Electrophysiologic Demonstration of an Atriofascicular Accessory Pathway

KOU, W.H., ET AL.: Electrophysiologic demonstration of an atriofascicular accessory pathway. Evi-dence of an atriofascicular accessory pathway has not been reported previously. In the patient presented in this case report, an electrophysiology study demonstrated a constant left bundle branch block QRS configu-ration despite varying degrees of ventricular preexcitation, in association with a constant atrioventricular interval during incremental atrial pacing and programmed atrial stimulation. The presence of an atrio-ventricular, nodoventricular, nodofascicular, and atrial-His accessory pathway was ruled out. The findings are best explained by the presence of an underlying left bundle branch block and an atriofascicular accessory pathway connecting the atrium and right bundle. The atriofascicular accessory pathway was a passive bystander during an atrial tachycardia and was not directly involved in the generation of the tachycardia. To our knowledge, this is the first report of an atriofascicular accessory pathway. (PACE, Vol. 11, February 1988) atriofascicular accessory pathway, ventricular preexcitatio