Ventricular epicardial activation studies in experimental and spontaneous right bundle branch block in the dog

Abstract

The time and sequence of right ventricular epicardial activation were determined by measuring the onset of activation at 27 representative sites. Studies were performed on normal and experimental dogs, 1 dog with spontaneous complete right bundle branch block, 1 with spontaneous incomplete right bundle branch block and 1 with an atypical configuration of the QRS complex. In both experimental and spontaneous complete and incomplete right bundle branch block, the total right ventricular epicardial activation time was prolonged beyond that found in the control dogs. The sequence of right ventricular epicardial activation in the spontaneous cases of right bundle branch block was not different from that found in the normal dogs; however, in experimentally produced complete right bundle branch block, the sequence was altered so that earliest activity occurred along the dorsal interventricular sulcus. In both experimental and spontaneous incomplete and complete right bundle branch block, many of the right ventricular epicardial sites were activated later in the QRS complex than in normal dogs.