The Cardiovascular
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Stroke volume & cardiac output (LVOT VTI)

Doppler stroke volume, cardiac output and cardiac index from the LVOT.

Stroke volume & cardiac output (LVOT VTI)
LVOT diameter
LVOT VTI
cm
Heart rate
/min
Body surface area (optional)
m²
Complete the fields above to see the result.

When to use

  • Non-invasive assessment of cardiac output, and the flow measurement underpinning valve-area calculations and low-flow aortic stenosis grading.

Formula

CSA = π × (LVOT diameter / 2)². SV = CSA × LVOT VTI. CO = SV × heart rate. Cardiac index = CO / BSA.

Pearls and pitfalls

  • The LVOT diameter is squared, so it is the dominant source of error — measure carefully in the parasternal long-axis view in mid-systole.
  • Stroke volume index <35 mL/m² defines the low-flow state relevant to aortic stenosis grading.

References

  1. Mitchell C, et al. Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019;32(1):1–64.