[Extrasystolic ventricular bigeminy in ventricular tachycardia].

A patient with recent myocardial infarction presented with premature ventricular contractions (PVCs), couplets, and runs of ventricular tachycardia (VT). Two types of ectopic complexes, labeled A and B, were present. Isolated PVCs, as well as the first complex in a couplet, were always type A beats. In contrast, the second beat in a couplet was always a type B beat. Any run of VT was initiated by a type A beat. Monomorphic VT was made only of type B complexes, apart from the first one. Several episodes of VT, however, reflected an alternation of type A and type B complexes with alternating cycle length. This is a manifestation of extrasystolic ventricular bigeminy where any VT impulse (type B) is followed by an extrasystole (type A). In addition, extrasystolic impulses affect the tachycardia, resetting its cycle.