthesiaUK](http://www.frca.co.uk/default.aspx) - is a comprehensive e-resource and CME site for anasthesiologists. Site is maintained and updated actively, which means it deserves a bookmark if your into anasthesia or critical care medicine. [Critical Care Reviews](http://criticalcarereviews.com) - Dr Rob Mac Sweeney's superb website which is a must for anyone interested in critical care medicine. Content is evidence based, comprehensive and qualitative. [Dr Goldberger et al ECG Wave Maven](https://ecg.bidmc.harvard.edu/maven/mavenmain.asp) - It is likely that this Dr Goldberger is related to the Dr Goldberger who invented the ECG leads aVR, aVL and aVF (unconfirmed). There is no doubt, however, that anyone interested in learning ECG interpretation should pay a visit to this maven (which is hebrew for "master"). ECG Wave Maven includes over 500 ECG cases, all interpreted by experts in electrocardiology. [Dr Smith's ECG blog](http://hqmeded-ecg.blogspot.se) - This blog is one of the most comprehensive blogs in practical ECG interpretation. Taught by professor Smith, any reader is guaranteed to quickly acquire state of the art knowledge and practical training. [Professor Smith published a book as well](https://www.amazon.com/s/ref=nb_sb_noss/163-2287888-6471902?url=search-alias%3Daps\&field-keywords=ecg+in+acute+mi), which we've read and recommend to virtually anyone interested in ECG interpretation. [Diabetes](http://www.diabeteson.com) - Education for individuals with diabetes. [Rebel EM](http://rebelem.com) - Rebel EM is a high-quality emergency medicine blog covering a myriad of topics, primarily focusing on evidence-based clinical topics, ECG cases, and high-yield exam review. This is one of few EM blogs with up-to-date research discussions. [EMcrit](http://emcrit.org) - Superb website by Dr Scott Weingart. Frequently updated, evidence based, clinically oriented and just great. A must if your into emergency medicine. [Broome docs](http://broomedocs.com) - Dr Casey Parker's site covers a wide range of topics. The archive is loaded with great articles which physicians should be interested in. Updates occur frequently. [Nuemblog](http://www.nuemblog.com) - A residents blog with superb, and expanding, content. Beautifully presented and highly relevant for many of us. [EKG-tolkning](http://www.ekg.nu) - ECG interpretation in Swedish. [EKG und Echokardiographie](http://www.ekgecho.de) - ECG and echocardiography in German. # Early repolarization on ECG: when guidelines confuse ECG criteria (/docs/blog/guidelines-confuse-ecg-criteria) *Published 2016-11-17* # Early repolarization pattern: confused J points, notches and slurs [#early-repolarization-pattern-confused-j-points-notchesand-slurs] I once had the privilige of attending a lecture given by professor Salim Yusuf of McMaster University.  [Professor Yusuf](https://en.wikipedia.org/wiki/Salim_Yusuf) is the most cited researcher in cardiovascular medicine, a real giant. During his lecture professor Yusuf said that he was not too impressed with current guidelines. He said that guidelines tend to be too complicated and too verbose. Those of us who have read guidelines may agree with those viewpoints. Going through some guidelines the other day I realized that they are indeed becoming thicker and thicker. Guidelines issued by AHA, ACC and ESC could actually serve as textbooks. In fact, going to AHA/ACC/ESC websites, you can make yourself a textbook by downloading all their guidelines. Nevertheless, I recently read [**Recommendations for interpretation of 12-lead electrocardiogram in the athlete**](http://eurheartj.oxfordjournals.org/content/ehj/31/2/243.full.pdf), which is a great paper written by a dozen of merited scholars. In this paper the authors discuss normal variants and abnormalities which athletes may exhibit on the 12-lead ECG. However, the second ECG in the paper is wrongly interpreted by the authors. They intend to present an ECG with early repolarization (which is associated with 5 times as great a risk of ventricular fibrillation and sudden cardiac death), but instead they display an ECG with male/female pattern. The ECG from the article follows. [skarmavbild-2016-11-17-kl-21-15-29](/img/2016/11/Skarmavbild-2016-11-17-kl.-21.15.29.webp) As evident, the figure legend states that the ECGs show two patterns of early repolarization. They assert that the early repolarization in ECG (A) is characterized by upward concavity of the ST segment and positive T-waves. In ECG (B) they state something similar. Unfortunately, these ECGs do not show any sign of early repolarization. Note that this paper has been cited almost 500 times since publication. It should also be noted that this ECG actually shows male/female pattern, which is by far the most common cause of ST segment elevation in any population (up to 90% of males aged 40 years or younger display this). Hence, the authors have confused a completely benign condition (male/female pattern) with a condition which is associated with 5 times as great a risk of sudden cardiac death. For readers interested in recognizing [early repolarization, I recommend a recent consensus document written by MacFarlane et al](http://content.onlinejacc.org/article.aspx?articleID=2398001). Reading this you will realize that early repolarization is actually reocgnized in the J point (where the QRS complex fuses with the ST segment). Early repolarization is defined by a notch or slur in the J point (where the QRS fuses with the ST segment). This is often referred to as "end-QRS slur" or "end-QRS notch". Se figure below.[](/img/2016/11/Skärmavbild-2016-11-17-kl.-21.25.34.jpg) ## ECG criteria for early repolarization [#ecg-criteria-for-early-repolarization] According to MacFarlane et al (JACC, 2015). **Early repolarization is present if all of the following criteria are met (illustrated above):** * 1. There is an end-QRS notch or slur on the downslope of a prominent R-wave. If there is a notch, it should lie entirely above the baseline. The onset of a slur must also be above the baseline. * 2. Jp is ≥0.1 mV in 2 or more contiguous leads of the 12-lead ECG, excluding leads V1 to V3. * 3. QRS duration is \<120 ms.     Panel B in Figure 5 below shows another example of early repolarization. [Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J).](/img/2016/09/x-DIFF-tidig-repolarisation-1.webp) Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J).   Readers interested in ST segment elevation differential diagnoses may read our own article. **Take home message:** Inspect the J point!     Posted by Dr Dan Olsson. # Incretins in Cardiometabolic Medicine: Leveraging GLP-1, GIP, and Glucagon Receptor Agonism for Cardiovascular Risk Reduction (/docs/blog/incretins-in-cardiometabolic-medicine-leveraging-glp-1-gip-and-glucagon-receptor) *Published 2026-01-13* Cardiovascular medicine is currently witnessing a paradigm shift. For decades, the management of type 2 diabetes mellitus (T2DM) and obesity was siloed, with clinicians focusing primarily on hemoglobin A1c (HbA1c) reduction, blood pressure, lipids and smoking cessation. Weight loss was considered extremely difficult across patient categories. However, the emergence of incretin-based therapies, starting with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and evolving into multi-receptor agonists, has unleashed a new paradigm in cardiometabolic medicine. These therapies are revolutionizing public health strategies, transcending their original roles as glucose-lowering agents to become essential tools for cardiovascular risk reduction, offering profound benefits in major adverse cardiovascular events (MACE), heart failure with preserved ejection fraction (HFpEF), chronic kidney disease (CKD), and peripheral artery disease (PAD). **Figure 1** (below) shows weight loss effects of novel multi-agonists in recent clinical trials ([Rawshani et al](https://metdis.org)). Recommended reading: [MetDis Database of Obesity Trials](https://metdis.org). ## **Obesity and Cardiovascular Outcomes** [#obesity-and-cardiovascular-outcomes] The global burden of obesity is increasingly defined by its cardiovascular consequences. In 2015, high body mass index (BMI) was linked to approximately 4.0 million deaths worldwide, with more than two-thirds—roughly 67%—of these fatalities resulting from cardiovascular disease (CVD).1 While BMI remains the most widely utilized metric for assessing weight, its clinical utility is frequently limited by its inability to distinguish between muscle mass and various fat depots, or to identify the precise location of excess adiposity.2 Clinical guidelines now emphasize that a BMI within the conventional "normal" range (up to 25 kg/m²) does not necessarily equate to optimal cardiovascular health.2 Evidence suggests that a lower BMI, potentially around 21 kg/m², may represent a more favorable profile, as the upper limit of the "healthy" range can still harbor significant metabolic risk.3 For patients with a BMI below 35 kg/m², direct assessments such as waist circumference, waist-to-hip ratio, or dual X-ray absorptiometry are recommended to more accurately diagnose clinical obesity and assess cardiovascular risk.4 Furthermore, ectopic fat accumulation, such as intermuscular adipose tissue (IMAT), is independently associated with coronary microvascular dysfunction and major adverse cardiovascular events (MACE), whereas BMI alone often fails to capture these specific pathological drivers.5 ## **Physiological Mechanisms of Cardioprotection: Direct vs. Weight-Mediated** [#physiological-mechanisms-of-cardioprotection-direct-vs-weight-mediated] The profound cardiovascular benefits observed with incretin-based therapies cannot be explained by glucose lowering alone. Meta-analyses have shown that the risk reduction in MACE is largely independent of baseline HbA1c or the magnitude of HbA1c reduction.7 Instead, these agents exert multifaceted effects through direct activation of receptors in target tissues.15 Recent evidence clarifies that while the benefits in conditions like osteoarthritis and obstructive sleep apnea primarily reflect the extent of weight loss, the reductions in hard cardiovascular outcomes (MI, stroke) and metabolic liver disease involve significant weight-independent pathways.15 ### **Metabolic Reprogramming and Vascular Health** [#metabolic-reprogramming-and-vascular-health] GLP-1 RAs facilitate "metabolic reprogramming," shifting myocardial energy metabolism toward more efficient pathways. By modulating fatty acid uptake and mitochondrial function, these agents increase cardiac efficiency. Furthermore, they directly target the vasculature: 1. **Endothelial Function:** Activation of GLP-1 receptors in the endothelium increases nitric oxide bioavailability.10 2. **Anti-Inflammatory Signaling:** These agents inhibit pro-inflammatory pathways (NF-κB and MAPK) in vascular smooth muscle cells, reducing cytokines like IL-6 and TNF-α.11 3. **Plaque Stability:** By reducing macrophage infiltration and inhibiting foam cell formation, they stabilize the fibrous cap of atherosclerotic plaques, preventing rupture.15 ### **The Role of GIP and Glucagon Agonism** [#the-role-of-gip-and-glucagon-agonism] Dual agonists like tirzepatide incorporate GIP receptor (GIPR) activation, which increases lipoprotein lipase (LPL) activity in adipocytes, promoting healthy lipid storage and reducing ectopic fat accumulation.12 Newer "triple-action" agents (e.g., retatrutide) incorporate glucagon receptor (GCGR) activity, which increases energy expenditure through hepatic thermogenesis and promotes fat oxidation.15 ## **Cardiovascular and Mortality Outcomes** [#cardiovascular-and-mortality-outcomes] A pooled analysis demonstrates a significant 19% reduction in the risk of all-cause death (HR 0.81; 95% CI 0.72–0.92). * **Route Consistency:** This survival advantage is cohesive across both subcutaneous and oral preparations, including oral semaglutide (PIONEER-6, SOUL) and various injectable agents (STRIDE, FLOW, SELECT). * **Broad Efficacy:** The benefit extends from GLP-1 mono-agonists to GIP/GLP-1 dual agonists like tirzepatide, which reduced all-cause mortality by 16% compared to dulaglutide in the SURPASS-CVOT trial.15 ### **Atherothrombotic Protection: MACE** [#atherothrombotic-protection-mace] Pooled analyses of 3-point MACE (CV death, nonfatal MI, and nonfatal stroke) reveal a robust 21% reduction in major adverse cardiovascular events (HR 0.79; 95% CI 0.72–0.87). This cardioprotective effect is notably independent of dosing intensity or mode of administration. Furthermore, the benefit remains uniform even in the presence of other foundational therapies, such as SGLT2 inhibitors. ## **Anti-Inflammatory Effects and Biomarkers** [#anti-inflammatory-effects-and-biomarkers] A hallmark of incretin therapy is the robust attenuation of systemic inflammation. Pooled estimates across clinical trial programs demonstrate a striking 43.1% reduction in high-sensitivity C-reactive protein (hsCRP) levels. * **Combination Efficacy:** The highest reductions are reported with combination therapies like CagriSema (cagrilintide/semaglutide) and triple agonists like retatrutide.15 * **Weight Independence:** Evidence suggests that the magnitude of hsCRP reduction is only partially mediated by weight loss, pointing to a direct immunomodulatory effect on immune cells.15 ## **PAD, OSA, and MASH** [#pad-osa-and-mash] The utility of incretins has expanded rapidly beyond the traditional T2DM/obesity: * **Peripheral Artery Disease (PAD):** The STRIDE trial demonstrated that semaglutide improves walking capacity in patients with symptomatic PAD and T2DM.15 * **Obstructive Sleep Apnea (OSA):** Tirzepatide significantly improved the apnea-hypopnea index in patients with OSA and obesity, primarily through profound weight reduction.15 * **Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD/MASH):** Trial data for semaglutide and survodutide show biopsy-proven resolution of MASH and potential improvements in liver fibrosis.15 ## **The SELECT Trial: Rapid Cardioprotection** [#the-select-trial-rapid-cardioprotection] The SELECT trial (17,604 non-diabetic patients with obesity and CVD) showed a 20% reduction in MACE.14 Crucially, significant benefits were evident within the first 6 months, before maximum weight loss occurred. * **The Paradox:** Analysis revealed an HR of 0.58 at 20 weeks. Weight reduction accounted for virtually none of this early benefit, whereas reduction in waist circumference (visceral fat) explained only 33% of the overall effect. The remaining 67% is attributed to direct vascular and anti-inflammatory pleiotropic mechanisms.15 ## **The Next Frontier: Multi-Agonists and Small Molecules** [#the-next-frontier-multi-agonists-and-small-molecules] | | | | | ---------------- | --------------------------- | --------------------------------------------------------------------- | | **Drug** | **Mechanism** | **Status/Result** | | **Tirzepatide** | GLP-1R / GIPR Agonist | Superior weight loss and glycemic control vs. semaglutide 15 | | **CagriSema** | Amylin / GLP-1R Agonist | 17.3% weight loss in REDEFINE-1; consistent safety 15 | | **Maritide** | GIPR Antagonist / GLP-1RA | Once-monthly dosing; 17.3% weight loss in phase 2 15 | | **Retatrutide** | GIPR / GCGR / GLP-1RA | Up to 24.2% weight loss; potential for energy expenditure increase 15 | | **Orforglipron** | Oral Small-Molecule GLP-1RA | -1.6% HbA1c and 12.4% weight loss; needle-free alternative 15 | | **Amycretin** | Oral GLP-1 / Amylin Agonist | Up to 13.1% weight loss over only 12 weeks 15 | ## **Clinical Challenges and Precision Medicine** [#clinical-challenges-and-precision-medicine] ### **Muscle Health and Sarcopenic Obesity** [#muscle-health-and-sarcopenic-obesity] Extensive weight loss (25-35%) with newer agents is often accompanied by 20-40% reductions in lean mass. Investigational "muscle-sparing" agents, such as bimagrumab (activin/myostatin inhibitor), are being studied in combination with GLP-1 RAs to ensure that weight loss is "healthy" and functional.15 ### **Heterogeneity of Response** [#heterogeneity-of-response] Considerable variability exists in weight loss response, with some patients losing $>20\\%$ and others gaining weight. Currently, genetic variants in $GLP1R$ or $ARRB1$ (encoding $\beta$-arrestin) explain only marginal differences in response, and no biomarkers yet accurately predict who will be a "super-responder".15 ## **Safety and Long-term Management** [#safety-and-long-term-management] While generally safe, clinicians must monitor for: 1. **Gastrointestinal (GI) Events:** Nausea and diarrhea are common but typically resolve with slow titration. Multi-agonists like tirzepatide may utilize GIP's "anti-aversive" actions to improve GI tolerability relative to the degree of weight loss.15 2. **Kidney Health:** Sustained GI side effects can lead to dehydration and acute kidney injury (AKI), warranting close monitoring in high-risk patients.15 3. **Diabetic Retinopathy:** Rapid glucose lowering can cause transient worsening. The randomized FOCUS trial is currently investigating semaglutide's long-term ocular effects.15 4. **Pregnancy:** While stopping GLP-1 RAs before conception is standard, registry data of inadvertent first-trimester exposure have not shown evidence of teratogenicity or major birth defects.15 ## **Conclusion** [#conclusion] The integration of GLP-1 RAs and multi-agonists represents the most significant advancement in cardiometabolic risk reduction of the 21st century. We have moved from a model of reactive management to a proactive strategy of addressing the common metabolic drivers of heart failure, stroke, and chronic kidney disease. As we move toward more powerful combinations and oral non-peptides, the goal for the cardiovascular team is now to ensure equitable access to these life-saving tools and to transition from treating "obesity" to treating "cardiometabolic disease." #### **References** [#references] 1. Health Effects of Overweight and Obesity in 195 Countries over 25 ..., accessed on January 12, 2026, [https://pmc.ncbi.nlm.nih.gov/articles/PMC5477817/](https://pmc.ncbi.nlm.nih.gov/articles/PMC5477817/) 2. American College of Cardiology Issues Guidance on Weight ..., accessed on January 12, 2026, [https://www.acc.org/About-ACC/Press-Releases/2025/06/20/14/11/American-College-of-Cardiology-Issues-Guidance-on-Weight-Management-Drugs](https://www.acc.org/About-ACC/Press-Releases/2025/06/20/14/11/American-College-of-Cardiology-Issues-Guidance-on-Weight-Management-Drugs) 3. 2025 Concise Clinical Guidance: An ACC Expert Consensus Statement on Medical Weight Management for Optimization of Cardiovascular Health - Portail Vasculaire, accessed on January 12, 2026, [https://www.portailvasculaire.fr/sites/default/files/docs/gilbert-et-al-2025-concise-clinical-guidance-an-acc-expert-consensus-statement-on-medical-weight-management-for.pdf](https://www.portailvasculaire.fr/sites/default/files/docs/gilbert-et-al-2025-concise-clinical-guidance-an-acc-expert-consensus-statement-on-medical-weight-management-for.pdf) 4. Study Details | NCT06383390 | The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Outcomes in Adults Living With Obesity (TRIUMPH-Outcomes) | ClinicalTrials.gov, accessed on January 12, 2026, [https://www.clinicaltrials.gov/study/NCT06383390](https://www.clinicaltrials.gov/study/NCT06383390) 5. The Cardiovascular Effect of Tirzepatide: A Glucagon-Like Peptide-1 and Glucose-Dependent Insulinotropic Polypeptide Dual Agonist - NIH, accessed on January 12, 2026, [https://pmc.ncbi.nlm.nih.gov/articles/PMC10548186/](https://pmc.ncbi.nlm.nih.gov/articles/PMC10548186/) 6. Semaglutide and Cardiovascular Outcomes - NEJM | Request PDF - ResearchGate, accessed on January 12, 2026, [https://www.researchgate.net/publication/378366495\_Semaglutide\_and\_Cardiovascular\_Outcomes\_-\_NEJM](https://www.researchgate.net/publication/378366495_Semaglutide_and_Cardiovascular_Outcomes_-_NEJM) 7. 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Nature Medicine](https://www.nature.com/articles/s41591-025-04124-5). # Blog (/docs/blog) Articles, case discussions and commentary. # CME: How dietary fat affects coronary arteries, LDL cholesterol and body weight (/docs/blog/ischemic-heart-disease-ldl-cholesterol-dietary-fat-statins) *Published 2018-03-22* # Coronary artery disease: On LDL cholesterol, dietary fat & statins [#coronary-artery-disease-on-ldl-cholesterol-dietary-fat--statins] You are probably aware that ischemic heart disease, also known as coronary artery disease, has been the number one killer worldwide since the 1960s. In 1948 the NHLBI initiated the Framingham Heart Study, which demonstrated that high blood pressure and high cholesterol levels, among other risk factors, were strongly associated with coronary artery disease and myocardial infarction. However, *association* is not the same as *causation*. A *cause* is something completely different. It took roughly 50 years for researchers to finally conclude that high cholesterol levels caused coronary artery disease and atherosclerosis in general. This required thousands of observational studies, genetic studies and randomized controlled clinical trials. This knowledge has been translated into remarkable advances in the management of coronary artery disease, as demonstrated in the figure below (from [Nabel et al, NEJM, 2014](http://www.nejm.org/doi/full/10.1056/NEJMra1112570)). In this post I would like to discuss hot topics related to coronary artery disease and I will emphasize on issues that are typically raised by patients.     ## **The controversy: How media and bloggers questioned LDL, dietary fat and statins** [#thecontroversy-how-media-and-bloggers-questioned-ldl-dietary-fat-and-statins] Popular blogs and media reach out to billions of individuals worldwide. They exert enormous influence over their visitors daily lives. However, media outlets and bloggers are not necessarily experienced researchers, nor do they always take advice from experts (for whatever reason). LDL cholesterol, dietary fat and statins have been debated intensely in the past decade. A quick search (on Google) for anything related to statins, LDL cholesterol and dietary fat returns thousands of blogs and media posts that are skeptical of everything surrounding these topics. In the UK it was estimated that around [200.000 individuals stopped taking their statins](https://www.theguardian.com/society/2016/jun/28/statins-controversy-uk-people-stop-taking-pills-heart-attack-stroke) after a study reported that there was no association between cholesterol and coronary artery disease in the elderly. That study spread like a virus through social media and it is likely that it may have resulted in increased mortality due to stopping statins. There are three main questions discussed in media, blogs and on social plattforms: 1. **Is high cholesterol a true cause of coronary artery disease?** 2. **Does diet affect cholesterol levels?** 3. **Are statins really effective, or is it all just a "big pharma" sham?** **These are actually questions that patients tend to ask nowadays and therefore I will make an effort to clarify the issues.**   ## Is high cholesterol levels a true cause of coronary artery disease? [#is-high-cholesterol-levels-a-true-cause-of-coronary-artery-disease] First of all, don't confuse various lipids, since they are extremely different with regards to their effects and hazards. For example, high HDL cholesterol levels appears to be beneficial, whereas triglyceride levels seem to be of little or no importance for atherosclerosis. When discussing atherosclerosis, the focus is on LDL cholesterol. Virtually all evidence demonstrate clearly that LDL cholesterol is a true cause of coronary artery disease. What is the evidence? [The evidence is vast](https://www.eas-society.org/page/LDLcausesASCVD). Some examples follow. Consider people with the genetic disorder familial hypercholesterolemia (FH), which is caused by genetic mutations affecting the elimination of LDL cholesterol from the blood. Individuals with familial hypercholesterolemia may have either one defect gene copy (heterozygous FH) or two defect gene copies (homozygous FH). Heterozygous FH results in high LDL cholesterol levels (but nothing else) and increases the risk of acute myocardial infarction by more than 50 times. Individuals with homozygous FH typically die from acute myocardial infarction at 20 to 30 years of age. People with familial hypercholesterolemia have no other metabolic aberration, besides high LDL cholesterol. Treating these individuals with LDL lowering drugs, such as statins, reduces their risks markedly. Epidemiological studies have consistently demonstrated that those with high LDL cholesterol levels are at increased risk of atherosclerotic disease, including coronary artery disease, acute myocardial infarction, stroke, peripheral artery disease etc. There are thousands of studies in this category. A strong proof that LDL cholesterol causes myocardial infarction was obtained from clinical trials that evaluated the effect of lowering LDL cholesterol. These trials were mostly evaluating the effect of statins. [There is no doubt](https://www.sciencedirect.com/science/article/pii/S0140673616313575) that statins lowers the risk of acute myocardial infarction, coronary artery disease and stroke by means of lowering LDL cholesterol. Finally, nature brought us another piece of strong evidence. There is a phenomenon in nature called "Mendelian Randomization". For any given gene in the body there are 2 copies. These copies are inherited from our parents, which themselves also had 2 copies of each gene. Each of us has inherited 1 copy of each gene from each parent. Which ones we have inherited has actually been completely random. Hence, our 2 copies of each gene are actually a random selection of the 4 candidate genes our parents had. Some gene variants actually affect our physiology; for example some gene variants may result in diminished ability to clear LDL cholesterol from the blood stream, and thus cause elevated LDL cholesterol levels. We can use gene variants to study how they affect the risk of coronary artery disease, and that is done under the framework of Mendelian Randomization. Under laws of Mendelian Randomization, our genes are randomly assigned to us, which means that any effect of the gene variant will be a causal effect. Mendelian Randomization can therefore be used to decipher causal pathways. [These studies](https://www.eas-society.org/page/LDLcausesASCVD) also show, clearly, that high LDL cholesterol is a cause of coronary artery disease and atherosclerosis in general. **In summary, there is no doubt that LDL cholesterol is a true cause of atherosclerosis**.   ### But bloggers always say that LDL cholesterol is natural? [#but-bloggers-always-say-that-ldl-cholesterol-is-natural] This is the oldest trick in the book. Certainly, LDL cholesterol is natural and thousands of species have LDL particles to deliver cholesterol to all tissues in the organism. However, the fact that LDL cholesterol is natural does not affect its tendency to accumulate within our coronary arteries. Unfortunately, bloggers often claim that LDL cholesterol cannot be hazardous because it is natural. This is false. To make the argument clear, consider potassium or thyroid hormone (T3, T4), which are both natural and abundant in our bodies. What occurs if potassium levels or thyroid hormone levels are doubled? Answer: you may actually die immediately if potassium levels go up twice, and a doubling of thyroid hormone levels would be very disturbing. Likewise, a doubling of LDL cholesterol also has negative effects; it accelerates the atherosclerotic process in our coronary arteries and elsewhere. **Thus, the notion that LDL cannot be hazardous because its natural is false.**   ### What about food? Does diet affect LDL cholesterol? [#what-about-food-does-diet-affect-ldl-cholesterol] We used to believe that diet has a large effect of LDL cholesterol. More specifically, we believed that saturated fats were capable of elevating LDL cholesterol. This is probably not true and [recent research](http://www.thelancet.com/journals/lancet/article/PIIS0140-6736\(17\)32252-3/abstract) have questioned the long standing notion that dietary fat has a significant effect on LDL cholesterol. Likewise, it seems that there is no association between dietary fat and risk of acute myocardial infarction. So in summary: no, dietary fat does not seem to have any considerable impact on blood fats (notably LDL cholesterol) nor the risk of acute myocardial infarction. **Thus, don't mix blood fats with dietary fats, there is simply no strong correlation.**   ## Are statins effective? Big pharma is making so much money... [#are-statins-effective-big-pharma-is-making-so-much-money] Despite the criticism, the pharmaceutical industry has financed clinical trials which have saved millions of lives and the statin trials are some of the most important trials ever conducted. I urge you to read Dr Collin's and Dr Yusufs' review of the [statin trials](http://www.thelancet.com/journals/lancet/article/PIIS0140-6736\(16\)31357-5/abstract). Briefly, statins are effective and they reduce the risk of myocardial infarction and cardiovascular disease. Statins cost approximately $3 per month and generic drugs are available worldwide. Many researchers are, however, concerned that the pharmaceutical companies have refused to release data from the statin trials, so that data on side effects can be better evaluated. I agree and wish that key data from clinical trials should be made publicly available. **People at risk of acute myocardial infarction should are strong candidates for statin treatment.**   As a final remark I would like to note that despite the many flaws in media and blog posts, it is absolutely right that there is public debate about the benefits and harms of treatments and clinical management.     **Dr Araz Rawshani, MD, PhD** **Institute of Medicine, Department of Molecular and Clinical Medicine** **University of Gothenburg, Sweden**   **Published:** 2018-03-23 **Conflict of interest:** None # Myocardial ischemia and infarction: lack of oxygen or imbalance between supply/demand (/docs/blog/myocardial-ischemia-ischaemia-grand-textbook-failure) *Published 2016-11-24* # Myocardial ischemia [#myocardial-ischemia] The definition of *ischemia* may appear trivial but it is actually a very complicated topic. The term *ischemia* was coined in 1858 by *Virchow* (the same Virchow who unraveled thrombosis). He used te term to describe a reduction of blood flow to tissues and organs. A few decades later *Cohnheim* demonstrated that ligation of the left anterior descending artery in dogs resulted in myoardial infarction. An important discovery was reported in 1930 when *Buchner* and colleages showed that myocardial contractility was closely related to myocardial blood flow. This concept is of outmost importance, as it suggests that myocardial contractility and blood flow are closely matched. Indeed, studies demonstrate that the relation between contractility and blood flow is virtually linear (there are rather few linaer associations in physiology). Refer to Figure 1.   [Figure 1. The relation between myocardial oxygen supply and contractile function. The relation is almost linear, meaning that contractile function is perfectly aligned with blood flow. It follows that contractility increases when blood flow increases (to a certain limit) and it may also decreases when blood flow is reduced.](/img/2016/11/graf.webp) Figure 1. The relation between myocardial oxygen supply and contractile function. The relation is almost linear, meaning that contractile function is perfectly correlated with blood flow. This implies that contractility increases when blood flow increases (to a certain limit) and vice versa.   The relationship illustrated in Figure 1 has been confirmed in numerous studies \[1]. Perhaps the most important implication of the theory is that However, the vast majority of cardiology textbooks still teach that ischemia is the result of a mismatch (imbalance) between oxygen supply and oxygen demand, as illustrated in Figure 2. This theory suggests that ischemia occurs as soon as oxygen supply exceeds oxygen demands.   [Figure 2. The balance between oxygen supply and demand.](/img/2016/11/graf2.webp) Figure 2. The balance between oxygen supply and demand.   In spite of its spread in textbooks, this theory has not been proven, mostly because **we have never been able to measure oxygen demand** (measuring oxygen supply is easy). Thus, the theory regarding supply/demand balance has always been conceptual and lacks scientific evidence. As suggested by Heusch, \[1] this may be due to the fact that interventions that appear to modify oxygen demand also modify infarct size. The most notable interventions are cathcholamines and beta-blockers. Catecholamines incrases oxygen consumption and thus infarct size. Beta-blockers may limit or even reduce infarct size, which is generally attributed to its reduction of heart rate and contractility. But as it turns out, \[2] the reduction in heart rate and contractility appears to act through a redistribution of blood from non-ischemic to ischemic myocardium (i.e an increase in blood flow in the ischemic area!) \[2]. #### Take home message: in the setting of acute coronary syndromes, be quick to administer antithrombotic medications and reperfusion. [#take-home-message-in-the-setting-of-acute-coronary-syndromes-be-quick-to-administerantithrombotic-medications-and-reperfusion] Refer to G Heusch's excellent review on this topic \[1].   ### **References** [#references] \[1] G Heusch. Myocardial Ischemia: Lack of Coronary Blood Flow or Myocardial Oxygen Supply/Demand Imbalance? Circ Res. 2016;119:194-196. \[2] Guth BD, Heusch G, Seitelberger R, Ross J Jr. Mechanism of beneficial ef- fect of beta-adrenergic blockade on exercise-induced myocardial ischemia in conscious dogs. Circ Res. 1987;60:738–746. doi: 10.1161/01.RES.60.5.738. # A Novel Familial Cardiac Arrhythmia Syndrome Identified Using ECG (/docs/blog/novel-familial-cardiac-arrhythmia-syndrome-identified-using-ecg) *Published 2018-11-11* # A novel potentially life-threatening cardiac arrhythmia syndrome identified with ECG [#a-novel-potentially-life-threatening-cardiac-arrhythmia-syndrome-identified-with-ecg] The ECG may be used to diagnose several cardiac genetic disorders, such as Brugada syndrome, long QT syndrome  and early repolarization syndrome. These conditions have an underlying genetic basis and may precipitate lethal arrhythmias. Long QT syndrome was identified several decades ago by *Jervell et al*. Brugada syndrome was identified in the early 1990s and early repolarization was identified as a risk factor for sudden cardiac arrest in 2008 (1, 2, 3). In November 2018 researchers from Denmark, Netherlands and United Kingdom reported a novel ECG syndrome characterized by widespread ST-segment depressions and an increased risk of sudden cardiac arrest. They identified five unrelated families with features that represent a previously unrecognized autosomal dominant syndrome (4). 12-lead ECG (presented according to Cabrera), recorded at 63 years of age, demonstrates concave-upward ST-segment depression in leads I, II, aVL, aVF, and V2 through V6; and ST-segment elevation in lead aVR (which corresponds to an identical ST-segment depression in the inverted lead -aVR). A notch is evident in the ascending part of the ST segment. **Figure 1**. 12-lead ECG (presented according to Cabrera), recorded at 63 years of age, demonstrates concave-upward ST-segment depression in leads I, II, aVL, aVF, and V2 through V6; and ST-segment elevation in lead aVR (which corresponds to an identical ST-segment depression in the inverted lead -aVR). A notch is evident in the ascending part of the ST segment. A male patient (Figure 1) presented at age 36 years with an ECG showing deep and persistent, concave-upward ST-segment depression in leads I, II, aVL, aVF, and V2 through V6. These ECG changes were stable over a period of 30 years. The ST-segment depressions were accentuated during exercise. The patient developed atrial fibrillation at 55 years of age. At age 64 he developed ventricular fibrillation and aborted sudden cardiac death. His son and daughter presented with similar ECG changes. Four additional family members presented with similar ECG changes. Two relatives died from sudden cardiac death. Atrial fibrillation and ventricular arrhythmias were observed in the fifth decade of life in several family members. Imaging studies did not reveal structural cardiac abnormalities, nor coronary artery disease. Another male patient, with similar ST-segment changes, experienced syncopal episodes, ventricular tachycardia (including torsades des pointes), ventricular-fibrillation arrests and moderate left ventricular dysfunction. This patient died at age 17 years due to complications related to his arrhythmia. His father and uncle, with similar ST-segment changes, were diagnosed with atrial fibrillation in their 60s. The father had repeated episodes of ventricular tachycardia and ventricular fibrillation. Several relatives presented with identical ECG changes (the youngest at age 6 years). Another 9 affected individuals were presented in the study. All genetic tests, using gene panels for known gene mutations for cardiovascular disease, were negative. ## Summary [#summary] * *Bundgaard et al* have presumably identified a novel familial (autosomal dominant) cardiac syndrome. The underlying genetic abnormality is yet to be discovered. * Diagnosis of this syndrome is based on ECG, family history and clinical presentation. * Patients present with syncope, early onset of atrial fibrillation, ventricular arrhythmias and sudden cardiac arrest. * Given the prevalence of atrial arrhythmias, ventricular arrhythmias and sudden cardiac arrests, this syndrome appears to be very serious. * The ECG is characterized by marked, persistent, nonischemic ST-segment depression. These ST-segment changes are stable over time (as compared with Brugada syndrome and LQTS, which both exhibit highly dynamic ECG changes). ### Related topics [#related-topics] ST-segment and T-wave changes Ischemic and nonischemic ST-segment depressions Brugada syndrome Long QT syndrome ### Author [#author] **Dr Araz Rawshani, MD, PhD** **University of Gothenburg, The Sahlgrenska University Hospital, Sweden** ### References [#references] 1. Jervell A, Lange-Nielsen F. Congenital deaf-mutism, functional heart disease with prolongation of the Q-T interval and sudden death. Am Heart J 1957;54:59-68. 2. Brugada P, Brugada J. Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome — a multicenter report. J Am Coll Cardiol 1992;20:1391-1396. 3. Haïssaguerre M, Derval N, Sacher F, et al. Sudden cardiac arrest associated with early repolarization. N Engl J Med 2008;358:2016-2023. 4. Bundgaard et al. [A Novel Familial Cardiac Arrhythmia Syndrome with Widespread ST-Segment Depression. N Engl J Med 2018; 379:1780-1781](https://www.nejm.org/doi/full/10.1056/NEJMc1807668?query=featured_cardiology). # Overview of the ECG Waves, Deflections, Intervals, Durations (/docs/blog/overview-of-the-ecg-waves-deflections-intervals-durations) *Published 2018-05-14* # Video lecture: The ECG curve: P-wave, PR Interval, Q-wave, R-wave, S-wave, QRS complex, ST segment, T-wave and QT interval [#video-lecture-the-ecg-curve-p-wave-pr-interval-q-wave-r-wave-s-wave-qrs-complex-st-segment-t-wave-and-qt-interval] This video is accompanied by the detailed article The normal electrocardiogram (ECG). A brief summary of that article is provided below.   ## Summary of lecture [#summary-of-lecture] ## The Normal ECG (EKG) waves, intervals, durations and rhythm [#the-normal-ecg-ekg-waves-intervals-durations-and-rhythm] ECG interpretation requires firm knowledge of the characteristics of the normal ECG. The waves, intervals, durations and assessment of rhythm is fundamental to ECG interpretation. Below follows a brief summary of the ECG waves, their appearance, terminology, physiological background and interpretation. ## Overview of the normal electrocardiogram (ECG / EKG) [#overview-of-the-normal-electrocardiogram-ecg--ekg] [Figure 1. The classical ECG curve with its most common waveforms. Important intervals and points of measurement are depicted. ECG interpretation requires knowledge of these waves and intervals.](/img/2016/08/x-EKG-kurvans-komponenter-2.webp) Figure 1. The classical ECG curve with its most common waveforms. Important intervals and points of measurement are depicted. ECG interpretation requires knowledge of these waves and intervals.   ## The P-wave, PR interval and PR segment [#the-p-wave-pr-interval-and-pr-segment] ECG interpretation starts with assessment of the P-wave and PR interval. The **P-wave** is generated by depolarization (activation, contraction) of the atria. The **PR interval** is the interval between the start of the P-wave and the start of the QRS complex. The PR interval determines whether impulse transmission from atria to ventricles is normal. The isoelectric (flat) line between the end of the P-wave and the start of the QRS complex is called the **PR segment.** The PR segment is the baseline (also referred to as **reference line** or **isoelectric line**) of the ECG curve. Thus, when measuring the amplitude of a wave on the ECG, the PR segment is the baseline. Refer to **Figure 1**. ## The QRS complex [#the-qrs-complex] The **QRS complex** reflects the depolarization (activation, contraction) of the ventricles. Although it may not always include a Q-wave, R-wave and S-wave, it is still referred to as a *QRS complex*. In other words, if ventricular depolarization only generates a Q-wave and an R-wave, that complex may still be referred to as a *QRS complex*. However, one may also be more explicit and refer to such a complex as a QR complex. Because the left ventricle is usually considerably larger than the right ventricle, the QRS complex is actually a reflection of the electrical potentials generated by the left ventricle. ### QRS duration [#qrs-duration] **QRS duration** is the time duration from the start to the end of the QRS complex. A short QRS complex implies that the ventricles are depolarized rapidly, which in turn implies that the electrical conduction system functions normally. Wide (also referred to as *broad)* QRS complexes indicate that ventricular depolarization is slow, which may be a consequence of disturbances in the electrical conduction system. ### The J point and the ST segment [#the-j-point-and-the-st-segment] The ST segment must always be studied carefully since its appearance may be changed in a wide range of serious conditions. The ST segment is of special interest in the setting of acute myocardial ischemia. This is explained by the fact that ongoing ischemia causes deviation (shift) of the ST segment (**ST segment deviation**). **ST segment depression** implies that the ST segment is depressed below the level of the PR segment. **ST segment elevation** implies that the ST segment is elevated above the level of the PR segment. The magnitude of any ST segment deviation is measured as the height difference (millimeters) between the **J point** and the PR segment. The J point is where the ST segment starts. ### The T-wave [#the-t-wave] The T-wave reflects the rapid repolarization (recovery) of the myocardium and T-wave changes occur in numerous conditions. T-wave changes are frequently misunderstood. The transition from the ST segment to the T-wave should be smooth. The normal T-wave is somewhat asymmetric, with a steeper downward slope. ### The U-wave [#the-u-wave] The U-wave, which is a positive wave after the T-wave, appears occasionally on the ECG. Its height (amplitude) is approximately one fourth of the amplitude of the T-wave. The U-wave is most often seen in leads V2, V3 and V4. Individuals with prominent T-waves display U-waves more often. Moreover, the U-wave is clearer during slow heart rates (bradycardia). The physiological process that generates the U-wave remain elusive. ### QT duration and QTc duration (corrected QT duratation) [#qt-duration-and-qtc-duration-corrected-qt-duratation] **QT duration** reflects the total duration of ventricular depolarization (activation) and repolarization (recovery). It is measured from the start of the QRS complex to the end of the T-wave. The QT interval increases at slower heart rates and vice versa (i.e it decreases at higher heart rates). Therefore, to judge whether the QT interval is normal it is necessary to take the heart rate into account. The heart rate adjusted QT interval is the **corrected QT interval,** or simply the **QTc interval**. A long QTc interval causes electrical instability in the ventricles and this may cause lethal ventricular arrhythmias. # P-wave, PR interval, PR segment: physiology, criteria & ECG findings (/docs/blog/p-wave-pr-interval-segment-physiology-criteria-ecg) *Published 2018-07-22* # Physiology and ECG features of the P-wave, PR interval and PR segment [#physiology-and-ecg-features-of-the-p-wave-pr-interval-and-pr-segment] ## The P-wave [#the-p-wave] ECG interpretation usually starts with assessment of the P-wave. The P-wave is a small, positive and smooth wave. It is small because the atria make a relatively small muscle mass. If the rhythm is sinus rhythm (i.e under normal circumstances) the P-wave vector is directed downwards and to the left in the frontal plane and this yields a positive P-wave in lead II (**Figure 2**, right hand side). The P-wave is always positive in lead II during sinus rhythm. This is rather easy to understand because lead II is angled alongside the P-wave vector, and the exploring electrode is located in front of the P-wave vector (**Figure 2,** right hand side). **This article is part of the comprehensive chapter: How to interpret the ECG** The P-wave vector is slightly curved in the horizontal plane. It is initially directed forward but then turns left to activate the left atrium (**Figure 2**, left hand side). Lead V1 might therefore display a **biphasic (diphasic) P-wave**, meaning that the greater portion of the P-wave is positive but the terminal portion is slightly negative (the vector generated by left atrial activation heads away from V1). Occasionally, the negative deflection is also seen in lead V2. lead V5 only notes vectors heading towards the exploring electrode (albeit with somewhat varying angles) and therefore displays a positive P-wave throughout.   Figure 2. P-wave morphology in chest and limb leads. Figure 2. P-wave morphology in chest and limb leads. Figure 2 (above) does not show that the P-wave in lead II might actually be slightly asymmetric by having two humps. This is often (but not always) seen on ordinary ECG tracings and it is explained by the fact that the atria are depolarized sequentially, with the right atrium being depolarized before the left atrium. The first half of the P-wave is therefore a reflection of right atrial depolarization and the second half is a reflection of left atrial depolarization. This is shown in Figure 3 (upper panel). Recall that the P-wave in V1 is often biphasic, which is also shown in Figure 3. Figure 3. The contour of the normal and abnormal P-wave (P pulmonale and P mitrale). Figure 3. The contour of the normal and abnormal P-wave (P pulmonale and P mitrale). If an atria becomes enlarged (typically as a compensatory mechanism) its contribution to the P-wave will be enhanced. Enlargement of the left and right atria causes typical P-wave changes in lead II and lead V1 (**Figure 3**). Enlargement of the right atrium is commonly a consequence of increased resistance to empty blood into the right ventricle. This may be due to pulmonary valve stenosis, increased pulmonary artery pressure *etc*. The right atrium must then enlarge (hypertrophy) in order to manage to pump blood into the right ventricle. Right atrial enlargement (hypertrophy) leads to stronger electrical currents and thus enhancement of the contribution of the right atrium to the P-wave. The P-wave will display higher amplitude in lead II and lead V1. Such a P-wave is called **P pulmonale** because pulmonary disease is the most common cause (**Figure 3, P-pulmonale**). If the left atrium encounters increased resistance (e.g due to mitral valve stenosis) it becomes enlarged (hypertrophy) which amplifies its contribution to the P-wave. The second hump in lead II becomes larger and the negative deflection in V1 becomes deeper. This is called **P mitrale**, because mitral valve disease is a common cause (**Figure 25, P-mitrale**). If the atria are depolarized by impulses generated by cells outside of the sinoatrial node (i.e by an ectopic focus), the morphology of the P-wave may differ from the P-waves in sinus rhythm. If the ectopic focus is located close to the sinoatrial node, the P-wave will have a morphology similar to the P-wave in sinus rhythm. However, an ectopic focus may be located anywhere. If it is located near the atrioventricular node, activation of the atria will proceed in the opposite direction, which produces an **inverted (retrograde) P-wave**. ### P-wave checklist [#p-wave-checklist] * The P-wave is always positive in lead II during sinus rhythm. * The P-wave is virtually always positive in leads aVL, aVF, –aVR, I, V4, V5 and V6. It is negative in lead aVR. * The P-wave is frequently biphasic in V1 (occasionally in V2). The negative deflection is normally \<1 mm. * P-wave duration should be ≤0,12 seconds. * P-wave amplitude should be \<2,5 mm in the limb leads. * P-pulmonale implies that the P-wave has abnormally high amplitude in lead II (and in other leads in general). * P-mitrale implies that the second hump of the P-wave in lead II and the negative deflection of the P-wave in lead V1 are both enhanced. ## PR interval and PR segment [#pr-interval-and-pr-segment] The PR interval starts at the onset of the P-wave and ends at the onset of the QRS complex (**Figure 1**). It reflects the time interval from start of atrial depolarization to start of ventricular depolarization. The PR interval is assessed in order to determine whether impulse conduction from the atria to the ventricles is normal in terms of speed. The PR interval must not be too long nor too short. A normal PR interval ranges between 0.12 seconds to 0.22 seconds. The flat line between the end of the P-wave and the onset of the QRS complex is called the **PR segment** and it reflects the slow impulse conduction through the atrioventricular node. The PR segment serves as the baseline (also referred to as **reference line** or **isoelectric line**) of the ECG curve. The amplitude of any deflection/wave is measured by using the PR segment as the baseline. Figure 4. Impulse transmission from the atria to the ventricles. The PR interval reflects whether the impulse transmission through the AV-node is normal (first panel), abnormally slow (second panel) or bypassed (third panel). Figure 4. Impulse transmission from the atria to the ventricles. The PR interval reflects whether the impulse transmission through the AV-node is normal (first panel), abnormally slow (second panel) or bypassed (third panel). Numerous conditions can diminish the capacity of the atrioventricular node to conduct the atrial impulse to the ventricles. As the conduction diminishes, the PR interval becomes longer. When the PR interval exceeds 0.22 seconds, **first-degree AV-block** is manifest. The term *block* is somewhat misleading since it is actually a matter of abnormal delay and not a block *per se*. The most common cause of first-degree AV-block is degenerative (age-related) fibrosis in the conduction system. Myocardial ischemia/infarction and medications (e.g beta-blockers) may also cause first-degree AV-block. Note that the upper reference limit (0.22 seconds) should be related to the age of the patient; 0.20 seconds is more suitable for young adults because they have a faster impulse conduction. Refer to **Figure 4** (second panel). AV-blocks are discussed in detail later. The atrioventricular (AV) node is normally the only connection between the atria and the ventricles. The atria and the ventricles are electrically isolated from each other by the fibrous rings (*anulus fibrosus).