Problems with permanent atrial pacing in the Fontan patient.

Transvenous atrial pacing is the preferred method for control of both brady and tachyarrhythmias in the postoperative pediatric patient with normal atrioventricular conduction. We reviewed our experience with the use of permanent atrial pacing for the control of bradycardia and tachycardia in the Fontan patient. We then compared this pacing experience to atrial pacing data compiled for postop Transposition of the Great Arteries (TGA) patients. Out of twenty-five Fontan patients followed at the Medical University of South Carolina, six patients have had atrial arrhythmias necessitating pacing (24%). Underlying congenital heart disease included tricuspid atresia physiology in three and single ventricle in three. The indications for atrial pacing was brady-tachy syndrome in four patients and sick sinus syndrome in two. Pacers were inserted immediately post-op in three patients and 1.5 years, 2 years, and 8 years post Fontan in the other three. These six patients have required a total of nine pulse generator implantations. Five of the nine pacers were inserted transvenously and four via thoracotomy. In contrast to our experience with permanent atrial pacing in post TGA patients, dysrhythmia control with atrial pacing in the Fontan patient has been more difficult to achieve. The Fontan patients have a higher incidence of symptomatic dysrhythmias, hospitalizations, and antidysrhythmic medication requirements after pacer insertion. Implantation thresholds of the Fontan patients are higher than those of the transposition group. While successful atrial demand pacing is attainable in both groups, antitachycardia pacing is more reliable in the post-op TGA patient. The Fontan procedure seems to present a new set of obstacles for successful atrial pacing in the pediatric post-op patient.