Atrial septal defect, primum type. Results of surgical closure in 46 patients.

Surgical closure of an atrial septal defect of the ostium primum type was performed in 46 patients during the years 1965-78. All closures were performed with a Dacron patch and the mitral valve defect was sutured. The operative mortality was 6.5%. Pre-operatively, all patients had right bundle-branch block with left axis deviation. Severe heart block did not develop in any of the survivors. One of the patients who died had a partial atrioventricular block postoperatively. Arrhythmia developed in 5 patients, but was cardioverted to sinus rhythm. The operative technique of placing the lower sutures at the mitral valve parallel to the annulus to avoid the conduction bundle is emphasized. Repair of the tricuspid valve was performed in 10 cases and simultaneous closure of a secundum defect was made in 14. Preoperative catheterization revealed arteriovenous shunts ranging from 60 to 500% of the cardiac output. Recatheterization of 32 patients one year postoperatively showed residual shunts ranging from 20 to 75% in 5 patients who were otherwise without clinical symptoms. All survivors had a systolic apical murmur of the mitral insufficiency type.