Atriofascicular Accessory Pathways

Abstract

Uncommon accessory pathways presenting decremental properties and inserting into the right ventricle have been described as Mahaim pathways, and these fibers are distinct form of preexcitation. Those anomalous pathways are subdivided into three types, and it is recently said that most of them in fact originate from the right atrial free wall near the tricuspid annulus and terminate in the distal right bundle branch, which is called as atriofascicular pathways. Atriofascicular pathways differ from typical atrioventricular pathways in some electrophysiological respects. These atriofascicular pathways are found to conduct only in the anterograde direction with a long conduction time, and these pathways can only form antidromic tachycardia or as bystanders during atrioventricular nodal reentrant tachycardia or atrial fibrillation. And, these pathways characterize decremental conduction property as like atrioventricular node. Recently, catheter ablation for atriofascicular pathways came to be widely recognized. Although atriofascicular pathways do not insert at the tricuspid annulus, high-frequency Mahaim accessory pathway potential around the tricuspid annulus is helpful to identify an alternative site for catheter ablation. When this potential cannot be found along the tricuspid annulus, catheter ablation targeting at the ventricular insertion is an option for separating those pathways. Mahaim potential mapping using electroanatomical system during tachycardia seems to be also another therapeutic option. The acute success rate of catheter ablation of atriofascicular accessory pathway is more than 95%, and the recurrence rate is not so high.