Figure 1. Aberrant conduction. The figure shows a supraventriclar extrasystole (an extra atrial impulse, discharged by an ectopic focus outside of the sinoatrial node). The supraventricular extrasystole arrives into the ventricles while the right bundle branch is still refractory, which is why it blocks the impulse. The resulting QRS-complex has a right bundle branch block pattern.
