Permanent cardiac pacing after the Fontan procedure.

Permanent cardiac pacing after a Fontan procedure is complicated by complex cardiovascular anatomy. Of 332 patients undergoing the Fontan procedure at the Mayo Clinic, we evaluated 15 who postoperatively required permanent pacing (mean age 16.5 years, range 4 to 31 years). Underlying congenital cardiac defects included univentricular heart in nine patients, double-outlet right ventricle in three, and tricuspid atresia in three. The indication for pacing was postoperative heart block in seven patients, congenital heart block in five, postoperative sick sinus syndrome in two, and heart block because of previous operation in one. Pacemakers were implanted immediately postoperatively in 11 patients and 12 to 57 months later in four patients. VVI systems were used in nine patients, DDD in four, AAI in one, and a Medtronic Activitrax VVI in one. All ventricular leads were epicardial. Four atrial leads were transvenous endocardial and one was epicardial. Three patients died 4, 9, and 69 months later of causes unrelated to pacing. Among the 12 survivors, mean follow-up was 34 months (range 1 to 107 months). Two patients had a total of three episodes of loss of ventricular capture because of increased chronic thresholds. Our current approach to pacing after a Fontan procedure includes (1) intraoperative placement of temporary atrial and ventricular electrodes, (2) intraoperative attachment of a permanent ventricular epicardial lead for congenital or surgically induced high-grade atrioventricular block, (3) postoperative insertion of transvenous atrial leads if dual-chamber pacing is indicated, and (4) use of programmable pulse generators with high output capability.