Left ventricular end-diastolic extrasystole with pseudonormalization of a left bundle branch block unmasking inferior ischemia

An electrocardiogram tracing of a patient in conducted sinus rhythm with le ft bundle branch block is shown, in which occasional pseudonormalization of intraventricular conduction is seen. This event is attributed to ventricul ar fusions with end-diastolic extrasystoles of the left His-Purkinje system distal to the block site. This type of extrasystole is discussed. In this case, normalization of ventricular activation allowed for diagnosis of infe rior sub-epicardial ischemia.