Early and delayed atrioventricular conduction block after routine surgery for congenital heart disease

Patients undergoing surgical closure of ventricular septal defects are at risk for immediate or delayed atrioventricular conduction block. Our goal was to better define the incidence of delayed atrioventricular conduction block.

A retrospective review was conducted of hospital records and pacemaker database for ventricular septal defect, atrioventricular canal, and tetralogy of Fallot repairs between 1999 and 2004. A total of 922 patients were identified (atrioventricular canal in 197, tetralogy of Fallot in 222, and ventricular septal defect in 503). Median follow-up was 4.1 years.

There were 472 male and 450 female patients, median age 6 months (0-444 months) and median weight 5.8 kg (1.3-116 kg) at surgery. Postoperative atrioventricular conduction block developed in 21 (2.3%) of the 922, being transient, with return of conduction 3 days (1-14 days) after surgery, in 13 (1.4%) and permanent, with pacemakers implanted 10 days (6-20 days) after surgery, in 8 (0.9%). Of the 905 patients at risk for delayed atrioventricular conduction block, 3 (0.3%) had second- or third-degree block at 2, 8, and 16 months after surgery. Two of these 3 had transient postoperative block. For isolated ventricular septal defects, the incidence was 1 (0.2%) of 496. There were 8 late deaths at 31 months (7-45 months) after surgery. Five had normal conduction at death, but for 3 patients the conduction status at death could not be determined. Including these 3 patients as possible cases of delayed atrioventricular block yields an incidence of 0.3% to 0.7%.

The incidence of early atrioventricular conduction block requiring a pacemaker was 0.9% and that of delayed atrioventricular conduction block was 0.3% to 0.7%. Transient atrioventricular conduction block may be a marker for increased risk of delayed block. These data may be useful for evaluation of new techniques.