Complete intraventricular dissociation. Electrocardiographic manifestation of a rare intracardiac complete dissociation.

Complete Intraventricular Dissociation manifesting as dual ventricular rhythm was observed on surface electrocardiography in two middle-aged males with acute myocardial infarction. The first patient had a dominant accelerated (AV) junctional rhythm, and there was a sudden emergence of an additional independent slow and regular idioventricular escape rhythm. These ventricular complexes were bizarre and markedly widened, waveform with prolonged undulating electric potentials. In the second case, the emergence of a dominant idioventricular rhythm was coexistent with an additional independent escape rhythm with monophasic wider agonal ventricular complexes. Terminal tracings recorded later were essentially the same, except that an ill sustained ventricular fibrillation had replaced the ectopic agonal beats, and there was an enhanced automaticity in the dominant ventricular part. The sites of ectopic ventricular rhythms were thought to be in the ischaemic damaged ventricular myocardium, with a surrounding zone of conduction block.