Unusual Location for the Fast Pathway

Radiofrequency ablation was attempted in a 17-year-old man with atrioventricular node re-entry of the common variety. Energy was delivered to three sites around the ostium of the coronary sinus. The third attempt resulted in a sudden increase in AH interval with loss of retrograde conduction. The arrhythmia was no longer inducible. These observations may suggest the unusual location of the fast pathway. (Chest 1994; 105:1869-70) W ith the advant of radiofrequency ablation for atrioventricular (AV) node re-entry tachycardia, therapy for this arhythmia has been dramatically changed.”2 By creating only a small area of tissue injury, this procedure has allowed a person to speculate on the mechanism underlying this tachycardia. With this approach, the fast pathway is generally ablated near the AV node-His area,1 whereas the slow pathway is located around the orifice of the coronary l2 Therefore, these pathways appear to be located at fairly specific sites. We describe a case in which the fast pathway was unusually located to the site of