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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 cases and other reports that document conduction across the atrio–atrial anastomosis3 4 the authors suggest that growth of excitable tissue across the surgical scar may be possible in patients who have undergone this type of the Fontan operation.
We have observed the de novo appearance of a pre-excitation pattern after a Fontan operation. A 16 year old woman had been diagnosed with tricuspid atresia at birth, and an atrioventricular type of Fontan anastomosis was undertaken when she was 5 years old. Twelve months after surgery the ECG pattern suddenly changed suggesting an atrioventricular bypass tract that had not been recorded previously (fig 1). Although we cannot rule out that the bypass tract was congenital in origin, it is possible that this could be a new case of conduction across the surgical scar. The direction of the initial forces of the depolarisation suggests a right anterolateral location of the bypass tract, which would be unusual in cases with absent right atrioventricular connection, as in our case. In contrast with the two previously reported cases who had concealed accessory pathways, our patient had an overt pre-excitation pattern with short PR and delta wave.
Arrhythmias after Fontan operation may be related to the surgical dissection around the sinoatrial node or to a deterioration in function.5 The appearance of acquired atrioventricular conduction as in our case and others,1 2 complicates even more the scope of postsurgical arrhythmias in Fontan patients. It seems therefore appropriate to avoid atrioventricular anastomosis in favour of lateral tunnel techniques.