* However, it is not rare to have an additional – accessory – pathway between the atria and the ventricles. Such an accessory pathway is an embryological remnant which may be located almost anywhere between the atria and the ventricles. It enables the atrial impulse to pass directly to the ventricles and start ventricular depolarization prematurely. If the atrial impulse uses an accessory pathway, the impulse delay in the atrioventricular node is bypassed and therefore the PR interval becomes shortened (PR interval \<0.12 seconds). The condition is referred to as **pre-excitation**, because the ventricles are excited prematurely. This is illustrated in **Figure 4** (third panel). As seen in **Figure 4** (third panel) the initial depolarization of the ventricles (starting where the accessory pathway inserts into the ventricular myocardium) is slow because the impulse will not spread via the normal His-Purkinje pathway. The slow initial depolarization is seen as a **delta wave** on the ECG (**Figure 4**, third panel). However, apart from the delta wave, the R-wave will appear normal because ventricular depolarization will be executed normally as soon as the atrioventricular node delivers the impulse to the His-Purkinje system. ### PR interval checklist [#pr-interval-checklist] * Normal PR interval: 0,12–0,22 seconds. Upper reference limit is 0,20 seconds in young adults. * A prolonged PR interval (>0.22 s) is consistent with first-degree AV-block. * A shortened PR interval (\<0,12 s) indicates pre-excitation (presence of an accessory pathway). This is associated with a delta wave. **This article is part of the comprehensive chapter: How to read and interpret the normal ECG** # Introduction to pediatric & neonatal ECG interpretation (/docs/blog/pediatric-neonatal-ecg-interpretation) *Published 2018-02-05* # Principles of pediatric & neonatal ECG interpretation [#principles-of-pediatric--neonatal-ecg-interpretation] Pediatric and neonatal ECG interpretation follows the same principles as ECG interpretation in adults, but there are important differences. These differences are largely explained by the dramatic physiological and anatomical changes that take place during infancy and childhood. The most dramatic changes occur during the first year of life. The electrocardiogram (ECG) evolves in parallel with the changing anatomy and physiology of the heart. ECG amplitudes, intervals and waveforms are therefore different in children and there are marked age variations throughout childhood. Clinicians who work in pediatric and neonatal care must have knowledge of age-related variations in the ECG, as well as cardiac diseases that may affect infants and children. ## Physiological and anatomical development during infancy & childhood [#physiological-and-anatomical-development-during-infancy--childhood] In adults, the left ventricle is considerably larger than the right ventricle. This is the result of ventricular adaptation to the resistance that must be overcome by the ventricles. The left ventricle must overcome the pressure in the aorta and systemic circulation (normally 120 mmHg in adults). The right ventricle must overcome the pressure in the pulmonary circulation (normally 15 mmHg in adults). Hence, the pressure in the systemic circulation is many times greater than the pressure in the pulmonary circulation, which explains why the left ventricle is much larger (ventricular volume and muscle mass) than the right ventricle. Refer to **Figure 1**. Figure 1. Cross-sectional view of ventricular wall thickness in children (<1 months old) and adults. Figure 1. Cross-sectional view of ventricular wall thickness in children (\<1 months old) and adults. Because the left ventricle, in adults, is much larger than the right ventricle, the QRS complexes are dominated completely by the electrical currents generated by the left ventricle. This explains why leads V4–V6 normally displays large R-waves in adults (refer to The Normal ECG). ## The fetal circulation [#the-fetal-circulation] During the fetal period and the first month of life the right ventricle is larger than the left ventricle. This is explained by the fact that the right ventricle pumps blood against greater resistance, as compared with the left ventricle. Understanding this requires knowledge of the fetal circulation, which is illustrated in **Figure 2**. The fetus obtains oxygenated blood from the placenta via *the inferior vena cava*. Blood in the inferior vena cava continues to the right atrium. Meanwhile, deoxygenated blood in *the superior vena cava* (which returns blood from the head and upper limbs) also enters the right atrium. Oxygenated and deoxygenated blood is then mixed in the right atrium. In the fetus, there is an opening – namely *the foramen ovale* – between the right and left atrium. Most of the blood in the right atrium flows through the foramen ovale into the left atrium. The blood continues from the left atrium into the left ventricle, and from there it is pumped into the aorta (i.e systemic circulation. Note that blood also flows from the right atrium into the right ventricle, from where it is pumped into *the pulmonary artery*. In the fetus, a shunt called *ductus arteriosus* connects the pulmonary artery and the aorta. Since the resistance in the pulmonary circulation is high, the majority of the blood entering the pulmonary artery will be shunted through the ductus arteriosus into the aorta. It is important to note that right ventricular load is greater than left ventricular load during the fetal period. This is explained by the configuration of the fetal circulation; pulmonary resistance is high (which means that resistance in the pulmonary artery is high), whereas resistance in the systemic circulation (and thus the aorta) is relatively low. Figure 2. The fetal circulation. Figure 2. The fetal circulation. Therefore, the right ventricle is larger than the left ventricle during the fetal period. In the fetus, as well as in the newborn, the QRS complex is dominated by electrical currents generated by the right ventricle. Large R-waves in leads V1–V3 are therefore normal. Right ventricular dominance also explains why the electrical axis of the heart is more rightwards in newborns. ## The postnatal circulation [#the-postnatal-circulation] The circulation undergoes dramatic changes after birth. The resistance (pressure) in the pulmonary circulation decreases immediately when the child takes her first breath and thereby right ventricular load drops rapidly. The *ductus arteriosus* closes, which results in increased perfusion in the pulmonary circulation. Resistance in the systemic circulation increases, which results in increased left ventricular load. At the age of 1 month the left ventricle is larger than the right ventricle. At the age of 6 months, the proportions (between right and left ventricles) are comparable to those seen in adults. * Functional closure of the *foramen ovale* usually takes a few minutes to 24 hours. Anatomical closure occurs later. Right atrial pressure may vary during the first days after birth, which may explain shunting of blood through the foramen ovale during the first days. * *Ductus arteriosus* closes completely within a few days after birth. * Pulmonary resistance drops slowly, such that pressure in the right ventricle is at 25% of the left ventricle after 4 to 6 weeks. As described above, the fetal circulation undergoes remarkable changes after birth. The process is, however, vulnerable. Any neonatal condition with hypoxia or acidosis may disrupt the adaptation process. Hypoxia and acidosis prevents vasodilatation in the pulmonary circulation. This results in *persistent pulmonary hypertension*, which may cause continued shunting of blood through the foramen ovale (from the right atrium to the left atrium). Because such shunting implies bypassing the lungs, cyanosis will ensue. ## ECG intervals are proportional to myocardial mass [#ecg-intervals-are-proportional-to-myocardial-mass] Because the child's heart is small, compared with adults, it has fewer myocardial cells to depolarize and repolarize. This explains why all ECG intervals (PR interval, QRS duration, QTc interval etc) are significantly shorter in children. As the heart grows, these intervals also increase. **Figure 3** presents an ECG recorded in an 8 days old female. The electrical axis is deviated rightwards (negative QRS i lead I and positive QRS in lead II). R-waves are prominent in leads V1, V2 and V3. There are negative T-waves in V1–V3, which are also normal. There are Q-waves in inferior limb leads (II, aVF and III) and lateral chest leads (V5, V6). Figure 3. ECG recorded in a 8 days old female. The electrical axis is deviated rightwards (negative QRS i lead I and positive QRS in lead II). The R-waves are prominent in leads V1, V2 and V3. There are negative T-waves in V1–V3, which are also normal. There are Q-waves in inferior limb leads (II, aVF and III) and lateral chest leads (V5, V6).  Figure 3. ECG recorded in a 8 days old female. The electrical axis is deviated rightwards (negative QRS i lead I and positive QRS in lead II). The R-waves are prominent in leads V1, V2 and V3. There are negative T-waves in V1–V3, which are also normal. There are Q-waves in inferior limb leads (II, aVF and III) and lateral chest leads (V5, V6). ## Normal values (reference values) for ECG in neonatal and pediatric patients [#normal-values-reference-values-for-ecg-in-neonatal-and-pediatric-patients] There are numerous databases and publications on normal values in adults. However, there are few studies in the pediatric population. This is unfortunate since reference values play a central role in pediatric ECG interpretation. Clinicians have traditionally used normal values published in 1979 ([Davignon et al](http://link.springer.com/article/10.1007/BF02083144)) and in 2001 ([Rijnbeek et al](https://www.ncbi.nlm.nih.gov/pubmed/11286528)). The European Society for Cardiology recommends that normal values published by *Davignon et al* should be used for neonatal ECG interpretation, since Rijnbeek et al included too few children younger than 30 days. For children aged 30 days or older, both *Rijnbeek et al* and *Davignon et al* can be used. The difference between these two are, however, small and both are provided in detail below (refer to Normal values for pediatric and neonatal ECG interpretation). ## Indications for ECG in children (neonatal and pediatric patients) [#indications-for-ecg-in-children-neonatal-and-pediatric-patients] * Syncope * Seizers * Cardiopulmonary symptoms during exercise * Poor physical performance * Drug side effect or intoxication * Tachycardia (tachyarrhythmia) * Bradycardia (bradyarrhythmia) * Cyanosis * Heart failure * Hypothermia * Electrolyte imbalance * Kawasaki disease * Rheumatic heart disease * Myocarditis, pericarditis, perimyocarditis * Cardiac concussion * Congenital heart disease * Monitoring of vital parameters * Post-operative monitoring # Download the Pocket Guide to ECG Interpretation (PDF) (/docs/blog/pocket-guide-to-ecg-interpretation-pdf) *Published 2017-06-29* The ECG must always be interpreted systematically. Failure to perform systematic interpretation may actually be detrimental. We have therefore compiled a pocket guide with a universal interpretation algorithm. These 22 pages includes all you need to perform methodological ECG interpretation. We recommend this approach as it minimizes the risk of missing important abnormalities and also speeds up the ECG interpretation. Press the *Download* button to download the pocket guide. ### **[Download](/img/2017/10/Pocket-guide-ECG-interpretation.pdf)** [#download] ### Become a member and unlock all chapters and video lectures [#become-a-member-and-unlock-all-chapters-and-video-lectures] **Select membership** The membership gives you unlimited access without any recurring costs. Purchasing this membership grants you permanent access to the website and there are no additional costs and no recurring costs. Ever. # Posterior acute myocardial infarction (STEMI) (/docs/blog/posterior-acute-myocardial-infarction-stemi) *Published 2023-06-28* ## Posterior (posterolateral) acute myocardial infarction (STEMI) [#posterior-posterolateral-acute-myocardial-infarction-stemi] The heart is rotated 30° to the left in the thorax. This positions the basal portion of the left lateral wall posteriorly in thorax (Figure 1). This area is most frequently designated as the posterolateral wall, but it may also be referred to as the posterior wall, or the inferobasal wall. Transmural ischemia located in this area yields an injury current (ST vector) directed towards the back, where there is no exploring electrode (in the 12-lead ECG) that can present the ST segment elevations (**Figure 1**). Thus, the 12-lead ECG does not display ST segment elevations during posterior (posterolateral) transmural ischemia. On the other hand, leads V1–V3 (occasionally V4) may detect the injury currents and present them as ST segment depressions. These depressions are reciprocal ST segment depressions, meaning that they mirror the ST segment elevations. If the terminal portion of the T-wave in V1–V3 is positive, it increases the likelihood of posterior ischemia. Such positive T-waves are reciprocal (mirror images) to posterior T-wave inversions (negative T-waves). Moreover, V1–V3 may also show larger R-waves, which are reciprocal to posterior Q-waves. As mentioned above, posterior myocardial infarction may be accompanied by inferior infarction if the occlusion affects both vascular territories. This will result in ST segment elevations in II, aVF and III. Figure 1. Posterolateral (posterior, inferobasal) transmural ischemia causes reciprocal ST-segment depressions in V1–V3 (ocasionally V4). Leads V7–V9 must be placed to reveal the ST-segment elevations. Figure 1. Posterolateral (posterior, inferobasal) transmural ischemia causes reciprocal ST-segment depressions in V1–V3 (occasionally V4). Leads V7–V9 must be placed to reveal the ST-segment elevations. North American (AHA, ACC) and European (ESC) guidelines recommend that patients presenting with ST segment depressions in V1–V3 should be managed as patients with STE-ACS (STEMI) if there are symptoms suggestive of myocardial ischemia. It is also recommended that leads V7, V8 and V9 be connected to the patient, as these leads may reveal the ST segment elevations on the back. In clinical practice, this is often performed by simply placing the electrodes to lead V4, V5 and V6 on the back. One might wonder what the probability is that the patient actually has NSTE-ACS (NSTEMI) since they present with ST segment depressions on the 12-lead ECG (recall that ST segment depression is the hallmark of NSTE-ACS/NSTEMI). The answer is rather simple: the probability that the patient has NSTE-ACS/NSTEMI is small and the vast majority has STE-ACS/STEMI. This is explained by the fact that NSTE-ACS/NSTEMI rarely presents with ST-segment depressions exclusively in V1–V3. ST segment depressions in V1–V3 in patients with NSTE-ACS/NSTEMI are almost invariably accompanied by ST segment depressions in other leads (particularly V5) and that is not consistent with posterior transmural ischemia. To conclude, patients with chest discomfort who display ST segment depressions in leads V1–V3 are likely have posterior transmural ischemia and should be managed as STE-ACS/STEMI (ST elevation myocardial infarction). **ECG criteria for posterolateral (posterior, inferobasal) ST segment elevation myocardial infarction (STE-ACS/STEMI):** * ST-segment elevation in V7-V9: ≥0,5 mm in at least one lead (males and females). ### Differentiating posterolateral ischemia from right ventricular hypertrophy (RVH) [#differentiating-posterolateral-ischemia-from-right-ventricular-hypertrophy-rvh] It is occasionally difficult to differentiate right ventricular hypertrophy (RVH) from posterior acute ischemia. Both these conditions cause ST segment depressions in V1–V3 along with large R-waves (**Figure 2** shows right ventricular hypertrophy). The following rules will distinguish the two conditions in the vast majority of cases: * Right ventricular hypertrophy shifts the electrical axis to the right. * The terminal portion of the T-wave is not positive in right ventricular hypertrophy. * The ST-segment depressions have an upward bulging ST segment in right ventricular hypertrophy, whereas the ST segment is usually horizontal or downward bulging in ischemia. [Figure 2. Right ventricular hypertrophy.](/img/2016/09/rvh_fraga.webp) Figure 2. Right ventricular hypertrophy. # QT duration & corrected QT (QTc) duration: ECG features & implications (/docs/blog/qt-duration-corrected-qt-qtc-duration-ecg-features) *Published 2018-07-22* # QT duration and corrected QT (QTc) duration [#qt-duration-andcorrected-qt-qtc-duration] ECG interpretation always includes an assessment of the QT interval (QT duration). The QT duration represents the total time for depolarization and repolarization. It is measured from the beginning of the QRS complex to the end of the T-wave. Prolonged QT duration predisposes to life-threatening ventricular arrhythmias and therefore QT duration must always be assessed. QT prolongation may be congenital (due to genetic mutations) or acquired (secondary to medications, electrolyte disorders). QT duration is inversely related to heart rate; QT duration increases at slow heart rates and *vice versa*. Hence, the QT duration must be adjusted for heart rate, which yields the **corrected QT duration (QTc)**. There are several equations for calculating the QTc duration. **Bazett's formula** is used widely, despite several shortcomings. The formula is as follows: Bazett's formula for calculating corrected QT duration (QTc). Bazett's formula for calculating corrected QT duration (QTc). QT correction according to *Bazzet*, *Fridericia*, *Framingham* and *Hodges* follow in the calculator below. ## Normal values for QTc interval [#normal-values-for-qtc-interval] Bazett's formula is several decades old and has been questioned because it performs poorly at low (\<50) and high (>100) heart rates. Newer formulas (which are incorporated in modern ECG machines) are to be preferred. QTc duration is calculated automatically in all modern ECG machines. Most machines present the longest QTc interval, which typically occurs in leads V2–V3. ## How to measure the QT interval [#how-to-measure-the-qt-interval] Measurement of the QT interval may be difficult due to T wave changes. ## **Causes of prolonged QTc duration** [#causes-of-prolonged-qtc-duration] * Antiarrhythmics (procainamide, disopyramide, amiodarone, sotalol) * Psychiatric medications (tricyclic antidepressants, SSRI, lithium etc) * Antibiotics (macrolides, kinolones, atovaquone, klorokine, amantadine, foscarnet, atazanavir) * Hypokalemia * Hypocalcemia * Hypomagnesemia * Cerebrovascular insult (bleeding) * Myocardial ischemia * Cardiomyopathy * Bradycardia * Hypothyroidism * Hypothermia A separate chapter discusses Long QT syndrome (LQTS). A complete list of drugs causing QT prolongation can be found [here](https://crediblemeds.org/). Corrected QT intervals (QTc) can be calculated below. ## **Short (QT) QTc syndrome** [#short-qt-qtc-syndrome] Short QT syndrome (QTc \<0,390 seconds) is uncommon and can be seen in hypocalcemia and during digoxin treatment. It is very rare but may cause malignant arrhythmias. ## QT dispersion [#qt-dispersion] The QT interval varies somewhat in the different leads. The difference between the shortest and the longest QT interval is the QT dispersion. Increased QT dispersion is associated with increased morbidity and mortality. This is presumably explained by a higher incidence of malignant ventricular arrhythmias. It has been suggested that the high risk of ventricular arrhythmias is due to the vulnerability caused by marked local differences in repolarization. **This article is part of the comprehensive chapter: How to read and interpret the normal ECG** # Quiz: ECG in athletes (/docs/blog/quiz-ecg-in-athletes) *Published 2025-11-15* **1. Which of the following ECG findings is typically considered a normal variant in asymptomatic athletes with no significant family history?** A: Mobitz Type II 2nd AV block B: Prolonged QT interval (QTc ≥ 480 ms for females) C: Incomplete Right Bundle Branch Block (rSR' pattern in lead V1 and qRS pattern in V6 with QRS duration \<120 ms) D: Profound sinus bradycardia (\<30 beats/min or sinus pauses ≥3 s) Explanation: Incomplete Right Bundle Branch Block, defined by an rSR' pattern in lead V1 and a qRS pattern in lead V6 with QRS duration \<120 ms, is listed as a 'Normal ECG finding' and considered a normal variant in asymptomatic athletes with no significant family history, not requiring further evaluation. Mobitz Type II 2nd AV block, prolonged QT interval, and profound sinus bradycardia are typically considered abnormal or profound findings that may require further investigation. **2. What heart rate range is ideally recommended for measuring the QT interval corrected for heart rate (QTc) using Bazett's formula?** A: Less than 50 beats/min B: 60 to 90 beats/min C: 90 to 120 beats/min D: Greater than 100 beats/min Explanation: The QT interval corrected for heart rate is ideally measured using Bazett's formula with heart rates between 60 and 90 beats/min. **3. What is the recommended action if a QTc value is borderline or abnormal and the heart rate is less than 50 beats/min?** A: Proceed directly to an exercise ECG test without repeating the resting ECG. B: Repeat the ECG after mild aerobic activity. C: Immediately refer to a heart rhythm specialist. D: Disregard the borderline QTc as it is likely a normal variant. Explanation: If the QTc value is borderline or abnormal and the heart rate is less than 50 beats/min, it is recommended to repeat the ECG after mild aerobic activity. If the heart rate is greater than 100 beats/min, repeating the ECG after a longer resting period is advised. **4. Which of the following describes a 'Black athlete repolarization variant' considered a normal ECG finding?** A: T-wave inversion in leads V1-V3 in athletes age \<16 years. B: J-point elevation and convex ('domed') ST-segment elevation followed by T-wave inversion in leads V1-V4 in black athletes. C: PR interval \<120 ms with a delta wave and wide QRS (≥120 ms). D: QRS duration ≥140 ms. Explanation: The 'Black athlete repolarization variant' is defined as J-point elevation and convex ('domed') ST-segment elevation followed by T-wave inversion in leads V1-V4 specifically in black athletes. T-wave inversion in V1-V3 for athletes \<16 years is a 'Juvenile T-wave pattern'. PR interval \<120 ms with a delta wave and wide QRS is indicative of 'Ventricular pre-excitation', and QRS duration ≥140 ms is considered 'Profound nonspecific intra-ventricular conduction delay', both of which are not typical normal findings. **5. Which of the following is true regarding sinus bradycardia in athletes?** A: Any sinus bradycardia, regardless of heart rate, requires immediate cardiological referral. B: Heart rates of ≥30 beats/min are considered normal in highly trained athletes in the absence of symptoms. C: Sinus bradycardia should persist with the onset of physical activity. D: Sinus bradycardia with heart rates between 50-60 beats/min always indicates a pathological condition. Explanation: In the absence of symptoms, heart rates ≥30 beats/min are considered normal in highly trained athletes. Sinus rhythm should resume and bradycardia should resolve with the onset of physical activity. Profound sinus bradycardia (\<30 beats/min or sinus pauses ≥3 s) would warrant further investigation. **6. Which of the following ECG findings is generally considered a normal variant in asymptomatic athletes and typically does not require further evaluation, assuming no significant family history?** A: Brugada Type 1 pattern B: Profound sinus bradycardia (\<30 beats/min or sinus pauses ≥3s) C: Increased QRS voltage (isolated QRS voltage criteria for left ventricular hypertrophy or right ventricular hypertrophy) D: Mobitz Type II 2nd AV block Explanation: Increased QRS voltage, specifically isolated QRS voltage criteria for left (SV1+RV5) or right ventricular hypertrophy (RV1+SV5 or SV6 >1.1 mV), is considered a normal variant in athletes and does not require further evaluation in asymptomatic athletes with no significant family history. Brugada Type 1 pattern, profound sinus bradycardia, and Mobitz Type II 2nd AV block are considered abnormal or require further investigation. **7. Which of the following best defines 'Incomplete RBBB' as a normal ECG finding in athletes?** A: rSR' pattern in lead V1 and a qRS pattern in lead V6 with QRS duration \<120 ms. B: rSR' pattern in lead V1 and a qRS pattern in lead V6 with QRS duration ≥120 ms. C: J-point elevation and convex ST-segment elevation followed by T-wave inversion in leads V1-V4. D: PR interval \<120 ms with a delta wave (slurred upstroke in the QRS complex) and wide QRS (≥120 ms). Explanation: Incomplete RBBB is defined as an rSR' pattern in lead V1 and a qRS pattern in lead V6 with a QRS duration of \<120 ms. Option B describes complete RBBB if the QRS duration is ≥120 ms. Option C describes the Black athlete repolarization variant. Option D describes ventricular pre-excitation. **8. An athlete presents with a prolonged QTc interval (e.g., QTc ≥470 ms for males or ≥480 ms for females). What is the initial recommended action?** A: Immediately refer to a heart rhythm specialist for an electrophysiological study. B: Repeat resting ECG on a separate day, review for QT prolonging medication, and acquire ECG of 1st-degree relatives if possible. C: Schedule an immediate cardiac MRI. D: Prescribe beta-blockers without further investigation. Explanation: For a prolonged QTc interval, the initial recommendations include repeating a resting ECG on a separate day, reviewing for any QT prolonging medications, and acquiring an ECG from 1st-degree relatives if feasible. Referral to a heart rhythm specialist or sports cardiologist is specifically considered for a QTc ≥500 ms. **9. An asymptomatic athlete presents with profound sinus bradycardia (\<30 beats/min or sinus pauses ≥3s). What is the initial recommended step?** A: Immediate referral for pacemaker implantation. B: Repeat ECG after mild aerobic activity. C: Direct referral to a cardiac surgeon. D: Prescribe atropine to increase heart rate. Explanation: For profound sinus bradycardia (\<30 beats/min or sinus pauses ≥3s), the initial recommendation is to repeat the ECG after mild aerobic activity to assess the heart rate response. Further testing is considered based on clinical suspicion. **10. The QT interval corrected for heart rate (QTc) is ideally measured using Bazett's formula under which heart rate conditions?** A: Heart rates \<50 beats/min. B: Heart rates between 60 and 90 beats/min. C: Heart rates >100 beats/min. D: Heart rates exclusively during vigorous exercise. Explanation: The QT interval corrected for heart rate (QTc) is ideally measured using Bazett's formula when heart rates are between 60 and 90 beats/min. If the heart rate is outside this range (e.g., \<50 beats/min or >100 beats/min) and the QTc value is borderline or abnormal, repeating the ECG after mild aerobic activity or a longer resting period, respectively, is advised. **11. Which statement accurately describes the general clinical significance of isolated borderline ECG findings in athletes and the recommendation when multiple borderline findings are present?** A: Isolated borderline findings always indicate underlying pathological cardiovascular disease, requiring immediate extensive investigation. B: Isolated borderline findings often represent normal variants or physiological cardiac remodeling, but the presence of two or more borderline findings may warrant additional investigation. C: Borderline findings are always benign and never require any further evaluation, regardless of their number. D: Borderline findings necessitate immediate referral to an electrophysiologist for an invasive procedure. Explanation: Recent data suggest that isolated ECG findings categorized as borderline in athletes often represent normal physiological cardiac remodeling or variants and do not typically indicate pathological cardiac disease. However, if an athlete presents with two or more borderline findings, further investigation may be warranted. **12. What is the recommended approach for 'juvenile ECG pattern' characterized by TWI (T-wave inversion) confined to the anterior precordial leads in adolescent athletes up to 16 years old?** A: It should be immediately investigated with a cardiac MRI to rule out cardiomyopathy. B: It is considered a normal age-related pattern and typically does not require further investigation in the absence of other clinical or ECG features of cardiomyopathy. C: It indicates a high risk of sudden cardiac death and mandates immediate sports cessation. D: It requires an exercise ECG test to assess for myocardial ischemia. Explanation: TWI confined to the anterior precordial leads in adolescent athletes up to 16 years of age may be considered a normal age-related 'juvenile ECG pattern' and should not result in further investigation if there are no other clinical or ECG features suggesting cardiomyopathy. **13. What is the correlation of isolated axis deviation or voltage criteria for atrial enlargement with cardiac pathology in athletes?** A: These findings always correlate with major structural or functional cardiac abnormalities. B: They are highly specific for myocardial disease and require immediate treatment. C: They account for a significant percentage of abnormal ECG patterns but do not correlate with cardiac pathology, and echocardiographic evaluation often fails to identify major structural or functional abnormalities. D: They are contraindications to participation in competitive sports. Explanation: Axis deviation and voltage criteria for atrial enlargement are common 'abnormal' ECG patterns in athletes, accounting for over 40% of such findings. However, they generally do not correlate with cardiac pathology, and studies have shown that echocardiographic evaluation in athletes with these isolated findings often fails to identify major structural or functional abnormalities. **14. What is the recommended initial evaluation for an athlete who presents with two or more borderline ECG findings?** A: Direct referral for an invasive electrophysiology study. B: Immediate genetic testing for inherited cardiac conditions. C: Echocardiography, with consideration for additional testing based on clinical suspicion. D: No further evaluation is needed, as borderline findings are by definition not clinically significant. Explanation: For an athlete presenting with two or more borderline ECG findings, echocardiography is the recommended initial evaluation, with additional testing to be considered based on clinical suspicion. **15. If an athlete's QTc value is found to be borderline or abnormal, what is a key recommendation regarding the ECG measurement?** A: Immediately prescribe beta-blockers without further assessment. B: Perform an exercise ECG test to check for QT shortening. C: Consider repeating the ECG after mild aerobic activity if the heart rate is \<50 beats/min, or after a longer resting period if the heart rate is >100 beats/min. D: Refer directly for an implantable cardioverter-defibrillator (ICD) evaluation. Explanation: When an athlete's QTc value is borderline or abnormal, it is recommended to consider repeating the ECG. This repeat should be done after mild aerobic activity if the heart rate is below 50 beats/min, or after a longer resting period if the heart rate is above 100 beats/min, to ensure a more accurate measurement. **16. What QTc duration in an athlete is considered 'marked QT prolongation' and prompts a direct referral to a heart rhythm specialist or sports cardiologist?** A: QTc ≥ 450 ms B: QTc ≥ 470 ms C: QTc ≥ 480 ms D: QTc ≥ 500 ms Explanation: A QTc ≥ 500 ms is defined as marked QT prolongation, and direct referral to a heart rhythm specialist or sports cardiologist should be considered. **17. In which specific group of athletes might T-wave inversion confined to the anterior precordial leads be considered a normal age-related pattern, often referred to as a 'juvenile ECG pattern'?** A: Adult athletes over 30 years old. B: Adolescent athletes up to the age of 16 years old. C: Female athletes of all ages. D: Athletes with a history of hypertension. Explanation: T-wave inversion confined to the anterior precordial leads may be considered a normal age-related pattern in adolescent athletes up to the age of 16 years old. **18. For an athlete with a prolonged QTc, what is one of the initial recommended evaluation steps?** A: Immediately schedule an invasive electrophysiology study. B: Refer directly for cardiac surgery. C: Repeat a resting ECG on a separate day and review for QT prolonging medication. D: Start antiarrhythmic medication without further testing. Explanation: For prolonged QTc, initial recommended evaluation steps include repeating a resting ECG on a separate day and reviewing for QT prolonging medication. **19. If an athlete presents with J-point elevation and convex ST-segment elevation in anterior leads (V1 to V4) followed by TWI, what is the typical recommendation in the absence of other clinical or ECG features of cardiomyopathy?** A: It is regarded as a normal variant and should not result in further investigation. B: It necessitates immediate cardiac catheterization. C: It indicates an urgent need for an implantable cardioverter-defibrillator (ICD). D: It requires long-term antiarrhythmic drug therapy. Explanation: J-point elevation and convex ST-segment elevation in the anterior leads (V1 to V4) followed by TWI is regarded as a normal variant and should not result in further investigation, in the absence of other clinical or ECG features of cardiomyopathy. **20. An athlete presents with a QTc interval of ≥500 ms on an ECG. What is the most appropriate next step?** A: Initiate immediate antiarrhythmic medication. B: Repeat a resting ECG on a separate day and review for QT prolonging medication. C: Direct referral to a heart rhythm specialist or sports cardiologist. D: Perform an exercise ECG test immediately. Explanation: For a QTc ≥500 ms, the international recommendations advise considering a direct referral to a heart rhythm specialist or sports cardiologist. While repeating an ECG and reviewing medications are part of the overall evaluation for prolonged QTc, a value this high warrants specialist input directly. **21. For T-wave inversion in the lateral or inferolateral leads, which of the following diagnostic tools is considered superior for detecting conditions like apical HCM, LVH localized to the free lateral wall, ARVC with predominant left ventricular involvement, and myocarditis?** A: Exercise ECG test B: Minimum 24-hour ECG monitor C: Cardiac Magnetic Resonance (CMR) D: Standard echocardiography Explanation: Cardiac Magnetic Resonance (CMR) is recommended as a routine diagnostic test for this ECG phenotype and is superior to echocardiography for detecting apical HCM, LVH localized to the free lateral wall, ARVC with predominant left ventricular involvement, and myocarditis. **22. In an athlete with ventricular pre-excitation (WPW), what finding on an exercise ECG test denotes a low-risk pathway?** A: Persistence of the delta wave throughout exercise. B: Abrupt cessation of the delta wave (pre-excitation) on exercise ECG. C: Widening of the QRS complex during exercise. D: Development of ST-segment depression during exercise. Explanation: Abrupt cessation of the delta wave (pre-excitation) on exercise ECG denotes a low-risk pathway for ventricular pre-excitation. **23. An athlete's ECG reveals multiple premature ventricular contractions (≥2 PVCs per 10-second tracing). What is the minimum recommended evaluation to exclude underlying structural heart disease?** A: A repeat ECG at rest. B: An ambulatory Holter monitor, echocardiogram, and exercise ECG test. C: Genetic testing and family screening only. D: Prescription of a beta-blocker. Explanation: For multiple premature ventricular contractions (≥2 PVCs), the finding should prompt more extensive evaluation to exclude underlying structural heart disease. At a minimum, an ambulatory Holter monitor, echocardiogram, and exercise ECG test are recommended. **24. What QTc interval is considered prolonged in a male, warranting further investigation?** A: QTc ≥ 450 ms B: QTc ≥ 460 ms C: QTc ≥ 470 ms D: QTc ≥ 500 ms Explanation: A prolonged QT interval is defined as a QTc ≥ 470 ms in males and QTc ≥ 480 ms in females. A QTc ≥ 500 ms is considered marked QT prolongation. **25. T-wave inversion in the lateral or inferolateral leads on an ECG may suggest several potential cardiac diseases. Which of the following is NOT typically listed as a potential cardiac disease associated with this finding?** A: Hypertrophic Cardiomyopathy (HCM) B: Dilated Cardiomyopathy (DCM) C: Left Ventricular Non-Compaction (LVNC) D: Anomalous coronary arteries Explanation: T-wave inversion in the lateral or inferolateral leads is associated with potential cardiac diseases such as HCM, DCM, LVNC, ARVC (with predominant LV involvement), and Myocarditis. Anomalous coronary arteries are generally not detectable by ECG. **26. A patient's ECG shows intermittently non-conducted P waves with a fixed PR interval. What type of AV block does this describe, and what is an essential next step in evaluation?** A: First-degree AV block; no further action needed. B: Mobitz Type I AV block; repeat ECG in 6 months. C: Mobitz Type II AV block; further evaluation including echocardiogram, ambulatory ECG monitor, and referral to an electrophysiologist. D: Third-degree AV block; immediate pacemaker implantation. Explanation: Intermittently non-conducted P waves with a fixed PR interval describe Mobitz Type II AV block. If detected, further evaluation includes an echocardiogram, ambulatory ECG monitor, and exercise ECG test. Referral to an electrophysiologist is essential. **27. Which of the following ECG characteristics is defining for a Brugada Type 1 pattern?** A: ST-segment depression in leads V1-V3 with a positive T-wave. B: Coved-type ST-segment elevation ≥ 2 mm in ≥ 1 leads in V1-V3, followed by a negative symmetric T-wave. C: Saddle-back type ST-segment elevation \< 2 mm in V1-V3 with a positive T-wave. D: Q waves ≥ 40 ms in leads V1-V3 with ST-segment elevation. Explanation: A Brugada Type 1 pattern is characterized by a coved-type ST-segment elevation of ≥ 2 mm (high take-off) with a downsloping ST-segment elevation followed by a negative symmetric T-wave in at least one lead in V1-V3. **28. What initial evaluation is recommended if a Mobitz Type II atrioventricular (AV) block is detected on an ECG?** A: Immediate antiarrhythmic medication and a stress test. B: An echocardiogram, ambulatory ECG monitor, and exercise ECG test. C: Only an ambulatory ECG monitor to confirm the diagnosis. D: Direct referral for pacemaker implantation without further testing. Explanation: If Mobitz Type II AV block or complete AV block is detected, further evaluation should include an echocardiogram, an ambulatory ECG monitor, and an exercise ECG test. Based on these results, laboratory testing and cardiac MRI may be considered, and referral to an electrophysiologist is essential. **29. What is a key ECG criterion for diagnosing ventricular pre-excitation (e.g., Wolff-Parkinson-White syndrome)?** A: PR interval > 200 ms with a narrow QRS complex. B: PR interval \< 120 ms with a delta wave and a wide QRS (≥ 120 ms). C: Normal PR interval with inverted T-waves in precordial leads. D: ST-segment elevation in leads V1-V3 without a delta wave. Explanation: Ventricular pre-excitation is characterized by a PR interval \< 120 ms, the presence of a delta wave (a slurred upstroke in the QRS complex), and a wide QRS complex (≥ 120 ms). **30. For an athlete presenting with an indeterminate Brugada pattern on ECG, which of the following is a recommended next step for evaluation?** A: Immediate implantation of an implantable cardioverter-defibrillator (ICD). B: Consideration of a high precordial lead ECG with leads V1 and V2 in the 2nd intercostal space. C: Initiation of antiarrhythmic medication without further testing. D: A 24-hour ambulatory ECG monitor as the sole follow-up. Explanation: If the Brugada pattern is indeterminate, consider a high precordial lead ECG with leads V1 and V2 in the 2nd intercostal space or sodium channel blockade. **31. What is the definition of profound sinus bradycardia that warrants further investigation in an athlete, and what is an initial recommended step?** A: Heart rate \<40 beats/min with immediate referral to an electrophysiologist. B: Heart rate \<30 beats/min or sinus pauses ≥3 seconds, with a repeat ECG after mild aerobic activity. C: Heart rate \<50 beats/min and symptoms, requiring an immediate exercise stress test. D: Heart rate \<35 beats/min at rest, necessitating cardiac MRI. Explanation: Profound sinus bradycardia is defined as \<30 beats/min or sinus pauses ≥3 seconds. The initial recommended step is to repeat the ECG after mild aerobic activity. **32. For an athlete with ventricular pre-excitation (WPW), when should an electrophysiological (EP) study for risk assessment be considered?** A: Only if the delta wave disappears abruptly on exercise ECG. B: If a low-risk accessory pathway cannot be confirmed by non-invasive testing, or for moderate to high intensity sports. C: Only for athletes engaging in low-intensity sports. D: Never, as ventricular pre-excitation is always a benign finding in athletes. Explanation: An EP study for risk assessment should be considered if a low accessory pathway cannot be confirmed by non-invasive testing. Additionally, considering an EP study for moderate to high intensity sports is recommended. Abrupt cessation of the delta wave on exercise ECG denotes a low-risk pathway, which would typically reduce the immediate need for an EP study. **33. What is the recommended evaluation if Mobitz Type II AV block or complete AV block is detected?** A: Only an echocardiogram and a 24-hour ambulatory ECG monitor. B: An echocardiogram, ambulatory ECG monitor, and exercise ECG test, followed by referral to an electrophysiologist. C: Direct genetic testing without further cardiac imaging. D: No further evaluation if the patient is asymptomatic. Explanation: If Mobitz Type II AV block or complete AV block is detected, further evaluation includes an echocardiogram, ambulatory ECG monitor, and exercise ECG test. Based on these results, laboratory testing and cardiac MRI may be considered, and referral to an electrophysiologist is essential. **34. What is the leading cause of mortality in athletes during sport?** A: Traumatic brain injury B: Dehydration C: Cardiovascular-related sudden death D: Heatstroke Explanation: Cardiovascular-related sudden death is the leading cause of mortality in athletes during sport. **35. Despite a normal ECG, when should further assessment be considered for an athlete according to the recommendations?** A: Only if the athlete requests it. B: Only after a year of consistent athletic training. C: In the presence of cardiac symptoms or a family history of inherited cardiovascular disease or premature sudden cardiac death (SCD). D: If the athlete is participating in a new sport. Explanation: The document highlights that a normal ECG should not preclude further assessment if the athlete has cardiac symptoms or a family history of inherited cardiovascular disease or premature sudden cardiac death. **36. Which of the following conditions may an electrocardiogram (ECG) be unable to detect, as noted in the limitations section?** A: Sinus bradycardia B: Ventricular pre-excitation C: Anomalous coronary arteries D: Left ventricular hypertrophy Explanation: The ECG is unable to detect anomalous coronary arteries, premature coronary atherosclerosis, and aortopathies. # The ST segment: physiology, normal appearance, ST depression & ST elevation (/docs/blog/st-segment-normal-abnormal-depression-elevation-causes) *Published 2018-08-22* # The ST segment: physiology, normal appearance, ST depression & ST elevation [#the-st-segment-physiology-normal-appearance-st-depression--st-elevation] The ST segment corresponds to the plateau phase of the action potential (**Figure 13**). The ST segment extends from the J point to the onset of the T-wave. Because of the long duration of the plateau phase most contractile cells are in this phase at the same time (more or less). Moreover, the membrane potential is relatively unchanged during the plateau phase. These two factors are the reason why the ST segment is flat and isoelectric (i.e in level with the baseline). Figure 13. ST segment elevation and depression. Figure 13. ST segment elevation and depression. Displacement of the ST segment is of fundamental importance, particularly in acute myocardial ischemia. Because myocardial ischemia affects a limited area and disturbs the cells' membrane potential (during phase 2), it engenders electrical potential difference in the myocardium. The electrical potential difference exists between ischemic and normal myocardium and it results in displacement of the ST segment. The ST segment may be displaced upwards (ST segment elevation) or downwards (ST segment depression). The term ST segment deviation refers to elevation and depression of the ST segment. The magnitude of ST segment deviation is measured as the height difference (in millimeters) between the J point and the PR segment. Refer to **Figure 13** for examples. **Figure 14** below shows how to measure ST segment deviation. Figure 14. Example of measuring ST deviation (elevation and depression). Figure 14. Example of measuring ST deviation (elevation and depression). **The following must be noted regarding the ST segment:** * The normal ST segment is flat and isoelectric. The transition from ST segment to T-wave is smooth, and not abrupt. * ST segment deviation (elevation, depression) is measured as the height difference (in millimeters) between the J point and the baseline (the PR segment). ST segment deviation occurs in a wide range of conditions, particularly acute myocardial ischemia. * Because the ST segment and the T-wave are electrophysiologically related, changes in the ST segment are frequently accompanied by T-wave changes. The term ST-T segment changes (or simply ST-T changes) is used to refer to such ECG changes. It must also be noted that the J point is occasionally suboptimal for measuring ST segment deviation. This is explained by the fact that the J point is not always isoelectric; this occurs if there are electrical potential differences in the myocardium by the end of the QRS complex (it typically causes J point depression). The reason for such electrical potential difference is that not all ventricular myocardial cells will finish their action potential simultaneously. Myocardial cells which depolarized at the beginning of the QRS complex will not be in the exact same phase as cells which depolarized during the end of the QRS complex. Due to this it is sometimes recommended that ST segment deviation be measured in the J-60 point, or J-80 point, which is located 60 and 80 milliseconds, respectively, after the J point (*Comprehensive Electrocardiology, MacFarlane et al, Springer, 2010; Chou's Electrocardiologi, Surawicz, Elsevier 2010*). At the time of J-60 and J-80, there is minimal chance that there are any electrical potential differences in the myocardium. Current guidelines, however, still recommend the use of the J point for assessing acute ischemia (*Third Universal Definition of Myocardial Infarction, Thygesen et al, Circulation*). A notable exception to this rule is the exercise stress test, in which the J-60 or J-80 is always used (because exercise frequently causes J point depression). As mentioned above there are numerous other conditions that affect the ST-T segment and it is fundamental to be able to differentiate these. For this purpose it is wise to subdivide ST-T changes into primary and secondary. ## Primary and secondary ST-T changes [#primary-and-secondary-st-t-changes] **Primary ST-T changes** are caused by **abnormal repolarization**. This is seen in ischemia, electrolyte disorders (calcium, potassium), tachycardia, increased sympathetic tone, drug side effects etc. **Secondary ST-T changes** occur when **abnormal depolarization causes abnormal repolarization**. This is seen in bundle branch blocks (left and right bundle branch block), pre-excitation, ventricular hypertrophy, premature ventricular complexes, pacemaker stimulated beats etc. In each of these conditions the depolarization is abnormal and this affects the repolarization so that it cannot be carried out normally. The next discussion will be devoted to characterize important and common ST-T changes. ## ST segment depression [#st-segment-depression] ST segment depression is measured in the J point. The reference point is, as usual, the PR segment. ST segment depression less than 0.5 mm is accepted in all leads. ST segment depression 0.5 mm or more is considered pathological. Some expert consensus documents also note that any ST segment depression in V2–V3 should be considered abnormal (because healthy individuals rarely display depressions in those leads). Please note that every cause of ST segment depression discussed below is illustrated in **Figure 15**.  Study this figure carefully. Figure 15. Various causes of ST segment depressions and their appearance. Figure 15. Various causes of ST segment depressions and their appearance. ### Primary ST depressions [#primary-st-depressions] Physiological ST segment depressions occur during **physical exercise**. These ST segment depressions display an upsloping ST segment, typically depressed \<1 mm in the J-60 point and the depressions are normalized rapidly after the exercise has ended. **Hyperventilation** bring about the same ST segment depressions as physical exercise. **Figure 15 A**. **Digoxin** causes generalized ST segment depressions with a curved ST segment (generalized implies that the depression can be seen in most ECG leads). **Figure 15 B**. **Sympathetic tone** and **hypokalemia** causes ST segment depressions (typically \<0.5 mm). **Heart failure** may cause ST segment depression in the left lateral leads (V5, V6, aVL and I) and these depressions are generally horizontal or downsloping. **Supraventricular tachycardias** also cause ST segment depressions which typically occur in V4–V6 with a horizontal or slightly upsloping ST segment. These ST segment depression should resolve within minutes after termination of the tachycardia. **Ischemic ST depressions** display a horizontal or downsloping ST segment (this is a requirement according to North American and European guidelines). The horizontal ST segment depression is most typical of ischemia (**Figure 15 C**). ST segment depressions with upsloping ST segments are rarely caused by myocardial ischemia. However there is one notable exception, when an upsloping ST segment is actually caused by ischemia and the condition is actually alarming. Upsloping ST segment depressions which are accompanied by prominent T-waves in the majority of the precordial leads may be caused by an acute occlusion of the left anterior descending coronary artery (LAD). This constellation – with upsloping ST depression and prominent T-waves in the precordial leads during chest discomfort – is referred to as **de Winters sign** (**Figure 15 C**). ### Secondary ST depression [#secondary-st-depression] Secondary ST segment depressions occur in the following conditions: * Left ventricular hypertrophy * Right ventricular hypertrophy * Left bundle branch block * Right bundle branch block * Pre-excitation * Pacemaker stimulation in the (right) ventricle These are all common conditions in which an abnormal depolarization (altered QRS complex) causes abnormalities in the repolarization (altered ST-T segment). For example, a block in the left bundle branch means that the left ventricle will not be depolarized via the Purkinje network, but rather via spread of the depolarization from the right ventricle. The abnormal ventricular depolarization will cause an abnormal repolarization. As evident from **Figure 35** (panel D) these conditions are characterized by oppositely directed QRS- and ST-T-segments (recall that this is referred to as *discordance).