Late onset of heart block after open heart surgery for congenital heart disease.

Late onset of complete heart block is a potentially dangerous complication after open heart surgery for congenital heart disease. The characteristics of patients with late-onset heart block have not been well described. A retrospective review of a pacemaker database was done to identify patients who presented with new onset heart block between 1988 and 2006, after they had been discharged from the hospital after open heart surgery with normal AV conduction. Fifteen patients were identified. The age at the time of the last surgery before the onset of heart block was 2.0 +/- 3.2 years (range: 3 days to 10 years). Nine had a ventricular septal defect repair, four had an atrioventricular canal, and two other patients had other types of heart defect. The last EKG available for analysis before the onset of heart block had been obtained 5.1 +/- 6.5 years (range: 7 days to 16 years) after surgery. The symptoms at the time of presentation were variable. Four patients presented with fatigue or exercise intolerance, two with syncope, two with congestive heart failure, and one with irritability, and the remaining six patients were diagnosed during routine follow-up. The time between open heart surgery and placement of a permanent pacemaker was 6.8 +/- 7.3 years (range: 2 months to 19 years). There were seven patients in whom the onset of heart block was more than 6 years after surgery. Late onset of complete heart block after open heart surgery could be dangerous when presenting without warning. These data would support the notion that patients should be followed for life after repair of congenital heart defects, with special attention to the conduction system, particularly after repair of septal defects.