Sir,—Rosenthal et alrecently documented the presence of an atrioventricular bypass tract after a modified Fontan operation in which the right atrial appendage was anastomosed to the right ventricular outflow tract.1Their patient developed persistent supraventricular tachycardia resulting from atrioventricular re-entry within the surgical right anastomosis, which was abolished by radiofrequency ablation. They also mentioned a previous report of ablation after the Fontan operation.2 Based on the evidence of these …