Physiologic Studies Following Surgical Correction of Atrial Septal Defect and Similar Lesions

Physiologic observations were made on eight patients following repair of atrial septal defect or total anomalous pulmonary venous connection. A pattern of changes in cardiac output and atrial pressures during the first 3 postoperative days was noted. Cardiac output was abnormally low in some patients with obstructive pulmonary vascular disease or low atrial pressures. Transfusion of whole blood was effective in elevating cardiac output in the operating room and after operation. Left atrial pressure was higher than right atrial pressure in the operating room. Postoperatively left and right atrial pressures tended to become equal in some patients, and the levels were slightly elevated. Heart rate did not seem to be directly related to cardiac output. Ventilation was adequate with regard to elimination of carbon dioxide. Arterial oxygen saturation was maintained at 93 per cent or more by the use of oxygen-enriched mixtures. The difference in arteriovenous oxygen content was inversely related to cardiac output. Acidemia was present 2 to 4 hours after operation, but in general the pH of arterial blood had returned to normal by day 2. Some mechanisms possibly related to the observations are discussed.