* Hence, ECG leads with net positive QRS complexes will show ST segment depressions (as well as T-wave changes). ECG changes in myocardial ischemia are discussed in section 3 (Acute & Chronic Myocardial Ischemia & Infarction) and a specific chapter discusses ST depression. ## ST segment elevation [#st-segment-elevation] ST segment elevation is measured in the J-point. In the setting of chest discomfort (or other symptoms suggestive of myocardial ischemia) ST segment elevation is an alarming finding as it indicates that the ischemia is extensive and the risk of malignant arrhythmias is high. However, there are many other causes of ST segment elevations and for obvious reasons one must be able to differentiate these. **Figure 16** displays characteristics of ischemic and non-ischemic ST segment elevations. This figure must also be studied in detail. Figure 16. ST segment elevations. Figure 16. ST segment elevations. Ischemia typically causes ST segment elevations with straight or convex ST segments (**Figure 16, panel A**). The straight ST segment can be either upsloping, horizontal or (rarely) downsloping. Non-ischemic ST segment elevations are typically concave (**Figure 16, panel B**). Concave ST segment elevations are extremely common in any population; e.g ST segment elevation in leads V2–V3 occur in 70% of all men under the age of 70. There is no definite way to rule out myocardial ischemia by judging the appearance of the ST segment, which is why North American and European guidelines assert that the appearance of the ST segment cannot be used to rule out ischemia. ECG changes in ischemia are discussed in detail in section 3 (Acute & Chronic Myocardial Ischemia & Infarction) and a specific chapter discusses ST elevation in detail. **This article is part of the comprehensive chapter: How to read and interpret the normal ECG** # The Best Clinical ECG Book: ECG Made Easy or Complete? (/docs/blog/the-best-ecg-book-recommended-ekg-book) *Published 2021-08-02* # The best ECG book is not the one making it simple [#the-best-ecg-book-is-not-the-one-making-it-simple] In the thrilling and ever-evolving field of medicine, a question echoes in the hallways of hospitals, universities, and medical institutions around the world: **What is the best ECG book?** This question is far from trivial and the stakes are high; mastering ECG interpretation will frequently be a matter of life and death. ECG interpretation is a sophisticated art, even in the current era of artificial intelligence (AI). ECG interpretation requires a comprehensive understanding of cardiovascular pathophysiology and electrocardiology. Unfortunately, numerous books and online resources fall into the trap of oversimplification. Physicians, nurses, paramedics and physician assistants who rely on such books will realize their shortcomings at their first encounter with an ECG in reality. Books that claim to make it "simple" can provide a quick entry point but fail to delve into the crucial depths needed for clinical practice. Ultimately, such books leave clinicians unprepared for real-world scenarios where ECG interpretation often makes a life-altering difference. Dr. Araz Rawshani, a leading cardiovascular researcher at the University of Gothenburg and Sahlgrenska University Hospital, Sweden, is the force behind the comprehensive online course at ecgwaves.com. This website provides a comprehensive learning ecosystem. It includes a complete ECG book, enriched with over 600 pages, engaging video lectures, challenging tests, and versatile study tools. From basic cardiac physiology to the nuanced strategies of evidence-based management, this book and course have been meticulously crafted. ECGwaves.com welcomes readers regardless of their previous training and profession. Read Dr Rawshani's book Below follows a review, compiled by Dr Araz Rawshani, of the most widely used books in ECG education. ## Review of the most popular ECG books and resources [#review-of-the-most-popular-ecg-books-and-resources] Recognizing that many visitors are interested in other books and online resources, we have plowed through more than 30 of the most popular ECG books (according to Amazon and Google Shop). A number of online resources are also reviewed. Our recommendations below are based on how well each book/website have covered the following aspects: 1. Physiology (particularly cardiac electrophysiology) 2. Pathophysiology (causes and mechanisms underlying various conditions diagnosed using ECG) 3. Epidemiology 4. Clinical aspects 5. ECG criteria/characteristics 6. Electrophysiological explanations for ECG changes 7. Differential diagnoses for ECG findings 8. Concordance with guidelines (AHA, ACC, ESC) 9. Evidence-based management/treatment. These 9 aspects are all necessary to become confident in ECG interpretation and making clinical decisions using the ECG. Interestingly, none of the books reviewed include all these aspects. Most books lacked clinical management, key aspects of pathophysiology and discussions on differential diagnoses for each condition. Moreover, most books included very few real-world examples of the conditions, or provided too few tests to result in any clinical proficiency. ## The best ECG books and the most frequently recommended ECG books [#the-best-ecg-books-and-the-most-frequently-recommended-ecg-books] The following is Dr Rawshani's review of the most popular books. ## **Rapid Interpretation of EKG's, Sixth Revised Edition. By Dale Dubin** [#rapid-interpretation-of-ekgs-sixth-revised-edition-by-dale-dubin] I read this book as a medical student since it was recommended by our professor of cardiology. It is often marketed as being the easiest book in the field, and readers are apparently appealed by that. I initially thought it was a decent book with an abundance of illustrations that appeared pedagogical, despite the fact that it had not been updated for decades. As I got more involved with cardiovascular research and dug deeper into electrocardiology and ECG interpretation, I realized that this book was at best poor. It is outdated, oversimplifies the concepts and basically lacks everything you need for clinical purposes. Regrettably, I cannot recommend this book, despite it being the most-sold book on Amazon. This is simply because it has simplified ECG interpretation beyond what is reasonable and clinically sound. ECG interpretation is not easy and any book that portrays it as such has simply failed. Perhaps this book can be recommended to laymen who are interested in the subject. Very poor *Suitable for laymen.* *Not for students or professionals*. ## **The Only EKG Book You'll Ever Need by Malcolm S. Thaler.** [#the-only-ekg-book-youll-ever-need-bymalcolm-s-thaler] This book is slightly better than Dale Dubin's book. It will suffice for students (medical school, nursing, paramedics *etc)* but not for clinical situations\*.\* The author has a clear and fun way of presenting the topics and most topics are covered, albeit oversimplified and occasionally flawed. Differential diagnostics is blatantly missing, as is treatment and management. The ischemia chapter is quite poor. To conclude, this book will suffice if you want to pass an exam in school but it will not meet the demands of clinical duty unless you combine it with other resources. Not recommended Many topics are covered, although superficially explained\*.\* Not sufficient for clinical work as it leaves out key aspects of diagnosis and management. ## **Marriott's Practical Electrocardiography by Galen S. Wagner.** [#marriotts-practical-electrocardiography-bygalen-s-wagner] The late professor *Galen Wagner* has written, according to my personal opinion, one of the best books on ECG interpretation, namely this one. Professor Wagner was an authority in electrocardiology and produced hundreds of research papers in the field. This book is concise yet comprehensive (and affordable). This is probably the one I would recommend the most. It does not require any prior knowledge (but you are guaranteed to acquire state-of-the-art knowledge). It is suitable for students and professionals of all categories. Excellent choice. One of the best books on ECG interpretation. All chapters are superb. Does not include clinical management/treatment (beyond general aspects). ## **Clinical Electrocardiography: A Simplified Approach by Ary L. Goldberger**. [#clinical-electrocardiography-a-simplified-approach-byary-l-goldberger] [](/img/2017/06/ikon_star_4.webp) One of the best books available. One of the best books on ECG interpretation. Does not include clinical management/treatment. ## **Chou's Electrocardiography in Clinical Practice by Borys Surawicz & Timothy Knilans**. [#chous-electrocardiography-in-clinical-practice-byborys-surawicz--timothy-knilans] This is slightly more advanced than Galen Wagner's book. It can definitely be recommended to professionals who are interested in ECG interpretation, particularly if details are appreciated. Contrary to the majority of the books on this list, this one includes pediatric ECG interpretation. [](/img/2017/06/ikon_star_4.webp) Great choice for professionals with a preference for details. Includes pediatric ECG interpretation. Great chapter on ischemia/infarction. Does not include clinical management/treatment (beyond general aspects). ## **ECGs for the Emergency Physician 1, by Amal Mattu and William Brady** [#ecgs-for-the-emergency-physician-1-by-amal-mattu-and-william-brady] The target audience of this superb book is emergency physicians with basic knowledge of ECG interpretation. It includes 200 clinical cases which are explained clearly. This book is highly recommended for emergency physicians. This book has a sequel that I, unfortunately, have not had the pleasure to read, but given Dr Amal's earlier work, it is most likely well-invested money. [](/img/2017/06/ikon_star_4.webp)  A great choice for emergency physicians. Straight forward, clinically oriented, clearly explained, details included. Less suitable outside target audience. Lacks treatment details. ## **12-Lead ECG: The Art of Interpretation 1st Edition by Garcia and Holtz** [#12-lead-ecg-the-art-of-interpretation-1st-edition-by-garcia-and-holtz] This is a great book for students. Content is succinct and constructed in a stepwise fashion. The quality of ECGs is good and the layout is pedagogical. There are plenty of practice examples that are discussed in detail. The book is more detailed than Dubin's book but less detailed than Goldberger's and Wagner's. Hence, this is an intermediate book that is well-suited for students. Most (but not all) topics are covered and they are simplified. There is perhaps a tendency for oversimplification.  A great choice for students.  Offers basic ECG interpretation skills.  Lacks clinical management. Oversimplifies matters. ## **Comprehensive Electrocardiology by P Macfarlane, P.W.; Oosterom, A. van; Pahlm, O.; Kligfield, P.; Janse, M.; Camm, J. (red).** [#comprehensive-electrocardiology-bypmacfarlane-pw-oosterom-a-van-pahlm-o-kligfield-p-janse-m-camm-j-red] This book spans over 2400 pages. It is not suitable for students or the vast majority of physicians. However, for those who are interested in electrocardiology – notably researchers – this is perhaps one of the best books available. It has left nothing out and it is written by the legends in the field of electrocardiology. Again, this book is intended for researchers.  The most comprehensive opus in the field. Suitable for researchers. The Bible of electrocardiology. Does not include clinical management/treatment (beyond general aspects). Expensive ($800). ## **Clinical Arrhythmology and Electrophysiology: A Companion to Braunwald's Heart Disease by Zipes D et al**. [#clinical-arrhythmology-and-electrophysiology-a-companion-to-braunwalds-heart-disease-byzipes-d-et-al] This is an outstanding book edited by professor Douglas Zipes who is one of the most prominent electrophysiologist of our era. This book is not only extremely comprehensive (and expensive) it is the Bible for arrhythmologists.  Excellent choice for those interested in arrhythmology.   Covers arrhythmology completely. Including evidence-based management.. Does not cover other aspects of ECG interpretation. Expensive. ### **Electrophysiological disorders of the heart by AJ Camm.** [#electrophysiological-disorders-of-the-heart-by-aj-camm] This is a superb book written by professor AJ Camm. The content and intended audience is the same as for professor Douglas Zipe's book. There are actually a few differences between these books.  Excellent choice for those interested in arrhythmology.   Covers arrhythmology completely. Including evidence-based management. Does not cover other aspects of ECG interpretation. Expensive. ### **Braunwald’s Heart Disease by Peter Libby, Robert O. Bonow, Douglas L. Mann** [#braunwalds-heart-disease-bypeter-libby-robert-o-bonow-douglas-l-mann] This book is rather brief on ECG interpretation. The chapters are written by Ary L Goldberger, Douglas Zipes et al. The arrhythmia chapters are better (personal opinion) than the other ECG chapters. However, this book discusses treatment and management in detail.  A rather advanced crash course in ECG interpretation.  Covers most topics. Includes management. Frequently too concise to cover the topics satisfactorily. Expensive. ## E-resources: ECG books, ECG tests, ECG practice examples [#e-resources-ecg-books-ecg-tests-ecg-practice-examples] [Life in the Fast Lane](http://www.lifeinthefastlane.com) - Australian site with one of the most impressive ECG libraries available. A must for anyone interested in ECG interpretation. Also includes vast amounts of clinically relevant discussions and articles in emergency medicine. [AnaesthesiaUK](http://www.frca.co.uk/default.aspx) - is a comprehensive e-resource and CME site for anaesthesiologists. The site is maintained and updated actively, which means it deserves a bookmark. [Critical Care Reviews](http://criticalcarereviews.com) - Dr Rob Mac Sweeney's superb website which is a must for anyone interested in critical care medicine. Content is evidence-based, comprehensive and qualitative. [Dr Goldberger et al ECG Wave Maven](https://ecg.bidmc.harvard.edu/maven/mavenmain.asp) - It is likely that this Dr Goldberger is related to the Dr Goldberger who invented the ECG leads aVR, aVL and aVF (unconfirmed). There is no doubt, however, that anyone interested in learning ECG interpretation should pay a visit to this maven (which is hebrew for "master"). ECG Wave Maven includes over 500 ECG cases, all interpreted by experts in electrocardiology. [Dr Smith's ECG blog](http://hqmeded-ecg.blogspot.se) - This blog is one of the most comprehensive blogs in practical ECG interpretation. Taught by professor Smith, any reader is guaranteed to quickly acquire state-of-the-art knowledge and practical training. [Professor Smith published a book as well](https://www.amazon.com/s/ref=nb_sb_noss/163-2287888-6471902?url=search-alias%3Daps\&field-keywords=ecg+in+acute+mi), which we've read and recommend to virtually anyone interested in ECG interpretation. [Rebel EM](http://rebelem.com) - Rebel EM is a high-quality emergency medicine blog covering a myriad of topics, primarily focusing on evidence-based clinical topics, ECG cases, and high-yield exam reviews. This is one of the few EM blogs with up-to-date research discussions. [EMcrit](http://emcrit.org) - Superb website by Dr Scott Weingart. Frequently updated, evidence-based, clinically oriented and just great. A must if your into emergency medicine. [Broome docs](http://broomedocs.com) - Dr Casey Parker's site covers a wide range of topics. The archive is loaded with great articles that physicians should be interested in. Updates occur frequently. [Nuemblog](http://www.nuemblog.com) - A resident blog with superb, and expanding, content. Beautifully presented and highly relevant for many of us. # The electrical axis of the heart (ECG axis) (/docs/blog/the-electrical-axis-of-the-heart-ecg-axis) *Published 2023-06-28* ## The electrical axis of the heart [#the-electrical-axis-of-the-heart] Although often ignored, assessment of the electrical axis is an integral part of ECG interpretation. The electrical axis reflects the average direction of ventricular depolarization during ventricular contraction. The direction of the depolarization (and thus the electrical axis) is generally alongside the heart's longitudinal axis (to the left and downwards). Figure 38 shows the coordinate system where the green area displays the range of the normal heart axis. Figure 1. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is between –30° and 90°. If the axis is more positive than 90° it is referred to as right axis deviation. If the axis is more negative than –30° it is referred to as left axis deviation. The axis is calculated (to the nearest degree) by the ECG machine. The axis can also be approximated manually by judging the net direction of the QRS complex in leads I and II. The following rules apply: * **Normal axis**: Net positive QRS complex in leads I and II. * **Right axis deviation**: Net negative QRS complex in lead I but positive in lead II. * **Left axis deviation**: Net positive QRS complex in lead I but negative in lead II. * **Extreme axis deviation (–90°to 180°)**: Net negative QRS complex in leads I and II. Figure 2. The direction of the QRS complex. ### Axis deviation: right axis deviation (RAD) and left axis deviation (LAD) [#axis-deviation-right-axis-deviation-rad-and-left-axis-deviation-lad] #### **Causes of right axis deviation** [#causes-of-right-axis-deviation] * Normal in newborns. * Right ventricular hypertrophy. * Acute cor pulmonale (pulmonary embolism). * Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). * Lateral ventricular infarction. * Pre-excitation. * Switched arm electrodes (negative P and QRS-T in lead I). * Situs inversus. * Left posterior fascicular block is diagnosed when the axis is between 90° and 180° with rS complex in I and aVL as well as qR complex in III and aVF (with QRS duration \<0.12 seconds), provided that other causes of right axis deviation have been excluded. #### **Causes of left axis deviation** [#causes-of-left-axis-deviation] * Left bundle branch block. * Left ventricular hypertrophy. * Inferior infarction. * Pre-excitation. * Left anterior fascicular block is diagnosed if the axis is between -45° and 90° with qR complex in aVL and QRS duration 0,12 s, provided that other causes of left axis deviation have been excluded. #### **Causes of extreme axis deviation** [#causes-of-extreme-axis-deviation] Extreme axis deviation is rare. It is most likely due to misplaced limb electrodes. If the rhythm is tachycardia with wide QRS complexes, then ventricular tachycardia is the most likely cause. # The T-wave: physiology, variants and ECG features (/docs/blog/the-t-wave-physiology-variants-and-ecg-features) *Published 2018-08-22* # The normal T-wave [#the-normal-t-wave] Assessment of the T-wave represents a difficult but fundamental part of ECG interpretation. The normal T-wave in adults is positive in most precordial and limb leads. The T-wave amplitude is highest in V2–V3. The amplitude diminishes with increasing age. As noted above, the transition from the ST segment to the T-wave should be smooth. The T-wave is normally slightly asymmetric since its downslope (second half) is steeper than its upslope (first half). Women have a more symmetrical T-wave, a more distinct transition from ST segment to T-wave and lower T-wave amplitude. The T-wave should be concordant with the QRS complex, meaning that a net positive QRS complex should be followed by a positive T-wave, and vice versa (**Figure 17**). Otherwise there is discordance (opposite directions of QRS and T) which might be due to pathology. A negative T-wave is also called an inverted T-wave. Figure 17. Discordance and concordance between QRS and ST-T. Figure 17. Discordance and concordance between QRS and ST-T. T-wave changes are notoriously misinterpreted, particularly inverted T-waves. Below follows a discussion which aims to clarify some of the common misunderstandings. All T-waves are illustrated in **Figure 18**. Figure 18. Normal and pathological T-waves. Figure 18. Normal and pathological T-waves. ## Positive T-waves [#positive-t-waves] Positive T-waves are rarely higher than 6 mm in the limb leads (typically highest in lead II). In the chest leads the amplitude is highest in V2–V3, where it may occasionally reach 10 mm in men and 8 mm in women. Usually, though, the amplitude in V2–V3 is around 6 mm and 3 mm in men and women, respectively. T-waves that are higher than 10 mm and 8 mm, in men and women, respectively, should be considered abnormal. A common cause of abnormally large T-waves is hyperkalemia, which results in high, pointed and asymmetric T-waves. These must be differentiated from hyperacute T-waves seen in the very early phase of myocardial ischemia. Hyperacute T-waves are broad based, high and symmetric. Their duration is short; they typically disappear within minutes after a total occlusion in a coronary artery occurs (then of course, the ST segment will be elevated). ## T-wave inversion (inverted / negative T-waves) [#t-wave-inversion-inverted--negative-t-waves] T-wave inversion means that the T-wave is negative. The T-wave is negative if its terminal portion is below the baseline, regardless of whether its other parts are above the baseline. T-wave inversions are frequently misunderstood, particularly in the setting of ischemia. ### Normal T-wave inversion [#normal-t-wave-inversion] An isolated (single) T-wave inversion in lead V1 is common and normal. It is generally concordant with the QRS complex (which is negative in lead V1). Isolated T-wave inversions also occur in leads V2, III or aVL. In any instance, one must verify whether the inversion is isolated, because if there is T-wave inversion in two anatomically contiguous leads, then it is pathological. ### T-wave inversion in myocardial ischemia [#t-wave-inversion-in-myocardial-ischemia] Ischemia never causes isolated T-wave inversions. It is a general misunderstanding that T-wave inversions, without simultaneous ST-segment deviation, indicate acute (ongoing) myocardial ischemia. T-wave inversions without simultaneous ST-segment deviation are not ischemic! However, T-wave inversions that are accompanied by ST-segment deviation (either depression or elevation) is representative of ischemia (but in that scenario, it is actually the ST-segment deviation that signals that the ischemia is ongoing). Then one might wonder why T-wave inversions are included as criteria for myocardial infarction. This is explained by the fact that T-wave inversions do occur *after* an ischemic episode, and these T-wave inversions are referred to as *post-ischemic T-waves*. Such T-waves are seen after periods of ischemia, after infarction and after successful reperfusion (PCI). Post-ischemic T-wave inversion is caused by abnormal repolarization. These T-wave inversions are symmetric with varying depth. They may be gigantic (10 mm or more) or less than 1 mm. Negative U-waves my occur when post-ischemic T-wave inversions are present. T-wave inversions may actually become chronic after myocardial infarction. Normalization of T-wave inversion after myocardial infarction is a good prognostic indicator. Please refer to Figure 37. ### Secondary T-wave inversion [#secondary-t-wave-inversion] Secondary T-wave inversions – similar to secondary ST-segment depressions – are caused by bundle branch block, pre-excitation, hypertrophy and ventricular pacemaker stimulation. T-wave inversions that are secondary to these conditions are typically symmetric and there is simultaneous ST-segment depression. Note that the T-wave inversion may actually persist for a period after normalization of the depolarization (if it occurs). This is referred to as T-wave memory or cardiac memory. Secondary T-wave inversions are illustrated in **Figure 19** (as well as **Figure 18 D**). Figure 19. Secondary T-wave inversions. Figure 19. Secondary T-wave inversions. ## Flat T-waves [#flat-t-waves] T-waves with very low amplitude are common in the post-ischemic period. They are commonly seen in leads V1–V3 if the stenosis/occlusion is located in the left anterior descending artery. If the stenosis/occlusion is located in the left circumflex artery or right coronary artery, the flat T-waves are seen in leads II, aVF and III. ## Biphasic (diphasic) T-waves [#biphasic-diphasic-t-waves] A biphasic T-wave have a positive and a negative deflection (Figure 37, panel C). It should be noted that the term "biphasic" is unfortunate because (1) biphasic T-waves carry no particular significant and (2) a T-wave is classified as positive or inverted based on its terminal portion; if the terminal portion is positive then the T-wave is positive and vice versa. Thus, a biphasic T-wave should be classified accordingly. ## The T-waves in children and adolescents [#the-t-waves-in-children-and-adolescents] The T-wave vector is directed to the left, downwards and to the back in children and adolescents. This explains why these individuals display T-wave inversions in the chest leads. T-wave inversions may be present in all chest leads. However, these inversions are normalized gradually during puberty. Some individuals may display persisting T-wave inversion in V1–V4, which is called *persisting juvenile T-wave pattern*. If all T-waves persist inverted into adulthood, the condition is referred to as *idiopathic global T-wave inversion*. ## T-wave progression [#t-wave-progression] T-wave progression follows the same rules as R-wave progression (see earlier discussion). ## T-wave checklist [#t-wave-checklist] * I, II, -aVR, V5 and V6: should display positive T-waves in adults. aVR displays a negative T-wave. * III and aVL: These leads occasionally display an isolated (single) T-wave inversion. * aVF: positive T-wave, but occasionally flat. * V1: Inverted or flat T-wave is rather common, particularly in women. The inversion is concordant with the QRS complex. * V7–V9: should display a positive T-wave. **This article is part of the comprehensive chapter: How to read and interpret the normal ECG** # Cardiology board certification in the USA and Canada: ABIM and Royal College exams (/docs/board-exams/cardiology-board-certification-usa-canada) North America has two routes to cardiology certification: the **American Board of Internal Medicine (ABIM) Cardiovascular Disease Certification Examination** in the United States, and the **Royal College of Physicians and Surgeons of Canada (RCPSC) Examination in Cardiology (Adult)** in Canada. They test the same specialty, but they are built very differently. The ABIM exam is a written examination spanning **one and a half days**, including a distinctive half-day of electrocardiogram and imaging interpretation. The Royal College examination pairs a written component with an **applied (oral) component** in which examiners question you directly. This guide covers both. It reflects information published by ABIM and the Royal College; confirm current dates, fees and requirements with the boards themselves before you register. ## At a glance [#at-a-glance] | | ABIM (United States) | Royal College (Canada) | | --------------------- | --------------------------------------------- | --------------------------------------------- | | **Credential** | Board certification in Cardiovascular Disease | Certification in Cardiology (Adult) | | **Prerequisite** | ABIM certification in internal medicine | Royal College Internal Medicine certification | | **Fellowship** | 36 months, of which 24 clinical | Subspecialty training in Adult Cardiology | | **Written component** | 240 multiple-choice questions | Written examination | | **Second component** | ECG and imaging cases (\~72) | Applied examination (stations, examiner-led) | | **Total length** | One and a half days | Written plus applied | | **Question style** | Single best answer, clinical stem | MCQ plus examiner discussion | ## The ABIM Cardiovascular Disease exam (United States) [#the-abim-cardiovascular-disease-exam-united-states] ### Eligibility [#eligibility] ABIM sets clear prerequisites. To sit the Cardiovascular Disease certification examination you must: * Be **previously certified in internal medicine by ABIM** * Complete **36 months** of fellowship training, of which **24 months must be clinical** * Train in a programme accredited by **ACGME**, the **Royal College of Physicians and Surgeons of Canada**, or the **Collège des médecins du Québec** * Have completed that training, including vacation time, **by October 31st of the year of the examination** * Hold a **valid, unrestricted and unchallenged licence** to practise medicine You also need satisfactory ratings from your programme director across the **six ACGME/ABMS competencies** and on overall clinical competence in your final training year. ### Procedural competence [#procedural-competence] Beyond knowledge, ABIM requires demonstrated competence in a defined list of procedures: * Advanced cardiac life support with cardioversion * Electrocardiography, including ambulatory monitoring and exercise testing * Echocardiography * Arterial catheter insertion * Right-heart catheterisation with temporary pacemaker insertion and management * Left-heart catheterisation and diagnostic coronary angiography ### Format: a day of questions, then a day of images [#format-a-day-of-questions-then-a-day-of-images] This is the part that distinguishes the ABIM cardiology exam from most other board examinations, and the part candidates most often under-prepare for. **Day one — multiple choice.** **240 questions** delivered in **four two-hour sessions**, with a maximum of 60 questions per session, taking approximately **ten hours** in total. Questions are single-best-answer and the overwhelming majority use a clinical stem: a patient scenario that tests decision-making rather than recall. **A separate day — electrocardiograms and imaging studies.** Approximately **72 cases** across two sessions, taking around **five hours**: * **Electrocardiograms** — up to two hours, maximum **35 cases** * **Imaging studies** — up to two hours and fifteen minutes, maximum **37 cases** Each case gives a brief patient description and one or more images. The published weighting **within that component** is: | Component | Share | | ------------------- | ------- | | Electrocardiograms | **48%** | | Echocardiograms | **37%** | | Coronary angiograms | **15%** | Nearly half of the image component is ECG interpretation. If your revision has concentrated on management algorithms, that is a large and very trainable gap. Questions across the exam may require interpretation of intracardiac electrograms, haemodynamic recordings, chest radiographs, photomicrographs, ventriculograms, myocardial perfusion images, CT, MRI and intravascular ultrasound. For the full blueprint — the medical content categories and their exact percentage weightings — use ABIM's published [Cardiovascular Disease certification blueprint](https://www.abim.org/about/abim-exams/blueprints/), which is the authoritative source and is updated periodically. ### After certification: maintenance [#after-certification-maintenance] Certification is not permanent. ABIM offers two routes to maintain it: * The **traditional 10-year MOC examination** — **220 single-best-answer questions**, of which roughly **50 are new and unscored**. Candidates have access to an external resource (**UpToDate®**) for the entire exam. * The **Longitudinal Knowledge Assessment (LKA®)** — a **five-year cycle** in which you answer questions on an ongoing basis and receive feedback as you go. The MOC blueprint is deliberately weighted differently from the certification blueprint: it places **less emphasis on rare conditions** and more on situations where intervention changes outcomes, and for conditions usually managed by other specialists it focuses on **recognition rather than management**. ## The Royal College examination in Cardiology (Adult) — Canada [#the-royal-college-examination-in-cardiology-adult--canada] The Royal College examination has **two components: a written examination and an applied examination**. **The written component** assesses the knowledge and application of knowledge needed to function unsupervised as a competent cardiologist. Most questions concentrate on the **Medical Expert** role, but the examination also assesses the other intrinsic **CanMEDS** roles — Communicator, Professional, Health Advocate, Leader, Collaborator and Scholar. That is a real difference from the ABIM exam, which does not examine those domains as named roles. **The applied component** is examiner-led. Stations may present written clinical vignettes, with or without images, followed by questions from the examiner covering diagnostic interventions, therapy, and the natural course of disease. Stations may also require interpretation of **videos, diagnostic imaging studies, laboratory investigations** and other test results. Performance is scored with a **global rating scale (GRS)** suited to each station, focused on your ability to "systematically work through a case, with a focused, rational and efficient approach." The emphasis on approach, not just the final answer, is worth internalising: an examiner can see your reasoning, and a correct answer reached chaotically scores differently from one reached methodically. Content is based on a blueprint reflecting the **Competencies in the Subspecialty of Cardiology (Adult)**. For the current number of stations, question counts and session timings, consult the Royal College's own [examination format page for Cardiology (Adult)](https://www.royalcollege.ca/en/eligibility-and-exams/exam-formats/cardiology-adult-exam-format.html), which publishes the specifications for each examination year. ## How the two compare [#how-the-two-compare] **Breadth is similar; the assessment method is not.** Both examinations cover the whole of adult cardiology. But ABIM tests entirely in writing, over a long and demanding one and a half days, with a large dedicated block of image interpretation. The Royal College splits assessment between written questions and a live applied component where you explain your reasoning to an examiner. **Preparation should differ accordingly.** For ABIM, sustained accuracy over many hours and fluency at ECG and imaging interpretation are decisive. For the Royal College, you additionally need to be able to *articulate* a structured approach out loud, under questioning. **What they share** is the style of the underlying question: a clinical scenario with a single best answer, testing judgement rather than recall. That is the format worth practising in either case. ## Preparing for either examination [#preparing-for-either-examination] 1. **Start from the blueprint.** ABIM publishes content categories with percentage weightings; the Royal College publishes competencies. Both tell you where the marks are. Revising without them means allocating your time by instinct. 2. **Train ECG interpretation deliberately.** For ABIM this is 48% of an entire half-day component. For the Royal College it appears throughout the applied stations. 3. **Build imaging fluency.** Echocardiograms are 37% of the ABIM image component and coronary angiograms 15%. 4. **Practise long.** Ten hours of multiple-choice in a day is an endurance problem as much as a knowledge one. Sitting full-length blocks in advance is the only way to find out how your accuracy holds up in hour eight. 5. **Rehearse reasoning aloud** if you are sitting the Royal College applied component. Structure is being scored, not only the conclusion. 6. **Review your errors properly.** In a well-built exam the distractors are the common misconceptions — understanding why you were drawn to one teaches more than re-reading the correct answer. ### Practise with our question banks [#practise-with-our-question-banks] Our [interactive exam bank](/docs/quizzes) holds **1,666 questions across 25 banks** in the single-best-answer, clinical-stem format both examinations use. Each question gives instant feedback, and progress saves so you can work in short sessions. Particularly relevant: * [General Cardiology Quiz 1](/docs/quizzes/general-cardiology-quiz-1) — the first of **nine mixed banks** drawn from the MedMCQA, MedQA (USMLE) and AMQA open question banks, closest in style to US board questions * [Management of Heart Failure](/docs/quizzes/management-of-heart-failure) — 230 questions * [Management of Acute Coronary Syndromes](/docs/quizzes/management-of-acute-coronary-syndromes) — 171 questions * [Management of Valvular Heart Disease](/docs/quizzes/management-of-valvular-heart-disease) — 161 questions * [ECG Test — Acute Coronary Syndromes](/docs/quizzes/ecg-test-acute-coronary-syndromes) and the other ECG banks, for the image component For the underlying content, our [knowledge base](/docs/books) covers adult cardiology in full, and the [clinical calculators](/docs/tools/calculators) cover the risk scores — GRACE, TIMI, CHA₂DS₂-VASc, HAS-BLED and others — that board questions routinely turn on. ## Frequently asked questions [#frequently-asked-questions] ### Do I need internal medicine certification first? [#do-i-need-internal-medicine-certification-first] For ABIM, yes — you must be previously certified in internal medicine by ABIM before certifying in cardiovascular disease. ### How long is the ABIM cardiology exam? [#how-long-is-the-abim-cardiology-exam] One and a half days: approximately ten hours of multiple-choice questions across four two-hour sessions, plus roughly five hours of ECG and imaging cases on a separate day. ### How many questions are on the ABIM cardiology certification exam? [#how-many-questions-are-on-the-abim-cardiology-certification-exam] 240 multiple-choice questions, plus approximately 72 ECG and imaging cases. ### What proportion of the ABIM image component is ECG? [#what-proportion-of-the-abim-image-component-is-ecg] 48%, with echocardiograms at 37% and coronary angiograms at 15%. ### Does ABIM certification expire? [#does-abim-certification-expire] It must be maintained, either through the traditional 10-year MOC examination (220 questions, with UpToDate access during the exam) or the five-year Longitudinal Knowledge Assessment. ### Is the Canadian exam oral? [#is-the-canadian-exam-oral] Partly. It has a written component and an applied component; the applied component is examiner-led, with stations built around clinical vignettes and image interpretation, scored using a global rating scale. ### Can I use my Canadian fellowship to sit the ABIM exam? [#can-i-use-my-canadian-fellowship-to-sit-the-abim-exam] ABIM accepts training accredited by the Royal College of Physicians and Surgeons of Canada and the Collège des médecins du Québec alongside ACGME-accredited programmes. Confirm your specific circumstances with ABIM. ## Official sources [#official-sources] * [ABIM Cardiovascular Disease exam information](https://www.abim.org/certification/exam-information/cardiovascular-disease) * [ABIM Cardiovascular Disease exam content and format](https://www.abim.org/certification/exam-information/cardiovascular-disease/exam-content) * [ABIM exam blueprints](https://www.abim.org/about/abim-exams/blueprints/) * [Royal College — examination format, Cardiology (Adult)](https://www.royalcollege.ca/en/eligibility-and-exams/exam-formats/cardiology-adult-exam-format.html) * [Royal College — Subspecialty Training Requirements in Adult Cardiology](https://www.royalcollege.ca/content/dam/documents/ibd/cardiology/cardiology-adult-str-e.pdf) Requirements and formats are revised periodically. Treat this page as orientation and the boards as the authority. *** *Training in Europe instead? See our guide to the [European Exam in Core Cardiology (EECC)](/docs/board-exams/european-exam-in-core-cardiology-eecc).* # European Exam in Core Cardiology (EECC): format, eligibility and preparation (/docs/board-exams/european-exam-in-core-cardiology-eecc) The **European Exam in Core Cardiology (EECC)** is the examination used across much of Europe to test whether a cardiology trainee has the core knowledge required for independent practice. It is run as a joint venture between the **European Society of Cardiology (ESC)**, the **Union of European Medical Specialists Cardiology Section (UEMS-CS)** and participating National and Affiliated Cardiac Societies, with independent academic oversight. In the ESC's own words, the exam sets out to "provide a broad, balanced and up-to-date test of the core cardiology knowledge required by cardiology specialty trainees for independent practice." This guide covers what the exam contains, who can sit it, how it is delivered and how to prepare. It reflects the information published by the ESC for the **2026 examination**; always confirm the current details with your own National Cardiac Society, which is the body that registers you. ## At a glance [#at-a-glance] | | | | ------------------------ | ----------------------------------------------------------------- | | **Full name** | European Exam in Core Cardiology (EECC) | | **Run by** | ESC, UEMS Cardiology Section and participating national societies | | **Questions** | 120 multiple-choice questions | | **Duration** | 3 hours, with no break | | **Options per question** | 5, with one best answer | | **Negative marking** | None | | **Language** | English only | | **Delivery** | Online, on your own computer, with live human proctoring | | **Next exam date** | 16 June 2026 | | **Registration** | Only through your National or Affiliated Cardiac Society | | **Curriculum** | ESC Core Curriculum for the Cardiologist (2020) | ## Who can sit the EECC [#who-can-sit-the-eecc] This is the point that surprises most candidates, and it is worth stating plainly: > Registration is exclusively restricted to the candidates identified and registered by their National Cardiology Society and is not open to individuals. You cannot sign up directly with the ESC. Eligibility is decided **individually by each National and Affiliated Cardiology Society**, so the training stage at which you are permitted to sit — and whether the exam is compulsory at all — depends entirely on the country you train in. In some countries the EECC forms part of the national specialty certification process; in others it is voluntary. The practical consequence: your first step is not the ESC website but your own national society. They decide who is put forward, when, and at what cost. As of the 2025 examination, the EECC involved **29 ESC National Cardiac Societies**, **3 ESC Affiliated Cardiac Societies** and **2 ESC Global Partners** — the Asian Pacific Society of Cardiology (APSC) and the Gulf Heart Association (GHA). That international reach is part of why the exam has become a common reference point for the standard of a European-trained cardiologist. ## Exam format [#exam-format] The EECC is a **single written paper of 120 multiple-choice questions**, sat in **three hours with no break**. Each question offers **five options with a single best answer**, and there is **no negative marking** — so an unanswered question and a wrong answer score the same. Leave nothing blank. Questions are **based on clinical scenarios** rather than isolated factual recall. This matters for preparation: the exam is testing whether you can apply knowledge to a patient in front of you, not whether you can recite a guideline table. Three hours for 120 questions works out at **90 seconds per question**. That is a genuine time pressure when each item carries a clinical vignette to read, and it is the single most common reason well-prepared candidates underperform. Practising against the clock matters as much as knowing the content. ### How it is delivered [#how-it-is-delivered] The exam is taken **online through a proctoring platform** (CYIM with ProctorU®), described by the ESC as "accessible from anywhere in the world." You sit it on **your own device — a computer only, not a tablet or phone** — and you are **monitored by a human proctor** in real time. There is no test centre to travel to, but there are consequences worth planning for: * Your computer, webcam, microphone and internet connection become part of the exam. Test them well in advance. * You need a quiet, private room for three uninterrupted hours. * Live proctoring means rules about what may be on your desk, who may enter the room, and where you may look. Read your society's instructions carefully rather than assuming. ## What the exam covers [#what-the-exam-covers] The EECC is aligned to the **ESC Core Curriculum for the Cardiologist**, published in 2020. That document is the definitive statement of scope, and it is the right place to start when planning revision. The ESC is explicit that there is **no single source from which all questions are developed**, and encourages candidates to read widely — including **ESC Clinical Practice Guidelines**, the **ESC Textbook of Cardiovascular Medicine**, and **practice-changing clinical trials**. In practice, the core curriculum spans the breadth of general cardiology: * **Coronary artery disease** — chronic coronary syndromes, acute coronary syndromes, secondary prevention * **Heart failure** — acute and chronic, HFrEF, HFmrEF and HFpEF, devices and advanced therapies * **Arrhythmias** — supraventricular and ventricular arrhythmias, atrial fibrillation, bradycardia and conduction disease, pacing and ICDs * **Valvular heart disease** — assessment, timing of intervention, surgical and transcatheter options * **Cardiomyopathies and myocardial disease** — hypertrophic, dilated, restrictive, infiltrative and inflammatory * **Pericardial disease** * **Aortic and peripheral vascular disease** * **Adult congenital heart disease** * **Pulmonary hypertension and pulmonary embolism** * **Hypertension and cardiovascular prevention** * **Cardiovascular imaging** — echocardiography, CMR, cardiac CT and nuclear techniques * **Electrocardiography** — a thread running through almost every other topic Because the questions are scenario-based, topics rarely appear in isolation. A single question may require you to read an ECG, recognise the underlying condition, and choose the management step the guidelines support. ## Pass mark and results [#pass-mark-and-results] There is **no fixed pass mark published in advance**. After each administration, the standard is set through **independent psychometric analysis** and review by a **Standard Setting Group**. This is normal practice for high-stakes medical examinations — it allows the pass standard to account for the difficulty of the particular paper rather than fixing an arbitrary percentage. Results are **not sent to you by the ESC**. The ESC states that "under no circumstances will the ESC communicate results directly to candidates" — your **National or Affiliated Cardiac Society** releases them. If you are waiting on a result, your society is who to contact. ## Fees [#fees] The ESC does not set a single price. **Fees are determined by individual National and Affiliated Cardiology Societies**, so what you pay depends on where you train. Some societies subsidise or fully cover the cost for their trainees. Ask yours directly. ## Preparing for the EECC [#preparing-for-the-eecc] The ESC runs an **official online preparatory course**, and is unusually direct about its status: it is described as the **only official preparatory resource**, with access opening to registered candidates from **16 March 2026** for the June 2026 sitting. The ESC notes that other preparation materials "have been developed without the support of the ESC and may therefore not be suitable for adequate preparation." That is worth reading carefully rather than dismissing. It does not mean other resources are useless — it means no other resource can claim to mirror the exam blueprint. Use the official course as your spine, and everything else as supplementary practice. A workable approach: 1. **Read the ESC Core Curriculum first.** It tells you the scope. Revising without it means guessing at what is examinable. 2. **Work through the current ESC Guidelines** for the major topics. Scenario questions tend to hinge on the recommendation, and on the class and level of evidence behind it. 3. **Drill ECGs.** Electrocardiography threads through the whole curriculum, and reading one under time pressure is a skill that only improves with repetition. 4. **Practise question banks against the clock.** Ninety seconds per question is the real constraint. 5. **Review why each wrong answer was wrong**, not just what the right answer was. Distractors in well-written exams are built from the common misconceptions. ### Practise with our question banks [#practise-with-our-question-banks] We maintain a free, [interactive exam bank of 1,666 questions across 25 banks](/docs/quizzes), written in the single-best-answer format the EECC uses. Answer a question and you see immediately whether you were right, with an explanation where one exists; your progress saves, so you can work through a bank in short sessions. Banks that map most directly onto EECC topics include: * [Management of Heart Failure](/docs/quizzes/management-of-heart-failure) — 230 questions * [Management of Acute Coronary Syndromes](/docs/quizzes/management-of-acute-coronary-syndromes) — 171 questions * [Management of Valvular Heart Disease](/docs/quizzes/management-of-valvular-heart-disease) — 161 questions * [Management of Supraventricular Tachycardias](/docs/quizzes/management-of-supraventricular-tachycardias) — 118 questions * [Management of Ventricular Arrhythmias and Sudden Cardiac Arrest](/docs/quizzes/management-of-ventricular-arrhythmias-and-sudden-cardiac-arrest-part-2) — 167 questions * [General Cardiology Quiz 1](/docs/quizzes/general-cardiology-quiz-1) — the first of nine mixed banks Alongside them, our [knowledge base](/docs/books) covers the same curriculum in long form, and the [clinical calculators](/docs/tools/calculators) cover the risk scores that scenario questions routinely turn on. ## Frequently asked questions [#frequently-asked-questions] ### Can I register for the EECC myself? [#can-i-register-for-the-eecc-myself] No. Registration is handled exclusively by National and Affiliated Cardiac Societies, and is not open to individuals. Contact your national society. ### Is the EECC compulsory? [#is-the-eecc-compulsory] That depends on your country. Each participating national society decides how the exam fits into its own training and certification pathway. ### What language is the exam in? [#what-language-is-the-exam-in] English only. ### Can I sit it from home? [#can-i-sit-it-from-home] Yes. The exam is delivered online through a proctored platform and can be taken anywhere with a suitable computer and internet connection, under live human supervision. ### Is there negative marking? [#is-there-negative-marking] No. There is no penalty for a wrong answer, so answer every question. ### What is the pass mark? [#what-is-the-pass-mark] It is not published in advance. The standard is set after each exam by independent psychometric analysis and a Standard Setting Group. ### When is the next exam? [#when-is-the-next-exam] 16 June 2026. Confirm with your national society, which controls registration. ## Official sources [#official-sources] * [European Exam in Core Cardiology — European Society of Cardiology](https://www.escardio.org/education/career-development/certification-programmes/european-exam-in-core-cardiology-eecc/) * [ESC Core Curriculum for the Cardiologist](https://www.escardio.org/Education/Core-Curriculum) * [ESC Clinical Practice Guidelines](https://www.escardio.org/Guidelines) Details change between sittings. Treat this page as an orientation and your National Cardiac Society as the authority on dates, eligibility and fees. *** *Sitting the North American equivalent instead? See our guide to [cardiology board certification in the United States and Canada](/docs/board-exams/cardiology-board-certification-usa-canada).