Reentrant and focal activations during atrial fibrillation in patients with atrial septal defect

Adult patients with atrial septal defect frequently experience atrial fibrillation. However, the electrophysiologic mechanism has not been directly examined, and the optimal surgical procedure has not been determined.

Ten patients undergoing operations for atrial septal defect and atrial fibrillation underwent intraoperative mapping by use of 253 epicardial electrodes. There were 7 men and 3 women, whose average age was 54 ± 11 years. Eight patients had a secundum defect and 2 a primum defect. There were 4 patients with paroxysmal atrial fibrillation and 6 with long-standing persistent atrial fibrillation. A modified biatrial Maze procedure was performed in 6 patients and pulmonary vein isolation with no other left atrial lesions in 4.

The reentrant or focal activations driving atrial fibrillation were confined within the right atrium in all patients with paroxysmal atrial fibrillation, whereas multiple focal activations arising from the pulmonary veins or posterior left atrium and reentrant activations in the left atrium were observed in 5 of 6 patients with long-standing persistent atrial fibrillation. In 9 patients, sinus rhythm was restored postoperatively and 8 of those patients have been free of any atrial fibrillation during a follow-up period of 94 ± 45 months.

The pattern of the atrial activation during atrial fibrillation correlated with the type of atrial fibrillation and varied from a simple right atrial reentry to complex reentrant and focal activations in the left atrium.