The Pulmonary Arterial Tree in Atrial Septal Defect

Abstract

The pulmonary vascular tree was studied in 12 cases of uncomplicated atrial septal defect in fetuses, infants, and children. The ages of these subjects ranged from 24 weeks of fetal life to 11 years. A quantitative analysis was made of the medial thickness and of the index of medial surface area (ratio of medial tissue to pulmonary parenchyma) of the pulmonary arterial branches. In contrast to subjects with ventricular septal defect in corresponding age groups, the three fetuses in this series had medial hypertrophy, as indicated by a high index of medial surface area. In the postnatal group, both the medial thickness and the index of medial surface area were also usually greater than in the controls of corresponding ages, notably in two patients, who, at the ages of 7 weeks and 4 months, died of cardiac failure. No satisfactory explanation for these unexpected findings can be offered. Slight to moderate intimal proliferation was observed in some muscular and elastic pulmonary arteries, in bronchial arteries, and in pulmonary veins in several subjects. Thickening of the intima in elastic arteries was observed in a fetus of 26 weeks' gestation. Pronounced obliterative intimal changes were found in only one subject, an 11-year-old girl with severe pulmonary hypertension.