* # Cardiology board exams (/docs/board-exams) Whichever system you train in, the final hurdle is the same in principle: a high-stakes examination that asks whether you can practise cardiology independently. The details differ sharply — in length, in format, in who is even allowed to register. These guides cover what each examination actually tests and how it is run. ## Practise before you sit [#practise-before-you-sit] Reading about an exam format is not the same as answering under it. Our [interactive exam bank](/docs/quizzes) contains **1,666 questions across 25 question banks**, written in the single-best-answer style used by all three examinations, with instant feedback and saved progress. # Knowledge base (/docs/books) Every chapter from all eight books, in one list. Filter by book, then by section, or search across every title and summary at once. # Differential Diagnosis of Chest Pain: A Clinical Overview This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/clinical-qa/differential-diagnosis-of-chest-pain-a-clinical-overview — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG Criteria for STEMI (ST Elevation Myocardial Infarction) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/clinical-qa/ecg-criteria-for-stemi-st-elevation-myocardial-infarction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clinical Q&A (/docs/clinical-qa) Short, referenced answers to questions that come up on the ward. # Left Bundle Branch Block: ECG criteria and clinical implications This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/clinical-qa/left-bundle-branch-block-ecg-criteria-and-clinical-implications — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Torsades de Pointes: Definition, Characteristics, and Management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/clinical-qa/torsades-de-pointes-definition-characteristics-and-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # What is the difference between cardioversion and defibrillation for arrhythmias? This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/clinical-qa/what-is-the-difference-between-cardioversion-and-defibrillation-for-arrhythmias — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ICD-10 Codes (/docs/icd) Type a code (e.g. `I21`) or part of a diagnosis name to search all ICD-10 codes. # About (/docs/pages/about-ecgwaves-com) # Welcome to the world's most popular ECG book [#welcome-to-the-worlds-most-popular-ecg-book] ecgwaves.com is a comprehensive online book and course in clinical ECG interpretation. This course covers all topics, from basic cardiac electrophysiology to advanced ECG interpretation. It is suitable for anyone interested in ECG interpretation, particularly physicians, assistant physicians, nurses, paramedics, biomedical analysts, students and researchers. All recommendations presented here are in line with American and European guidelines (ACC, AHA, ESC). ### **Non-commercial project** [#non-commercial-project] ecgwaves.com is a non-profit project and differs from many online resources for learning ECG interpretation. In order to provide you with the best possible learning experience we have invested significantly in developing and maintaining this course. We continue to pursue our mission with great enthusiasm, because we love ECG interpretation and teaching. Nevertheless, in order to reduce our losses we currently charge $10 for a permanent membership. $10 is a fraction of the cost of comparable books and courses (which costs anywhere between $60 and $600) and it does not cover our costs of maintaining the course. ## **Course content** [#course-content] This online course includes an ECG book, video lectures, test/quiz and other resources to enhance your ECG interpretation skills. Emphasis is on clinical ECG interpretation but the course will also touch on other topics to cover important concepts in cardiovascular medicine. The course content is in line with American and European guidelines (ACC, AHA, ESC). Thus, our recommendations regarding diagnosis and management is concordant with current clinical guidelines. We aim to provide reliable and qualitative ECG and cardiology education. We encourage you to spread the word. All content of ecgwaves.com is copyright of the authors, unless otherwise stated. ### Dr Araz Rawshani, MD, PhD [#dr-araz-rawshani-md-phd] This book and course is created by Dr Araz Rawshani (MD, PhD) from the University of Gothenburg, Sweden. Dr Rawshani is a cardiovascular researcher with interest in acute and cardiovascular medicine, as well as diabetology. His research encompasses both clinical studies and basic science. Dr Rawshani has published papers in The New England Journal of Medicine, The Lancet, JAMA (Internal Medicine), The British Medical Journal etc. Dr Rawshani serves as reviewer for more than 30 peer-reviewed journals and teaches evidence-based cardiology and ECG interpretation at all levels. **Dr Araz Rawshani, MD, PhD** **Institute of Medicine, University of Gothenburg, Sweden** # Clinical Calculators (/docs/pages/clinical-calculators-ecg-echocardiography) Exercise ECG Brugada Ventricular Tachycardia Criteria Sgarbossa Criteria Modified Sgarbossa Criteria 6 Minute Walk Test (6MWT) AHA/ACC Heart Failure HASBLED CHADSVASC # Contact (/docs/pages/contact) ## Get in touch [#get-in-touch] Get in touch with us using the form below. All requests, including support, are handled using this form. # Course in Clinical ECG Interpretation (/docs/pages/course-clinical-ecg-interpretation) ## Courses [#courses] ## The ECG Book [#the-ecg-book] The ECG book is a comprehensive e-book, covering all aspects of clinical ECG interpretation, and will take you from cell to bedside. ## The Normal ECG: From Normality to Pathology [#the-normal-ecg-from-normality-to-pathology] In the second part of the course you will learn all about the normal ECG, normal variants and diagnosis of pathological findings. A total of… ## Introduction to ECG Interpretation [#introduction-to-ecg-interpretation] In this course you will learn about cardiac physiology, anatomy and the principles of electrocardiography. ## ECG Tests (Quiz) [#ecg-tests-quiz] All articles loaded No more articles to load # Pages (/docs/pages) Site information pages. * [About](/docs/pages/about-ecgwaves-com) * [Contact](/docs/pages/contact) * [The ultimate ECG book & course: learn ECG interpretation, videos, test/quiz](/docs/pages/ultimate-ecg-book-course-learn-ecg-interpretation-videos-test-quiz) * [Course in Clinical ECG Interpretation](/docs/pages/course-clinical-ecg-interpretation) * [Terms of Service](/docs/pages/terms-of-service) * [Privacy Policy](/docs/pages/privacy-policy) * [Reference (normal) values for echocardiography](/docs/pages/reference-values-for-echocardiography) * [Reference (normal) values for ECG (electrocardiography)](/docs/pages/reference-values-for-ecg-electrocardiography) * [Reference (normal) values for pediatric & neonatal ECG interpretation](/docs/pages/reference-values-for-pediatric-ecg-interpretation) * [Clinical Calculators](/docs/pages/clinical-calculators-ecg-echocardiography) * [The best membership for learning ECG & echo](/docs/pages/shop-e-books-courses) * [Manuals and reference values](/docs/pages/reference-values) * [Teach on ECGwaves](/docs/pages/teach) * [Privacy Statement](/docs/pages/privacy-statement) * [Submit echocardiography case / content](/docs/pages/teach-echo) # Privacy Policy (/docs/pages/privacy-policy) # Privacy policy [#privacy-policy] This privacy policy applies between you, the User of this Website and Rawshani Research AB (LLC), the owner and provider of this Website. Rawshani Research AB takes the privacy of your information very seriously. This privacy policy applies to our use of any and all Data collected by us or provided by you in relation to your use of the Website. This privacy policy should be read alongside, and in addition to, our Terms and Conditions, which can be found at:  **Please read this privacy policy carefully**. ## Definitions and interpretation [#definitions-and-interpretation] 1. In this privacy policy, the following definitions are used: 1. **Data**: collectively all information that you submit to Rawshani Research AB via the Website. This definition incorporates, where applicable, the definitions provided in the Data Protection Laws; 2. **Cookies:** a small text file placed on your computer by this Website when you visit certain parts of the Website and/or when you use certain features of the Website. Details of the cookies used by this Website are set out in the clause below (**Cookies**); 3. **Data Protection Laws**: any applicable law relating to the processing of personal Data, including but not limited to the Directive 96/46/EC (Data Protection Directive) or the GDPR, and any national implementing laws, regulations and secondary legislation, for as long as the GDPR is effective in the UK; 4. **GDPR** the General Data Protection Regulation (EU) 2016/679; 5. **Rawshani Research AB, we** or **us** Rawshani Research AB, a company incorporated in with registered number whose registered office is at Doteviksvägen 6, Gothenburg, Sweden, ; 6. **UK and EU Cookie Law** the Privacy and Electronic Communications (EC Directive) Regulations 2003 as amended by the Privacy and Electronic Communications (EC Directive) (Amendment) Regulations 2011; 7. **User** or **you**: any third party that accesses the Website and is not either (i) employed by Rawshani Research AB and acting in the course of their employment or (ii) engaged as a consultant or otherwise providing services to Rawshani Research AB and accessing the Website in connection with the provision of such services; and 8. **Website** the website that you are currently using, [https://ecgwaves.com](https://ecgwaves.com), and any sub-domains of this site unless expressly excluded by their own terms and conditions. 2. In this privacy policy, unless the context requires a different interpretation: 1. the singular includes the plural and vice versa; 2. references to sub-clauses, clauses, schedules or appendices are to sub-clauses, clauses, schedules or appendices of this privacy policy; 3. a reference to a person includes firms, companies, government entities, trusts and partnerships; 4. "including" is understood to mean "including without limitation"; 5. reference to any statutory provision includes any modification or amendment of it; 6. the headings and sub-headings do not form part of this privacy policy. ## Scope of this privacy policy [#scope-of-this-privacy-policy] 1. This privacy policy applies only to the actions of Rawshani Research ABand Users with respect to this Website. It does not extend to any websites that can be accessed from this Website including, but not limited to, any links we may provide to social media websites. 2. For purposes of the applicable Data Protection Laws, Rawshani Research AB is the "data controller". This means that Rawshani Research AB determines the purposes for which, and the manner in which, your Data is processed. ## Data collected [#data-collected] 1. We may collect the following Data, which includes personal Data, from you: 1. name; 2. profession; 3. contact Information such as email addresses and telephone numbers; 4. IP address (automatically collected); 5. web browser type and version (automatically collected); 6. operating system (automatically collected); 7. a list of URLs starting with a referring site, your activity on this Website, and the site you exit to (automatically collected);in each case, in accordance with this privacy policy. ## How we collect Data [#how-we-collect-data] 1. We collect Data in the following ways: 1. data is given to us by you; and 2. data is collected automatically. ## Data that is given to us by you [#data-that-is-given-to-us-by-you] 1. Rawshani Research AB will collect your Data in a number of ways, for example: 1. when you contact us through the Website, by telephone, post, e-mail or through any other means; 2. when you register with us and set up an account to receive our products/services; 3. when you make payments to us, through this Website or otherwise; 4. when you elect to receive marketing communications from us; 5. when you use our services;in each case, in accordance with this privacy policy. ## Data that is collected automatically [#data-that-is-collected-automatically] 1. To the extent that you access the Website, we will collect your Data automatically, for example: 1. we automatically collect some information about your visit to the Website. This information helps us to make improvements to Website content and navigation, and includes your IP address, the date, times and frequency with which you access the Website and the way you use and interact with its content. 2. we will collect your Data automatically via cookies, in line with the cookie settings on your browser. For more information about cookies, and how we use them on the Website, see the section below, headed "Cookies". ## Our use of Data [#our-use-of-data] 1. Any or all of the above Data may be required by us from time to time in order to provide you with the best possible service and experience when using our Website. Specifically, Data may be used by us for the following reasons: 1. internal record keeping; 2. improvement of our products / services; 3. transmission by email of marketing materials that may be of interest to you;in each case, in accordance with this privacy policy. 2. We may use your Data for the above purposes if we deem it necessary to do so for our legitimate interests. If you are not satisfied with this, you have the right to object in certain circumstances (see the section headed "Your rights" below). 3. For the delivery of direct marketing to you via e-mail, we'll need your consent, whether via an opt-in or soft-opt-in: 1. soft opt-in consent is a specific type of consent which applies when you have previously engaged with us (for example, you contact us to ask us for more details about a particular product/service, and we are marketing similar products/services). Under "soft opt-in" consent, we will take your consent as given unless you opt-out. 2. for other types of e-marketing, we are required to obtain your explicit consent; that is, you need to take positive and affirmative action when consenting by, for example, checking a tick box that we'll provide. 3. if you are not satisfied about our approach to marketing, you have the right to withdraw consent at any time. To find out how to withdraw your consent, see the section headed "Your rights" below. 4. When you register with us and set up an account to receive our services, the legal basis for this processing is the performance of a contract between you and us and/or taking steps, at your request, to enter into such a contract. ## Who we share Data with [#who-we-share-data-with] 1. We may share your Data with the following groups of people for the following reasons: 1. our employees, agents and/or professional advisors - to provide support to our users.;in each case, in accordance with this privacy policy. ## Keeping Data secure [#keeping-data-secure] 1. We will use technical and organisational measures to safeguard your Data, for example: 1. access to your account is controlled by a password and a user name that is unique to you. 2. we store your Data on secure servers. 2. Technical and organisational measures include measures to deal with any suspected data breach. If you suspect any misuse or loss or unauthorised access to your Data, please let us know immediately by contacting us via this e-mail address: [hej@ekg.nu](mailto:hej@ekg.nu). 3. If you want detailed information from Get Safe Online on how to protect your information and your computers and devices against fraud, identity theft, viruses and many other online problems, please visit [www.getsafeonline.org](http://www.getsafeonline.org). Get Safe Online is supported by HM Government and leading businesses. ## Data retention [#data-retention] 1. Unless a longer retention period is required or permitted by law, we will only hold your Data on our systems for the period necessary to fulfil the purposes outlined in this privacy policy or until you request that the Data be deleted. 2. Even if we delete your Data, it may persist on backup or archival media for legal, tax or regulatory purposes. ## Your rights [#your-rights] 1. You have the following rights in relation to your Data: 1. **Right to access** - the right to request (i) copies of the information we hold about you at any time, or (ii) that we modify, update or delete such information. If we provide you with access to the information we hold about you, we will not charge you for this, unless your request is "manifestly unfounded or excessive." Where we are legally permitted to do so, we may refuse your request. If we refuse your request, we will tell you the reasons why. 2. **Right to correct** - the right to have your Data rectified if it is inaccurate or incomplete. 3. **Right to erase** - the right to request that we delete or remove your Data from our systems. 4. **Right to restrict our use of your Data** - the right to "block" us from using your Data or limit the way in which we can use it. 5. **Right to data portability** - the right to request that we move, copy or transfer your Data. 6. **Right to object** - the right to object to our use of your Data including where we use it for our legitimate interests. 2. To make enquiries, exercise any of your rights set out above, or withdraw your consent to the processing of your Data (where consent is our legal basis for processing your Data), please contact us via this e-mail address: [hej@ekg.nu](mailto:hej@ekg.nu). 3. If you are not satisfied with the way a complaint you make in relation to your Data is handled by us, you may be able to refer your complaint to the relevant data protection authority. For the UK, this is the Information Commissioner's Office (ICO). The ICO's contact details can be found on their website at [https://ico.org.uk/](https://ico.org.uk/). 4. It is important that the Data we hold about you is accurate and current. Please keep us informed if your Data changes during the period for which we hold it. ## Links to other websites [#links-to-other-websites] 1. This Website may, from time to time, provide links to other websites. We have no control over such websites and are not responsible for the content of these websites. This privacy policy does not extend to your use of such websites. You are advised to read the privacy policy or statement of other websites prior to using them. ## Changes of business ownership and control [#changes-of-business-ownership-and-control] 1. Rawshani Research AB may, from time to time, expand or reduce our business and this may involve the sale and/or the transfer of control of all or part of Rawshani Research AB. Data provided by Users will, where it is relevant to any part of our business so transferred, be transferred along with that part and the new owner or newly controlling party will, under the terms of this privacy policy, be permitted to use the Data for the purposes for which it was originally supplied to us. 2. We may also disclose Data to a prospective purchaser of our business or any part of it. 3. In the above instances, we will take steps with the aim of ensuring your privacy is protected. ## Cookies [#cookies] 1. This Website may place and access certain Cookies on your computer. Rawshani Research AB uses Cookies to improve your experience of using the Website and to improve our range of services. Rawshani Research AB has carefully chosen these Cookies and has taken steps to ensure that your privacy is protected and respected at all times. 2. All Cookies used by this Website are used in accordance with current UK and EU Cookie Law. 3. Before the Website places Cookies on your computer, you will be presented with a message bar requesting your consent to set those Cookies. By giving your consent to the placing of Cookies, you are enabling Rawshani Research AB to provide a better experience and service to you. You may, if you wish, deny consent to the placing of Cookies; however certain features of the Website may not function fully or as intended. 4. This Website may place the following Cookies:**Type of CookiePurpose**Strictly necessary cookiesThese are cookies that are required for the operation of our website. They include, for example, cookies that enable you to log into secure areas of our website, use a shopping cart or make use of e-billing services.Analytical/performance cookiesThey allow us to recognise and count the number of visitors and to see how visitors move around our website when they are using it. This helps us to improve the way our website works, for example, by ensuring that users are finding what they are looking for easily. 5. You can find a list of Cookies that we use in the Cookies Schedule. 6. You can choose to enable or disable Cookies in your internet browser. By default, most internet browsers accept Cookies but this can be changed. For further details, please consult the help menu in your internet browser. 7. You can choose to delete Cookies at any time; however you may lose any information that enables you to access the Website more quickly and efficiently including, but not limited to, personalisation settings. 8. It is recommended that you ensure that your internet browser is up-to-date and that you consult the help and guidance provided by the developer of your internet browser if you are unsure about adjusting your privacy settings. 9. For more information generally on cookies, including how to disable them, please refer to aboutcookies.org. You will also find details on how to delete cookies from your computer. ## General [#general] 1. You may not transfer any of your rights under this privacy policy to any other person. We may transfer our rights under this privacy policy where we reasonably believe your rights will not be affected. 2. If any court or competent authority finds that any provision of this privacy policy (or part of any provision) is invalid, illegal or unenforceable, that provision or part-provision will, to the extent required, be deemed to be deleted, and the validity and enforceability of the other provisions of this privacy policy will not be affected. 3. Unless otherwise agreed, no delay, act or omission by a party in exercising any right or remedy will be deemed a waiver of that, or any other, right or remedy. 4. This Agreement will be governed by and interpreted according to the law of England and Wales. All disputes arising under the Agreement will be subject to the exclusive jurisdiction of the English and Welsh courts. ## Changes to this privacy policy [#changes-to-this-privacy-policy] 1. Rawshani Research AB reserves the right to change this privacy policy as we may deem necessary from time to time or as may be required by law. Any changes will be immediately posted on the Website and you are deemed to have accepted the terms of the privacy policy on your first use of the Website following the alterations.  You may contact Rawshani Research AB by email at [hej@ekg.nu](mailto:hej@ekg.nu). ## Attribution [#attribution] 1. This privacy policy was created using a document from [Rocket Lawyer](https://www.rocketlawyer.com/gb/en/) ([https://www.rocketlawyer.com/gb/en).\*\*01](https://www.rocketlawyer.com/gb/en\).**01) November 2019\*\* ## Cookies [#cookies-1] Below is a list of the cookies that we use. We have tried to ensure this is complete and up to date, but if you think that we have missed a cookie or there is any discrepancy, please let us know. Strictly necessary We use the following strictly necessary cookies: We use this session cookie to remember you and maintain your session whilst you are using our website. We use the following analytical/performance cookies: We use this cookie to help us analyse how users use the website. # Privacy Statement (/docs/pages/privacy-statement) # ECGwaves.com for Business Privacy Statement [#ecgwavescom-for-business-privacy-statement] *Updated on April 1 2020.* Rawshani Research AB ("**RRAB**", "**we**", "**our**"; Swedish company nr 559160-0530, Gothenburg, Sweden) owns [www.ecgwaves.com](http://www.ecgwaves.com). In order to provide courses and services to corporate, non-profit organizations, academic institutions and governmental customers (**“Customers”**), RRAB will receive and have access to personal data of individual users ("**Users**") to whom Customers grant access. For the purposes of this privacy statement, Customers are data controllers and RRAB is a data processor. RRAB’s processing of User data and the security measures implemented to protect such data are detailed in this privacy statement. In the event where RRAB makes any significant changes to the manner in which it processes User data to provide its services to Customers, it will notify Customers. As the data processor, RRAB will access, store and use the personal data of individual Users solely for the purpose of providing the services to its Customers and will process the data as instructed by its Customers. As data controllers, Customers decide which of their employees, students or other personnel are given access to the services. They do this by designating one or more administrators (**“Administrator”**) who can add and remove User accounts. ## Information about Users collected and stored by RRAB [#information-about-users-collected-and-stored-by-rrab] 1. Accessing our services requires creating an individual User account. 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These companies are contractually required to use User data solely as directed by RRAB for the purpose of providing services to RRAB. * ECGwaves.com contracts with Kinsta LLC ([www.kinsta.com](http://www.kinsta.com)) for hosting services. * ECGwaves.com uses Amazon Web Services (AWS) to perform email services. * RRAB shares User information with Google Analytics to better understand how Users use our service. Any other sharing of User data is subject to the consent and instructions of Customer. # Reference (normal) values for ECG (electrocardiography) (/docs/pages/reference-values-for-ecg-electrocardiography) Rhythm #### Checklist [#checklist] **Assess ventricular (RR intervals) and atrial (PP intervals) rate and rhythm:** * Is ventricular rhythm regular? What is the ventricular rate (beats/min)? * Is atrial rhythm regular? What is the atrial rate (beats/min)? * P-waves should precede every QRS complex and the P-wave should be positive in lead II. #### Common findings [#commonfindings] * **Sinus rhythm** (which is the normal rhythm) has the following characteristics: (1) heart rate 50–100 beats per minute; (2) P-wave precedes every QRS complex; (3) the P-wave is positive in lead II and (4) the PR interval is constant. * **Causes of bradycardia**: sinus bradycardia, sinoatrial block, sinoatrial arrest/inhibition, second-degree AV block, third-degree AV block. Note that escape rhythms may arise during bradycardia. Also note that bradycardia due to dysfunction in the sinoatrial node is referred to as *sinus node dysfunction (SND).* If a person with ECG signs of SND is symptomatic, the condition is classified as *sick sinus syndrome (SSS)*. * **Causes of tachycardia (tachyarrhythmia) with narrow QRS complexes (QRS duration \<0,12 s):** sinus tachycardia, inappropriate sinus tachycardia, sinoatrial re-entry tachycardia, atrial fibrillation, atrial flutter, atrial tachycardia, multifocal atrial tachycardia, AVNRT, AVRT (pre-excitation, WPW). Note that narrow complex tachyarrhythmia rarely cause circulatory compromise or collapse. * **Causes of tachycardia (tachyarrhythmia) with wide QRS complexes (QRS duration ≥0,12 s)**: ventricular tachycardia is the most common cause and it is potentially life-threatening. Note that 10% of wide complex tachycardias actually originate from the atria but the QRS complexes become wide due to abnormal ventricular depolarization (e.g sinus tachycardia with simultaneous left bundle branch block). P-wave morphology and PR interval #### Checklist [#checklist-1] * P-wave always positive in lead II (actually always positive in leads II, III and aVF). * P-wave duration should be \<0,12 s (all leads). * P-wave amplitude should be ≤2,5 mm (all leads). * PR interval must be 0,12–0,22 s (all leads). #### Common findings [#commonfindings-1] * P-wave must be positive in lead II, otherwise the rhythm cannot be sinus rhythm. * P-wave may be biphasic (diphasic) in V1 (the negative deflection should be \<1 mm). It may have a prominent second hump in the inferior limb leads (particularly lead II). * **P mitrale**: increased P-wave duration, enhanced second hump in lead II and enhanced negative deflection in V1. * **P pulmonale**: increased P-wave amplitudes in lead II and V1. * **If P-wave not clearly visible:** look for retrograde (inverted) P-waves, which can be located anywhere between the J point and the terminal part of the T-wave. * **PR interval >0,22 s**: first-degree AV block. * **PR interval \<0,12 s**: Pre-excitation (WPW syndrome). * **Second-degree AV-block Mobitz type I (Wenckebach block)**: repeated cycles of gradually increasing PR interval until an atrial impulse (P-wave) is blocked in the atrioventricular node and the QRS complex does not appear. * **Second-degree AV-block Mobitz type II**: intermittently blocked atrial impulses (no QRS seen after P) but with constant PR interval. * **Third-degree AV-block**: All atrial impulses (P-waves) are blocked by the atrioventricular node. An escape rhythm arises (cardiac arrest ensues otherwise), which may have narrow or wide QRS complexes, depending on its origin. There is no relation between P-waves and the escape rhythm’s QRS complexes, and atrial rhythm is typically faster than the escape rhythm (both rhythms are typically regular). QRS-complex #### Checklist [#checklist-2] * **QRS duration** must be \<0,12 s (normally 0,07-0,10 s). * There must be at least one limb lead with R-wave amplitude >5 mm and at least one chest (precordial) lead with R-wave amplitude >10 mm; otherwise there is **low voltage**. * **High voltage** exists if the amplitudes are too high, i.e if the following condition is satisfied: *S-waveV1 or V2 + R-waveV5 >35 mm.* * Look for pathological Q-waves. *Pathological Q-waves* are ≥0,03 s and/or amplitude ≥25% of R-wave amplitude in same lead, in at least 2 anatomically contiguous leads. * Is the R-wave progression in the chest leads (V1–V6) normal? * Is the electrical axis normal? Electrical axis is assessed in limb leads and should be between –30° to 90°. #### Common findings [#commonfindings-2] * **Wide QRS complex (QRS duration ≥0.12 s)**: Left bundle branch block. Right bundle branch block. Nonspecific intraventricular conduction disturbance. Hyperkalemia. Class I antiarrhythmic drugs. Tricyclic antidepressants. Ventricular rhythms and ventricular extrasystoles (premature complexes). Artificial pacemaker which stimulates in the ventricle. Aberrant conduction (abberancy). Pre-excitation (Wolff-Parkinson-White syndrome). * **Short QRS duration**: no clinical relevance. * **High voltage**: Hypertrophy (any lead). Left bundle branch block (leads V5, V6, I, aVL). Right bundle branch block (V1–V3). Normal variant in younger, well-trained and slender individuals. * **Low voltage**: Normal variant. Misplaced leads. Cardiomyopathy. Chronic obstructive pulmonary disease. Perimyocarditis. Hypothyreosis (typically accompanied by bradycardia). Pneumothorax. Extensive myocardial infarction. Obesity. Pericardial effusion. Pleural effusion. Amyloidosis. * **Pathological Q-waves**: Myocardial infarction. Left-sided pneumothorax. Dextrocadia. Perimyocarditis. Cardiomyopathy. Amyloidosis. Bundle branch blocks. Anterior fascicular block. Pre-excitation. Ventricular hypertrophy. Acute cor pulmonale. Myxoma. * **Fragmented QRS complexes** indicates myocardial scarring (mostly due to infarction). * **Abnormal R-wave progression**: Myocardial infarction. Right ventricular hypertrophy (reversed R-wave progression). Left ventricular hypertrophy (amplified R-wave progression). Cardiomyopathy. Chronic cor pulmonale. Left bundle branch block. Pre-excitation. * **Dominant R-wave in V1/V2**: Misplaced chest electrodes. Normal variant. Situs inversus. Posterolateral infarction/ischemia (if patient experiences chest discomfort). Right ventricular hypertrophy. Hypertrophic cardiomyopathy. Right bundle branch block. Pre-excitation. * **Right axis deviation:** Normal in newborns. Right ventricular hypertrophy. Acute cor pulmonale (pulmonary embolism). Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). Lateral ventricular infarction. Pre-excitation. Switched arm electrodes (negative P and QRS-T in lead I). Situs inversus. Left posterior fascicular block is diagnosed when the axis is between 90° and 180° with rS complex in I and aVL as well as qR complex in III and aVF (with QRS duration \<0.12 seconds), provided that other causes of right axis deviation have been excluded. * **Left axis deviation**: Left bundle branch block. Left ventricular hypertrophy. Inferior infarction. Pre-excitation. Left anterior fascicular block is diagnosed if the axis is between -45° and 90° with qR-complex in aVL and QRS duration is 0,12 s, provided that other causes of left axis deviation have been excluded. * **Extreme axis deviation**: Rarely seen. Probably misplaced electrodes. If the rhythm is wide QRS complex tachycardia, then the cause is probably ventricular tachycardia. ST-segment #### Checklist [#checklist-3] * The ST-segment should be flat and isoelectric (in level with the baseline). It may be slightly upsloping at the transition with the T-wave. * ST segment deviation (elevation and depression) is measured in the J point. #### Common findings [#commonfindings-3] * **Benign ST segment elevation** is very common in the population, particularly in the precordial leads (V2–V6). Up to 90% (in some age-ranges) of healthy men and women display concave ST-segment elevations in V2–V6 (this is called male/female pattern). ST-segment elevations which are not benign nor due to ischemia are rather common (listed below). * ST-segment depression is uncommon among healthy individuals. ST-segment depression is particularly suspicious in the chest leads. Guidelines recommend that \<0.5 mm ST-segment depression be accepted in all leads. * **Causes of ST-segment elevation**: Ischemia. ST segment elevation myocardial infarction (STEMI/STE-AKS). Prinzmetal’s angina (coronary vasospasm). Male/female pattern. Early repolarization. Perimyocarditis. Left bundle branch block. Nonspecific intraventricular conduction disturbance. Left ventricular hypertrophy. Brugada syndrome. Takotsubo cardiomyopathy. Hyperkalemia. Post cardioversion. Pulmonary embolism. Pre-excitation. Aortic dissection engaging the coronary arteries. Left ventricular aneurysm. * **Causes of ST-segment depression**: Ischemia. Non-ST segment elevation myocadial infarction (NSTEMI/NSTE-AKS). Physiological ST-segment depression. Hyperventilation. Hypokalemia. High sympathethic tone. Digoxin. Left bundle branch block. Right bundle branch block. Pre-excitation. Left ventricular hypertrophy. Right ventricular hypertrophy. Heart failure. Tachycardia. * **Causes of waves/deflections in the J point (J wave syndromes)**: Brugada syndrome. Early repolarization. T-wave #### Checklist [#checklist-4] * Should be concordant with the QRS complex. Should be positive in most leads. * T-wave progression should be normal in chest leads. * In limb leads the amplitude is highest in lead II, and in the chest leads the amplitude is highest in V2–V3. #### Common findings [#commonfindings-4] * **Normal variants**: An isolated (single) T-wave inversion is accepted in lead V1 and lead III. In some instances the T-wave inversions from childhood may persist in V1–V3(V4), which is called *persistent juvenile T-wave pattern*. Rarely, all T-waves remain inverted, which is called *global idiopathic T-wave inversion* (V1–V6). * **T-wave inversion without simultaneous ST-segment deviation**: This is not a sign of ongoing ischemia, but may be post-ischemic. One type of post-ischemic T-wave inversion is especially acute, namely Wellen’s syndrome (characterized by deep T-wave inversions in V1–V6 in patient with recent episodes of chest pain). Cerebrovascular insult (bleeding). Pulmonary embolism. Perimyocarditis (after normalization of the ST-segment elevation, T-waves become inverted in perimyocarditis). Cardiomyopathy. * **T-wave inversion with simultaneous ST-segment deviation**: acute (ongoing) myocardial ischaemia. * **High T-waves:** Normal variant. Early repolarization. Hyperkalemia. Left ventricular hypertrophy. Left bundle branch block. Occasionally perimyocarditis. High (hyperacute) T-waves may be seen in the very early phase of STEMI. QTc interval and U-wave ### Checklist [#checklist-5] * QTc duration men ≤0,45 s. * QTc duration women ≤0,46 s. * Prolonged QTc duration may cause malignant arrhythmias (torsade de pointes, which is a type of ventricular tachycardia). * Shortened QTc duration (≤0.32 s) is rare, but may also cause malignant ventricular arrhythmias. * The U-wave is seen occasionally, especially in well-trained individuals, and during low heart rate. It is largest in V3–V4. Amplitude is one fourth of T-wave amplitude. ### Common findings [#common-findings] * **Acquired QT prolongation:** anti arrhythmic drugs (procainamide, disopyramide, amiodarone, sotalol), psychiatric medications (tricyclic antidepressants, SSRI, lithium etc); antibiotics (macrolides, kinolones, atovaquone, klorokine, amantadin, foscarnet, atazanavir); hypokalemia, hypocalcemia, hypomagnesemia; cerebrovascular insult (bleeding); myocardial ischemia; cardiomyopathy; bradycardia; hypothyroidism; hypothermia. A complete list of drugs causing QT prolongation can be found [here](https://crediblemeds.org/). * **Congenital QT prolongation:** genetic disease of which there are approximately 15 variants. * **Short QTc syndrome (≤ 0,32 s):** caused by hyperkalcemia and digoxin treatment. May cause malignant ventricular arrhythmia. * **Negative U-wave:** high specificity for heart disease (including ischemia). Clinical context **Compare with earlier ECG** It is fundamental to compare the current ECG with previous recordings. All changes are of interest and may indicate pathology. # Reference (normal) values for echocardiography (/docs/pages/reference-values-for-echocardiography) ## Aorta [#aorta] Aorta ### **Normal values for aorta in 2D echocardiography** [#normal-values-for-aorta-in-2d-echocardiography] | | | | | -------------------- | --------------- | ------------------------- | | | Normal interval | Normal interval, adjusted | | Aortic annulus | 20-31 mm | 12-14 mm/m2 | | Sinus valsalva | 29-45 mm | 15-20 mm/m2 | | Sinotubular junction | 22-36 mm | 13-17 mm/m2 | | Ascending aorta | 22-36 mm | 13-17 mm/m2 | | Aortic arch | 22-36 mm | | | Descending aorta | 20-30 mm | | ​Adjustment refers to adjusting for body surface area (BSA). Aorta, predicted Aorta, standardized ### Standardized values for aorta (mean ± SD) [#standardized-values-for-aorta-mean--sd] | | | | | | | ----- | -------------- | -------------- | ---------- | ------------ | | | Aortic annulus | Sinus valsalva | | | | Age | Women | Men | Women | Men | | \<30 | 11.4 ± 1.1 | 11.4 ± 1.2 | 15.5 ± 1.5 | 15.3 ± 1.8 | | 30–39 | 11.7 ± 1.0 | 11.4 ± 1.1 | 16.5 ± 1.6 | 15.7 ± 1.3\* | | 40–49 | 11.7 ± 1.0 | 11.5 ± 0.9 | 16.8 ± 1.4 | 16.6 ± 1.5 | | 50–59 | 12.0 ± 0.9 | 11.5 ± 0.9 | 17.9 ± 1.6 | 16.8 ± 1.7\* | | 60–69 | 11.7 ± 1.1 | 12.1 ± 1.0 | 17.5 ± 1.7 | 17.8 ± 1.6 | | >70 | 11.6 ± 1.1 | 12.0 ± 1.0 | 18.2 ± 1.9 | 18.1 ± 1.7 | | All | 11.7 ± 1.0 | 11.6 ± 1.0 | 17.0 ± 1.9 | 16.6 ± 1.8 | | | | | | | | ----- | -------------------- | --------------- | ---------- | ------------ | | | Sinotubular junction | Ascending aorta | | | | Age | Women | Men | Women | Men | | \<30 | 13.5 ± 1.4 | 12.7 ± 2.3 | 15.1 ± 1.6 | 14.3 ± 1.6\* | | 30–39 | 14.3 ± 1.5 | 13.3 ± 1.3 | 16.4 ± 1.8 | 14.5 ± 1.4\* | | 40–49 | 14.6 ± 1.2 | 14.1 ± 1.5\* | 16.4 ± 1.4 | 15.5 ± 1.5\* | | 50–59 | 15.7 ± 1.3 | 14.1 ± 1.5 | 18.0 ± 1.4 | 16.2 ± 1.6\* | | 60–69 | 14.7 ± 1.6 | 15.1 ± 1.6\* | 17.6 ± 1.7 | 17.3 ± 1.7 | | >70 | 15.5 ± 2.0 | 14.7 ± 1.6 | 18.2 ± 3.3 | 17.5 ± 1.4 | | All | 14.7 ± 1.7 | 13.9 ± 1.8 | 16.9 ± 2.3 | 15.7 ± 1.8 | | | | | | ----- | ----------- | ------------ | | | Aortic arch | | | Age | Women | Men | | \<30 | 10.7 ± 1.0 | 10.1 ± 1.3\* | | 30–39 | 11.6 ± 1.6 | 10.8 ± 1.3\* | | 40–49 | 11.5 ± 1.2 | 11.3 ± 1.3 | | 50–59 | 12.7 ± 1.1 | 11.3 ± 1.2\* | | 60–69 | 12.5 ± 1.4 | 12.0 ± 1.1 | | >70 | 12.7 ± 1.2 | 12.2 ± 1.3 | | All | 11.9 ± 1.5 | 11.2 ± 1.4 | Aortic valve regurgitation ### Aortic valve regurgitation, normal values [#aortic-valve-regurgitation-normal-values] ### Primary parameters [#primary-parameters] | | | | | | ----------------------------------------------------- | --------------------------- | ---------------------- | -------------------- | | | Mild regurgitation | Moderate regurgitation | Severe regurgitation | | Vena contracta (cm) | \< 0,3 | 0,3-0,6 | > 0,6 | | PHT (pressure half time) – CW doppler | > 500 | 200-500 | \< 200 | | Diastolic flow reversal – PW doppler aorta descendens | if present, early diastolic | early diastolic | holodiastolic | #### Quantification of jet [#quantification-of-jet] | | | | | | ---------------------- | ------------------ | ---------------------- | -------------------- | | | Mild regurgitation | Moderate regurgitation | Severe regurgitation | | Jet-width / LVOT-width | \< 0,25 | 0,25-0,64 | > 0,64 | | Jet-area / LVOT-area | \< 0,05 | 0,05-0,59 | > 0,59 | #### Qualitative parameters [#qualitative-parameters] | | | | | | ------------------------------- | ------------------ | ---------------------- | --------------------------------------- | | | Mild regurgitation | Moderate regurgitation | Severe regurgitation | | Jet area | small | variable | large if central, variable if excentric | | Coaptation defect | mild | moderate | severe | | CW-profile aortic regurgitation | weak | variable | dense | | Size left atrium | normal | normal or enlarged | enlarged | | Size left ventricle | normal | normal or enlarged | enlarged | #### Additional PISA-parameters [#additional-pisa-parameters] | | | | | | ------------------------------ | ------------------ | ---------------------- | -------------------- | | | Mild regurgitation | Moderate regurgitation | Severe regurgitation | | EROA (cm²) | \< 0,10 | 0,10-0,29 | > 0,29 | | Regurgitation volume (ml/beat) | \< 30 | 30-59 | > 59 | | Regurgitation fraction (%) | \< 30 | 30-49 | > 49 | EROA = (CSA\*v)/v(maxMR) \{\{ Flödeshastighet = CSA\*v = 6.28\*r2\*v(aliasing) **References** 1\. Zoghbi, William A.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A.; Kraft, Carol D.; Levine, Robert A. et al. (2003): Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 16 (7), pp. 777–802. DOI: 10.1016/S0894-7317(03)00335-3. 2\. Zoghbi, William A.; Adams, David; Bonow, Robert O.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A. et al. (2017): Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation. A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 30 (4), pp. 303–371. DOI: 10.1016/j.echo.2017.01.007. Aortic valve stenosis ### Aortic valve stenosis [#aortic-valve-stenosis] #### Disease defining parameters [#disease-defining-parameters] | | | | | | ------------------------------ | ------------- | ----------------- | --------------- | | | Mild stenosis | Moderate stenosis | Severe stenosis | | Valve area (cm²) | > 1,5 | 1,0-1,5 | \< 1,0 | | Normalized valve area (cm²/m²) | >0,85 | 0,6-0,85 | \< 0,6 | #### Measured parameters [#measured-parameters] | | | | | | | ------------------------------------ | ---------------- | ------------- | ----------------- | --------------- | | | Aortic sclerosis | Mild stenosis | Moderate stenosis | Severe stenosis | | Mean gradient (mmHg) | | \< 20 | 20-40 | > 40 | | Peak velocity (m/s) | 1,8-2,5 | 2,6-2,9 | 3,0-4,0 | > 4,0 | | Peak gradient (mmHg) | | \< 35 | 35-65 | > 65 | | Velocity ratio (LVOT / aortic valve) | | > 0,5 | 0,5-0,25 | \< 0,25 | #### References [#references] 1\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 22 (1), 1-23; quiz 101-2. DOI: 10.1016/j.echo.2008.11.029. 2\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology 10 (1), pp. 1–25. DOI: 10.1093/ejechocard/jen303. 3\. Vahanian, Alec; Alfieri, Ottavio; Andreotti, Felicita; Antunes, Manuel J.; Barón-Esquivias, Gonzalo; Baumgartner, Helmut et al. (2012): Guidelines on the management of valvular heart disease (version 2012). In European heart journal 33 (19), pp. 2451–2496. DOI: 10.1093/eurheartj/ehs109. 4\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Edvardsen, Thor; Goldstein, Steven et al. (2017): Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis. A Focused Update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 30 (4), pp. 372–392. DOI: 10.1016/j.echo.2017.02.009. ## Left and right ventricle [#left-and-right-ventricle] Visual assessment of systolic function ### Visual assessment of regional wall motion (left ventricle) [#visual-assessment-of-regional-wall-motion-left-ventricle] | | | | | -------------- | --------------------------------------------------------------------------------- | ----------------- | | TYPE OF MOTION | DEFINITION | WALL MOTION SCORE | | Normal | Normal thickening (typically >30% thickening from end-diastole to end-systole). | 1 | | Hypokinesia | Reduced thickening (typically 10–30% thickening from end-diastole to end-systole) | 2 | | Akinesia | Markedly reduced, or no thickening (\<10%) | 3 | | Dyskinesia | Paradoxical thinning and/or outward directed motion during systole | 4 | | Aneurysmatic | Diastolic deformation | 5 | Recommended by American Society for Echocardiography (J Am Soc Echocardiogr 18:1440-1463, 2005). Left ventricular mass and geometry ### **Reference values for left ventricular mass and geometry** [#reference-values-for-left-ventricular-mass-and-geometry] | | | | | | | | | | | ---------------------------- | --------- | -------------- | ------------------- | ----------------- | --------- | --------------- | ------------------- | ----------------- | | | Women | | | | Men | | | | | | Reference | Mildy abnormal | Moderately abnormal | Severely abnormal | Reference | Mildly abnormal | Moderately abnormal | Severely abnormal | | **LINEAR METHOD** | | | | | | | | | | LV mass, g | 67–162 | 163–186 | 187–210 | >211 | 88–224 | 225–258 | 259–292 | >293 | | LV mass/BSA, g/m2 | 43–95 | 96–108 | 109–121 | > 122 | 49–115 | 116–131 | 132–148 | > 149 | | LV mass/height, g/m | 41–99 | 100–115 | 116–128 | >129 | 52–126 | 127–144 | 145–162 | >163 | | LV mass/height 2,7 , g/m2,7 | 18–44 | 45–51 | 52–58 | >59 | 20–48 | 49–55 | 56–63 | >64 | | Relative wall thickness, cm | 0.22–0.42 | 0.43–0.47 | 0.48–0.52 | >0.53 | 0.24–0.42 | 0.43–0.46 | 0.47–0.51 | >0.52 | | Septal thickness, cm | 0.6–0.9 | 1.0–1.2 | 1.3–1.5 | > 1.6 | 0.6–1.0 | 1.1–1.3 | 1.4–1.6 | > 1.7 | | Posterior wall thickness, cm | 0.6–0.9 | 1.0–1.2 | 1.3–1.5 | > 1.6 | 0.6–1.0 | 1.1–1.3 | 1.4–1.6 | > 1.7 | | 2D METOD | | | | | | | | | | LV mass, g | 66–150 | 151–171 | 172–182 | > 193 | 96–200 | 201–227 | 228–254 | > 255 | | LV mass/BSA, g/m2 | 44–88 | 89–100 | 101–112 | > 113 | 50–102 | 103–116 | 117–130 | > 131 | BSA, Body surface area; LV, left ventricular; 2D, 2-dimensional. Left ventricular dimension and volume ### **Referensvärden för vänster kammares storlek** [#referensvärden-för-vänster-kammares-storlek] | | | | | | | | | | | ---------------------------------- | ------------ | --------------- | ------------------- | ----------------- | ------------ | --------------- | ------------------- | ----------------- | | | Women | | | | Men | | | | | | Normal range | Mildly abnormal | Moderately abnormal | Severely abnormal | Normal range | Mildly abnormal | Moderately abnormal | Severely abnormal | | **LV DIMENSIONS** | | | | | | | | | | LV diastolic diameter | 3.9–5.3 | 5.4–5.7 | 5.8–6.1 | >6.2 | 4.2–5.9 | 6.0–6.3 | 6.4–6.8 | >6.9 | | LV diastolic diameter/BSA, cm/m 2 | 2.4–3.2 | 3.3–3.4 | 3.5–3.7 | >3.8 | 2.2–3.1 | 3.2–3.4 | 3.5–3.6 | >3.7 | | LV diastolic diameter/height, cm/m | 2.5–3.2 | 3.3–3.4 | 3.5–3.6 | >3.7 | 2.4–3.3 | 3.4–3.5 | 3.6–3.7 | >3.8 | | **LV VOLUME** | | | | | | | | | | LV diastolic volume, mL | 56–104 | 105–117 | 118–130 | >131 | 67–155 | 156–178 | 179–201 | >201 | | LV diastolic volume/BSA, mL/m 2 | 35–75 | 76–86 | 87–96 | > 97 | 35–75 | 76–86 | 87–96 | > 97 | | LV systolic volume, mL | 19–49 | 50–59 | 60–69 | >70 | 22–58 | 59–70 | 71–82 | >83 | | LV systolic volume/BSA, mL/m 2 | 12–30 | 31–36 | 37–42 | > 43 | 12–30 | 31–36 | 37–42 | > 43 | BSA, body surface area; LV, left ventricular. Left ventricular function (ejection fraction) ### **Reference values for left ventricular function (ejection fraction)** [#reference-values-for-left-ventricular-function-ejection-fraction] | | | | | | | | | | | ------------------------------------ | ------ | --------------- | ------------------- | ----------------- | ------ | --------------- | ------------------- | ----------------- | | | Women | | | | Men | | | | | | Normal | Mildly abnormal | Moderately abnormal | Severely abnormal | Normal | Mildly abnormal | Moderately abnormal | Severely abnormal | | **LINEAR METHOD** | | | | | | | | | | Endocardial fractional shortening, % | 27–45 | 22–26 | 17–21 | \<16 | 25–43 | 20–24 | 15–19 | \<14 | | Midwall fractional shortening, % | 15–23 | 13–14 | 11–12 | \<10 | 14–22 | 12–13 | 10–11 | \<10 | | **2D METOD** | | | | | | | | | | Ejection fraction, % | >55 | 45–54 | 30–44 | \<30 | >55 | 45–54 | 30–44 | \<30 | 2D, Two-dimensional. ### Classification of ejection fraction [#classification-of-ejection-fraction] | | | | | | | -------------------------------------- | ------ | --------------- | ------------------- | ----------------- | | | Normal | Mildly abnormal | Moderately abnormal | Severely abnormal | | Ejection fraction (%), biplan, males | 52-72 | 41-51 | 30-40 | \<30 | | Ejection fraction (%), biplan, females | 54-74 | 41-53 | 30-40 | \<30 | ### References [#references-1] 1\. Lang, Roberto M.; Badano, Luigi P.; Mor-Avi, Victor; Afilalo, Jonathan; Armstrong, Anderson; Ernande, Laura et al. (2015): Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. In European heart journal cardiovascular Imaging 16 (3), pp. 233–270. DOI: 10.1093/ehjci/jev014. 2\. Lang, Roberto M.; Bierig, Michelle; Devereux, Richard B.; Flachskampf, Frank A.; Foster, Elyse; Pellikka, Patricia A. et al. (2005): Recommendations for chamber quantification: a report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 18 (12), pp. 1440–1463. DOI: 10.1016/j.echo.2005.10.005. –>Pubmed-Link Diastolic function | | | | | | | | | -------------------------- | ------------- | ------------- | ----------------------------------------- | ------------------------------------------- | ---------------------------------------------------- | ------------------------------------------------------ | | Criteria | Normal, young | Normal, adult | Abnormal relaxation (grade 1 dysfunction) | Pseudonormal (grade 2 dysfunction) | Reversible restrictive filling (grade 3 dysfunction) | Irreversible restrictive filling (grade 4 dysfunction) | | E/A-ratio | 1–2 | 1–2 | \<1 | 1–1.5 (not reversed with Valsalva maneuver) | >1.5 | 1.5–2.0 (not reversed with Valsalva maneuver) | | Deceleration time (DT), ms | \<240 | 150–240 | ≥240 | 150–200 | \<150 | \<150 | | IVRT (ms) | 70–90 | 70–90 | >90 | \<90 | \<70 | \<70 | | S/D-ratio | \<1 | ≥1 | ≥1 | \<1 | \<1 | \<1 | | ARdur – Adur (ms) | ≥30 | ≤0 | ≤0 or ≥30 | ≥30 | ≥30 | ≥30 | | AR speed (cm/s) | \<35 | \<35 | \<35 | ≥35 | ≥35 | ≥35 | | e’ speed (cm/s) | >10 | >8 | \<8 | \<8 | \<8 | \<8 | Right ventricle & pulmonary artery | | | | | | | ------------------------------------------ | --------------- | --------------- | ------------------- | ----------------- | | | Normal interval | Mildly abnormal | Moderately abnormal | Severely abnormal | | **RV DIMENSIONS** | | | | | | Basal RV diameter (RVD 1), cm | 2.0–2.8 | 2.9–3.3 | 3.4–3.8 | >3.9 | | Mid RV diameter (RVD 2), cm | 2.7–3.3 | 3.4–3.7 | 3.8–4.1 | >4.2 | | Base-to-apex length (RVD 3), cm | 7.1–7.9 | 8.0–8.5 | 8.6–9.1 | >9.2 | | **RVOT DIAMETER** | | | | | | Above aortic valve (RVOT 1), cm | 2.5–2.9 | 3.0–3.2 | 3.3–3.5 | >3.6 | | Above pulmonic valve (RVOT 2), cm | 1.7–2.3 | 2.4–2.7 | 2.8–3.1 | >3.2 | | **PA DIAMETER** | | | | | | Below pulmonic valve (PA 1), cm | 1.5–2.1 | 2.2–2.5 | 2.6–2.9 | >3.0 | | **RV SIZE AND FUNCTION (MEASURED IN A4C)** | | | | | | RV diastolic area, cm2 | 11–28 | 29–32 | 33–37 | >38 | | RV systolic area, cm2 | 7.5–16 | 17–19 | 20–22 | >23 | | RV fractional area change, % | 32–60 | 25–31 | 18–24 | \<17 | ## Left and right atrium [#left-and-right-atrium] Left and right atrium ### **Reference values for atrial size and volume** [#reference-values-for-atrial-size-and-volume] | | | | | | | | | | | ---------------------------------- | ------------ | --------------- | ------------------- | ----------------- | ------------ | --------------- | ------------------- | ----------------- | | | Women | | | | Men | | | | | | Normal range | Mildly abnormal | Moderately abnormal | Severely abnormal | Normal range | Mildly abnormal | Moderately abnormal | Severely abnormal | | **ATRIAL DIMENSIONS** | | | | | | | | | | LA diameter, cm | 2.7–3.8 | 3.9–4.2 | 4.3–4.6 | >4.7 | 3.0–4.0 | 4.1–4.6 | 4.7–5.2 | >5.2 | | LA diameter/BSA, cm/m2 | 1.5–2.3 | 2.4–2.6 | 2.7–2.9 | >3.0 | 1.5–2.3 | 2.4–2.6 | 2.7–2.9 | >3.0 | | RA minor-axis dimension, cm | 2.9–4.5 | 4.6–4.9 | 5.0–5.4 | >5.5 | 2.9–4.5 | 4.6–4.9 | 5.0–5.4 | >5.5 | | RA minor-axis dimension/BSA, cm/m2 | 1.7–2.5 | 2.6–2.8 | 2.9–3.1 | >3.2 | 1.7–2.5 | 2.6–2.8 | 2.9–3.1 | >3.2 | | **ATRIAL AREA** | | | | | | | | | | LA area, cm2 | \<20 | 20–30 | 30–40 | >40 | \<20 | 20–30 | 30–40 | >40 | | **ATRIAL VOLUMES** | | | | | | | | | | LA volume, mL | 22–52 | 53–62 | 63–72 | >73 | 18–58 | 59–68 | 69–78 | >79 | | LA volume/BSA, mL/m2 | 22 ± 6 | 29–33 | 34–39 | >40 | 22 ± 6 | 29–33 | 34–39 | >40 | ​BSA, Body surface area; LA, left atrial; RA, right atrial. ## Mitral valve [#mitral-valve] Mitral valve regurgitation ### Mitral valve regurgitation [#mitral-valve-regurgitation] #### Primary parameters [#primary-parameters-1] | | | | | | ------------------- | -------------------------------- | --------------------------------- | -------------------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Vena contracta (cm) | \< 0,3 | 0,3-0,69 | > 0,69 | | EROA (cm²) | \< 0,20 | 0,20-0,39 | > 0,39 | | Jet size | \< 4cm² or \< 20% of atrial size | 4-10 cm² or 20-40% of atrial size | > 10 cm² or > 40% of atrial size | | Jet orientation | central | variable | excentric | | Pulmonary vein flow | S-dominant | reduced S-wave | systolic flow reversal, | #### Qualitative parameters [#qualitative-parameters-1] | | | | | | ------------------------------------- | ------------------------- | ---------------------- | ------------------------ | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Mitral valve apparatus | normal or mildly abnormal | often abnormal | abnormal, possibly flail | | CW-profile mitral regurgitation | weak | variable | dense | | Shape CW-profile mitral regurgitation | parabolic | variable | early peak, triangular | | Size left atrium | normal | normal or dilated | dilated | | Size left ventricle | normal | normal or dilated | dilated | Additional PISA-parameters | | | | | | --------------------------------- | ----------------- | ---------------------- | -------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Regurgitation volume (ml/beat) | \< 30 | 30-59 | > 59 | | Regurgitation volume = EROA x TVI | | | | | Regurgitation fraction (%) | \< 30 | 30-49 | > 49 | Miscellaneous parameters | | | | | | ----------------------- | ----------------- | ---------------------- | -------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | PW-Doppler mitral valve | A dominant | variable | high E values | #### ​References [#references-2] 1\. Zoghbi, William A.