ATRIAL SEPTAL DEFECT WITH PULMONARY HYPERTENSION

Abstract

Forty-one patients with atrial septal defect (ASD) complicated by significant pulmonary hypertension have been investigated. The hypertension was classed as obstructive when the pulmonary vascular resistance exceeded 5 units (400 dynes sec./ cm-5) or when there was central cyanosis with a reversed atrial shunt: it was classed as hyperkinetic when the resistance was below 5 units and the pulmonary flow much increased. Pulmonary hypertension complicating Lutembacher''s syndrome, though usually hyperkinetic, has been separately considered. The overall incidence of pulmonary hypertension in 225 patients with ASD was 16%, but it was far more frequent in superior caval defects, in primum defects with common A-V canal, and in Lutembacher''s syndrome than in ordinary fossa-ovalis defects. Female predominance was twice as great in ASD with pulmonary hypertension as in ASD as a whole. Anginal pain, effort syncope, central cyanosis, and pulmonary regurgitation were only encountered in obstructive hypertension which modified the usual clinical signs of ASD in a characteristic way. In both types of pulmonary hypertension, the ecg usually showed inversion of the T waves in the chest leads from leads V1 to V5 or even V6. The pattern of QRS in V1 was not characteristic, but the R/S ratios in V1 and V6 were of some value in the diagnosis of pulmonary hypertension. Surgical closure of the ASD was performed in 14 patients with hyperkinetic pulmonary hypertension, including 6 with Lutembacher''s syndrome, with 4 deaths. Patients with obstructive hypertension were excluded from operation under hypothermia. The etiology of pulmonary hypertension in ASD has been discussed. In about 10% of such patients, obstructive hypertension is probably congenital and due to a persistence of the fetal type of pulmonary vasculature: in these, the heart is relatively small. In the majority, obstructive pulmonary hypertension is probably acquired and follows hyperkinetic hypertension. Pulmonary thrombosis and recurrent respiratory infection are probably factors in provoking acquired pulmonary hypertension of the obstructive kind. The heart is much larger in the acquired than in the congenital form of pulmonary hypertension and the largest hearts occur in Lutembacher''s syndrome.