Postoperative conduction disturbances in atrial septal defect

Abstract

The electrocardiograms of 60 patients with atrial septal defect, aged 23 months to 37 years, were obtained after open heart surgery and analyzed. The over-all incidence of conduction abnormalities was 60 per cent; excluding first degree A-V block, it was 52 per cent. There was no significant difference in incidence between cases of secundum and primum atrial septal defect, or between those with patch repair and suture repair. Arrhythmia after total body perfusion lasting over one hour was not significantly higher than that following shorter perfusion times.The incidence of the various conduction disturbances was: A-V block, 28 per cent; right bundle branch block, 30 per cent; A-V junctional rhythm, 20 per cent; supraventricular tachycardia, 5 per cent; and atrial flutter, 2 per cent. As a rule, the arrhythmias were benign. Excluding right bundle branch block, they also tended to be transient. However, postoperative complete A-V block has persisted in 1 child for over a year.The P-R interval in the immediate postoperative period increased, decreased, or remained essentially unchanged; that observed several weeks later did not differ significantly from the preoperative level. Surgically induced right bundle branch block resulted in a distinct increase of the RS ratio in V1. This regressed after disappearance of block.The possible mechanisms for the postoperative A-V block and right bundle branch block are discussed.