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A.; Kraft, Carol D.; Levine, Robert A. et al. (2003): Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 16 (7), pp. 777–802. DOI: 10.1016/S0894-7317(03)00335-3. 2\. Zoghbi, William A.; Adams, David; Bonow, Robert O.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A. et al. (2017): Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation. A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 30 (4), pp. 303–371. DOI: 10.1016/j.echo.2017.01.007. –>Pubmed-Link​ Mitral valve stenosis ### Mitral valve stenosis [#mitral-valve-stenosis] #### Primary parameters [#primary-parameters-2] | | | | | | ------------- | ------------- | ----------------- | --------------- | | | Mild stenosis | Moderate stenosis | Severe stenosis | | Valve area | > 1,5 cm² | 1,5 – 1,0 cm² | \< 1,0 cm² | | Mean gradient | \< 5 mmHg | 5-10 mmHg | > 10 mmHg | #### Additional parameters [#additional-parameters] | | | | | | ------------------------- | ------------- | ----------------- | --------------- | | | Mild stenosis | Moderate stenosis | Severe stenosis | | Pulmonary artery pressure | \<30 | 30-50 | >50 | #### References [#references-3] 1\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology 10 (1), pp. 1–25. DOI: 10.1093/ejechocard/jen303. 2\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 22 (1), 1-23; quiz 101-2. DOI: 10.1016/j.echo.2008.11.029. 3\. Vahanian, Alec; Alfieri, Ottavio; Andreotti, Felicita; Antunes, Manuel J.; Barón-Esquivias, Gonzalo; Baumgartner, Helmut et al. (2012): Guidelines on the management of valvular heart disease (version 2012). In European heart journal 33 (19), pp. 2451–2496. DOI: 10.1093/eurheartj/ehs109. ## Tricuspid valve [#tricuspid-valve] Tricuspid valve regurgitation ### Tricuspid valve regurgitation [#tricuspid-valve-regurgitation] #### Primary parameters [#primary-parameters-3] | | | | | | ------------------- | ----------------- | ---------------------- | ------------------------------------------------ | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | PISA radius | \< 0,6 | 0,6-0,9 | > 0,9 | | Vena contracta (cm) | not defined | \< 0,7 | > 0,7 | | Liver vein flow | S-dominant | Reduced S-wave | systolic flow reversal, jet reaching liver veins | #### Additional quantitative parameters [#additional-quantitative-parameters] | | | | | | ----------------------- | -------------------------- | ---------------------- | --------------------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Jet size | \< 5cm² | 5-10 cm² | > 10 cm² | | size vena cava inferior | \< 2,1 cm and compressible | in between | > 2,1 cm, almost not compressible | #### Additional qualitative parameters [#additional-qualitative-parameters] | | | | | | ---------------------------------------- | ----------------- | ---------------------- | ---------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Coaptation defect | mild | moderate | severe | | Size right ventricle | normal | normal or enlarged | enlarged | | Size right atrium | normal | normal or enlarged | enlarged | | CW-profile tricuspid regurgitation | weak | variable | dense | | Shape CW-profile tricuspid regurgitation | parabolic | variable | early peak, triangular | #### References [#references-4] 1\. Zoghbi, William A.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A.; Kraft, Carol D.; Levine, Robert A. et al. (2003): Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 16 (7), pp. 777–802. DOI: 10.1016/S0894-7317(03)00335-3. 2\. Zoghbi, William A.; Adams, David; Bonow, Robert O.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A. et al. (2017): Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation. A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 30 (4), pp. 303–371. DOI: 10.1016/j.echo.2017.01.007. –>Pubmed-Link Tricuspid valve stenosis ### Tricuspid valve stenosis [#tricuspid-valve-stenosis] | | | | ----------------------------------------------------- | ---------------- | | Mean pressure gradient | ≥ 5 mmHg | | Valve area according to the continuity equation (cm²) | ≤ 1 cm² | | ZTime-velocity-integral of the tricuspid inflow (cm) | > 60 cm | | Pressure half time (T ½,ms) | ≥ 190 ms | | Right atrium | Severly enlarged | | Vena cava inferior | enlarged | #### References [#references-5] 1\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology 10 (1), pp. 1–25. DOI: 10.1093/ejechocard/jen303. 2\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 22 (1), 1-23; quiz 101-2. DOI: 10.1016/j.echo.2008.11.029. –>Pubmed-Link ## Pulmonary valve [#pulmonary-valve] Pulmonary valve regurgitation ### Pulmonary valve regurgitation [#pulmonary-valve-regurgitation] | | | | | | ----------------------------- | -------------------------------------- | ---------------------- | -------------------------------------------------------------- | | | Mild regurgiation | Moderate regurgitation | Severe regurgitation | | Pulmonary valve morphology | normal | normal/abnormal | abnormal | | Density CW-Doppler | weak, slow deceleration | variable | dense, steep deceleration, early termination of diastolic flow | | Jet width colour Doppler | small,, \< 10 mm length, narrow origin | variable | large, wide origin | | Ratio pulmonic to aortic flow | normal | variable | significantly increased | #### References [#references-6] 1\. Zoghbi, William A.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A.; Kraft, Carol D.; Levine, Robert A. et al. (2003): Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 16 (7), pp. 777–802. DOI: 10.1016/S0894-7317(03)00335-3. 2\. Zoghbi, William A.; Adams, David; Bonow, Robert O.; Enriquez-Sarano, Maurice; Foster, Elyse; Grayburn, Paul A. et al. (2017): Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation. A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 30 (4), pp. 303–371. DOI: 10.1016/j.echo.2017.01.007. 3\. Lancellotti, Patrizio; Tribouilloy, Christophe; Hagendorff, Andreas; Moura, Luis; Popescu, Bogdan A.; Agricola, Eustachio et al. (2010): European Association of Echocardiography recommendations for the assessment of valvular regurgitation. Part 1: aortic and pulmonary regurgitation (native valve disease). In European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology 11 (3), pp. 223–244. DOI: 10.1093/ejechocard/jeq030. Pulmonary valve stenosis ### Pulmonary valve stenosis [#pulmonary-valve-stenosis] | | | | | | -------------------- | ------------- | ----------------- | --------------- | | | Mild stenosis | Moderate stenosis | Severe stenosis | | Peak velocity (m/s) | \< 3 | 43528 | > 4 | | Peak gradient (mmHg) | \< 36 | 36-64 | > 64 | #### References [#references-7] 1\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology 10 (1), pp. 1–25. DOI: 10.1093/ejechocard/jen303. 2\. Baumgartner, Helmut; Hung, Judy; Bermejo, Javier; Chambers, John B.; Evangelista, Arturo; Griffin, Brian P. et al. (2009): Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. In Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 22 (1), 1-23; quiz 101-2. DOI: 10.1016/j.echo.2008.11.029. –>Pubmed-Link Figure 1. Standardized myocardial segmentation and nomenclature for echocardiography. The left ventricle is divided into 17 segments for 2D echocardiography. One can identify these segments in multiple views. Figure 2. Display, on a circumferential polar plot, of the 17 myocardial segments and the recommended nomenclature for tomographic imaging of the heart. Figure 3. Assignment of the 17 myocardial segments to the territories of the left anterior descending (LAD), right coronary artery (RCA), and the left circumflex coronary artery (LCX). # Reference (normal) values for pediatric & neonatal ECG interpretation (/docs/pages/reference-values-for-pediatric-ecg-interpretation) ## Neonatal period [#neonatal-period] #### Table 1. Normal limits for ECG parameters during neonatal period (Davignon et al) [#table-1-normal-limits-for-ecg-parameters-during-neonatal-period-davignon-et-al] These reference values are the best available for the neonatal period. The intervals are 98% confidence intervals (the mean is presented in the parenthesis). Values without confidence interval are simply the 98th percentile (i.e the upper reference limit). | Age | \<1 day | 1–3 days | 3–7 days | 7–30 days | 1–3 months | 3–6 months | 6–12 months | 1–3 years | 3–5 years | 5–8 years | 8–12 years | 12–16 years | >16 years | | ----------------------------- | ------------- | ------------- | ------------- | ------------- | ------------- | ------------- | ------------- | ------------- | ------------ | ------------ | ------------ | ------------ | ----------- | | Heart rate (beats per minute) | 93–155 (122) | 91–158 (124) | 90–166 (128) | 106–182 (148) | 120–179 (149) | 105–185 (142) | 107–168 (132) | 90–151 (119) | 73–137 (108) | 65–133 (100) | 63–129 (92) | 66–120 (86) | 50 – 120 | | Electrical axis (degrees) | 58–168 (>135) | 65–171 (>134) | 76–168 (>133) | 65–159 (110) | 31–115 (75) | 7–105 (60) | 7–98 (54) | 8–100 (55) | 7–104 (55) | 10–140 (66) | 9–115 (61) | 11–133 (58) | -15 – 110 | | QRS duration | 21–76 | 22–67 | 21–68 | 22–79 | 23–75 | 22–79 | 23–76 | 27–75 | 30–72 | 32–79 | 32–85 | 34–88 | 0.05 – 0.10 | | PR interval | 79–160 (107) | 81–139 (108) | 75–137 (104) | 73–138 (101) | 73–130 (98) | 74–145 (106) | 73–156 (156) | 82–148 (114) | 85–161 (118) | 90–164 (124) | 87–171 (128) | 92–175 (135) | 0.12 – 0.20 | | Q-wave in III (mm) | 0.1–5 | 0.1–5 | 0.1–5 | 0.1–5 | 0.1–5 | \<6.6 | \<6.3 | \<5.3 | \<4.2 | \<3.2 | \<2.7 | \<3.0 | \<3 | | R-wave in V1 (mm) | 5–27 (14) | 5–27 (15) | 3–25 (13) | 3–22 (11) | 3–19 (10) | 3–20 (10) | 2–20 (9) | 3–18 (9) | 2–18 (8) | 1–13 (7) | 0.5–10 (6) | 0.5–10 (5) | 0.5 – 14 | | S-wave in V1 (mm) | 0.5–23 (9) | 0.5–21 (10) | 0.5–17 (7) | 0.5–12 (4) | 0.5–13 (5) | 0.5–17 (6) | 0.5–18 (7) | 1–21 (9) | 2–22 (10) | 3–24 (12) | 3–26 (12) | 3–22 (11) | 0.5 – 23 | | R/S-ratio in V1 | 0.2–9.8 (2.3) | 0.2–6.0 (2.0) | 0.2–9.8 (2.8) | 1.0–7.0 (2.9) | 0.3–7.5 (2.3) | 0.2–6.0 (2.4) | 0.1–3.9 (1.8) | 0.1–4.2 (1.4) | 0–2.8 (0.9) | 0–2.0 (0.8) | 0–1.9 (0.6) | 0–1.8 (0.5) | | | R-wave in V6 (mm) | 0–12 (5) | 0.1–12 (5) | 0.5–12 (5) | 3–17 (8) | 5–22 (12) | 6–23 (14) | 6–23 (13) | 6–23 (14) | 9–25 (15) | 9–27 (17) | 10–26 (17) | 7–23 (15) | 4 – 21 | | S-wave in V6 (mm) | 0.2–10 (4) | 0.2–10 (3) | 0.4–10 (4) | 0.2–10 (3) | 0.3–7 (3) | 0.2–10 (3) | 0.2–8 (2) | 0.1–7 (2) | 0.1–6 (2) | 0.1–4 (1) | 0.0–4 (1) | 0–4 (1) | 0 – 4 | | R/S-ratio in V6 | 0.5–9 (2.5) | 0.5–11 (3) | 0.5–10 (2.5) | 0.5–12 (4) | 0.5–12 (4.5) | 0.5–18 (6.5) | 0.5–22 (8) | 0.5–28 (9.5) | 0.8–30 (11) | 1–30 (12) | 2–33 (14) | 2–39 (15) | | ## Childhood, overview [#childhood-overview] #### Table 2. Reference values for the most important parameters (Rijnbeek et al) [#table-2-reference-values-for-the-most-important-parameters-rijnbeek-et-al] Numbers are medians with 2nd and 98th percentile in parenthesis. These numbers were published by Rijnbeek et al and are currently the most reliable for patients aged 1 month to 16 years. Reference values for patients aged \<1 month are less reliable due to the small sample size in Rijnbeek et al. Therefore, Davignon et al is preferred for patients aged \<1 month. |   |   | 0–1 month | 1–3 months | 3–6 months | 6–12 months | 1–3 years | 3–5 years | 5–8 years | 8–12 years | 12–16 years | | ----------------------------------- | ----- | -------------- | -------------- | -------------- | -------------- | -------------- | -------------- | -------------- | -------------- | -------------- | | Heart rate (beats per minute) | Boys | 160 (129, 192) | 152 (126, 187) | 134 (112, 165) | 128 (106, 194) | 119 (97, 155) | 98 (73, 123) | 88 (62, 113) | 78 (55, 101) | 73 (48, 99) | | | Girls | 155 (136, 216) | 154 (126, 200) | 139 (122, 191) | 134 (106, 187) | 128 (95, 178) | 101 (78, 124) | 89 (68, 115) | 80 (58, 110) | 76 (54, 107) | | P-wave electrical axis (degrees) | Boys | 56 (13, 99) | 52 (10, 73) | 49 (–5, 70) | 49 (9, 87) | 48 (–12, 78) | 43 (–13, 69) | 41 (–54, 72) | 39 (–17, 76) | 40 (–24, 76) | | | Girls | 52 (24, 80) | 48 (20, 77) | 51 (16, 80) | 50 (14, 69) | 47 (1, 90) | 44 (–6, 90) | 42 (–13, 77) | 42 (–15, 82) | 45 (–18, 77) | | P-wave duration (ms) | Boys | 78 (64, 85) | 79 (65, 98) | 81 (64, 103) | 80 (66, 96) | 80 (63, 113) | 87 (67, 102) | 92 (73, 108) | 98 (78, 117) | 100 (82, 118) | | | Girls | 79 (69, 106) | 78 (62, 105) | 78 (63, 106) | 80 (64, 07) | 83 (62, 104) | 84 (66, 101) | 89 (71, 107) | 94 (75, 114) | 98 (78, 122) | | PR interval (ms) | Boys | 99 (77, 120) | 98 (85, 120) | 106 (87, 134) | 114 (82, 141) | 118 (86, 151) | 121 (98, 152) | 129 (99, 160) | 134 (105, 174) | 139 (107, 178) | | | Girls | 101 (91, 121) | 99 (78, 133) | 106 (84, 127) | 109 (88, 133) | 113 (78, 147) | 123 (99, 153) | 124 (92, 156) | 129 (103, 163) | 135 (106, 176) | | Electrical (QRS) axis (degres) | Boys | 97 (75, 140) | 87 (37, 138) | 66 (–6, 107) | 68 (14, 122) | 64 (–4, 118) | 70 (7, 112) | 70 (–10, 112) | 70 (–21, 114) | 65 (–9, 112) | | | Girls | 110 (63, 155) | 80 (39, 121) | 70 (17, 108) | 67 (1, 102) | 69 (2, 121) | 69 (3, 106) | 74 (27, 117) | 66 (5, 117) | 66 (5, 101) | | QRS duration (ms) | Boys | 67 (50, 85) | 64 (52, 77) | 66 (54, 85) | 69 (52, 86) | 71 (54, 88) | 75 (58, 92) | 80 (63, 98) | 85 (67, 103) | 91 (78, 111) | | | Girls | 67 (54, 79) | 63 (48, 77) | 64 (50, 78) | 64 (52, 80) | 68 (54, 85) | 71 (58, 88) | 77 (59, 95) | 82 (66, 99) | 87 (72, 106) | | QTc interval (ms, Bazzet's formula) | Boys | 413 (378, 448) | 419 (396, 458) | 422 (391, 453) | 411 (379, 449) | 412 (383, 455) | 412 (377, 448) | 411 (371, 443) | 411 (373, 440) | 407 (362, 449) | | | Girls | 420 (379, 462) | 424 (381, 454) | 418 (386, 448) | 414 (381, 446) | 417 (381, 447) | 415 (388, 442) | 409 (375, 449) | 410 (365, 447) | 414 (370, 457) | ## Childhood, P-waves [#childhood-p-waves] #### Table 3. Reference values for P-wave amplitude (Rijnbeek et al) [#table-3-reference-values-for-p-wave-amplitude-rijnbeek-et-al] Numbers are median with 98th percentile (i.e the upper reference limit) in parenthesis. All values are millivolt (mV). Multiply by 10 to transform to millimeters (mm). | Lead |   | 0–1 month | 1–3 months | 3–6 months | 6–12 months | 1–3 years | 3–5 years | 5–8 years | 8–12 years | 12–16 years | | ---- | ----- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | | II | Boys | 0.15 (0.23) | 0.16 (0.25) | 0.15 (0.22) | 0.16 (0.26) | 0.15 (0.25) | 0.13 (0.23) | 0.12 (0.22) | 0.12 (0.22) | 0.13 (0.24) | | | Girls | 0.16 (0.25) | 0.16 (0.23) | 0.16 (0.23) | 0.16 (0.24) | 0.16 (0.25) | 0.13 (0.23) | 0.12 (0.24) | 0.14 (0.24) | 0.15 (0.26) | | V1 | Boys | 0.12 (0.22) | 0.10 (0.19) | 0.09 (0.17) | 0.10 (0.17) | 0.13 (0.20) | 0.12 (0.19) | 0.12 (0.20) | 0.11 (0.19) | 0.11 (0.18) | | | Girls | 0.10 (0.19) | 0.10 (0.16) | 0.10 (0.16) | 0.11 (0.21) | 0.12 (0.20) | 0.12 (0.20) | 0.11 (0.18) | 0.11 (0.19) | 0.10 (0.17) | ## Childhood, Q-waves [#childhood-q-waves] #### Table 4. Reference values for Q-wave amplitude (Rijnbeek et al) [#table-4-reference-values-for-q-wave-amplitude-rijnbeek-et-al] Numbers are median with 98th percentile (i.e the upper reference limit) in parenthesis. All values are millivolt (mV). Multiply by 10 to transform to millimeters (mm). | Lead |   | 0–1 month | 1–3 months | 3–6 months | 6–12 months | 1–3 years | 3–5 years | 5–8 years | 8–12 years | 12–16 years | | ---- | ------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | | II | Pojkar | 0.14 (0.23) | 0.18 (0.32) | 0.14 (0.34) | 0.18 (0.48) | 0.15 (0.44) | 0.11 (0.26) | 0.10 (0.28) | 0.09 (0.24) | 0.08 (0.21) | | | Flickor | 0.09 (0.26) | 0.14 (0.32) | 0.15 (0.43) | 0.16 (0.44) | 0.16 (0.48) | 0.13 (0.27) | 0.08 (0.26) | 0.08 (0.21) | 0.09 (0.20) | | III | Pojkar | 0.15 (0.26) | 0.29 (0.50) | 0.31 (0.71) | 0.35 (0.79) | 0.30 (0.74) | 0.19 (0.46) | 0.15 (0.36) | 0.10 (0.28) | 0.10 (0.29) | | | Flickor | 0.18 (0.35) | 0.24 (0.50) | 0.28 (0.65) | 0.34 (0.79) | 0.31 (0.73) | 0.18 (0.40) | 0.16 (0.38) | 0.10 (0.27) | 0.10 (0.21) | | aVF | Pojkar | 0.13 (0.23) | 0.20 (0.35) | 0.20 (0.40) | 0.22 (0.58) | 0.20 (0.54) | 0.14 (0.34) | 0.12 (0.25) | 0.09 (0.25) | 0.08 (0.23) | | | Flickor | 0.10 (0.27) | 0.17 (0.35) | 0.20 (0.44) | 0.23 (0.52) | 0.20 (0.54) | 0.12 (0.31) | 0.11 (0.31) | 0.08 (0.21) | 0.09 (0.18) | | V6 | Pojkar | 0.11 (0.22) | 0.16 (0.31) | 0.17 (0.35) | 0.20 (0.60) | 0.20 (0.56) | 0.15 (0.42) | 0.12 (0.39) | 0.12 (0.43) | 0.11 (0.43) | | | Flickor | 0.09 (0.17) | 0.15 (0.37) | 0.15 (0.40) | 0.18 (0.39) | 0.17 (0.49) | 0.15 (0.42) | 0.10 (0.41) | 0.11 (0.34) | 0.09 (0.23) | ## Childhood, R-waves [#childhood-r-waves] ## Table 5. Normal limits for R-wave amplitude (Rijnbeek et al) [#table-5-normal-limits-for-r-wave-amplitude-rijnbeek-et-al] Numbers are median with 98th percentile (i.e the upper reference limit) in parenthesis. All values are millivolt (mV). Multiply by 10 to transform to millimeters (mm). | Lead |   | 0–1 month | 1–3 months | 3–6 months | 6–12 months | 1–3 years | 3–5 years | 5–8 years | 8–12 years | 12–16 years | | ---- | ----- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | | I | Boys | 0.25 (0.45) | 0.56 (1.12) | 0.80 (1.52) | 0.82 (1.52) | 0.77 (1.37) | 0.63 (1.09) | 0.62 (1.16) | 0.59 (1.04) | 0.58 (1.09) | | | Girls | 0.31 (0.62) | 0.55 (1.09) | 0.74 (1.26) | 0.75 (1.38) | 0.68 (1.52) | 0.65 (1.20) | 0.49 (1.00) | 0.54 (1.21) | 0.48 (1.02) | | II | Boys | 0.64 (1.28) | 1.08 (1.76) | 1.27 (1.97) | 1.27 (2.09) | 1.27 (2.47) | 1.36 (2.20) | 1.24 (2.42) | 1.39 (2.23) | 1.31 (2.08) | | | Girls | 0.70 (1.21) | 1.15 (2.04) | 1.33 (2.24) | 1.35 (2.21) | 1.27 (2.34) | 1.38 (2.24) | 1.33 (2.27) | 1.32 (2.29) | 1.32 (2.03) | | III | Boys | 0.79 (1.44) | 0.76 (1.60) | 0.72 (1.50) | 0.82 (1.65) | 0.80 (1.96) | 0.94 (1.82) | 0.80 (1.92) | 0.89 (1.86) | 0.85 (1.74) | | | Girls | 0.85 (1.50) | 0.91 (1.82) | 0.95 (1.85) | 0.90 (1.95) | 0.96 (2.00) | 0.94 (1.96) | 1.03 (2.09) | 0.92 (1.88) | 0.88 (1.66) | | aVL | Boys | 0.16 (0.32) | 0.35 (0.66) | 0.40 (1.09) | 0.44 (1.04) | 0.38 (0.86) | 0.26 (0.58) | 0.22 (0.70) | 0.17 (0.52) | 0.19 (0.69) | | | Girls | 0.18 (0.45) | 0.25 (0.69) | 0.37 (0.78) | 0.40 (0.92) | 0.38 (1.02) | 0.24 (0.70) | 0.18 (0.55) | 0.17 (0.69) | 0.16 (0.53) | | aVF | Boys | 0.59 (1.36) | 0.88 (1.58) | 0.93 (1.70) | 0.96 (1.81) | 1.00 (2.20) | 1.13 (1.97) | 1.00 (2.19) | 1.16 (2.00) | 1.06 (1.88) | | | Girls | 0.72 (1.26) | 0.98 (1.91) | 1.07 (1.82) | 1.11 (2.04) | 1.10 (2.08) | 1.14 (2.06) | 1.20 (2.17) | 1.09 (2.06) | 1.10 (1.84) | | V3R | Boys | 0.62 (1.04) | 0.58 (1.24) | 0.57 (1.20) | 0.48 (1.24) | 0.49 (1.06) | 0.41 (0.81) | 0.23 (0.63) | 0.22 (0.51) | 0.19 (0.54) | | | Girls | 0.68 (1.26) | 0.55 (0.93) | 0.49 (1.11) | 0.42 (0.98) | 0.43 (0.92) | 0.34 (0.64) | 0.21 (0.57) | 0.19 (0.47) | 0.17 (0.49) | | V1 | Boys | 1.10 (2.05) | 1.23 (2.07) | 1.32 (2.20) | 1.12 (2.14) | 1.08 (2.11) | 0.95 (1.78) | 0.63 (1.48) | 0.54 (1.14) | 0.48 (1.18) | | | Girls | 1.35 (2.22) | 1.17 (1.99) | 1.14 (2.04) | 1.01 (1.92) | 1.01 (1.91) | 0.77 (1.38) | 0.55 (1.24) | 0.49 (1.14) | 0.35 (1.10) | | V2 | Boys | 1.83 (2.67) | 1.82 (2.63) | 2.08 (2.54) | 1.94 (2.51) | 1.82 (2.41) | 1.58 (2.26) | 1.21 (2.22) | 1.02 (1.90) | 0.94 (1.87) | | | Girls | 1.83 (2.17) | 1.81 (2.45) | 1.88 (2.60) | 1.82 (2.36) | 1.75 (2.38) | 1.41 (2.25) | 1.06 (1.91) | 0.90 (1.86) | 0.69 (1.57) | | V4 | Boys | 1.80 (2.62) | 2.30 (3.05) | 2.32 (3.23) | 2.27 (3.32) | 2.37 (3.38) | 2.42 (3.30) | 2.11 (3.11) | 1.86 (3.16) | 1.87 (3.06) | | | Girls | 1.68 (2.21) | 2.26 (3.26) | 2.26 (3.31) | 2.23 (3.09) | 2.21 (3.54) | 2.24 (3.38) | 1.84 (3.04) | 1.72 (3.23) | 1.24 (2.55) | | V6 | Boys | 1.00 (1.78) | 1.55 (2.23) | 1.65 (2.73) | 1.70 (2.79) | 1.79 (2.96) | 1.94 (3.14) | 1.97 (2.98) | 2.18 (3.24) | 2.02 (3.05) | | | Girls | 0.93 (1.64) | 1.51 (2.67) | 1.60 (2.80) | 1.68 (2.74) | 1.68 (2.67) | 1.89 (2.91) | 2.05 (3.25) | 2.00 (3.04) | 1.65 (2.52) | # Manuals and reference values (/docs/pages/reference-values) ### Reference values [#-reference-values] Reference values for echocardiography Reference values for ECG - Adult Reference values for ECG - Pediatric ### Emergency manuals [#-emergency-manuals] Acute ventricular tachyarrhythmias (ventricular tachycardia, ventricular fibrillation) Hypertensive emergency (crisis) - Drugs, doses and administration List of drugs that prolong QT interval and cause torsade de pointes (TdP) Inotropes and Vasopressors: Doses, indications, contraindications and effects Conversion table for heart rate and cycle length # The best membership for learning ECG & echo (/docs/pages/shop-e-books-courses) You have already purchased **Clinical Echocardiography**, which gives you access to all echocardiography lessons. 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The most current version of the Terms will supersede all previous versions. RRAB encourages you to periodically review the Terms to stay informed of our updates. Contact us here Effective as of November 01, 2018 # The ultimate ECG book & course: learn ECG interpretation, videos, test/quiz (/docs/pages/ultimate-ecg-book-course-learn-ecg-interpretation-videos-test-quiz) # Master ECG, Echocardiography & Clinical Cardiology Now. [#master-ecg-echocardiography--clinical-cardiology-now] #### Acquire the clinical skills you need with the world's most popular e-book, video lectures and tests [#acquire-the-clinical-skills-you-need-with-the-worlds-most-popular-e-book-video-lectures-and-tests] Get started # Master ECG, Echocardiography & Clinical Cardiology Now. [#master-ecg-echocardiography--clinical-cardiology-now-1] Get started ECG book Echo book ## Audiobooks now available [#audiobooks-now-available] We are excited to announce that we have started creating audiobooks for all our online courses! This new format allows you to learn on the go, making it easier than ever to access our comprehensive content anytime, anywhere. Whether you’re commuting, exercising, or relaxing, you can now enhance your knowledge with our engaging audiobook versions. Listen ## Clearly illustrated [#clearly-illustrated] ## Recently Updated [#recently-updated] ## New Cardiology Board Exams [#new-cardiology-board-exams] Prepare for the Cardiology Board Exam with our comprehensive quiz. All questions have been checked for consistency with guidelines issued by the American Heart Association (AHA) and American College of Cardiology (ACC) and European Society for Cardiology (ESC). The quiz encompasses every topic from the guidelines, ensuring a thorough and current review. Take Exam ## New Guideline Summaries [#new-guideline-summaries] Get our comprehensive, up-to-date clinical guideline summaries based on the latest AHA, ACC, and ESC recommendations. These summaries are now available for download, providing a reliable and convenient resource for clinical decision-making. [](/img/2024/07/antiplatelet-therapy-in-acute-coronary-syndromes-stemi-nstemi-unstable-angina-aspirin-asa-ticagrelor-prasugrel-1.webp) [](/img/2024/07/reperfusion-strategies-guidelines-stemi-nstemi-pci-fibrinolysis-revascularization.webp) [](/img/2024/08/acute-coronary-syndromes-pci-angiography-fibrinolysis-nstemi-stemi-primary-pci-indications.webp) ## Search [#search] Find anything from ST-segment depressions to heart failure management ## Track your progress, test results and get certificates [#track-your-progress-test-results-and-get-certificates] Get our comprehensive, up-to-date clinical guideline summaries based on the latest AHA, ACC, and ESC recommendations. These summaries are now available for download, providing a reliable and convenient resource for clinical decision-making. ## Comprehensive, Richly Illustrated, and Evidence-Based [#comprehensive-richly-illustrated-and-evidence-based] Figure 1A. Detailed diagram of coronary artery segments. CT = computerized tomography. ## Echocardiography Made Easy [#echocardiography-made-easy] Our new e-book *Clinical Echocardiography* enables you to use echocardiography to its fullest potential in your initial diagnosis, decision making, and clinical management of patients with a wide range of heart diseases. ## Video Lectures Included [#video-lectures-included] ## Created by clinical experts. [#created-by-clinical-experts] # Exams (/docs/quizzes) Answer each question to see instantly whether you were right. Progress is saved, so you can stop and resume later. ## Sitting a certification exam? [#sitting-a-certification-exam] These banks use the single-best-answer, clinical-stem format that the major cardiology certification examinations are built on. If you are preparing for one, start with the format itself: * [European Exam in Core Cardiology (EECC)](/docs/board-exams/european-exam-in-core-cardiology-eecc) — 120 questions in three hours, sat online across Europe * [Board certification in the USA and Canada](/docs/board-exams/cardiology-board-certification-usa-canada) — the ABIM Cardiovascular Disease exam and the Royal College examination # Clinical Tools (/docs/tools) Point-of-care tools for clinicians. ### [Calculators](/docs/tools/calculators) [#calculators] * [Albumin-corrected calcium](/docs/tools/calculators/corrected-calcium) * [Anion gap (with albumin correction)](/docs/tools/calculators/anion-gap) * [Aortic valve area (continuity equation)](/docs/tools/calculators/aortic-valve-area) * [BMI and body surface area](/docs/tools/calculators/bmi-bsa) * [Cardiac output (Fick principle)](/docs/tools/calculators/fick-cardiac-output) * [CHA₂DS₂-VASc score](/docs/tools/calculators/cha2ds2-vasc) * [CHADS₂ score](/docs/tools/calculators/chads2) * [Corrected QT interval (QTc)](/docs/tools/calculators/qtc) * [Creatinine clearance (Cockcroft–Gault)](/docs/tools/calculators/cockcroft-gault) * [Duke treadmill score](/docs/tools/calculators/duke-treadmill-score) * [eGFR — CKD-EPI 2021 (creatinine)](/docs/tools/calculators/ckd-epi-2021) * [eGFR — MDRD study equation](/docs/tools/calculators/egfr-mdrd) * [Fractional shortening and Teichholz ejection fraction](/docs/tools/calculators/fractional-shortening) * [HAS-BLED score](/docs/tools/calculators/has-bled) * [HEART score for chest pain](/docs/tools/calculators/heart-score) * [Killip classification](/docs/tools/calculators/killip-class) * [LDL cholesterol — Friedewald equation](/docs/tools/calculators/ldl-friedewald) * [LDL cholesterol — Sampson equation](/docs/tools/calculators/ldl-sampson) * [Left ventricular mass and geometry](/docs/tools/calculators/lv-mass-index) * [Mean arterial pressure (MAP)](/docs/tools/calculators/mean-arterial-pressure) * [Mitral valve area (pressure half-time)](/docs/tools/calculators/mitral-valve-area-pht) * [Pulmonary Embolism Severity Index (PESI)](/docs/tools/calculators/pesi) * [Revised Geneva score for pulmonary embolism](/docs/tools/calculators/revised-geneva) * [Shunt fraction (Qp/Qs)](/docs/tools/calculators/qp-qs-shunt-fraction) * [Simplified PESI (sPESI)](/docs/tools/calculators/spesi) * [Sodium correction for hyperglycaemia](/docs/tools/calculators/sodium-correction-hyperglycemia) * [Stroke volume & cardiac output (LVOT VTI)](/docs/tools/calculators/stroke-volume-cardiac-output) * [Systemic and pulmonary vascular resistance](/docs/tools/calculators/vascular-resistance) * [TIMI risk score for STEMI](/docs/tools/calculators/timi-stemi) * [TIMI risk score for UA/NSTEMI](/docs/tools/calculators/timi-nstemi) * [Wells score for deep vein thrombosis](/docs/tools/calculators/wells-dvt) * [Wells score for pulmonary embolism](/docs/tools/calculators/wells-pe) * [1-2-3-LQTS Risk Calculator](/docs/tools/calculators/1-2-3-lqts-risk-calculator) * [Adjusted aortic root dimension](/docs/tools/calculators/adjusted-aortic-root-dimension) * [ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) Bleeding Risk Score](/docs/tools/calculators/atria-anticoagulation-and-risk-factors-in-atrial-fibrillation-bleeding-risk-scor) * [Brugada’s algorithm for diagnosing ventricular tachycardia (VT)](/docs/tools/calculators/brugadas-algorithm-for-distinguishing-ventricular-tachycardia-vt-from-supraventr) * [CHADS-VA Bleeding Risk Score](/docs/tools/calculators/chads-va-bleeding-risk-score) * [HCM Risk-SCD Calculator](/docs/tools/calculators/hcm-risk-calculator) * [HEMORR₂HAGES Bleeding Risk Score](/docs/tools/calculators/hemorr-e2-82-82hages-bleeding-risk-score) * [SYNTAX Score](/docs/tools/calculators/syntax-score) * [SYNTAX Score II](/docs/tools/calculators/syntax-score-ii) * [Vernakalant (Brinavess)](/docs/tools/calculators/vernakalant-brinavess) ### [Reference values](/docs/tools/reference-values) [#reference-values] * [Reference values for adult ECG](/docs/tools/reference-values/reference-values-for-adult-ecg) * [Reference values for pediatric and neonatal ECG](/docs/tools/reference-values/reference-normal-values-for-pediatric-neonatal-ecg-interpretation) * [Heart rate and cycle length conversion table](/docs/tools/reference-values/heart-rate-and-cycle-length-conversion-table) **Echocardiography** * [Left ventricular dimension and systolic function](/docs/tools/reference-values/left-ventricular-dimension-and-systolic-function) * [Left ventricular diastolic function](/docs/tools/reference-values/left-ventricular-diastolic-function) * [Left and right atrium](/docs/tools/reference-values/left-and-right-atrium) * [Aorta, aortic stenosis (AS), aortic regurgitation (AR)](/docs/tools/reference-values/reference-values-for-aorta-aortic-stenosis-as-aortic-regurgitation-ar) * [Mitral valve](/docs/tools/reference-values/mitral-valve) * [Tricuspid valve](/docs/tools/reference-values/tricuspid-valve) * [Pulmonary valve](/docs/tools/reference-values/pulmonary-valve) * [Right ventricle, pulmonary artery, pulmonary artery pressure](/docs/tools/reference-values/right-ventricle-pulmonary-artery-pulmonary-artery-pressure) ### [Drug manuals](/docs/tools/drug-manuals) [#drug-manuals] * [QT Drugs: Drugs causing QT prolongation, torsade de pointes (TdP) and long QT syndrome (LQTS)](/docs/tools/drug-manuals/comprehensive-list-of-drugs-causing-qt-prolongation-torsade-de-pointes-and-long-) * [Inotropes and Vasopressors](/docs/tools/drug-manuals/inotropes-and-vasopressors-doses-indications-contraindications-and-effects) * [Prasugrel (Effient, Efient, Prasita)](/docs/tools/drug-manuals/prasugrel-effient-efient-prasita) * [Ticagrelor (Brilinta, Brilique)](/docs/tools/drug-manuals/cv-drugs-ticagrelor-brilinta-brilique) * [Clevidipine](/docs/tools/drug-manuals/clevidipine) * [Nicardipine](/docs/tools/drug-manuals/nicardipine) * [Enalaprilat](/docs/tools/drug-manuals/enalaprilat) * [Esmolol](/docs/tools/drug-manuals/esmolol) * [Labetalol](/docs/tools/drug-manuals/labetalol) * [Metoprolol](/docs/tools/drug-manuals/metoprolol) * [Fenoldopam](/docs/tools/drug-manuals/fenoldopam) * [Clonidine](/docs/tools/drug-manuals/clonidine) * [Nitroglycerin](/docs/tools/drug-manuals/nitroglycerin) * [Nitroprusside](/docs/tools/drug-manuals/nitroprusside) * [Phentolamine](/docs/tools/drug-manuals/phentolamine) * [Hydralazine](/docs/tools/drug-manuals/hydralazine) * [Drug-Induced Cardiotoxicity](/docs/tools/drug-manuals/drug-induced-cardiotoxicity) * [Aspirin (Acetylsalicylic acid)](/docs/tools/drug-manuals/aspirin) ### [Treatment summaries](/docs/tools/treatment-summaries) [#treatment-summaries] **Acute coronary syndromes** * [Management of STEMI (ST-Elevation Acute Myocardial Infarction)](/docs/tools/treatment-summaries/management-of-stemi-st-elevation-acute-myocardial-infarction) * [Reperfusion therapy (primary PCI, fibrinolysis) in patients with acute coronary syndromes (STEMI, NSTEMI, unstable angina)](/docs/tools/treatment-summaries/reperfusion-therapy-primary-pci-fibrinolysis-in-patients-with-acute-coronary-syn) * [Reperfusion strategy and fibrinolysis in patients with STEMI](/docs/tools/treatment-summaries/reperfusion-strategy-and-fibrinolysis-in-patients-with-stemi) * [Management of multivessel disease in patients with ACS undergoing PCI](/docs/tools/treatment-summaries/management-of-multivessel-disease-in-patients-with-acs-undergoing-pci) * [Antiplatelet therapy and anticoagulants in STEMI, NSTEMI and unstable angina](/docs/tools/treatment-summaries/antiplatelet-therapy-and-anticoagulants-in-stemi-nstemi-and-unstable-angina) * [Antithrombotic regimens in patients with ACS with and without an indication for oral anticoagulation](/docs/tools/treatment-summaries/antithrombotic-regimens-in-patients-with-acs-with-and-without-an-indication-for-) * [Lipid lowering therapy after ACS](/docs/tools/treatment-summaries/lipid-lowering-therapy-after-acs) * [Lipid lowering therapy after acute coronary syndromes](/docs/tools/treatment-summaries/lipid-lowering-therapy-after-acute-coronary-syndromes) **Heart failure** * [Diagnosis and initial management of heart failure (HFrEF, HFmrEF, HFpEF)](/docs/tools/treatment-summaries/diagnosis-and-initial-management-of-heart-failure-hfref-hfmref-hfpef) * [Management of heart failure with reduced ejection fraction (HFrEF)](/docs/tools/treatment-summaries/management-of-heart-failure-with-reduced-ejection-fraction-hfref) * [Device therapy in patients with heart failure and reduced ejection fraction (HFrEF)](/docs/tools/treatment-summaries/device-therapy-in-patients-with-heart-failure-and-reduced-ejection-fraction-hfre) **Arrhythmia and hypertension** * [Antiarrhythmic drugs in acute ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation)](/docs/tools/treatment-summaries/antiarrhythmic-drugs-in-acute-ventricular-arrhythmias-ventricular-tachycardia-ve) * [Hypertensive emergency (crisis) – Drugs, doses & management](/docs/tools/treatment-summaries/hypertensive-emergency-crisis-drugs-doses-management) # Assessment of Pacemaker Malfunction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/assessment-of-pacemaker-malfunction-using-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Basic cardiac pacing, pacemaker functions and settings This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/basic-cardiac-pacing-pacemaker-functions-and-settings — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Interpretation of Pacemaker ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/ecg-pacemaker-rhythm-malfunction-failure-tachyarrhythmia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Components and construction of a pacemaker This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/how-pacemakers-work — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pacemakers and Cardiac Devices This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Indications for pacemaker This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/indications-for-pacemaker — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to Cardiac Pacing and Devices: Pacemaker, ICD, CRT This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiac-devices-pacemaker-icd-crt/introduction-till-cardiac-devices-pacemaker-icd-crt — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiovascular Medicine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clinical Echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Basic cardiac anatomy This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/ecg-video-course/basic-cardiac-anatomy-anatomy-of-the-heart — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac electrophysiology: action potentials and electrical vectors This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/ecg-video-course/ecg-cardiac-electrophysiology-action-potentials-and-electrical-vectors — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Basic Cardiac Anatomy & Physiology This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/ecg-video-course — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to Electrocardiology and ECG Interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/ecg-video-course/introduction-to-electrocardiology-and-ecg-interpretation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pediatric and Neonatal ECG Interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/pediatric-ecg-interpretation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to pediatric & neonatal ECG interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/pediatric-ecg-interpretation/introduction-to-pediatric-neonatal-ecg-interpretation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pediatric aspects of ECG leads & anatomy This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/pediatric-ecg-interpretation/pediatric-aspects-of-ecg-leads-anatomy — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Interpretation of neonatal and pediatric electrocardiograms (ECG) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/pediatric-ecg-interpretation/practical-pediatric-ecg-interpretation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reference values for pediatric and neonatal ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/pediatric-ecg-interpretation/reference-values-for-pediatric-electrocardiogram-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden Cardiac Arrest and Cardiopulmonary Resuscitation (CPR) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clinical ECG Interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Approach to ECG Interpretation, Assessment of Rhythm and the P-wave This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/approach-to-ecg-interpretation-assessment-of-rhythm-and-the-p-wave — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Normal ECG: From Normality to Pathology This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Electrical Axis of the Heart This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-electrical-axis-of-the-heart — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The PR Interval & PR segment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-pr-interval-pr-segment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The QRS Complex: Q-wave, R-wave, S-wave, R-wave progression This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-qrs-complex-q-wave-r-wave-s-wave-r-wave-progression — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The QT and QTc Interval This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-qt-and-qtc-interval — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The ST segment: J-point, J-60 point, ST depression, ST elevation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-st-segment-j-point-j-60-point-st-depression-st-elevation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The T-wave: T-wave inversions, hyperacute T-waves, large T-waves, flat T-waves This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-normal-ecg-normal-findings-normal-variants-pathology/the-t-wave-t-wave-inversions-hyperacute-t-waves-large-t-waves-flat-t-waves — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Aspirin (Acetylsalicylic acid) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/aspirin — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clevidipine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/clevidipine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clonidine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/clonidine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # QT Drugs: Drugs causing QT prolongation, torsade de pointes (TdP) and long QT syndrome (LQTS) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/comprehensive-list-of-drugs-causing-qt-prolongation-torsade-de-pointes-and-long- — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ticagrelor (Brilinta, Brilique) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/cv-drugs-ticagrelor-brilinta-brilique — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Drug-Induced Cardiotoxicity This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/drug-induced-cardiotoxicity — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Enalaprilat This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/enalaprilat — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Esmolol This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/esmolol — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Fenoldopam This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/fenoldopam — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hydralazine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/hydralazine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Drug manuals (/docs/tools/drug-manuals) Cardiovascular pharmacology by drug and by class. # Inotropes and Vasopressors This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/inotropes-and-vasopressors-doses-indications-contraindications-and-effects — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Labetalol This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/labetalol — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Metoprolol This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/metoprolol — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Nicardipine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/nicardipine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Nitroglycerin This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/nitroglycerin — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Nitroprusside This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/nitroprusside — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Phentolamine This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/phentolamine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Prasugrel (Effient, Efient, Prasita) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/drug-manuals/prasugrel-effient-efient-prasita — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Heart rate and cycle length conversion table This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/heart-rate-and-cycle-length-conversion-table — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reference values (/docs/tools/reference-values) Normal and abnormal ranges, as published in the source guidelines. # Left and right atrium This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/left-and-right-atrium — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular diastolic function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/left-ventricular-diastolic-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular dimension and systolic function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/left-ventricular-dimension-and-systolic-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Mitral valve This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/mitral-valve — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pulmonary valve This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/pulmonary-valve — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reference values for pediatric and neonatal ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/reference-normal-values-for-pediatric-neonatal-ecg-interpretation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reference values for adult ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/reference-values-for-adult-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Aorta, aortic stenosis (AS), aortic regurgitation (AR) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/reference-values-for-aorta-aortic-stenosis-as-aortic-regurgitation-ar — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Right ventricle, pulmonary artery, pulmonary artery pressure This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/right-ventricle-pulmonary-artery-pulmonary-artery-pressure — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Tricuspid valve This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/reference-values/tricuspid-valve — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Antiarrhythmic drugs in acute ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/antiarrhythmic-drugs-in-acute-ventricular-arrhythmias-ventricular-tachycardia-ve — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Antiplatelet therapy and anticoagulants in STEMI, NSTEMI and unstable angina This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/antiplatelet-therapy-and-anticoagulants-in-stemi-nstemi-and-unstable-angina — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Antithrombotic regimens in patients with ACS with and without an indication for oral anticoagulation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/antithrombotic-regimens-in-patients-with-acs-with-and-without-an-indication-for- — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Device therapy in patients with heart failure and reduced ejection fraction (HFrEF) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/device-therapy-in-patients-with-heart-failure-and-reduced-ejection-fraction-hfre — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Diagnosis and initial management of heart failure (HFrEF, HFmrEF, HFpEF) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/diagnosis-and-initial-management-of-heart-failure-hfref-hfmref-hfpef — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hypertensive emergency (crisis) – Drugs, doses & management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/hypertensive-emergency-crisis-drugs-doses-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Treatment summaries (/docs/tools/treatment-summaries) Current guideline recommendations, condensed to what changes management. # Lipid lowering therapy after ACS This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/lipid-lowering-therapy-after-acs — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Lipid lowering therapy after acute coronary syndromes This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/lipid-lowering-therapy-after-acute-coronary-syndromes — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Management of heart failure with reduced ejection fraction (HFrEF) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/management-of-heart-failure-with-reduced-ejection-fraction-hfref — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Management of multivessel disease in patients with ACS undergoing PCI This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/management-of-multivessel-disease-in-patients-with-acs-undergoing-pci — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Management of STEMI (ST-Elevation Acute Myocardial Infarction) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/management-of-stemi-st-elevation-acute-myocardial-infarction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reperfusion strategy and fibrinolysis in patients with STEMI This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/reperfusion-strategy-and-fibrinolysis-in-patients-with-stemi — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Reperfusion therapy (primary PCI, fibrinolysis) in patients with acute coronary syndromes (STEMI, NSTEMI, unstable angina) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/tools/treatment-summaries/reperfusion-therapy-primary-pci-fibrinolysis-in-patients-with-acute-coronary-syn — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Adenosine for tachyarrhythmias (AVNRT, AVRT, NCT) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals/adenosine — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Antiarrhythmic drugs in ventricular tachyarrhythmias This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals/antiarrhythmic-drugs-in-ventricular-tachyarrhythmias — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hypertensive emergency (crisis) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals/hypertensive-emergency-crisis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Drug Manuals This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Inotropes and Vasopressors: Doses, indications, contraindications and effects This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals/inotropes-and-vasopressors-doses-indications-contraindications-and-effects — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Levosimendan (Simdax, Simendan) in acute heart failure This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/drug-manuals/levosimendan-simdax-simendan-in-acute-heart-failure — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Myocardial perfusion imaging (SPECT, PET) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Indications and contraindications for myocardial perfusion imaging This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/indications-and-contraindications-for-myocardial-perfusion-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Interpretation of myocardial perfusion images (Myocardial SPECT / PET) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/interpretation-of-myocardial-perfusion-images-spect-pet — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pharmacologic agents in myocardial perfusion imaging This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/pharmacologic-agents-in-myocardial-perfusion-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Physics of myocardial perfusion imaging (SPECT, PET): Radiotracers, perfusion, blood flow and viability This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/physics-of-myocardial-perfusion-imaging-spect-pet-radiotracers-perfusion-and-blood-flow — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Principles of myocardial perfusion imaging (SPECT, PET), coronary blood flow and flow reserve (CFR) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/principles-of-myocardial-perfusion-imaging-vasodilators-radiotracers-and-imaging-techniques — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The ischemic cascade This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/myocardial-perfusion-imaging-spect-pet/the-ischemic-cascade — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Anticoagulation Strategies in Atrial Fibrillation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/atrial-fibrillation-anticoagulation-strategies — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Brugada Syndrome: Diagnosis & SCD Prevention This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/brugada-syndrome-diagnosis-scd-prevention — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Coronary Artery Disease This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/coronary-artery-disease — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Heart failure: Introduction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/heart-failure-introduction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Heart Failure with Preserved Ejection Fraction (HFpEF) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/heart-failure-with-preserved-ejection-fraction-hfpef — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Heart Failure with Reduced Ejection Fraction (HFrEF) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/heart-failure-with-reduced-ejection-fraction-hfref — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hypertension: Causes, investigations, complications & treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/hypertension-causes-investigations-complications-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Structural Heart Disease This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Management of bradycardia (bradyarrhythmia) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/management-of-acute-bradycardia-bradyarrhythmia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Non-ST Elevation Acute Myocardial Infarction (NSTEMI) and Unstable Angina This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/non-st-elevation-acute-myocardial-infarction-nstemi-and-unstable-angina — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Physiological Assessment of Coronary Stenoses and Revascularization Decisions This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/physiological-assessment-of-coronary-stenoses-and-revascularization-decisions — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pulmonary Embolism (PE) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/pulmonary-embolism-causes-risk-factors-diagnosis-wells-score-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ST-Elevation Myocardial Infarction (STEMI): Pathophysiology, Diagnosis, and Management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/st-elevation-myocardial-infarction-stemi-an-exhaustive-review-of-pathophysiology-diagnosis-and-contemporary-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ventricular