Variations of Aberrant Ventricular Conduction in Man: Evidence of Isolated and Combined Block Within the Specialized Conduction System

Aberrant ventricular conduction (AbC) was produced in 52 subjects, including 14 normal volunteers, by the introduction of atrial premature beats through a transvenous catheter electrode. Simultaneous standard electrocardiograms and vectorcardiogams permitted detailed analysis of configuration. Multiple patterns of AbC were produced in 29 of 52 subjects. The general categories and their frequency were as follows: right bundle-branch block without significant axis shift from control, 31; right bundle-branch block with left axis deviation, 27; left axis deviation, 14; inferior axis deviation, six; right bundle-branch block with inferior axis deviation, seven; and complete left bundle-branch block, six. These patterns were believed to depend on the location of isolated or combined functional block in the major pathways of the specialized conduction system, which include the right bundle branch, common left bundle branch, anterior division of the left bundle branch, and posterior division of the left bundle branch. The present study has documented the general varieties of AbC, their relevance to clinical cardiology, and the varieties most likely to cause diagnostic difficulty.