Intracardiac electrography in patients before and after surgical repair of secundum atrial septal defect.

Nine patients (mean age 32 years, range 9-58) with a secundum atrial septal defect (ASD) were investigated by intracardiac electrography before and, on an average, 14 months after circumclusion of the defect. Postoperatively, four patients developed atrial fibrillation or flutter requiring treatment. After the repair, sinus node recovery time and the H-V interval increased significantly. The P-A interval, the A-H interval, sinoatrial conduction time, and the effective refractory period of the atrium (ERPA) remained unchanged. In the patients who developed atrial tachyarrhythmias, the mean preoperative ERPA was significantly longer than in the remaining patients; in patients with ERPA less than 220 ms, no atrial arrhythmias occurred. Our findings suggest that circumclusion of a secundum ASD has a sustained deleterious effect on sinus node function and His-Purkinje conduction. Preoperative determination of ERPA might be of value for the prediction of postoperative atrial arrhythmias in patients submitted to ASD repair.