Tachycardia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/cardiovascular-medicine/structural-heart-disease/ventricular-tachycardia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Arrhythmogenic Right Ventricular Cardiomyopathy / Dysplasia (ARVC, ARVD) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/arrhythmogenic-right-ventricular-cardiomyopathy-dysplasia-arvc-arvd — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Dilated Cardiomyopathy (DCM): Definition, Types, Diagnostics & Treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/dilated-cardiomyopathy-dcm-definition-types-diagnostics-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Echocardiography in cardiomyopathies: an overview This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/echocardiography-in-cardiomyopathies-an-overview — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Heart failure: Causes, types, diagnosis, treatments & management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/heart-failure-causes-types-diagnosis-treatments-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hypertrophic Cardiomyopathy (HCM) & Hypertrophic Obstructive Cardiomyopathy (HOCM) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/hypertrophic-cardiomyopathy-hcm-hocm-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiomyopathies This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Tachycardia induced cardiomyopathy This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/cardiomyopathies/tachycardia-induced-cardiomyopathy — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Artifacts in ultrasound imaging This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/artifacts-in-ultrasound-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Color Doppler This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/color-doppler — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Continuous Wave Doppler (CW Doppler) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/continuous-wave-doppler-cw-doppler — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Doppler effect and Doppler echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/doppler-effect-and-doppler-studies-in-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to echocardiography and ultrasound imaging This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # M-mode (motion mode) echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/m-mode-motion-mode-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Optimization of the ultrasound image This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/optimization-of-the-ultrasound-image — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pulsed Wave Doppler This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/pulsed-wave-doppler — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Technical aspects of the ultrasound image This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/technical-aspects-of-the-ultrasound-image — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The ultrasound transducer This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/the-ultrasound-transmitter-probe — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Tissue Doppler (Tissue Velocity Imaging) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/tissue-doppler-tissue-velocity-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Two-dimensional (2D) echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/two-dimensional-2d-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Physics of ultrasound This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/introduction-to-echocardiography-and-ultraound-imaging/ultrasound-physics — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Assessment of diastolic function by echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-diastolic-function/assessment-of-diastolic-function-by-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular diastolic function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-diastolic-function/diastolic-heart-function-left-ventricular-diastolic-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular diastolic function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-diastolic-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Relaxation of the left ventricle This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-diastolic-function/relaxation-left-ventricle-compliance-diastolic-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Assessing left ventricular systolic function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/assessing-left-ventricular-systolic-function-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Strain, strain rate and speckle tracking: Myocardial deformation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/deformation-strain-strain-rate-speckle-tracking-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ejection fraction (EF): Physiology, Measurement & Clinical Evaluation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/ejection-fraction-ef-physiology-measurement-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Fractional shortening for estimation of ejection fraction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/fractional-shortening-for-estimation-of-ejection-fraction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular systolic function and contractility This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left Ventricular Function This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/left-ventricular-function — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left ventricular mass and volume (size) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/left-ventricular-mass-and-volume-size — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left Ventricular Segments for Echocardiography and Cardiac Imaging This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/left-ventricular-segments-echocardiography-cardiac-imaging — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ventricular Pressure-Volume Relationship: Preload, Afterload, Stroke Volume, Wall Stress & Frank-Starling's law This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/pressure-volume-curves-preload-afterload-stroke-volume-wall-stress-frank-starlings-law — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Regional Myocardial Contractile Function: Wall Motion Abnormalities This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/regional-myocardial-contractile-function-wall-motion-abnormality — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Myocardial Mechanics: Structure and Function of Myocardial Fibers This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/structure-and-function-of-myocardial-fibers-myocardium — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Coronary Arteries This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/left-ventricular-function-systolic-function-and-contractility/the-coronary-arteries — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac thromboembolism: cardiac sources of embolism This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions/cardiac-thromboembolism-cardiac-sources-of-embolism — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac tumors This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions/cardiac-tumors — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Congenital heart disease & GUCH (Grown Up Congenital Heart disease) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions/congenital-heart-disease-guch-grown-up-congenital-heart-disease — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Endocarditis: definitions, causes, diagnosis, echocardiography & treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions/endocarditis-definitions-causes-diagnosis-echocardiography-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Miscellaneous conditions This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Right ventricular strain: definition, causes, echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/miscellaneous-conditions/right-ventricular-strain-definition-causes-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Constrictive pericarditis: definition, causes, diagnosis & echocardiography This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/pericardial-disease/constrictive-pericarditis-definition-causes-diagnosis-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pericardial disease This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/pericardial-disease — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pericardial Effusion & Cardiac tamponade This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/pericardial-disease/pericardial-effusion-cardiac-tamponade — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Hemodynamic principles and calculations This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics/hemodynamic-principles-and-calculations — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Principles of hemodynamics This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Proximal Isovelocity Surface Area (PISA) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics/proximal-isovelocity-surface-area-pisa — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Stroke Volume, VTI (Velocity Time Integral) & Cardiac Output This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics/stroke-volume-vti-velocity-time-integral-cardiac-output — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Bernoulli principle and estimation of pressure gradients This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics/the-bernoulli-principle-and-calculation-of-pressure-difference-pressure-gradient — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Continuity Equation (The Principle of Continuity) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/principles-of-hemodynamics/the-continuity-equation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The echocardiographic examination This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/the-standard-echocardiographic-exam — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Performing Echocardiographic Examinations This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/the-standard-echocardiographic-exam/performing-echocardiographic-studies — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Principles and Preparations for Echocardiographic Examinations This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/the-standard-echocardiographic-exam/standard-adult-echocardiogram-principles-and-preparations — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Standard Transthoracic Echocardiogram: Complete Imaging Protocol This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/the-standard-echocardiographic-exam/the-standard-adult-transthoracic-echocardiogram-a-protocol-to-obtain-a-complete-study — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Aortic regurgitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/aortic-valve-regurgitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Aortic stenosis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/aortic-valve-stenosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Valvular heart disease This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Mitral regurgitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/mitral-valve-regurgitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Mitral valve stenosis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/mitral-valve-stenosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pulmonary regurgitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/pulmonic-pulmonary-valve-regurgitation-echocardiography — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pulmonary stenosis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/pulmonic-valve-stenosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Tricuspid regurgitation (TR/TI) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/tricuspid-regurgitation-tr-ti — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Tricuspid stenosis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/clinical-echocardiography/valvular-heart-disease/tricuspid-valve-stenosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Advanced cardiopulmonary resuscitation (CPR) - Advanced cardiovascular life support (ACLS) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/advanced-cpr-acls — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Arrhythmias before and during cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/arrhythmias-before-and-during-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Assessment of the pupillary reflex in cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/assessment-of-pupils-pupillary-reflex-in-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Basic Life Support (BLS) in cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/basic-cardiopulmonary-resuscitation-bls-basic-life-support — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Capnography (end-tidal carbon dioxide measurement, ETCO2) during cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/capnography-etco2-in-cardiac-arrest-and-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Extracorporeal cardiopulmonary resuscitation (ECPR) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/extracorporeal-cardiopulmonary-resuscitation-ecpr — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiopulmonary Resuscitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Interpretation of ECG after ROSC (Return of Spontaneous Circulation) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/interpretation-of-ecg-after-rosc-return-of-spontaneous-circulation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Care after return of spontaneous circulation (ROSC) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/post-resuscitation-care — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Short and long-term prognostication in cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/short-and-long-term-prognostication-in-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ultrasound (echocardiography) in cardiac arrest and resuscitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation/ultrasound-echocardiography-in-cardiac-arrest-and-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Causes of sudden cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/causes-of-sudden-cardiac-arrest-and-death/causes-of-sudden-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Causes of sudden cardiac arrest and death This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/causes-of-sudden-cardiac-arrest-and-death — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Risk factors for sudden cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/causes-of-sudden-cardiac-arrest-and-death/risk-factors-for-sudden-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 6 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/cardiac-arrest-case-6 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 1 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/case-1 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 2 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/case-2 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 3 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/case-3 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 4 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/case-4 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 5 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/case-5 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG atlas of ventricular tachyarrhythmias in cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 7 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/sudden-cardiac-arrest-case-7 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sudden cardiac arrest: Case 8 This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/ecg-atlas-of-ventricular-tachyarrhythmias-in-cardiac-arrest/sudden-cardiac-arrest-case-8 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Epidemiological aspects of cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/introduction-to-sudden-cardiac-arrest-and-resuscitation/epidemiological-aspects-of-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to sudden cardiac arrest and resuscitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/introduction-to-sudden-cardiac-arrest-and-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/introduction-to-sudden-cardiac-arrest-and-resuscitation/introduction-to-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Terminology of sudden cardiac arrest and resuscitation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/introduction-to-sudden-cardiac-arrest-and-resuscitation/terminology-of-sudden-cardiac-arrest-and-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The chain of survival in sudden cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/introduction-to-sudden-cardiac-arrest-and-resuscitation/the-chain-of-survival — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Resuscitation physiology and mechanisms This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/resuscitation-physiology-and-mechanisms — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The 3-phase model of sudden cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/resuscitation-physiology-and-mechanisms/the-3-phase-model-of-sudden-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The physiology of cardiopulmonary resuscitation (CPR) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/resuscitation-physiology-and-mechanisms/the-physiology-of-cardiopulmonary-resuscitation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac tamponade causing cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-at-tamponade-cardiac-tamponade — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest due to hypoxia and asphyxia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-due-to-hypoxia-and-asphyxia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest due to pneumothorax This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-due-to-pneumothorax — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest during pregnancy and childbirth This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-during-pregnancy-and-childbirth — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest due to electrolyte imbalance This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-in-electrolyte-disturbances — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest in hyperthermia and malignant hyperthermia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-in-hyperthermia-and-malignant-hyperthermia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest in hypothermia (accidental hypothermia) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-in-hypothermia-accidentel-hypothermia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest in intoxication (poisoning) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-in-intoxication-poisoning — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest during sepsis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/cardiac-arrest-in-sepsis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac arrest due to anaphylaxis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/hjartstopp-vid-anafylaxi — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Special Circumstances This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Traumatic cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/sudden-cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/special-circumstances/traumatic-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Aberrant ventricular conduction (aberrancy, aberration) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/aberrant-ventricular-conduction-aberrancy — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Atrial fibrillation: ECG, classification, causes, risk factors & management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/atrial-fibrillation-ecg-ekg-causes-classification-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Atrial flutter: classification, causes, ECG criteria and management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/atrial-flutter-ecg-treatment-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Atrioventricular nodal reentry tachycardia (AVNRT): ECG features & management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/av-atrioventricular-nodal-reentrant-tachyarrrhythmia-reentry — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Chronotropic incompetence (inability to increase heart rate) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/chronotropic-incompetence-ecg-ekg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Diagnosis and management of supraventricular and ventricular tachyarrhythmias: Narrow complex tachycardia & wide complex tachycardia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/diagnosis-management-tachycardia-tachyarrhythmia-wide-narrow — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ectopic atrial rhythm (EAT), atrial tachycardia (AT) & multifocal atrial tachycardia (MAT) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/ectopic-atrial-rhythm-multifocal-tachycardia-multifocal — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Arrhythmias and arrhythmology This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Junctional rhythm (escape rhythm) and junctional tachycardia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/junctional-rhythm-junctional-tachycardia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Long QT (QTc) interval, long QT syndrome (LQTS) & torsades de pointes This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/longt-qt-syndrome-interval-lqts-torsades-de-pointes — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Mechanisms of cardiac arrhythmias: from automaticity to re-entry (reentry) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/mechanisms-cardiac-arrhythmias-automaticity-reentry-triggered-activity — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinus rhythm: physiology, ECG criteria & clinical implications This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/normal-sinus-rhythm-ecg-criteria-sinoatrial-node — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pacemaker-mediated tachycardia (PMT): ECG and management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/pacemaker-medicate-tachycardia — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pre-excitation, Atrioventricular Reentrant (Reentry) Tachycardia (AVRT), Wolff-Parkinson-White (WPW) syndrome This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/pre-excitation-avrt-wolff-parkinson-white-wpw-syndrome — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Premature atrial contraction (premature atrial beat / complex): ECG and clinical implications This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/premature-atrial-contraction-beat-complex — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Premature ventricular contractions (premature ventricular complex, premature ventricular beats) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/premature-ventricular-contractions-complex-beats-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinoatrial arrest & sinoatrial pause (sinus pause / arrest) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinoatrial-arrest-sinoatrial-pause-sinus — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinoatrial block (SA block): ECG criteria, causes and clinical features This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinoatrial-block-sa-criteria-ecg-causes-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinus arrhythmia (respiratory sinus arrhythmia) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinus-arrhythmia-respiratory-ecg-cause-criteria — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinus bradycardia: definitions, ECG, causes and management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinus-bradycardia-ecg-causes-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinus node dysfunction (SND) and sick sinus syndrome (SSS) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinus-node-dysfunction-snd-sick-sinus-syndrome-sss — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Sinus tachycardia & Inappropriate sinus tachycardia This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/sinus-tachycardia-causes-ecg-inappropriate-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ventricular fibrillation, pulseless electrical activity and sudden cardiac arrest This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/ventricular-fibrillation-pulseless-electrical-activity-sudden-cardiac-arrest — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ventricular rhythm and accelerated ventricular rhythm (idioventricular rhythm) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/ventricular-rhythm-and-accelerated-ventricular-rhythm-idioventricular-rhythm — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Ventricular tachycardia (VT): ECG criteria, causes, classification, treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/arrhythmias-and-arrhythmology/ventricular-tachycardia-vt-ecg-treatment-causes-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Biventricular hypertrophy ECG and clinical characteristics This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement/biventricular-hypertrophy-ecg-clinical-characteristics — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Atrial and ventricular enlargement: hypertrophy and dilatation on ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement/cardiac-atrial-ventricular-hypertrophy-dilatation-enlargement-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left atrial enlargement (P mitrale) & right atrial enlargement (P pulmonale) on ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement/ecg-left-right-atrial-enlargement-p-pulmonale-mitrale — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG in left ventricular hypertrophy (LVH): criteria and implications This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement/ecg-left-ventricular-hypertrophy-lvh-clinical-characteristics — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac Hypertrophy & Enlargement This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Right ventricular hypertrophy (RVH): ECG criteria & clinical characteristics This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/cardiac-hypertrophy-enlargement/right-ventricular-hypertrophy-ecg-ekg-criteria — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Overview of atrioventricular (AV) blocks This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/atrioventricular-av-block-ecg-blocks — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Management and treatment of AV block (atrioventricular blocks) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/av-block-1-2-3-treatment-management-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # First-degree AV block (AV block I, AV block 1) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/ecg-first-degree-av-block-i-1-criteria-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Second-degree AV block: Mobitz type 1 (Wenckebach) & Mobitz type 2 block This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/ecg-second-degree-av-block-mobitz-type-1-2-wenckebach — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Third-degree AV block (3rd degree AV block, AV block 3, AV block III) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/ecg-third-degree-av-block-iii-3-criteria-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Conduction Defects This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Intraventricular conduction delay: bundle branch blocks & fascicular blocks This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/intraventricular-conduction-delay-ecg-bundle-branch-fascicular-block — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Fascicular block (hemiblock): Left anterior & left posterior fascicular block This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/left-anterior-posterior-fascicular-block-hemiblock-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left bundle branch block (LBBB) in acute myocardial infarction: the Sgarbossa criteria This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/left-bundle-branch-block-acute-coronary-syndromes-sgarbossa — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Left bundle branch block (LBBB): ECG criteria, causes, management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/left-bundle-branch-block-lbbb-ecg-criteria-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Nonspecific intraventricular conduction delay (defect) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/nonspecific-intraventricular-conduction-delay-defect — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Right bundle branch block (RBBB): ECG, criteria, definitions, causes & treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/conduction-defects/right-bundle-branch-block-rbbb-ecg-criteria-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Digoxin - ECG changes, arrhythmias, conduction defects & treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/drugs-electrolyte-imbalance/digoxin-ecg-changes-arrhythmias-digoxin-digitalis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG changes caused by antiarrhythmic drugs, beta blockers & calcium channel blockers This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/drugs-electrolyte-imbalance/ecg-arrhythmias-antiarrhythmic-drugs-beta-blockers-calcium-channel-blockers — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG changes due to electrolyte imbalance (disorder) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/drugs-electrolyte-imbalance/ecg-electrolyte-imbalance-electrolyte-disorder-calcium-potassium-magnesium — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Drugs & Electrolyte Imbalance This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/drugs-electrolyte-imbalance — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Indications, Contraindications, and Preparations for Exercise Stress Testing This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/exercise-stress-test-ecg-indications-contraindications-preparation — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Evaluation of exercise stress test: ECG, symptoms, blood pressure, heart rate, performance This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/exercise-stress-test-ecg-symptoms-blood-pressure-heart-rate-performance — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Exercise stress test (exercise ECG): protocols, evaluation & termination This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/exercise-stress-test-exercise-ecg-protocols-evaluation-parameters — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to exercise stress testing (treadmill test, exercise ECG) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/exercise-stress-test-treadmill-ecg-indications-background — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Exercise stress testing in special patient populations This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/exercise-stress-testing-patient-populations-ami-ecg-acs — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Exercise Stress Testing (Exercise ECG) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Exercise physiology: from normal response to myocardial ischemia & chest pain This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/exercise-stress-testing-exercise-ecg/physiological-mechanisms-exercise-stress-testing — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Brugada syndrome: ECG, clinical features and management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/brugada-syndrome-ecg-treatment-type-1-2-3 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Early repolarization pattern on ECG (early repolarization syndrome) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/early-repolarization-pattern-syndrome-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Pericarditis, myocarditis & perimyocarditis: ECG, criteria & treatment This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/ecg-pericarditis-myocarditis-perimyocarditis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Genetics, Syndromes & Miscellaneous This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG J wave syndromes: hypothermia, early repolarization, hypercalcemia & Brugada syndrome This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/j-wave-syndromes-hypothermia-early-repolarization-calcium-brugada-syndrome — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Long QT Syndrome (LQTS) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/long-qt-syndrome-lqts — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Eletrical alternans: the ECG in pericardial effusion & cardiac tamponade This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/pericardial-effusion-cardiac-tamponade-electrical-alternans-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Takotsubo cardiomyopathy (broken heart syndrome, stress induced cardiomyopathy) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/genetics-syndromes-miscellaneous/takotsubo-cardiomyopathy-broken-heart-syndrome-stress-induced-cardiomyopathy-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The Cabrera format of the 12-lead ECG and inverted lead aVR This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/12-lead-ecg-cabrera-format-inverting-lead-avr — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac electrophysiology: Action potential, automaticity and vectors This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/cardiac-electrophysiology-ecg-action-potential-automaticity-vector — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG interpretation: Characteristics of the normal ECG (P-wave, QRS complex, ST segment, T-wave) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/ecg-normal-p-wave-qrs-complex-st-segment-t-wave-j-point — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The ECG leads: Electrodes, limb leads, chest (precordial) leads and the 12-Lead ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/ekg-ecg-leads-electrodes-systems-limb-chest-precordial — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to ECG Interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2 — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac electrophysiology and ECG interpretation This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/introduction-electrocardiography-ecg-book — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # How to interpret the ECG: A systematic approach This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/introduction-to-ecg-interpretation-2/systematic-clinical-ecg-interpretation-review-guide — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # A New Approach to Acute Coronary Syndromes: Occlusion MI (OMI) vs. Non-Occlusion MI (NOMI) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/a-new-approach-to-acute-coronary-syndromes-occlusion-mi-omi-vs-non-occlusion-mi-nomi — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Classification of Acute Coronary Syndromes (ACS) & Acute Myocardial Infarction (AMI) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/acute-coronary-syndromes-acs-myocardial-infarction-ami — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Approach to patients with chest pain: differential diagnoses, management & ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/approach-patients-chest-pain-differential-diagnoses-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Cardiac troponin I (TnI) and T (TnT): Interpretation and evaluation in acute coronary syndromes This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/cardiac-troponin-i-tni-and-t-tnt-interpretation-and-evaluation-in-acute-coronary-syndromes — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Supraventricular and intraventricular conduction defects in myocardial ischemia and infarction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/conduction-defects-myocardial-ischemia-infarction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Introduction to Coronary Artery Disease (Ischemic Heart Disease) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/coronary-artery-disease-ischemic-ecg-risk-factors-atherosclerosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Diagnostic Criteria for Acute Myocardial Infarction: Cardiac troponins, ECG & Symptoms This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/diagnostic-criteria-acute-myocardial-infarction-troponins-ecg-symptoms — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Clinical application of ECG in chest pain & acute myocardial infarction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-chest-pain-acute-myocardial-infarction-coronary-syndrome — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG signs of myocardial infarction: pathological Q-waves & pathological R-waves This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-criteria-myocardial-infarction-pathological-q-waves-r-waves — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG manifestations of left main coronary artery (LMCA) occlusion and critical stenosis This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-manifestations-of-left-main-coronary-artery-lmca-occlusion-and-critical-stenosis — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG in myocardial ischemia: ischemic changes in the ST segment & T-wave This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-myocardial-ischemia-ischemic-changes-st-segment-t-wave — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ST segment elevation in acute myocardial ischemia and differential diagnoses This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-st-elevation-segment-ischemia-myocardial-infarction-stemi — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ST segment depression in myocardial ischemia and differential diagnoses This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/ecg-st-segment-depression-ischemia-infarction-differential-diagnoses — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Factors that modify the natural course in acute myocardial infarction (AMI) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/factors-modify-course-acute-myocardial-infarction-infarct-size-ami — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Myocardial Ischemia & Infarction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The left ventricle in myocardial ischemia and infarction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/left-ventricle-ischemia-acute-myocardial-infarction-coronary-artery — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ECG localization of myocardial infarction / ischemia and coronary artery occlusion (culprit) This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/localization-localize-myocardial-infarction-ischemia-coronary-artery-occlusion-culprit-stemi — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Myocardial Ischemia & infarction: Cellular changes, ECG and symptoms This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/myocardial-ischemia-infarction-reaction-ecg-changes-symptoms — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # NSTEMI (Non-ST Elevation Myocardial Infarction) & Unstable Angina: Diagnosis, Criteria, ECG, Management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/nstemi-non-st-elevation-myocardial-infarction-unstable-angina-criteria-ecg-diagnosis-management — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Other ECG changes in ischemia and infarction This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/other-ecg-changes-in-ischemia-infarction — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # Stable Coronary Artery Disease (Angina Pectoris): Diagnosis, Evaluation, Management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/stable-coronary-artery-disease-angina-pectoris-management-diagnosis-treatment — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # STEMI (ST Elevation Myocardial Infarction): Diagnosis, ECG, Criteria, and Management This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/stemi-st-elevation-myocardial-infarction-criteria-ecg — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # ST elevation myocardial infarction (STEMI) without ST elevations on 12-lead ECG This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/stemi-without-st-elevations-ecg-posterior-posterolateral — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # T-waves in ischemia: hyperacute, inverted (negative), Wellen's sign & de Winter's sign This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/t-wave-negative-inversions-hyperacute-wellens-sign-de-winters — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # The ECG in assessment of myocardial reperfusion This page is part of the subscriber library of The Cardiovascular and is not available in full without a subscription. Read it at https://cardvasc.org/docs/books/the-ecg-book/myocardial-ischemia-infarction/the-ecg-in-assessment-of-reperfusion — a limited number of articles are free, after which a subscription is required. Subscribe: https://cardvasc.org/register # 1-2-3-LQTS Risk Calculator (/docs/tools/calculators/1-2-3-lqts-risk-calculator) ## 5-Year Risk of Life-Threatening Ventricular Arrhythmias [#5-year-risk-of-life-threatening-ventricular-arrhythmias] Long QT Syndrome (LQTS) is an inherited cardiac channelopathy characterized by prolonged ventricular repolarization, which predisposes individuals to malignant ventricular arrhythmias, notably torsade de pointes. This condition is primarily attributed to specific genetic mutations: loss-of-function mutations in KCNQ1 (LQT1) and KCNH2 (LQT2), and gain-of-function mutations in SCN5A (LQT3). These genetic anomalies disrupt the cardiac ion channels, leading to delayed repolarization and an increased risk of life-threatening arrhythmic events. The cornerstone of LQTS management involves lifestyle modifications, pharmacotherapy, and, in high-risk cases, device implantation. Beta-blockers, particularly non-selective agents like nadolol and propranolol, are the first-line treatment for reducing arrhythmic risk across all LQTS genotypes. These medications mitigate adrenergic stimulation, thereby decreasing the likelihood of arrhythmia onset. However, beta-blockers do not fully eliminate the risk. In LQT3 patients, where arrhythmias often occur at rest due to late sodium current augmentation, the sodium channel blocker mexiletine has demonstrated efficacy in shortening the QT interval and reducing arrhythmic events, contingent upon the specific mutation present. For patients at elevated risk—such as those with a history of cardiac arrest, recurrent syncope despite beta-blocker therapy, or markedly prolonged QT intervals—the implantation of an implantable cardioverter-defibrillator (ICD) is recommended. ICDs provide immediate intervention during life-threatening arrhythmias, thereby preventing sudden cardiac death. The 2015 European Society of Cardiology (ESC) guidelines advocate for ICD implantation in high-risk LQTS patients, emphasizing a comprehensive risk assessment that includes genetic factors and QTc duration. ## **Risk Stratification and the 1-2-3-LQTS Risk Model** [#risk-stratification-and-the-1-2-3-lqts-risk-model] Accurate risk stratification is pivotal in guiding therapeutic decisions for LQTS patients. Traditional assessment methods have focused on genotype and QTc interval prolongation. In 2018, Mazzanti et al. introduced the 1-2-3-LQTS Risk model, a validated tool designed to estimate the 5-year risk of life-threatening arrhythmic events in individuals with LQT1, LQT2, and LQT3. This model was developed using a single-center longitudinal cohort and subsequently validated with an independent cohort of 1,689 patients from the International LQTS Registry in Rochester, NY, USA. The validation study reported a C-index of 0.69 (95% CI: 0.61–0.77) in the validation cohort, compared to a C-index of 0.79 (95% CI: 0.70–0.88) in the discovery cohort. A 5-year risk threshold of 5% or higher, determined by ROC curve analysis as the optimal balance for deciding on ICD implantation, yielded a number needed to treat (NNT) of nine (95% CI: 6.3–13.6). ### **References** [#references] 1.Mazzanti, A., Trancuccio, A., Kukavica, D., Pagan, E., Wang, M., Mohsin, M., Peterson, D., Bagnardi, V., Zareba, W., & Priori, S. G. (2022). Independent validation and clinical implications of the risk prediction model for long QT syndrome (1-2-3-LQTS-Risk). *EP Europace*, 24(4), 614–619. 2.Priori, S. G., Blomström-Lundqvist, C., Mazzanti, A., Blom, N., Borggrefe, M., Camm, J., Elliott, P. M., Fitzsimons, D., Hatala, R., Hindricks, G., Kirchhof, P., Kjeldsen, K., Kuck, K. H., Hernandez-Madrid, A., Nikolaou, N., Norekvål, T. M., Spaulding, C., & Van Veldhuisen, D. J. (2015). 2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. *European Heart Journal*, 36(41), 2793–2867. 3.Ackerman, M. J., Priori, S. G., Dubin, A. M., Kowey, P., Linker, N. J., Slotwiner, D., Triedman, J., Van Hare, G. F., & Gold, M. R. (2017). Beta-blocker therapy for long QT syndrome and catecholaminergic polymorphic ventricular tachycardia: Are all beta-blockers equivalent? *Heart Rhythm*, 14(1), e41–e44. 4.Schwartz, P. J., Crotti, L., & Insolia, R. (2012). Long-QT syndrome: From genetics to management. *Circulation: Arrhythmia and Electrophysiology*, 5(4), 868–877. 5.Wilde, A. A. M., & Amin, A. S. (2018). Clinical spectrum of SCN5A mutations: Long QT syndrome, Brugada syndrome, and cardiomyopathy. *Journal of Cardiovascular Electrophysiology*, 29(1), 109–120. 6.Mazzanti, A., Maragna, R., Vacanti, G., Monteforte, N., Bloise, R., Memmi, M., Pagan, E., & Priori, S. G. (2016). Gene-specific therapy with mexiletine reduces arrhythmic events in patients with long QT syndrome type 3. *Journal of the American College of Cardiology*, 67(9), 1053–1058. # 2HELPS2B score for seizure risk on cEEG (/docs/tools/calculators/2helps2b-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # 4 A's Test (4AT) for delirium screening (/docs/tools/calculators/4-as-test-delirium) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # 4C Mortality Score for COVID-19 (/docs/tools/calculators/4c-mortality-score-covid-19) {/* Write the article for this calculator below. 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Age-stratified formulas help determine expected normal values based on body surface area (BSA), aiding in the diagnosis of aortic root dilation. ### **Key Formulas** [#key-formulas] 1. **BSA Calculation** (Mosteller formula): \[ \text\{BSA (m²)} = \sqrt\{\frac\{\text\{Height (cm)} \times \text\{Weight (kg)}}\{3600}} ] 2. **SOVd Formulas**: * **\<20 years**: ( \text\{SOVd} = 1.02 + 0.98 \times \text\{BSA} ) * **20-39 years**: ( \text\{SOVd} = 0.97 + 1.12 \times \text\{BSA} ) * **≥40 years**: ( \text\{SOVd} = 1.92 + 0.74 \times \text\{BSA} ) ## Definition of aortic aneurysm [#definition-of-aortic-aneurysm] * Sinus of Valsalva >45 mm. * Any other segment >40 mm in diameter. ## Thresholds for surgery [#thresholds-for-surgery] | Threshold for surgery | Relevant patient category | | ------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | 27.5 mm/m2 | Turner syndrome | | 40 mm | • Patients with mutations in TGFBR1, TGFBR2 or Loes-Dietz syndrome, who have low BSA or severe extra aortic features | | 45 mm | • Patients who are undergoing aortic valve surgery • Patients with Marfan syndrome who have additional risk factors\* • Patients with mutations in TGFBR1, TGFBR2 or Loes-Dietz syndrome. | | 50 mm | • Marfan syndrome • Bicuspid aortic valve with coarctation or additional risk factors\* | | 55 mm (ascending aorta, aortic arch) | All individuals | | 60 mm (descending aorta) | All individuals | \***Risk factors**: previous dissection, family history of dissection, severe aortic regurgitation or mitral regurgitation, planning pregnancy, uncontrolled hypertension or annual growth >3 mm. ### **Limitations** [#limitations] * Formulas assume normal body habitus * Ethnic variations may require adjusted thresholds * Always correlate with imaging measurements * Not valid for pediatric patients \<15 years # Age-adjusted D-dimer for VTE (/docs/tools/calculators/age-adjusted-d-dimer) {/* Write the article for this calculator below. 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Developed from the ATRIA study cohort, this score aids clinicians in estimating the risk of bleeding complications due to anticoagulants. ## Components of the ATRIA Score [#components-of-the-atria-score] The ATRIA score assigns points based on five clinical factors: * **Anemia:** Hemoglobin \<13 g/dL in men or \<12 g/dL in women (3 points) * **Severe Renal Disease:** Estimated glomerular filtration rate (eGFR) \<30 mL/min or dialysis-dependent (3 points) * **Age ≥75 years:** (2 points) * **Prior Bleeding:** History of any prior bleeding (1 point) * **Hypertension:** History of hypertension (1 point) | | Score | 1-year risk of bleeding | | ----------------- | --------- | ----------------------- | | Low risk | 0-3 | 0.8% | | Intermediate risk | 4 | 2.6% | | High risk | 5 or more | 5.8% | Interpretation of ATRIA risk score. ## Comparison with other bleeding risk models [#comparison-with-other-bleeding-risk-models] Several bleeding risk assessment tools exist for patients with AF, including HAS-BLED, HEMORR2HAGES, and ORBIT scores. Each incorporates various clinical parameters to stratify bleeding risk. * **HAS-BLED:** Incorporates factors such as hypertension, abnormal renal/liver function, stroke history, bleeding history, labile INR, age >65, and concomitant drug/alcohol use. Some studies suggest HAS-BLED has comparable or slightly superior predictive capability for major bleeding compared to ATRIA. * **ORBIT:** Includes factors like older age, reduced hemoglobin/hematocrit, bleeding history, insufficient kidney function, and treatment with antiplatelet agents. Research indicates that the ORBIT score may offer better discrimination and calibration for major bleeding events compared to both HAS-BLED and ATRIA. Note that while these prediction models provide guidance, their accuracies are moderate. Clinical judgment should always complement risk scores, considering individual patient characteristics and preferences when making therapeutic decisions. ## References [#references] 1\. **Fang MC, Go AS, Chang Y, et al.** A new risk scheme to predict warfarin-associated hemorrhage: the ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) study. *J Am Coll Cardiol*. 2011;58(4):395-401. doi:10.1016/j.jacc.2011.03.031. 2\. **Proietti M, Raparelli V, Olshansky B, Lane DA, Lip GYH.** Comparison of bleeding risk scores in patients with atrial fibrillation: insights from the AFFIRM trial. *J Intern Med*. 2018;283(1):49-61. doi:10.1111/joim.12692. 3\. **Senoo K, Proietti M, Lane DA, Lip GYH.** Evaluation of the HAS-BLED, ATRIA, and ORBIT bleeding risk scores in atrial fibrillation patients on warfarin. *Am J Med*. 2016;129(6):600-607. doi:10.1016/j.amjmed.2015.11.027. 4\. **Olesen JB, Lip GY, Hansen ML, et al.** Bleeding risk in ‘real world’ patients with atrial fibrillation: comparison of two established bleeding prediction schemes in a nationwide cohort. *J Thromb Haemost*. 2011;9(8):1460-1467. doi:10.1111/j.1538-7836.2011.04378.x. 5\. **Apostolakis S, Lane DA, Guo Y, Buller H, Lip GY.** Performance of the HEMORR2HAGES, ATRIA, and HAS-BLED bleeding risk-prediction scores in patients with atrial fibrillation undergoing anticoagulation: the AMADEUS study. *J Am Coll Cardiol*. 2012;60(9):861-867. doi:10.1016/j.jacc.2012.06.019. 6\. **Lip GYH, Banerjee A, Boriani G, et al.** Antithrombotic therapy for atrial fibrillation: CHEST guideline and expert panel report. *Chest*. 2018;154(5):1121-1201. doi:10.1016/j.chest.2018.07.040. 7\. **Friberg L, Rosenqvist M, Lip GY.** Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. *Eur Heart J*. 2012;33(12):1500-1510. doi:10.1093/eurheartj/ehr488. 8\. **Pisters R, Lane DA, Nieuwlaat R, de Vos CB, Crijns HJ, Lip GY.** A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding in patients with atrial fibrillation: the Euro Heart Survey. *Chest*. 2010;138(5):1093-1100. doi:10.1378/chest.10-0134. 9\. **García-Fernández A, Roldán V, Lip GY, Marín F.** Predicting bleeding risk in patients with atrial fibrillation: comparison of the HAS-BLED and ABC-Bleeding risk scores. *J Am Coll Cardiol*. 2017;70(2):138-139. doi:10.1016/j.jacc.2017.05.029. 10\. **Hindricks G, Potpara T, Dagres N, et al.** 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association of Cardio-Thoracic Surgery (EACTS). *Eur Heart J*. 2021;42(5):373-498. doi:10.1093/eurheartj/ehaa612. # ATRIA Bleeding Risk Score (/docs/tools/calculators/atria-bleeding-risk-score) {/* Write the article for this calculator below. 