Specialized Cardiac Conduction System

Abstract

An electrophysiologic technique has been described to localize the atrioventricular (A-V) conduction system during cardiac surgery. The method utilizes atrial pacing with an electrode plaque to insure a supraventricular rhythm, and an electrode probe to localize the specialized A-V pathways. Atrial pacing assures unchanging antegrade conduction to the ventricles, which permits beat-to-beat observation of changes in the P-R interval or QRS configuration that might result from surgical manipulation. The anatomic course of the His bundle and bundle branches is delineated by observing a typical "His spike" during the P-R interval in the electrogram. While heart block is uncommon following repair of uncomplicated ventricular septal defect, this technique has been a distinct aid in the repair of ostium primum atrial septal defects (four cases) and fourteen other complex congenital anomalies.