Nonparoxysmal Bidirectional Rhythm

A bidirectional slow ventricular rhythm was observed in a 61-year-old man with acute myocardial infarction. The ventricular origin of this arrhythmia was suggested by the presence of fusion beats. Moreover, it was different from other types of bidirectional tachycardias in that the rate was below 100/min and because digitalis could not be incriminated as a causal factor. It was possible that this bidirectional tachycardia could have been due to the presence of two ventricular foci—one in the superior and the other in the inferior divisions of the left branch respectively.