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BMI is relevant for medical prognostication as it serves as a quick, low-cost, and reliable screening tool for body composition, risk of type 2 diabetes, metabolic syndrome and specific cancers. ## BMI and cardiovascular outcomes [#bmi-and-cardiovascular-outcomes] * High BMI is associated with several health conditions: * Type 2 diabetes * Hypertension * Coronary artery disease * Heart failure * Dyslipidemia (including high LDL, total cholesterol and triglycerides) * Atrial fibrillation ## BMI categories [#bmi-categories] The World Health Organization defines BMI categories as follows: **Underweight**: Less than 18.5 **Normal weight**: 18.5 to 24.9 **Overweight**: 25 to 29.9 **Obese**: 30 and above ## Limitations of BMI [#limitations-of-bmi] Despite its widespread use, BMI has several limitations: * It does not distinguish between fat, muscle, and bone mass. * It does not indicate the types or distribution of body fat. * It may not be accurate for all populations, particularly at the extremes of height and weight. * BMI is particularly poor a predictor in South Asians, who have substantially elevated risk of cardiovascular disease and diabetes at BMI levels of 23 kg/m2 or higher. ## Body surface area (BSA) [#body-surface-area-bsa] Body Surface Area is the total surface area of the body. It is often used in clinical settings because it is considered a more accurate indicator of metabolic mass than body weight alone. BSA is utilized in various medical applications: * Calculation of drug dosages, particularly in chemotherapy * Determination of fluid administration * Assessment of various hemodynamic and echocardiographic parameters. # BODE Index for COPD Survival (/docs/tools/calculators/bode-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Body Roundness Index (BRI) (/docs/tools/calculators/body-roundness-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Behavioral Observational Pain Scale (BOPS) for Post-Op Pediatric Pain (/docs/tools/calculators/bops-pediatric-pain) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Brugada’s algorithm for diagnosing ventricular tachycardia (VT) (/docs/tools/calculators/brugadas-algorithm-for-distinguishing-ventricular-tachycardia-vt-from-supraventr) Brugada's algorithm is the most used algorithm for distinguishing ventricular tachycardia (VT) and supraventricular tachycardia (SVT) with wide QRS complex. The algorithm entails 5 criteria, which are tested sequentially (Figure 1). Figure 1. Flowchart of Brugada's algorithm for distinguishing ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with wide QRS complex. Figure 1. Flowchart of Brugada's algorithm for distinguishing ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with wide QRS complex. #### Brugada's algorithm [#brugadas-algorithm] 1. If there is no RS complex in any chest lead (V1–V6) a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria. 2. Assess the RS interval (interval from start of the R-wave to the nadir of the S-wave). If any RS interval is >100 ms and the R-wave is wider than the S-wave, a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria. 3. If there is AV dissociation, a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria. 4. Assess the QRS morphology in V1, V2, V5 and V6 (see below). If the QRS morphology is compatible with ventricular tachycardia, then the diagnosis is ventricular tachycardia. 5. If no criteria have been fulfilled, a diagnosis of supraventricular tachycardia can be made. #### Judging the QRS morphology (criteria #4 in Brugada's algorithm) [#judging-the-qrs-morphology-criteria-4-in-brugadas-algorithm] ##### If the QRS complex in V1–V2 resembles a right bundle branch block (i.e positive QRS) [#if-the-qrs-complex-in-v1v2-resembles-a-right-bundle-branch-block-ie-positive-qrs] * **V1**: * Monophasic R complex suggests ventricular tachycardia. * qR complex suggests ventricular tachycardia. * if R is taller than R', ventricular tachycardia is suggested. * Triphasic complexes (rSr’, rsr’, rSR’, rsR’) suggests SVT * **V6**: * rS, QS, R or Rs complex suggests VT. ##### If the QRS complex in V1–V2 resembles a left bundle branch block (i.e negative QRS) [#if-the-qrs-complex-in-v1v2-resembles-a-leftbundle-branch-block-ie-negativeqrs] * **V1**: * The initial portion of the QRS complex is smooth in ventricular tachycardia. SVT has a sharp start of the QRS complex. * R-wave duration ≥40 ms suggest ventricular tachycardia. * Duration from start of QRS complex to nadir of S-wave ≥60 ms suggests ventricular tachycardia. * **V6**: * QR or QS complex suggest ventricular tachycardia. * R or RR complex without initial q-wave suggests SVT. All in all, Brugada's criteria have very high sensitivity (90%) and specificity (60–90%) for diagnosing ventricular tachycardia. ### Brugada's algorithm for differentiating ventricular tachycardia from antidromic AVRT [#brugadas-algorithm-for-differentiating-ventricular-tachycardia-from-antidromic-avrt] The algorithm above frequently fails to differentiate ventricular tachycardia from antidromic AVRT. Although antidromic AVRT is an uncommon cause of ventricular tachycardia, it is important to be able to differentiate these entities. The older the patient and the more significant the heart disease, the more likely ventricular tachycardia. The Brugada group has also developed an algorithm to differentiate antidromic AVRT from ventricular tachycardia. The algorithm follows: #### Brugada's algorithm for differentiating ventricular tachycardia and antidromic AVRT [#brugadas-algorithm-for-differentiating-ventricular-tachycardia-and-antidromic-avrt] 1. If the QRS complex is net negative in V4–V6, ventricular tachycardia is more likely. 2. If the QRS complex is net positive in V4–V6 and any of the leads V2–V6 display a qR complex, ventricular tachycardia is very likely. 3. If there is AV dissociation, ventricular tachycardia is very likely. 4. If there are no signs of ventricular tachycardia, antidromic AVRT should be strongly considered. # BUN:Creatinine Ratio (/docs/tools/calculators/bun-creatinine-ratio) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # CHA₂DS₂-VASc score (/docs/tools/calculators/cha2ds2-vasc) ## Interpretation of CHADS-VASc score and decisions on anticoagulation [#interpretation-of-chads-vasc-score-and-decisions-on-anticoagulation] | | Men | | Women | | | ---------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------- | | **Points** | Recommendation | Evidence | Recommendation | Evidence | | --- | --- | --- | --- | --- | | 0 | No treatment | Low | No treatment | High | | 1 | Oral anticoagulation (warfarin or NOAK1 is **considered** for male patients with a score of 1 or more. Patient preference and risk-benefit balance determine whether treatment is initiated. | High | No treatment | High | | 2 | Oral anticoagulation (warfarin or NOAC) is **recommended** for all male patients with scores of 2 or more. | Very high | Oral anticoagulation (warfarin or NOACs is **considered** for female patients with scores of 2 or more. Patient preference and the balance of risk and benefit determine whether treatment is initiated. | High | | 3-9 | As above. | Very high | Oral anticoagulation (warfarin or NOAC) is **recommended** for all female patients with a score of 3 or more. | Very high | 1NOAC = novel oral anticoagulants (new oral anticoagulants) include apixaban (Eliquis®), dabigatran (Pradaxa®), edoxaban (Lixiana®), rivaroxaban (Xarelto®). If oral anticoagulation is indicated, NOACs should be chosen except in patients with moderate to severe mitral stenosis or mechanical heart valves; for these patients, warfarin is chosen instead (Class 1 B recommendation). There are several models for risk-stratifying patients with atrial fibrillation, and CHADS-VASc is currently the most widely used model. The aim of CHADS-VASc is to identify patients at high risk of stroke, TIA or systemic thromboembolism and initiate treatment with anticoagulants (rarely with antiplatelet agents). CHADS-VASc predicts the risk of thromboembolism (stroke, TIA, systemic thromboembolism) in the next 12 months and the calculations apply to untreated patients with non-valvular atrial fibrillation (**Table 1**). | | | | | -------------------- | --------------------------- | ------------------------------------------------ | | **CHADS-VASc Score** | **Risk of ischemic stroke** | **Risk för stroke/TIA/systemisk tromboembolism** | | 0 | 0.2% | 0.3% | | 1 | 0.6% | 0.9% | | 2 | 2.2% | 2.9% | | 3 | 3.2% | 4.6% | | 4 | 4.8% | 6.7% | | 5 | 7.2% | 10.0% | | 6 | 9.7% | 13.6% | | 7 | 11.2% | 15.7% | | 8 | 10.8% | 15.2% | | 9 | 12.2% | 17.4% | ## CHADS-Vasc score [#chads-vasc-score] * C: Congestive heart failure (1 point) * H: Hypertension (1 point) * A: Age 75 and older (2 points) * D: Diabetes Mellitus (1 point) * S: Prior Stroke or TIA or thromboembolism (2 points) * V: Vascular disease (1 point) * A: Age 65 to 74 years (1 point) * Sc: Sex category: being female (1 point) In clinical trials (see References), patients with non-valvular atrial fibrillation and a CHADS-VASc score of 0 have had a very low incidence of thromboembolic events, therefore withholding treatment should be considered. Among patients who are updated for anticoagulation, bleeding risk should be calculated using risk models such as ATRIA or HAS-BLED. There is at best weak support that acetylsalicylic acid (ASA) can be used as monotherapy (this means that acetylsalicylic acid should not, as a rule, be used for stroke prevention in patients with atrial fibrillation). ## References [#references] [Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010 Feb;137(2):263-72. doi: 10.1378/chest.09-1584. Epub 2009 Sep 17. PubMed PMID: 19762550.](http://www.ncbi.nlm.nih.gov/pubmed/19762550) [Ntaios G, et al. CHADS2, CHA2DS2-VASc, and long-term stroke outcome in patients without atrial fibrillation. March 12, 2013 80:1009-1017; published ahead of print February 13, 2013](http://www.ncbi.nlm.nih.gov/pubmed/23408865) [Friberg L, Rosenqvist M, Lip GY. Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. Eur Heart J. 2012 Jun;33(12):1500-10. doi: 10.1093/eurheartj/ehr488. Epub 2012 Jan 13. PubMed PMID: 22246443.](http://www.ncbi.nlm.nih.gov/pubmed/22246443) [Okumura K, Inoue H, Atarashi H, Yamashita T, Tomita H, Origasa H; J-RHYTHM Registry Investigators.Validation of CHA₂DS₂-VASc and HAS-BLED scores in Japanese patients with nonvalvular atrial fibrillation: an analysis of the J-RHYTHM Registry. Circ J. 2014;78(7):1593-9. Epub 2014 Apr 22.](http://www.ncbi.nlm.nih.gov/pubmed/24759791) [Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, Hindricks G, Kirchhof P; ESC Committee for Practice Guidelines (CPG). 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012 Nov;33(21):2719-47. doi: 10.1093/eurheartj/ehs253. Epub 2012 Aug 24. Erratum in: Eur Heart J. 2013 Mar;34(10):790. Eur Heart J. 2013 Sep;34(36):2850-1. PubMed PMID: 22922413.](http://www.ncbi.nlm.nih.gov/pubmed/22922413) # CHADS-65 (Canadian Cardiovascular Society Algorithm) (/docs/tools/calculators/chads-65) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # CHADS-VA Bleeding Risk Score (/docs/tools/calculators/chads-va-bleeding-risk-score) The CHA₂DS₂-VA score has superseded the CHA₂DS₂-VASc score. As of 2025, it is recommended to use the CHA₂DS₂-VA score for stroke risk assessment in atrial fibrillation patients. By excluding the sex parameter, the CHA₂DS₂-VA score addresses concerns about overestimating stroke risk in women based solely on gender. This aims to prevent unnecessary anticoagulation in low-risk female patients, thereby reducing the potential for bleeding complications. The CHA₂DS₂-VA score is a clinical tool designed to assess stroke risk in patients with non-valvular atrial fibrillation (AF). It is a modification of the widely used CHA₂DS₂-VASc score, with the primary distinction being the exclusion of sex parameter (female sex) as a risk factor. ## Rationale for the development of CHA₂DS₂-VA [#rationale-for-the-development-of-chads-va] The CHA₂DS₂-VASc score includes female sex as a risk factor. However, recent studies have questioned the significance of female sex as an independent risk factor for stroke in AF patients. Evidence suggests that the increased stroke risk in women is more closely associated with other comorbidities and age rather than sex alone. Consequently, the CHA₂DS₂-VA score was developed to provide a more accurate risk assessment by omitting the sex category component. ## Components of the CHA₂DS₂-VA Score [#components-of-the-chads-va-score] The acronym CHA₂DS₂-VA represents the following parameters: * **C**ongestive Heart Failure (1 point) * **H**ypertension (1 point) * **A₂**ge ≥75 years (2 points) * **D**iabetes Mellitus (1 point) * **S₂**troke, Transient Ischemic Attack (TIA), or Thromboembolism history (2 points) * **V**ascular Disease (1 point) * **A**ge 65-74 years (1 point) The total score ranges from 0 to 9, with higher scores indicating an increased risk of stroke (Table 1). ## Interpretation of the CHA₂DS₂-VA score [#interpretation-of-the-chads-va-score] | CHA₂DS₂-VA Score | Risk Category | Annual Stroke Risk (%) | | ---------------- | ------------- | ---------------------- | | 0 | Low | 0.2 | | 1 | Low | 0.6 | | 2 | Intermediate | 2.2 | | 3 | Intermediate | 3.2 | | 4 | High | 4.8 | | 5 | High | 7.2 | | 6 | High | 9.7 | | 7 | High | 11.2 | | 8 | High | 10.8 | | 9 | High | 12.2 | Table 1. Interpretation of CHADS-VA score ## References [#references] **Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ.** Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the Euro Heart Survey on Atrial Fibrillation. *Chest*. 2010;137(2):263-272. doi:10.1378/chest.09-1584. **Friberg L, Rosenqvist M, Lip GY.** Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182,678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. *Eur Heart J*. 2012;33(12):1500-1510. doi:10.1093/eurheartj/ehr488. **Champsi S, et al.** CHA₂DS₂-VASc or a non-sex score (CHA₂DS₂-VA) for stroke risk prediction in atrial fibrillation: a cohort study. *Eur Heart J*. 2023;45(36):3718-3726. doi:10.1093/eurheartj/ehad456. **Stroke Risk Stratification: CHA₂DS₂-VA or CHA₂DS₂-VASc?** *Heart Lung Circ*. 2018;27(12):1478-1480. doi:10.1016/j.hlc.2018.08.011. **CHA₂DS₂-VA Score Calculator.** Available at: [https://chadsva.org/](https://chadsva.org/). # CHADS₂ score (/docs/tools/calculators/chads2) # CHALICE (Children's Head injury ALgorithm for the prediction of Important Clinical Events) Rule (/docs/tools/calculators/chalice-rule) {/* Write the article for this calculator below. 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Developed from the MDRD study, this equation incorporates variables such as serum creatinine, age, sex, and race to provide an eGFR value normalized to a standard body surface area of 1.73 m². ## Advantages of MDRD eGFR [#advantages-of-mdrd-egfr] **Clinical utility:** The MDRD equation has been instrumental in identifying and staging chronic kidney disease (CKD), facilitating early intervention and management. **Standardization:** Its widespread adoption has led to standardized reporting of eGFR in clinical laboratories, enhancing consistency in patient care. **Non-Invasiveness:** The calculation relies on readily available clinical parameters, eliminating the need for more invasive and costly direct measurements of GFR. ## Limitations of MDRD eGFR [#limitations-of-mdrd-egfr] **Accuracy at Higher GFR Levels:** The MDRD equation tends to underestimate GFR in individuals with near-normal or mildly reduced kidney function (eGFR >60 mL/min/1.73 m²), potentially leading to misclassification of CKD stages. **Population Specificity:** The equation was derived from a study population primarily consisting of individuals with CKD, limiting its accuracy when applied to healthy populations or those with acute kidney injury. **Influence of Muscle Mass and Diet:** Serum creatinine levels, a key component of the MDRD equation, can be affected by factors such as muscle mass, diet, and certain medications, potentially impacting the accuracy of eGFR estimations. **Ethnic and racial Variations:** The equation includes adjustments for race, particularly for individuals of African descent, which may not accurately reflect the diversity within racial groups and can lead to misestimations. **Clinical implications** While the MDRD eGFR calculator has significantly advanced the detection and management of CKD, clinicians should be aware of its limitations. In cases where precise GFR assessment is critical, especially in individuals with near-normal kidney function, alternative equations like the **Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation** may offer improved accuracy. Additionally, considering factors such as patient demographics, muscle mass, and clinical context is essential when interpreting eGFR results to ensure appropriate clinical decision-making. # EGSYS Score for Syncope (/docs/tools/calculators/egsys-syncope-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Emergency Heart Failure Mortality Risk Grade (EHMRG) (/docs/tools/calculators/ehmrg) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # El-Ganzouri Risk Index (EGRI) for difficult airway (/docs/tools/calculators/el-ganzouri-risk-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Eosinophilic Esophagitis Endoscopic Reference Score (EREFS) (/docs/tools/calculators/eosinophilic-esophagitis-erefs) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # EPIPHANY Index for pulmonary embolism in cancer (/docs/tools/calculators/epiphany-index) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fibrosis-4 (FIB-4) Index for Liver Fibrosis (/docs/tools/calculators/fibrosis-4-fib-4-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fibrotic NASH Index (FNI) (/docs/tools/calculators/fibrotic-nash-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Cardiac output (Fick principle) (/docs/tools/calculators/fick-cardiac-output) # FIGO Staging for Ovarian Cancer (2014) (/docs/tools/calculators/figo-staging-ovarian-cancer-2014) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # FINDRISC (Finnish Diabetes Risk Score) (/docs/tools/calculators/findrisc-diabetes-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fisher Grading Scale for Subarachnoid Hemorrhage (SAH) (/docs/tools/calculators/fisher-grading-scale-sah) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # FLACC scale for postoperative pain in children (/docs/tools/calculators/flacc-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fleischner Society Guidelines for Incidental Pulmonary Nodules (/docs/tools/calculators/fleischner-pulmonary-nodules) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Follicular Lymphoma International Prognostic Index (FLIPI) (/docs/tools/calculators/flipi-follicular-lymphoma) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Body Fluid Balance by Inputs and Outputs (/docs/tools/calculators/fluid-balance) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fomepizole dosing (/docs/tools/calculators/fomepizole-dosing) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fong Clinical Risk Score for Colorectal Cancer Recurrence (/docs/tools/calculators/fong-clinical-risk-score-colorectal) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Forrest classification of upper GI bleeding (/docs/tools/calculators/forrest-classification-ugib) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # FOUR (Full Outline of UnResponsiveness) score (/docs/tools/calculators/four-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fractional shortening and Teichholz ejection fraction (/docs/tools/calculators/fractional-shortening) # FRACTURE Index (/docs/tools/calculators/fracture-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Framingham Heart Failure Diagnostic Criteria (/docs/tools/calculators/framingham-heart-failure-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Framingham Risk Score for Hard Coronary Heart Disease (/docs/tools/calculators/framingham-risk-score-hard-chd) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Free water deficit in hypernatremia (/docs/tools/calculators/free-water-deficit-hypernatremia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Fuhrman Nuclear Grade for Clear Cell Renal Carcinoma (/docs/tools/calculators/fuhrman-nuclear-grade-clear-cell-rcc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Functional Outcome in Patients With Primary Intracerebral Hemorrhage (FUNC) Score (/docs/tools/calculators/func-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # G8 Geriatric Screening Tool (/docs/tools/calculators/g8-geriatric-screening-tool) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GAD-7 (Generalized Anxiety Disorder-7) (/docs/tools/calculators/gad-7) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GALAD Model for Hepatocellular Carcinoma (HCC) (/docs/tools/calculators/galad-model-hepatocellular-carcinoma) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Ganzoni Equation for Iron Deficiency Anemia (/docs/tools/calculators/ganzoni-equation-iron-deficiency-anemia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GAP index for idiopathic pulmonary fibrosis mortality (/docs/tools/calculators/gap-index-ipf) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GCS-Pupils (GCS-P) Score (/docs/tools/calculators/gcs-pupils-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Groupe d'Etude des Lymphomes Folliculaires (GELF) Criteria (/docs/tools/calculators/gelf-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Geneva Risk Score for Venous Thromboembolism (VTE) Prophylaxis (/docs/tools/calculators/geneva-risk-score-vte-prophylaxis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Geriatric Depression Scale (GDS-15) (/docs/tools/calculators/geriatric-depression-scale-15) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Graded Prognostic Assessment for Gastrointestinal Cancer (GI-GPA) (/docs/tools/calculators/gi-gpa) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Gillmore Staging System for Transthyretin Amyloid Cardiomyopathy (ATTR-CM) (/docs/tools/calculators/gillmore-staging-attr-cm) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Genetically Inspired Prognostic Scoring System (GIPSS) for Primary Myelofibrosis (PMF) (/docs/tools/calculators/gipss-primary-myelofibrosis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow Alcoholic Hepatitis Score (GAHS) (/docs/tools/calculators/glasgow-alcoholic-hepatitis-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow-Blatchford bleeding score (/docs/tools/calculators/glasgow-blatchford) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow Coma Scale (GCS) (/docs/tools/calculators/glasgow-coma-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow-Imrie Criteria for Severity of Acute Pancreatitis (/docs/tools/calculators/glasgow-imrie-criteria-pancreatitis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow Prognostic Score (GPS) for cancer outcomes (/docs/tools/calculators/glasgow-prognostic-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Gleason Score for Prostate Cancer (/docs/tools/calculators/gleason-score-prostate-cancer) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glucose infusion rate (GIR) (/docs/tools/calculators/glucose-infusion-rate) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Glasgow Modified Alcohol Withdrawal Scale (GMAWS) (/docs/tools/calculators/gmaws-alcohol-withdrawal) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GO-FAR (Good Outcome Following Attempted Resuscitation) Score (/docs/tools/calculators/go-far-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GOLD criteria for COPD airflow limitation severity (/docs/tools/calculators/gold-copd-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # GRACE ACS Risk and Mortality Calculator (/docs/tools/calculators/grace-acs-risk-mortality-calculator) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Grogan Staging System for Transthyretin Amyloid Cardiomyopathy (ATTR-CM) (/docs/tools/calculators/grogan-staging-attrwt-cm) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Gupta Perioperative Risk for Myocardial Infarction or Cardiac Arrest (MICA) (/docs/tools/calculators/gupta-perioperative-risk-mica) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # H2FPEF Score for Heart Failure with Preserved Ejection Fraction (/docs/tools/calculators/h2fpef-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HACOR Score (/docs/tools/calculators/hacor-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Hamilton Depression Rating Scale (HAM-D) (/docs/tools/calculators/ham-d) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Hamilton Anxiety Scale (HAM-A) (/docs/tools/calculators/hamilton-anxiety-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Harmless Acute Pancreatitis Score (HAPS) (/docs/tools/calculators/haps-pancreatitis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HARK intimate partner violence screen (/docs/tools/calculators/hark-ipv-screen) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Harvey-Bradshaw Index (HBI) for Crohn's Disease (/docs/tools/calculators/harvey-bradshaw-index-crohns) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HAS-BLED score (/docs/tools/calculators/has-bled) The HAS-BLED score is a widely recognized and validated tool used to assess the one-year risk of major bleeding in patients with atrial fibrillation (AF) who are taking anticoagulants. It was developed in 2010, using data from the EuroHeart survey. ## Components of the HAS-BLED Score [#components-of-the-has-bled-score] The HAS-BLED score is an acronym that stands for: * **H**ypertension * **A**bnormal renal/liver function * **S**troke * **B**leeding history or predisposition * **L**abile INR (International Normalized Ratio) * **E**lderly (age > 65 years) * **D**rugs/alcohol concomitantly Each component is assigned 1 point, with a maximum score of 9. The score takes into account various risk factors that contribute to bleeding risk, including uncontrolled hypertension, impaired renal or liver function, previous stroke, history of bleeding, unstable anticoagulation control, advanced age, and the use of certain medications or alcohol. ## Interpretation of HAS-BLED score [#interpretation-of-has-bled-score] * A score of 0-1 indicates low risk * A score of 2 suggests moderate risk * A score of 3 or higher indicates high risk of major bleeding Note that a high HAS-BLED score should not be used as a reason to withhold anticoagulation therapy. Instead, it serves as a tool to identify patients who may require more careful monitoring and management of modifiable risk factors. The HAS-BLED score has demonstrated moderate predictive abilities for bleeding risks in AF patients, regardless of the type of oral anticoagulant used. Studies have shown that it performs similarly or superiorly to other bleeding risk assessment tools, such as HEMORR2HAGES, ATRIA, ORBIT, and GARFIELD-AF scores. Moreover, the HAS-BLED score has been found to be predictive of intracranial hemorrhage, which is considered the most devastating complication related to anticoagulation use. # HAT score (haemorrhage after thrombolysis) (/docs/tools/calculators/hat-score-post-tpa-hemorrhage) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HCM Risk-SCD Calculator (/docs/tools/calculators/hcm-risk-calculator) ## Predicting Sudden Cardiac Death in Hypertrophic Cardiomyopathy (HCM) [#predicting-sudden-cardiac-death-in-hypertrophic-cardiomyopathy-hcm] Hypertrophic Cardiomyopathy (HCM) is a genetic cardiomyopathy characterized by left ventricular hypertrophy. It is the most prevalent cardiomyopathy worldwide, affecting 1 in 500 individuals in most societies. HCM is also the most common cause of sudden cardiac death (SCD) in young individuals and during exercise. The risk of ventricular arrhythmias correlates with the degree of hypertrophy, the extent of ventricular fibrosis, LVOT obstruction, age, and left ventricular function. The HCM Risk-SCD score aims to identify individuals with a high risk of SCD and determine whether an implantable cardioverter-defibrillator (ICD) is warranted. The HCM Risk-SCD calculator is validated to estimate the 5-year risk of SCD in patients with HCM. ## What is the HCM Risk Calculator? [#what-is-the-hcm-risk-calculator] The HCM Risk Calculator is based on the **HCM Risk-SCD formula**, a validated risk prediction model developed I relatively large patient cohorts. It incorporates key clinical and echocardiographic parameters to calculate an individual's risk of SCD over the next 5 years. The calculator is widely used in clinical practice and is endorsed by major cardiology guidelines, including those from the European Society of Cardiology (ESC), American College of Cardiology (ACC) and American Heart Association (AHA). The formula takes into account the following variables: 1. **Maximum Left Ventricular Wall Thickness (MaxLVWT)**: Hypertrophy is a hallmark of HCM and is associated with increased arrhythmic risk. 2. **Left Atrial Diameter (LA)**: Enlargement of the left atrium is a marker of elevated left ventricular filling pressures and is linked to adverse outcomes. 3. **Left Ventricular Outflow Tract Gradient (LVOTG)**: LVOT obstruction is a risk factor for heart failure and arrhythmias. 4. **Family History of Sudden Cardiac Death (FHSCD)**: A history of SCD in close relatives suggests a genetic predisposition to arrhythmias. 5. **Non-Sustained Ventricular Tachycardia (NSVT)**: Episodes of VT are a strong predictor of SCD. 6. **Unexplained Syncope**: Syncope without a clear cause may indicate underlying arrhythmias. 7. **Age**: Younger patients are generally at higher risk of SCD due to the progressive nature of HCM. By combining these factors, the calculator generates a **5-year SCD risk percentage**, which helps clinicians stratify patients into low, intermediate, or high-risk categories. A significant shortcoming of the HCM Risk-SCD Score is the absence of magnetic resonance imaging parameters (extent of myocardial fibrosis). ## Risk stratification [#risk-stratification] The calculator helps identify patients at high risk of SCD who may benefit from preventive interventions, such as ICD implantation. For example: * A 5-year SCD risk ≥ 6% is considered high risk, and ICD implantation is typically recommended. * A risk between 4% and 6% is considered intermediate, and additional clinical judgment is required. * A risk \< 4% is considered low risk, and routine follow-up is usually sufficient. ## Shared decision-making [#shared-decision-making] The calculator provides a quantitative estimate of SCD risk, which facilitates informed discussions between clinicians and patients. This is particularly important when considering ICD implantation, as the procedure carries both benefits (life-saving therapy) and risks (e.g., device-related complications). ## Monitoring disease progression [#monitoring-disease-progression] By periodically recalculating the SCD risk, clinicians can monitor changes in a patient's condition over time. For instance, an increase in left atrial size or the development of NSVT may warrant closer surveillance or a reassessment of treatment strategies. ## References [#references] [O’Mahony C, Jichi F, Pavlou M, et al. A novel clinical risk prediction model for sudden cardiac death in hypertrophic cardiomyopathy (Hcm risk-scd). European Heart Journal. 2014;35(30):2010-2020.](https://pubmed.ncbi.nlm.nih.gov/24126876/) [Vriesendorp PA, Schinkel AFL, Liebregts M, et al. Validation of the 2014 European Society of Cardiology guidelines risk prediction model for the primary prevention of sudden cardiac death in hypertrophic cardiomyopathy. Circ Arrhythm Electrophysiol. 2015;8(4):829-835.](https://pubmed.ncbi.nlm.nih.gov/25922410/)[O’Mahony C, Jichi F, Ommen SR, et al. International external validation study of the 2014 european society of cardiology guidelines on sudden cardiac death prevention in hypertrophic cardiomyopathy(Evidence-hcm). Circulation. 2018;137(10):1015-1023.](https://pubmed.ncbi.nlm.nih.gov/29191938/) [Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022;43(40):3997-4126.](https://pubmed.ncbi.nlm.nih.gov/36017572/)[Authors/Task Force members, Elliott PM, Anastasakis A, et al. 2014 esc guidelines on diagnosis and management of hypertrophic cardiomyopathy: the task force for the diagnosis and management of hypertrophic cardiomyopathy of the european society of cardiology(Esc). Eur Heart J. 2014;35(39):2733-2779.](https://pubmed.ncbi.nlm.nih.gov/25173338/)[Monda E, Limongelli G. Integrated sudden cardiac death risk prediction model for patients with hypertrophic cardiomyopathy. Circulation. 2023;147(4):281-283.](https://pubmed.ncbi.nlm.nih.gov/36689567/) # HCM Risk-SCD (/docs/tools/calculators/hcm-risk-scd) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) (/docs/tools/calculators/hct-ci) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HEADS-ED (/docs/tools/calculators/heads-ed) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HEAR Score (/docs/tools/calculators/hear-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HEART Pathway for Early Discharge in Acute Chest Pain (/docs/tools/calculators/heart-pathway-early-discharge-chest-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HEART score for chest pain (/docs/tools/calculators/heart-score) # HEAVEN criteria for difficult emergency airway (/docs/tools/calculators/heaven-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HEMORR₂HAGES Bleeding Risk Score (/docs/tools/calculators/hemorr-e2-82-82hages-bleeding-risk-score) The HEMORR₂HAGES bleeding risk score is a clinical tool developed to assess the risk of major bleeding in patients with atrial fibrillation (AF) on anticoagulation therapy. Its purpose is to guide clinicians in balancing estimating the risks of bleeding. ## Components of the HEMORR₂HAGES Score [#components-of-the-hemorrhages-score] The acronym HEMORR₂HAGES represents the following parameters: * **H**epatic or renal disease (1 point) * **E**thanol abuse (1 point) * **M**alignancy (1 point) * **O**lder age (>75 years) (1 point) * **R**educed platelet count or function (1 point) * **R**e-bleeding risk, i.e., prior bleeding (2 points) * **H**ypertension, uncontrolled (1 point) * **A**nemia (1 point) * **G**enetic factors (e.g., CYP2C9 variants) (1 point) * **E**xcessive fall risk (1 point) * **S**troke (1 point) | HEMORR₂HAGES Score | Risk category | Incidence of major bleeding (per 100 patient-years) | | ------------------ | ------------- | --------------------------------------------------- | | 0 | Low | 1.9 | | 1 | Low | 2.5 | | 2 | Intermediate | 5.3 | | 3 | Intermediate | 8.4 | | 4 | High | 10.4 | | ≥5 | High | 12.3 | Interpretation of HEMORR₂HAGES score. **Comparison with ATRIA and HAS-BLED Scores** Several studies have compared the predictive performance of HEMORR₂HAGES with other bleeding risk assessment tools, notably ATRIA and HAS-BLED: * **HAS-BLED Score:** In a study evaluating bleeding risk prediction in AF patients, the HAS-BLED score demonstrated superior predictive performance compared to both HEMORR₂HAGES and ATRIA. The HAS-BLED score had the highest net reclassification improvement for predicting clinically relevant bleeding, with a 10.3% and 13% improvement compared with HEMORR₂HAGES and ATRIA, respectively ([Apostolakis et al](https://pubmed.ncbi.nlm.nih.gov/22858389/)). * **ATRIA Score:** The same study found that the ATRIA score had a lower predictive performance for major bleeding compared to HAS-BLED. The C-indices were 0.60 for HAS-BLED, 0.55 for HEMORR₂HAGES, and 0.50 for ATRIA, indicating that HAS-BLED had better discrimination ability ([Apostolakis et al](https://pubmed.ncbi.nlm.nih.gov/22858389/)). Overall, the HAS-BLED score may offer better predictive accuracy for bleeding risk in AF patients undergoing anticoagulation therapy. ## References [#references] 1\. Gage BF, Yan Y, Milligan PE, et al. Clinical classification schemes for predicting hemorrhage: results from the National Registry of Atrial Fibrillation. *Am Heart J*. 2006;151(3):713-719. 2\. Apostolakis S, Lane DA, Guo Y, Buller H, Lip GY. Performance of the HEMORR₂HAGES, ATRIA, and HAS-BLED bleeding risk-prediction scores in patients with atrial fibrillation undergoing anticoagulation: the AMADEUS study. *J Am Coll Cardiol*. 2012;60(9):861-867. 3\. Pisters R, Lane DA, Nieuwlaat R, de Vos CB, Crijns HJ, Lip GY. A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding in patients with atrial fibrillation: the Euro Heart Survey. *Chest*. 2010;138(5):1093-1100. # HEMORR₂HAGES Score for Major Bleeding Risk (/docs/tools/calculators/hemorr2hages-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # HIT Expert Probability (HEP) score (/docs/tools/calculators/hep-score-hit) {/* Write the article for this calculator below. 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Every calculator cites the original publication, and values can be entered in either conventional or SI units — use the unit button beside each field to switch. ### Reference articles [#reference-articles] Articles in this section that are not interactive calculators. * [1-2-3-LQTS Risk Calculator](/docs/tools/calculators/1-2-3-lqts-risk-calculator) * [Adjusted aortic root dimension](/docs/tools/calculators/adjusted-aortic-root-dimension) * [ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) Bleeding Risk Score](/docs/tools/calculators/atria-anticoagulation-and-risk-factors-in-atrial-fibrillation-bleeding-risk-scor) * [Brugada’s algorithm for diagnosing ventricular tachycardia (VT)](/docs/tools/calculators/brugadas-algorithm-for-distinguishing-ventricular-tachycardia-vt-from-supraventr) * [CHADS-VA Bleeding Risk Score](/docs/tools/calculators/chads-va-bleeding-risk-score) * [HCM Risk-SCD Calculator](/docs/tools/calculators/hcm-risk-calculator) * [HEMORR₂HAGES Bleeding Risk Score](/docs/tools/calculators/hemorr-e2-82-82hages-bleeding-risk-score) * [SYNTAX Score](/docs/tools/calculators/syntax-score) * [SYNTAX Score II](/docs/tools/calculators/syntax-score-ii) * [Vernakalant (Brinavess)](/docs/tools/calculators/vernakalant-brinavess) # Infant Scalp Score (/docs/tools/calculators/infant-scalp-score) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mangled Extremity Severity Score (MESS) (/docs/tools/calculators/mangled-extremity-severity-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Manning Criteria for Diagnosis of Irritable Bowel Syndrome (IBS) (/docs/tools/calculators/manning-criteria-ibs) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mantle Cell Lymphoma International Prognostic Index (MIPI) (/docs/tools/calculators/mantle-cell-lymphoma-international-prognostic-index-mipi) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Marburg Heart Score (MHS) (/docs/tools/calculators/marburg-heart-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Martin Equation for Low-Density Lipoprotein Cholesterol (LDL-C) (/docs/tools/calculators/martin-equation-ldl-c) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # MASCC risk index for febrile neutropenia (/docs/tools/calculators/mascc-febrile-neutropenia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Maternal-Fetal Hemorrhage Rh(D) Immune Globulin Dosage (/docs/tools/calculators/maternal-fetal-hemorrhage-rhig-dosage) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Maximum allowable blood loss (ABL) without transfusion (/docs/tools/calculators/maximum-allowable-blood-loss) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mayo Score/Disease Activity Index (DAI) for Ulcerative Colitis (/docs/tools/calculators/mayo-score-ulcerative-colitis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # McDonald Criteria for Multiple Sclerosis (2017 Revision) (/docs/tools/calculators/mcdonald-criteria-2017) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # McMahon score for rhabdomyolysis (/docs/tools/calculators/mcmahon-rhabdomyolysis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mean arterial pressure (MAP) (/docs/tools/calculators/mean-arterial-pressure) Mean arterial pressure (MAP) represents the average pressure within the arteries throughout a single cardiac cycle, encompassing both systole and diastole. It is a critical parameter in cardiovascular physiology, providing insight into the perfusion pressure experienced by organs and tissues. Clinically, MAP is often estimated using the formula: **MAP ≈ Diastolic Blood Pressure (DBP) + 1/3 × (Systolic Blood Pressure – DBP)** This formula accounts for the longer duration of diastole compared to systole. ## Clinical utlility [#clinical-utlility] Monitoring MAP is essential for assessing adequate organ perfusion, especially in critically ill patients. A MAP of approximately 60 to 65 mmHg is generally considered the minimum threshold necessary to ensure sufficient blood flow to vital organs such as the brain and kidneys. Maintaining MAP within an optimal range is crucial in managing conditions like sepsis, trauma, and shock, where perfusion may be compromised. ## Hemodynamic determinants of MAP [#hemodynamic-determinants-of-map] Hemodynamically, MAP is influenced by cardiac output (CO) and systemic vascular resistance (SVR), as described by the relationship: **MAP = (CO × SVR) + Central Venous Pressure (CVP)** This equation illustrates that MAP is determined by the volume of blood the heart pumps and the resistance encountered in the systemic circulation. Therefore, alterations in heart rate, stroke volume, or vascular tone can significantly impact MAP, reflecting the dynamic interplay between cardiac function and vascular resistance. ## Advantages of measuring MAP over systolic blood pressure [#advantages-of-measuring-map-over-systolic-blood-pressure] While systolic blood pressure (SBP) indicates the maximum pressure during heart contraction, it does not provide a comprehensive view of the perfusion pressure throughout the cardiac cycle. MAP offers a more accurate representation of the average arterial pressure and is a better indicator of organ perfusion. In clinical settings, MAP is often preferred over SBP for the following reasons: * **Indicator of Organ Perfusion**: MAP is a more reliable indicator of blood flow to vital organs than systolic blood pressure alone. * **Predictive Value**: Elevated MAP has been associated with an increased risk of cardiovascular diseases, such as stroke, and mortality. * **Stability**: MAP readings tend to be more accurate than systolic blood pressure when using non-invasive blood pressure methods. ## Limitations in measuring and interpreting MAP [#limitations-in-measuring-and-interpreting-map] Despite its clinical utility, there are limitations in measuring and interpreting MAP. Non-invasive methods, such as oscillometric blood pressure devices, may provide less accurate MAP readings compared to invasive arterial catheterization, particularly in patients with irregular heart rhythms or low blood pressure. Additionally, individual variations in arterial compliance and pulse pressure can affect the accuracy of MAP estimations derived from standard formulas. Therefore, while MAP is a valuable indicator of hemodynamic status, it should be interpreted in conjunction with other clinical assessments and diagnostic information. # Mehran Score for Post-PCI Contrast Nephropathy (/docs/tools/calculators/mehran-score-contrast-nephropathy) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mekhail Extension of the Motzer Score (/docs/tools/calculators/mekhail-extension-motzer-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # MELD Na (UNOS/OPTN) (/docs/tools/calculators/meld-na-unos) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # MELD-Na score (/docs/tools/calculators/meld-na) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # MELD score (original, pre-2016) (/docs/tools/calculators/meld-original-pre-2016) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mentzer index (/docs/tools/calculators/mentzer-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Menza Score for HIV risk among MSM (/docs/tools/calculators/menza-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Metabolic Score for Insulin Resistance (METS-IR) (/docs/tools/calculators/mets-ir) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Early Warning Score (MEWS) for Clinical Deterioration (/docs/tools/calculators/mews-clinical-deterioration) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Myasthenia Gravis Activities of Daily Living (MG-ADL) (/docs/tools/calculators/mg-adl) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Michigan Risk Score for PICC-related thrombosis (/docs/tools/calculators/michigan-risk-score-picc-thrombosis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Migraine Disability Assessment (MIDAS) (/docs/tools/calculators/midas-migraine-disability) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Milan Criteria for Liver Transplantation (/docs/tools/calculators/milan-criteria-liver-transplantation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mutation-Enhanced International Prognostic Score System (MIPSS70) (/docs/tools/calculators/mipss70-mipss70-plus) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mirels' Criteria for Prophylactic Fixation (/docs/tools/calculators/mirels-criteria-prophylactic-fixation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mitral valve area (pressure half-time) (/docs/tools/calculators/mitral-valve-area-pht) # Morphine milligram equivalents (MME) per day (/docs/tools/calculators/mme) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Minnesota Detoxification Scale (mMINDS) (/docs/tools/calculators/mminds) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # mMRC (Modified Medical Research Council) Dyspnea Scale (/docs/tools/calculators/mmrc-dyspnea-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified NIH Stroke Scale (mNIHSS) (/docs/tools/calculators/mnihss) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Montreal Cognitive Assessment (MoCA) scoring (/docs/tools/calculators/moca) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Asthma Predictive Index (mAPI) (/docs/tools/calculators/modified-asthma-predictive-index-mapi) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Bishop Score for Vaginal Delivery and Induction of Labor (/docs/tools/calculators/modified-bishop-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Denver criteria for blunt cerebrovascular injury (/docs/tools/calculators/modified-denver-criteria-bcvi) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Fatigue Impact Scale (MFIS) (/docs/tools/calculators/modified-fatigue-impact-scale-mfis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Finnegan Neonatal Abstinence Score (NAS) (/docs/tools/calculators/modified-finnegan-neonatal-abstinence-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Fisher Grading Scale for Subarachnoid Hemorrhage (SAH) (/docs/tools/calculators/modified-fisher-grading-scale-sah) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Glasgow Prognostic Score (mGPS) for Cancer Outcomes (/docs/tools/calculators/modified-glasgow-prognostic-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Hoehn and Yahr Scale for Parkinson's Disease (/docs/tools/calculators/modified-hoehn-yahr-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Mallampati classification (/docs/tools/calculators/modified-mallampati-classification) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Rankin Scale (mRS) (/docs/tools/calculators/modified-rankin-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Response Evaluation Criteria in Solid Tumors (mRECIST) (/docs/tools/calculators/modified-recist-mrecist-hcc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Sgarbossa's Criteria for MI in Left Bundle Branch Block (/docs/tools/calculators/modified-sgarbossa-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified SOAR Score for Stroke (/docs/tools/calculators/modified-soar-score-stroke) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Montreal Classification for Inflammatory Bowel Disease (IBD) (/docs/tools/calculators/montreal-classification-ibd) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mood Disorder Questionnaire (MDQ) (/docs/tools/calculators/mood-disorder-questionnaire) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified Rankin Score-9Q (mRS-9Q) (/docs/tools/calculators/mrs-9q) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Memorial Sloan-Kettering Cancer Center (MSKCC/Motzer) Score for Metastatic RCC (/docs/tools/calculators/mskcc-motzer-score-metastatic-rcc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Modified SOFA (mSOFA) score (/docs/tools/calculators/msofa) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Migraine Treatment Optimization Questionnaire-4 (mTOQ-4) (/docs/tools/calculators/mtoq-4) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # MuLBSTA score for viral pneumonia mortality (/docs/tools/calculators/mulbsta-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Multiple Myeloma Diagnostic Criteria (/docs/tools/calculators/multiple-myeloma-diagnostic-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Multiple Myeloma International Staging System (ISS) (/docs/tools/calculators/multiple-myeloma-iss) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Multiple Myeloma Response Criteria (/docs/tools/calculators/multiple-myeloma-response-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mumtaz score for readmission in cirrhosis (/docs/tools/calculators/mumtaz-score-readmission-cirrhosis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Murray score for acute lung injury (/docs/tools/calculators/murray-lung-injury-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Malnutrition Universal Screening Tool (MUST) (/docs/tools/calculators/must-malnutrition) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Mutation-Adjusted Risk Score (MARS) for Advanced Systemic Mastocytosis (/docs/tools/calculators/mutation-adjusted-risk-score-mars) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Myelofibrosis Secondary to PV and ET Prognostic Model (MYSEC-PM) (/docs/tools/calculators/mysec-pm-secondary-myelofibrosis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Myxedema coma diagnostic score (/docs/tools/calculators/myxedema-coma-diagnostic-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # IV N-acetylcysteine dosing for acetaminophen overdose (/docs/tools/calculators/nac-dosing-acetaminophen-overdose) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NAFLD activity score (NAS) (/docs/tools/calculators/nafld-activity-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NAFLD Fibrosis Score (/docs/tools/calculators/nafld-fibrosis-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Naloxone continuous infusion dosing (/docs/tools/calculators/naloxone-drip) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Natriuretic Response Prediction Equation (NRPE) (/docs/tools/calculators/natriuretic-response-prediction-equation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NCCN International Prognostic Index (NCCN-IPI) (/docs/tools/calculators/nccn-ipi) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # National Cancer Institute Common Toxicity Criteria (NCI-CTC) for Mucositis (/docs/tools/calculators/nci-ctc-mucositis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Neck Disability Index (NDI) (/docs/tools/calculators/neck-disability-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NEDOCS score for emergency department overcrowding (/docs/tools/calculators/nedocs-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Neonatal Partial Exchange for Polycythemia (/docs/tools/calculators/neonatal-partial-exchange-polycythemia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Neuropathic Pain Scale (NPS) (/docs/tools/calculators/neuropathic-pain-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Neutrophil-lymphocyte ratio (NLR) (/docs/tools/calculators/neutrophil-lymphocyte-ratio) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # New Orleans criteria for minor head injury (/docs/tools/calculators/new-orleans-head-injury) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # National Early Warning Score (NEWS) (/docs/tools/calculators/news) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # National Early Warning Score 2 (NEWS2) (/docs/tools/calculators/news2) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Newsom Score for Non-traumatic Chest Pain (/docs/tools/calculators/newsom-score-nontraumatic-chest-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NEXUS Chest Decision Instrument for blunt chest trauma (/docs/tools/calculators/nexus-chest-blunt-trauma) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NEXUS Chest CT decision instrument (/docs/tools/calculators/nexus-chest-ct) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NEXUS criteria for cervical-spine imaging (/docs/tools/calculators/nexus-cspine-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NEXUS Head CT instrument (/docs/tools/calculators/nexus-head-ct) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # NIH Stroke Scale (NIHSS) (/docs/tools/calculators/nihss) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Noninvasive Ventilation Outcomes (NIVO) score (/docs/tools/calculators/nivo-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Nonverbal Pain Scale (NVPS) for nonverbal patients (/docs/tools/calculators/nonverbal-pain-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Nottingham Hip Fracture Score (NHFS) (/docs/tools/calculators/nottingham-hip-fracture-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Nutrition Risk in the Critically Ill (NUTRIC) score (/docs/tools/calculators/nutric-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Nutrition Risk Screening 2002 (NRS-2002) (/docs/tools/calculators/nutrition-risk-screening-2002) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Nutritional Risk Index (NRI) (/docs/tools/calculators/nutritional-risk-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # New York Heart Association (NYHA) Functional Classification for Heart Failure (/docs/tools/calculators/nyha-functional-classification) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Oakland score for lower GI bleeding (/docs/tools/calculators/oakland-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Ocular Hypertension Treatment Study (OHTS) calculator (/docs/tools/calculators/ocular-hypertension-treatment-study-ohts-calculator) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # OESIL Score for Syncope (/docs/tools/calculators/oesil-score-syncope) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Overall Neuropathy Limitations Scale (ONLS) (/docs/tools/calculators/onls-overall-neuropathy-limitations-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Opiate conversion calculator (/docs/tools/calculators/opiate-conversion-calculator) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Opioid Risk Tool (ORT) (/docs/tools/calculators/opioid-risk-tool) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Osteoporosis Risk Assessment Instrument (ORAI) (/docs/tools/calculators/orai-osteoporosis-risk) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Observatoire Regional Breton sur l'Infarctus (ORBI) Risk Score (/docs/tools/calculators/orbi-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # ORBIT Bleeding Risk Score for Atrial Fibrillation (/docs/tools/calculators/orbit-bleeding-risk-score-af) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Obesity Surgery Mortality Risk Score (OS-MRS) (/docs/tools/calculators/os-mrs-obesity-surgery-mortality-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Osteoporosis Index of Risk (OSIRIS) (/docs/tools/calculators/osiris-osteoporosis-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Osteoporosis Self-Assessment Tool (OST) (/docs/tools/calculators/ost-osteoporosis-self-assessment) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Ottawa ankle and foot rules (/docs/tools/calculators/ottawa-ankle-rule) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Oxygenation index (OI) (/docs/tools/calculators/oxygenation-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Pack-years (smoking history) (/docs/tools/calculators/pack-years) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Padua prediction score for VTE risk (/docs/tools/calculators/padua-vte) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Pain Assessment in Advanced Dementia (PAINAD) (/docs/tools/calculators/painad-dementia-pain) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Shunt fraction (Qp/Qs) (/docs/tools/calculators/qp-qs-shunt-fraction) ## Calculating Shunt Fraction (Qp/Qs) Using Echocardiography: A Guide to Methods and Clinical Relevance [#calculating-shunt-fraction-qpqs-using-echocardiography-a-guide-to-methods-and-clinical-relevance] The shunt fraction (Qp/Qs) is a critical hemodynamic parameter used to quantify the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs). This measurement is pivotal in diagnosing and managing congenital or acquired cardiac shunts, such as atrial septal defects (ASD), ventricular septal defects (VSD), and patent ductus arteriosus (PDA). Echocardiography provides a non-invasive, accessible method to calculate this ratio, guiding clinical decisions about intervention or monitoring. Below, we outline the methodology and clinical applications of shunt fraction calculation. ### **Echocardiographic Calculation of Qp/Qs** [#echocardiographic-calculation-of-qpqs] #### **1. Measurement of Left Ventricular Outflow Tract (LVOT) Diameter** [#1-measurement-of-left-ventricular-outflow-tract-lvot-diameter] * **Optimal View**: Mid-transgastric left ventricular short-axis (LVSAX) view. * **Method**: Zoom to maximize LVOT visibility. Freeze the image during mid-ejection, when the LVOT reaches maximal diameter. Measure from intimal wall to intimal wall, just proximal to the aortic valve. #### **2. Aortic Valve Velocity-Time Integral (AV VTI)** [#2-aortic-valve-velocity-time-integral-av-vti] * **Optimal View**: Deep transgastric or transgastric aortic valve long-axis (AVLAX) view. * **Method**: Use continuous-wave Doppler (CWD) across the aortic valve. Trace the Doppler profile to calculate the AV VTI, representing the distance blood travels during systole. #### **3. Right Ventricular Outflow Tract (RVOT) Diameter** [#3-right-ventricular-outflow-tract-rvot-diameter] * **Optimal View**: Right ventricular inflow-outflow (RVIO) view. * **Method**: Under zoomed conditions, measure the RVOT diameter perpendicular to the pulmonary valve. #### **4. Pulmonary Valve Velocity-Time Integral (PV VTI)** [#4-pulmonary-valve-velocity-time-integral-pv-vti] * **Optimal View**: Short-axis (SAX) view of the aortic arch, visualizing the pulmonary valve in long axis. * **Method**: Trace the pulmonary valve’s Doppler profile using CWD to derive PV VTI. ### **Formulas for Shunt Fraction Calculation** [#formulas-for-shunt-fraction-calculation] 1. **Stroke Volume (SV) Calculations**: * **Aortic SV** (Systemic flow): \[ \text\{Aortic SV} = 0.785 \times (\text\{LVOT diameter})^2 \times \text\{AV VTI} ] * **Pulmonic SV** (Pulmonary flow): \[ \text\{Pulmonic SV} = 0.785 \times (\text\{RVOT diameter})^2 \times \text\{PV VTI} ] The constant ( 0.785 ) ((\pi/4)) converts diameter to cross-sectional area. 1. **Shunt Fraction (Qp/Qs)**: \[ \text\{Qp/Qs} = \frac\{\text\{Aortic SV}}\{\text\{Pulmonic SV}} ] * **Interpretation**: * **Qp/Qs > 1.5**: Significant left-to-right shunt (e.g., large ASD/VSD). * **Qp/Qs \< 0.7**: Significant right-to-left shunt (e.g., Eisenmenger syndrome). * **Qp/Qs ≈ 1**: Normal, no significant shunt. ### **Clinical Relevance of Shunt Fraction** [#clinical-relevance-of-shunt-fraction] 1. **Diagnosis of Shunt Severity**: * Quantifies the magnitude of intracardiac shunts, distinguishing hemodynamically significant defects from incidental findings. 