[Alternating and intermittent bilateral bundle-branch block in acute myocardial infarct with development of total...

The development of bilateral bundle branch block of various degree in the course of an acute myocardial infarction was demonstrated in a 74-year-old man during continuous ecg-monitoring. Initially there was a tachycardia- and bradycardia-dependent left bundle branch block, followed by a right bundle branch block with second degree type II AV block (Mobitz), and finally complete bilateral bundle branch block with asystole. Different combinations of incomplete block were shown and the presence of type I and type II second degree block within the bundle branches could be demonstrated; Wenckebach periods became indirectly visualized through changes in the AV conduction. This case illustrates the prognostic importance of progressive intraventricular conduction disturbance and reveals the multiplicity and possible mechanisms of conduction defects within the bundle branches.