1. **Guidance for Intervention**: * A Qp/Qs > 1.5 often warrants surgical or percutaneous closure in ASD/VSD. * Serial measurements track shunt progression in chronic conditions. 1. **Post-Intervention Monitoring**: * Assess residual shunts after device closure or surgery. 1. **Differentiating Pathologies**: * Helps differentiate cardiac vs. non-cardiac causes of symptoms like dyspnea or failure to thrive. ### **Limitations and Considerations** [#limitations-and-considerations] * **Technical Challenges**: Poor acoustic windows or suboptimal Doppler alignment may skew results. * **Assumptions**: Formulas assume laminar flow and circular LVOT/RVOT geometry, which may not hold in all patients. * **Error in Calculation**: The original formula’s inclusion of “\* 100” for Qp/Qs is likely a typo; standard practice uses the ratio directly (e.g., 2:1, not 200%). ### **Conclusion** [#conclusion] Echocardiographic calculation of Qp/Qs is a cornerstone in managing patients with intracardiac shunts. By integrating anatomical measurements and Doppler hemodynamics, clinicians gain valuable insights into shunt severity and directionality. While the technique requires meticulous attention to imaging standards, its non-invasive nature and reproducibility make it indispensable in congenital and critical care cardiology. Regular echocardiographic assessment ensures timely intervention, improving outcomes for patients with shunting lesions. # qSOFA (Quick SOFA) score for sepsis (/docs/tools/calculators/qsofa) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Corrected QT interval (QTc) (/docs/tools/calculators/qtc) | | 1 – 15 years, male and female | Adult, male | Adult, female | | ----------- | ----------------------------- | ----------- | ------------- | | Normal | \<440 ms | \<430 ms | \<450 ms | | Upper limit | 440–460 ms | 430–450 ms | 450–470 ms | | Prolonged | >460 ms | >450 ms | >470 ms | **Table 1**. Reference intervals for QTc duration according to Bazett's formula. Note that a QTc interval >480 is always considered pathological. For patients with bundle branch blocks, the corresponding figure is >500 ms. The QT interval represents the time between the onset of ventricular depolarization and the end of ventricular repolarization. It reflects the total time the ventricles take to de- and repolarize. Abnormalities in the QT interval can cause serious arrhythmias and sudden cardiac death. QT prolongation can precipitate torsades de pointes, a specific form of polymorphic ventricular tachycardia characterized by irregular (polymorphic) QRS complexes that appear to twist around the isoelectric baseline. The risk of ventricular fibrillation is very high during *torsade de pointes*. ECG showing an episode of sinus rhythm (with multiple ventricular premature beats) spontaneously converting to Torsade de Pointes ventricular tachycardia. Notice how arterial blood pressure (ABP) drops at the onset of TdP. ECG by Nakstad et al (Scand J Trauma Resusc Emerg Med. 2010; 18: 7) ECG showing an episode of sinus rhythm (with multiple ventricular premature beats) spontaneously converting to Torsade de Pointes ventricular tachycardia. Notice how arterial blood pressure (ABP) drops at the onset of TdP. ECG by Nakstad et al (Scand J Trauma Resusc Emerg Med. 2010; 18:7). ## Short QT interval [#short-qt-interval] A shortened QT interval is also associated with an increased risk of ventricular arrhythmias. ## Corrected QT Interval (QTc interval) [#corrected-qt-interval-qtc-interval] The QT interval varies inversely with heart rate; it shortens at higher heart rates and lengthens at lower heart rates. To account for this variability, the QT interval is often corrected for heart rate, resulting in the corrected QT (QTc) interval. Several formulas exist to calculate QTc, each with its own characteristics. ### Bazett’s formula [#bazetts-formula] One of the earliest and most widely used correction methods, Bazett’s formula calculates QTc by dividing the QT interval by the square root of the RR interval (the time between two successive R-wave peaks). However, it tends to overcorrect at high heart rates and undercorrect at low heart rates, potentially leading to inaccuracies. **Bazett's Formula:** QTc = QT interval / √(RR interval) ### Fridericia’s formula [#fridericias-formula] This formula corrects the QT interval by dividing it by the cube root of the RR interval. Studies suggest that Fridericia’s formula may provide more accurate corrections across a wider range of heart rates compared to Bazett’s formula. **Fridericia's Formula:** QTc = QT interval / (RR interval)1/3 **Framingham (Sagie’s) Formula** Derived from the Framingham Heart Study, this linear correction formula adjusts the QT interval based on heart rate without involving square or cube roots. It has been shown to offer better correction over a broad spectrum of heart rates. **Framingham Formula:** QTc = QT interval + 154 x (1 - RR interval) **Hodges’ formula** This method corrects the QT interval by adding a factor based on the difference between the heart rate and 60 beats per minute. It is another approach used to account for heart rate variability. **Hodges Formula:** QTc = QT interval + 1.75 x \[(60 / RR interval) − 60] For all formulas: *RR interval = 60 / HR* ## Validity of QT correction formulas [#validity-of-qt-correction-formulas] The accuracy of QT correction formulas can vary depending on the heart rate and individual patient characteristics. * **Bazett’s formula** has a tendency to overcorrect or undercorrect at extreme heart rates. Thus, it should not be used during bradycardia and tachycardia. * **Fridericia’s and Framingham formulas** are often preferred in scenarios where a broader range of heart rates is encountered, as they may provide more reliable corrections. * **Hodges’ formula** offers an alternative linear correction method. article. ## References [#references] Luo, S., Michler, K., Johnston, P., & Macfarlane, P. W. (2004). A comparison of commonly used QT correction formulae: the effect of heart rate on the QTc of normal ECGs. *Journal of Electrocardiology*, 37, 81-90. Vandenberk, B., Vandael, E., Robyns, T., Vandenberghe, J., Garweg, C., Foulon, V., Ector, J., & Willems, R. (2016). Which QT correction formulae to use for QT monitoring? *Journal of the American Heart Association*, 5(6), e003264. Vandenberk, B., Vandael, E., Robyns, T., Vandenberghe, J., Garweg, C., Foulon, V., Ector, J., & Willems, R. (2016). Which QT Correction Formulae to Use for QT Monitoring? *Journal of the American Heart Association*, 5(6), e003264. Vandenberk, B., Vandael, E., Robyns, T., Vandenberghe, J., Garweg, C., Foulon, V., Ector, J., & Willems, R. (2016). Which QT Correction Formulae to Use for QT Monitoring? *Journal of the American Heart Association*, 5(6), e003264. # Quick Inventory of Depressive Symptomatology (QIDS-SR16) (/docs/tools/calculators/quick-inventory-depressive-symptomatology-qids) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # R Factor for Liver Injury (/docs/tools/calculators/r-factor-liver-injury) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rai Staging System for Chronic Lymphocytic Leukemia (CLL) (/docs/tools/calculators/rai-staging-cll) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Ranson's criteria for acute pancreatitis mortality (/docs/tools/calculators/ransons-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RAPID score for pleural infection (/docs/tools/calculators/rapid-pleural-infection) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RAPID Score for Acetabular Chondrolabral Disruption (/docs/tools/calculators/rapid-score-acetabular-chondrolabral-disruption) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Richmond Agitation-Sedation Scale (RASS) (/docs/tools/calculators/rass) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RBC Units to Screen for Compatibility (/docs/tools/calculators/rbc-units-to-screen-compatibility) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RCVS2 Score for Reversible Cerebral Vasoconstriction Syndrome (/docs/tools/calculators/rcvs2-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # REACH-B Score for Hepatocellular Carcinoma (HCC) (/docs/tools/calculators/reach-b-score-hepatocellular-carcinoma) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # READMITS score for readmissions in acute MI (/docs/tools/calculators/readmits-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RegiSCAR Score for DRESS (/docs/tools/calculators/regiscar-score-dress) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Reid's Colposcopic Index (RCI) (/docs/tools/calculators/reid-colposcopic-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Relative Fat Mass (RFM) (/docs/tools/calculators/relative-fat-mass) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Spanish Network on Mastocytosis (REMA) Score (/docs/tools/calculators/rema-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rapid Emergency Medicine Score (REMS) (/docs/tools/calculators/rems) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RENAL Nephrometry Score (/docs/tools/calculators/renal-nephrometry-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RESECT-90 model for 90-day mortality after lung resection (/docs/tools/calculators/resect-90) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RESP (Respiratory ECMO Survival Prediction) score (/docs/tools/calculators/resp-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Respiratory Distress Observation Scale (RDOS) (/docs/tools/calculators/respiratory-distress-observation-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Respiratory Score for Asthma (Liu et al) (/docs/tools/calculators/respiratory-score-for-asthma-liu) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Refractory Epilepsy Screening Tool for Lennox-Gastaut Syndrome (REST-LGS) (/docs/tools/calculators/rest-lgs) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Corrected Reticulocyte Percentage / Reticulocyte Production Index (RPI) (/docs/tools/calculators/reticulocyte-production-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # REVEAL Registry Risk Score 2.0 for Pulmonary Arterial Hypertension (PAH) (/docs/tools/calculators/reveal-2-0-pah-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Cardiac Risk Index (RCRI) for pre-operative risk (/docs/tools/calculators/revised-cardiac-risk-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Geneva score for pulmonary embolism (/docs/tools/calculators/revised-geneva) # Revised McDonald Criteria for Multiple Sclerosis Diagnosis (2010) (/docs/tools/calculators/revised-mcdonald-criteria-2010) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Natural History Model for Primary Sclerosing Cholangitis (/docs/tools/calculators/revised-natural-history-model-psc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Opioid Risk Tool (ORT-OUD) (/docs/tools/calculators/revised-opioid-risk-tool-ort-oud) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Original Score for Autoimmune Hepatitis (AIH) (/docs/tools/calculators/revised-original-score-autoimmune-hepatitis-aih) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Schwartz Equation for Glomerular Filtration Rate (GFR) (2009) (/docs/tools/calculators/revised-schwartz-gfr-2009) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Tokuhashi scoring system for metastatic spine tumour (/docs/tools/calculators/revised-tokuhashi-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Trauma Score (RTS) (/docs/tools/calculators/revised-trauma-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Revised Urinary Incontinence Scale (RUIS) (/docs/tools/calculators/revised-urinary-incontinence-scale-ruis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Reynolds Risk Score for Cardiovascular Risk in Women (/docs/tools/calculators/reynolds-risk-score-women) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RibScore (/docs/tools/calculators/ribscore) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RIETE Score for Risk of Hemorrhage in Pulmonary Embolism Treatment (/docs/tools/calculators/riete-score-hemorrhage-pe) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RIFLE criteria for acute kidney injury (/docs/tools/calculators/rifle-criteria-aki) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Recurrent Instability of the Patella (RIP) Score (/docs/tools/calculators/rip-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RIPASA Score for Acute Appendicitis (/docs/tools/calculators/ripasa-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Risk of Malignancy Index (RMI) for Ovarian Cancer (/docs/tools/calculators/risk-of-malignancy-index-ovarian-cancer) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # RiskE Score for Cardiac Surgery in Active Infective Endocarditis (/docs/tools/calculators/riske-score-endocarditis-surgery) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rochester criteria for febrile infants (/docs/tools/calculators/rochester-criteria-febrile-infants) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rockall Score for Upper GI Bleeding (Complete) (/docs/tools/calculators/rockall-score-complete) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rockall Score for Upper GI Bleeding (Pre-Endoscopy) (/docs/tools/calculators/rockall-score-pre-endoscopy) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome II Diagnostic Criteria for Irritable Bowel Syndrome (IBS) (/docs/tools/calculators/rome-ii-ibs-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome III Diagnostic Criteria for Irritable Bowel Syndrome (IBS) (/docs/tools/calculators/rome-iii-ibs-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Belching Disorders (/docs/tools/calculators/rome-iv-belching-disorders) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Biliary Pain (/docs/tools/calculators/rome-iv-biliary-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Cannabinoid Hyperemesis Syndrome (CHS) (/docs/tools/calculators/rome-iv-cannabinoid-hyperemesis-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Centrally Mediated Abdominal Pain Syndrome (CAPS) (/docs/tools/calculators/rome-iv-caps) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Abdominal Migraine (/docs/tools/calculators/rome-iv-child-abdominal-migraine) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Aerophagia (/docs/tools/calculators/rome-iv-child-aerophagia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Cyclic Vomiting Syndrome (/docs/tools/calculators/rome-iv-child-cyclic-vomiting-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Functional Abdominal Pain (FAP-NOS) (/docs/tools/calculators/rome-iv-child-functional-abdominal-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Functional Constipation (/docs/tools/calculators/rome-iv-child-functional-constipation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Functional Dyspepsia (/docs/tools/calculators/rome-iv-child-functional-dyspepsia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Functional Nausea and Vomiting (/docs/tools/calculators/rome-iv-child-functional-nausea-and-vomiting) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Irritable Bowel Syndrome (IBS) (/docs/tools/calculators/rome-iv-child-ibs) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Non-retentive Fecal Incontinence (/docs/tools/calculators/rome-iv-child-nonretentive-fecal-incontinence) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Child Rumination Syndrome (/docs/tools/calculators/rome-iv-child-rumination-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Chronic Nausea Vomiting Syndrome (CNVS) (/docs/tools/calculators/rome-iv-cnvs) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Cyclic Vomiting Syndrome (/docs/tools/calculators/rome-iv-cyclic-vomiting-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Fecal Incontinence (/docs/tools/calculators/rome-iv-fecal-incontinence) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Abdominal Bloating/Distension (/docs/tools/calculators/rome-iv-functional-abdominal-bloating-distension) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Anorectal Pain (/docs/tools/calculators/rome-iv-functional-anorectal-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Biliary Sphincter of Oddi Disorder (SOD) (/docs/tools/calculators/rome-iv-functional-biliary-sod) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Chest Pain (/docs/tools/calculators/rome-iv-functional-chest-pain) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Constipation (/docs/tools/calculators/rome-iv-functional-constipation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Defecation Disorders (/docs/tools/calculators/rome-iv-functional-defecation-disorders) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Diarrhea (/docs/tools/calculators/rome-iv-functional-diarrhea) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Dyspepsia (/docs/tools/calculators/rome-iv-functional-dyspepsia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Dysphagia (/docs/tools/calculators/rome-iv-functional-dysphagia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Gallbladder Disorder (/docs/tools/calculators/rome-iv-functional-gallbladder-disorder) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnosis Criteria for Functional Heartburn (/docs/tools/calculators/rome-iv-functional-heartburn) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Globus (/docs/tools/calculators/rome-iv-globus) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Infant Colic (/docs/tools/calculators/rome-iv-infant-colic) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Infant Dyschezia (/docs/tools/calculators/rome-iv-infant-dyschezia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Infant Functional Constipation (/docs/tools/calculators/rome-iv-infant-functional-constipation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Infant Functional Diarrhea (/docs/tools/calculators/rome-iv-infant-functional-diarrhea) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Infant Regurgitation (/docs/tools/calculators/rome-iv-infant-regurgitation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Irritable Bowel Syndrome (IBS) (/docs/tools/calculators/rome-iv-irritable-bowel-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Narcotic Bowel Syndrome (/docs/tools/calculators/rome-iv-narcotic-bowel-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Opioid-Induced Constipation (/docs/tools/calculators/rome-iv-opioid-induced-constipation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Functional Pancreatic Sphincter of Oddi Disorder (SOD) (/docs/tools/calculators/rome-iv-pancreatic-sphincter-of-oddi-disorder) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Proctalgia Fugax (/docs/tools/calculators/rome-iv-proctalgia-fugax) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV Diagnostic Criteria for Reflux Hypersensitivity (/docs/tools/calculators/rome-iv-reflux-hypersensitivity) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV diagnostic criteria for rumination syndrome (/docs/tools/calculators/rome-iv-rumination-syndrome) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rome IV diagnostic criteria for unspecified functional bowel disorder (/docs/tools/calculators/rome-iv-unspecified-functional-bowel-disorder) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Risk of Paradoxical Embolism (RoPE) Score (/docs/tools/calculators/rope-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # ROSE (Risk Stratification of Syncope in the Emergency Department) Rule (/docs/tools/calculators/rose-rule-syncope) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # ROSIER Scale (Recognition of Stroke in the ER) (/docs/tools/calculators/rosier-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Roth Score for Hypoxia Screening (/docs/tools/calculators/roth-score-hypoxia) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # ROX Index for Intubation after HFNC (/docs/tools/calculators/rox-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rapid Shallow Breathing Index (RSBI) (/docs/tools/calculators/rsbi) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rule of 7s for Lyme Meningitis (/docs/tools/calculators/rule-of-7s-lyme-meningitis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Rule of Nines for Burn Surface Area (/docs/tools/calculators/rule-of-nines) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Steatosis-Associated Fibrosis Estimator (SAFE) score (/docs/tools/calculators/safe-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # San Francisco Syncope Rule (/docs/tools/calculators/san-francisco-syncope-rule) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Simplified Acute Physiology Score (SAPS) 3 (/docs/tools/calculators/saps-3) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Simplified Acute Physiology Score (SAPS II) (/docs/tools/calculators/saps-ii) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SAVE (Survival after Veno-Arterial ECMO) Score (/docs/tools/calculators/save-score-va-ecmo) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Severe Community-Acquired Pneumonia (SCAP) Score (/docs/tools/calculators/scap-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Sequential Clinical Assessment of Respiratory Function (SCARF) Score (/docs/tools/calculators/scarf-score-rib-fracture) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Schwab and England Activities of Daily Living (ADL) Scale (/docs/tools/calculators/schwab-england-adl-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SCOFF Questionnaire (/docs/tools/calculators/scoff-questionnaire) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Systematic Coronary Risk Evaluation 2-Diabetes (SCORE2-Diabetes) (/docs/tools/calculators/score2-diabetes) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Systematic Coronary Risk Evaluation 2-Older Persons (SCORE2-OP) (/docs/tools/calculators/score2-op) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Systematic Coronary Risk Evaluation 2 (SCORE2) (/docs/tools/calculators/score2) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Scoring Mastocytosis (SCORMA) Index (/docs/tools/calculators/scorma-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SCORTEN for Toxic Epidermal Necrolysis (/docs/tools/calculators/scorten) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Simple Disease Activity Index (SDAI) for Rheumatoid Arthritis (/docs/tools/calculators/sdai-rheumatoid-arthritis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Secondary Intracerebral Hemorrhage (sICH) Score (/docs/tools/calculators/secondary-intracerebral-hemorrhage-sich-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SEDAN Score for Post-tPA Hemorrhage (/docs/tools/calculators/sedan-score) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Solitary Pulmonary Nodule (SPN) Malignancy Risk Score (Mayo Clinic Model) (/docs/tools/calculators/spn-mayo-clinic-malignancy-risk) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SpO2/FiO2 ratio (/docs/tools/calculators/spo2-fio2-ratio) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SSIGN Score for Renal Cell Carcinoma (RCC) (/docs/tools/calculators/ssign-score-rcc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Stanford Sleepiness Scale (SSS) (/docs/tools/calculators/stanford-sleepiness-scale) {/* Write the article for this calculator below. 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Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Stroke volume & cardiac output (LVOT VTI) (/docs/tools/calculators/stroke-volume-cardiac-output) # STUMBL/Battle Score for Blunt Chest Wall Trauma (/docs/tools/calculators/stumbl-battle-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Subaxial Injury Classification and Severity Scale (SLIC) (/docs/tools/calculators/subaxial-injury-classification-severity-scale-slic) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Subtle Anterior STEMI Calculator (4-Variable) (/docs/tools/calculators/subtle-anterior-stemi-4-variable) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Sudbury Vertigo Risk Score (/docs/tools/calculators/sudbury-vertigo-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Trimethoprim-Sulfamethoxazole Allergy Decision Rule (SULF-FAST) (/docs/tools/calculators/sulf-fast) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Surgical Apgar Score (SAS) for postoperative risk (/docs/tools/calculators/surgical-apgar-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Swede Score (/docs/tools/calculators/swede-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # SYNTAX Score II (/docs/tools/calculators/syntax-score-ii) #### **What is SYNTAX Score II?** [#what-is-syntax-score-ii] The **SYNTAX Score II** is an advanced version of the original SYNTAX Score, designed to improve the prediction of long-term outcomes after revascularization. It incorporates both **anatomical** (from the original SYNTAX Score) and **clinical variables** (e.g., age, sex, renal function, left ventricular ejection fraction) to provide a more personalized risk assessment. #### **Key Variables in SYNTAX Score II** [#key-variables-in-syntax-score-ii] 1. **Anatomical SYNTAX Score**: Derived from the original SYNTAX Score, which evaluates the complexity of coronary lesions. 2. **Clinical Variables**: * **Age**: Older patients have a higher risk. * **Sex**: Females may have different risk profiles. * **Creatinine Clearance**: Reduced renal function increases risk. * **Left Ventricular Ejection Fraction (LVEF)**: Lower LVEF is associated with worse outcomes. * **Unprotected Left Main Disease**: Increases complexity and risk. * **Peripheral Vascular Disease (PVD)**: Indicates systemic atherosclerosis. * **Chronic Obstructive Pulmonary Disease (COPD)**: Associated with higher perioperative risk. #### **Clinical Applications** [#clinical-applications] * **Personalized Decision-Making**: SYNTAX Score II helps determine whether a patient should undergo **PCI** or **CABG** based on their risk profile. * **Predicting Outcomes**: It predicts **10-year mortality** and **5-year major adverse cardiac events (MACE)** with greater accuracy than the original SYNTAX Score. * **Heart Team Collaboration**: Facilitates discussions between interventional cardiologists and cardiac surgeons to optimize treatment strategies. #### **Strengths** [#strengths] * Incorporates both anatomical and clinical factors. * Provides a more personalized risk assessment. * Validated in large clinical trials, including the SYNTAX trial. #### **Limitations** [#limitations] * Requires detailed clinical and angiographic data. * Calculation can be complex without dedicated software. * May not account for all patient-specific factors (e.g., frailty, comorbidities). ### **References** [#references] 1. SYNTAX Score II Official Website. [https://syntaxscore.org/](https://syntaxscore.org/) . 2. ESC/EACTS Guidelines on Myocardial Revascularization. [https://syntaxscore.org/index.php/references](https://syntaxscore.org/index.php/references) . 3. SYNTAX II 2020: Personalized Decision-Making Tool. [https://paper.sciencenet.cn/htmlpaper/2020/10/2020101216555179158941.shtm](https://paper.sciencenet.cn/htmlpaper/2020/10/2020101216555179158941.shtm) . # SYNTAX Score (/docs/tools/calculators/syntax-score) ### **SYNTAX Score: A Tool for Revascularization Strategy in Complex Coronary Artery Disease** [#syntax-score-a-tool-for-revascularization-strategy-in-complex-coronary-artery-disease] The **SYNTAX Score** is a semi-quantitative scoring system designed to assess the complexity of coronary artery disease (CAD) and guide the choice between **percutaneous coronary intervention (PCI)** and **coronary artery bypass grafting (CABG)**. Developed through expert consensus and validated in the SYNTAX trial, this tool evaluates angiographic characteristics to predict clinical outcomes and aid in personalized treatment decisions. The SYNTAX Score was created to address the need for a standardized method to evaluate the anatomical complexity of CAD, particularly in patients with **multivessel disease** or **left main coronary artery disease**. It integrates multiple variables, including the number of lesions, their location, and specific characteristics such as bifurcations, chronic total occlusions (CTOs), calcification, and thrombus presence. These factors are weighted and summed to produce a total score, which stratifies patients into low, intermediate, and high-risk categories. ## **Clinical applications** [#clinical-applications] The SYNTAX Score is primarily used to: 1. **Guide Revascularization Strategy**: Patients with low scores (≤22) are often recommended for PCI, while those with high scores (≥33) are typically advised to undergo CABG due to better long-term outcomes. Intermediate scores (23–32) require careful consideration by a heart team. 2. **Predict Outcomes**: The score has been validated to predict **major adverse cardiac events (MACE)**, including mortality, myocardial infarction, and repeat revascularization. For example, in the SYNTAX trial, patients with high scores had significantly higher mortality and MACE rates compared to those with low scores. 3. **Monitor Quality of Care**: By providing an objective measure of CAD complexity, the SYNTAX Score helps standardize treatment protocols and improve clinical decision-making. ## **Strengths and limitations** [#strengths-and-limitations] The SYNTAX Score's strength lies in its ability to comprehensively evaluate angiographic complexity, making it a valuable tool for risk stratification. However, it has several limitations: 1. **Reproducibility**: The score's calculation can be cumbersome and time-consuming, with reported inter-observer variability (κ values ranging from 0.45 to 0.76). 2. **Lack of Clinical Variables**: The original SYNTAX Score focuses solely on anatomical factors, ignoring clinical variables such as age, diabetes, and renal function, which significantly impact outcomes. 3. **Inconsistent Predictive Value**: While effective in PCI-treated patients, its predictive ability is less robust in CABG-treated patients, as surgery can bypass complex lesions irrespective of their angiographic complexity. #### **Evolution: SYNTAX Score II** [#evolution-syntax-score-ii] To address these limitations, the **SYNTAX Score II** was developed, incorporating both anatomical and clinical variables. This updated version improves predictive accuracy for 10-year mortality and 5-year MACE, offering a more personalized approach to revascularization strategy. For instance, SYNTAX Score II includes factors like age, creatinine clearance, and left ventricular ejection fraction, enhancing its utility in clinical practice. #### **Future Directions** [#future-directions] Ongoing research aims to refine the SYNTAX Score further. For example, the **CatLet Score** has been proposed as an alternative, addressing some of the SYNTAX Score's shortcomings, such as its inability to account for coronary dominance variability and its reliance on subjective lesion weighting. Additionally, integrating functional assessments like fractional flow reserve (FFR) could enhance the score's predictive accuracy. The SYNTAX Score remains a cornerstone in the management of complex CAD, providing a structured approach to revascularization strategy. While it has limitations, its evolution into SYNTAX Score II and potential future refinements underscore its enduring relevance in cardiology. By combining anatomical and clinical data, it continues to support heart teams in delivering personalized, evidence-based care. ### **References** [#references] 1. SYNTAX Score Official Website. [https://syntaxscore.org/](https://syntaxscore.org/) . 2. ESC/EACTS Guidelines on Myocardial Revascularization. [https://syntaxscore.org/index.php/references](https://syntaxscore.org/index.php/references) . 3. CatLet Score: A Potential Alternative to SYNTAX Score. [https://www.sohu.com/a/443524114\_186367](https://www.sohu.com/a/443524114_186367) . 4. SYNTAX Score II Validation Study. [https://syntaxscore.org/](https://syntaxscore.org/) . 5. SYNTAX II 2020: Personalized Decision-Making Tool. [https://paper.sciencenet.cn/htmlpaper/2020/10/2020101216555179158941.shtm](https://paper.sciencenet.cn/htmlpaper/2020/10/2020101216555179158941.shtm) . 6. Example Cases and Tutorials. [https://syntaxscore.org/index.php/tutorial/example-cases](https://syntaxscore.org/index.php/tutorial/example-cases) . # TASH Score (Trauma Associated Severe Hemorrhage) (/docs/tools/calculators/tash-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Acute renal failure after cardiac surgery (Thakar / Cleveland Clinic score) (/docs/tools/calculators/thakar-cardiac-surgery-aki) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Therapeutic Plasmapheresis Calculator (/docs/tools/calculators/therapeutic-plasmapheresis-calculator) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Therapy-Disability-Neurology (TDN) Grade (/docs/tools/calculators/therapy-disability-neurology-tdn-grade) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Thoracolumbar Injury Classification and Severity Scale (TLICS) (/docs/tools/calculators/thoracolumbar-injury-classification-severity-scale-tlics) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # THRIVE Score for Stroke Outcome (/docs/tools/calculators/thrive-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # TIMI risk score for UA/NSTEMI (/docs/tools/calculators/timi-nstemi) All patients with NSTE-ACS (NSTEMI or unstable angina) are treated similarly with respect to anti-ischemic and anti-thrombotic drugs. Management must, however, be individualized with respect to the delay to coronary angiography (PCI). The majority of patients should undergo angiography within 24 hours, but high-risk patients should be evaluated with angiography earlier. Guidelines recommend the use of validated risk models to estimate the risk of acute myocardial infarction, 30-day and 1-year mortality in patients with NSTE-ACS. TIMI, GRACE and PURSUIT are such risk models. The higher the estimated risk, the earlier should angiography be performed. ## TIMI risk score for NSTEMI and unstable angina [#timi-risk-score-for-nstemi-and-unstable-angina] | TIMI SCORE | 30-days mortality | 30-days acute MI | Probability of revascularization | | ---------- | ----------------- | ---------------- | -------------------------------- | | 0-1 | 1,2% | 2,3% | 1,2% | | 2 | 1,0% | 2,1% | 6,0% | | 3 | 1,7% | 3,7% | 9,5% | | 4 | 2,5% | 5,0% | 12,2% | | 5 | 5,6% | 8,5% | 14,3% | | 6-7 | 6,5% | 15,8% | 20,9% | Interpretation of TIMI Risk Score. ### References [#references] 1. [Morrow DA, Antman EM, Charlesworth A, Cairns R, Murphy SA, de Lemos JA, Giugliano RP, McCabe CH, Braunwald E. TIMI risk score for ST-elevation myocardial infarction: A convenient, bedside, clinical score for risk assessment at presentation: An intravenous nPA for treatment of infarcting myocardium early II trial substudy. Circulation. 2000 Oct 24;102(17):2031-7.](https://pubmed.ncbi.nlm.nih.gov/11044416/) 2. [The TIMI risk score for unstable angina/non-ST elevation MI: A method for prognostication and therapeutic decision making E M Antman, M Cohen, P J Bernink, C H McCabe, T Horacek, G Papuchis, B Mautner, R Corbalan, D Radley, E Braunwald.](https://pubmed.ncbi.nlm.nih.gov/10938172/) # TIMI Risk Index (/docs/tools/calculators/timi-risk-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # TIMI risk score for STEMI (/docs/tools/calculators/timi-stemi) | Points | 30-days mortality | | ------ | ----------------- | | 0 | 0,8% | | 1 | 1,6% | | 2 | 2,2% | | 3 | 4,4% | | 4 | 7,3% | | 5 | 12,4% | | 6 | 16,1% | | 7 | 23,4% | | 8 | 26,8% | | 9-14 | 35,9% | ### References [#references] 1. [Morrow DA, Antman EM, Charlesworth A, Cairns R, Murphy SA, de Lemos JA, Giugliano RP, McCabe CH, Braunwald E. TIMI risk score for ST-elevation myocardial infarction: A convenient, bedside, clinical score for risk assessment at presentation: An intravenous nPA for treatment of infarcting myocardium early II trial substudy. Circulation. 2000 Oct 24;102(17):2031-7.](https://pubmed.ncbi.nlm.nih.gov/11044416/) 2. [The TIMI risk score for unstable angina/non-ST elevation MI: A method for prognostication and therapeutic decision making E M Antman, M Cohen, P J Bernink, C H McCabe, T Horacek, G Papuchis, B Mautner, R Corbalan, D Radley, E Braunwald.](https://pubmed.ncbi.nlm.nih.gov/10938172/) # Tisdale Risk Score for QT Prolongation (/docs/tools/calculators/tisdale-risk-score-qt-prolongation) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Tenecteplase (TNK) Dosing for Ischemic Stroke Calculator (/docs/tools/calculators/tnk-dosing-ischemic-stroke) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Tokyo Guidelines for Acute Cholangitis 2018 (TG18) (/docs/tools/calculators/tokyo-guidelines-cholangitis-2018) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Tokyo Guidelines for Acute Cholecystitis 2018 (TG18) (/docs/tools/calculators/tokyo-guidelines-cholecystitis-2018) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # tPA (Alteplase) Dosing for Ischemic Stroke Calculator (/docs/tools/calculators/tpa-alteplase-dosing-ischemic-stroke) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Trauma Score and Injury Severity Score (TRISS) (/docs/tools/calculators/trauma-score-and-injury-severity-score-triss) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Travis criteria for acute severe ulcerative colitis (/docs/tools/calculators/travis-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Thrombosis Risk Prediction Following Cast Immobilization (TRiP(cast)) Score (/docs/tools/calculators/tripcast-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Truelove and Witts Severity Index for Ulcerative Colitis (/docs/tools/calculators/truelove-witts-severity-index-ulcerative-colitis) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Trunk Impairment Scale (/docs/tools/calculators/trunk-impairment-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Transtubular Potassium Gradient (TTKG) (/docs/tools/calculators/ttkg) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Testicular Workup for Ischemia and Suspected Torsion (TWIST) (/docs/tools/calculators/twist-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Ulcerative Colitis Endoscopic Index of Severity (UCEIS) (/docs/tools/calculators/uceis-ulcerative-colitis-endoscopic-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # UCSF-CAPRA Score for Prostate Cancer Risk (/docs/tools/calculators/ucsf-capra-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # UCLA Integrated Staging System (UISS) for Renal Cell Carcinoma (RCC) (/docs/tools/calculators/uiss-rcc) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # United Kingdom Model for End-Stage Liver Disease (UKELD) (/docs/tools/calculators/ukeld) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Urinary Protein Excretion Estimation (/docs/tools/calculators/urinary-protein-excretion) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Urine anion gap (/docs/tools/calculators/urine-anion-gap) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Urine Output and Fluid Balance (/docs/tools/calculators/urine-output-fluid-balance) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Urticaria Activity Score (UAS) (/docs/tools/calculators/urticaria-activity-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # US (MEDPED) diagnostic criteria for familial hypercholesterolemia (/docs/tools/calculators/us-medped-criteria-fh) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Utah COVID-19 Risk Score (/docs/tools/calculators/utah-covid19-risk-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Veterans Aging Cohort Study (VACS) 1.0 Index (/docs/tools/calculators/vacs-1-0-index) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Vancouver Chest Pain Rule (/docs/tools/calculators/vancouver-chest-pain-rule) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Systemic and pulmonary vascular resistance (/docs/tools/calculators/vascular-resistance) # VBAC Risk Score for Successful Vaginal Delivery (Flamm) (/docs/tools/calculators/vbac-flamm-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Vaginal birth after cesarean (VBAC) probability calculator (/docs/tools/calculators/vbac-mfmu-calculator) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Vernakalant (Brinavess) (/docs/tools/calculators/vernakalant-brinavess) ## Indications for vernakalant [#indications-for-vernakalant] * Vernakalant (Brinavess) is indicated in adults for chemical conversion of recent onset atrial fibrillation to sinus rhythm. Vernakalant is used in the following settings: * Non-surgery patients: atrial fibrillation ≤7 days duration. * Post-cardiac surgery: atrial fibrillation ≤3 days duration. Vernakalant does not convert atrial flutter to sinus rhythm. Vernakalant is only administered in a monitored clinical setting appropriate for cardioversion. ## Administration of vernakalant [#administration-of-vernakalant] * Vernakalant (Brinavess) is administered as an infusion. * The infusion is diluted to 4 mg/ml and administered over 10 minutes. * A maximum of two infusions can be given. Each infusion should be completed, even if the patient reverts to sinus rhythm. * The infusion must be aborted if hypotension or bradycardia occurs. A defibrillator should be immediately available as a precaution. ## Dosage of vernakalant [#dosage-of-vernakalant] * Vernakalant is dosed by body weight, with the maximum dose based upon 113 kg. * **Normal dilution: 4 mg/ml.** * **Recommended initial dose: 3 mg/kg, given over 10 minutes.** Maximum initial dose of 339 mg, which is 84.7 ml of the 4 mg/ml solution. A second infusion may be started if the initial infusion does not result in conversion to sinus rhythm within 15 minutes after the end of the infusion. * **Recommended second **dose**: 2 mg/kg, given over 10 minutes.** Maximum infusion of 226 mg, which is 56,5 ml of the 4 mg/ml solution. * Cumulative doses of more than 5 mg/kg should not be given within 24 hours. * If conversion to sinus rhythm is not successful, blood pressure and ECG should be observed for an additional 15 minutes after the completion of the infusion. * The initiated infusion should always be completed (regardless of whether conversion to sinus rhythm occurs) unless contraindications occur. * If hemodynamically stable atrial flutter occurs after the first dose, the second dose can still be given, as the patient can convert to sinus rhythm. **Dose adjustments** * **Patients with body weight > 113 kg**: The initial dose is 339 mg (84.7 ml of the 4 mg/ml solution). A second 10-minute infusion of 226 mg (56.5 mL of the 4 mg/mL solution) may be administered. * **After cardiac surgery**: No dose adjustments are necessary. * **Impaired renal function**: No dose adjustments are necessary. * **Impaired liver function**: No dose adjustments are necessary. * **Elderly (≥ 65 years)**: No dose adjustments are necessary. ## Contraindications to vernakalant [#contraindications-to-vernakalant] * Severe aortic stenosis * Systolic blood pressure \< 100 mm Hg. * Heart failure with NYHA class III–IV. * Prolonged QT at baseline (uncorrected > 440 ms), or severe bradycardia, sinus node dysfunction or second degree and third degree heart block in the absence of a pacemaker. * Use of intravenous rhythm control antiarrhythmics (class I and class III) within 4 hours prior to, as well as in the first 4 hours after, vernakalant administration. * Acute coronary syndrome (including myocardial infarction) within the last 30 days. # Vesicoureteral Reflux Index (VURx) (/docs/tools/calculators/vesicoureteral-reflux-index-vurx) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Venous Excess Ultrasound (VExUS) score (/docs/tools/calculators/vexus-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Villalta Score for Post-thrombotic Syndrome (PTS) (/docs/tools/calculators/villalta-score-pts) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # VIRSTA Score (/docs/tools/calculators/virsta-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # VTE-BLEED Score (/docs/tools/calculators/vte-bleed-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Waist-to-Hip Ratio (/docs/tools/calculators/waist-to-hip-ratio) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Woman Abuse Screening Tool (WAST) (/docs/tools/calculators/wast) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Withdrawal Assessment Tool (WAT-1) for pediatric withdrawal (/docs/tools/calculators/wat-1) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Webster Rating Scale for Parkinson's Disease (/docs/tools/calculators/webster-rating-scale-parkinsons) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Wells score for deep vein thrombosis (/docs/tools/calculators/wells-dvt) # Wells score for pulmonary embolism (/docs/tools/calculators/wells-pe) # West Haven criteria for hepatic encephalopathy (/docs/tools/calculators/west-haven-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Westley Croup Score (/docs/tools/calculators/westley-croup-score) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Wexner continence grading scale (/docs/tools/calculators/wexner-continence-grading-scale) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # World Health Organization (WHO) Diagnostic Criteria for Polycythemia Vera (/docs/tools/calculators/who-diagnostic-criteria-polycythemia-vera) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # World Health Organization (WHO) Diagnostic Criteria for Systemic Mastocytosis (/docs/tools/calculators/who-systemic-mastocytosis-criteria) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # WIfI (Wound, Ischemia, foot Infection) classification (/docs/tools/calculators/wifi-classification) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Winters’ formula for metabolic acidosis (/docs/tools/calculators/winters-formula) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # Wisconsin Criteria for maxillofacial CT in trauma (/docs/tools/calculators/wisconsin-criteria-facial-trauma) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # WPSS (WHO classification-based Prognostic Scoring System) for Myelodysplastic Syndrome (/docs/tools/calculators/wpss-mds) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */} # YEARS Algorithm for Pulmonary Embolism (PE) (/docs/tools/calculators/years-algorithm-pe) {/* Write the article for this calculator below. Free-form MDX — headings, images, tables and links all work, and nothing here is ever regenerated. */}