Bronchopulmonary circulation in d-transposition of the great arteries: possible role in genesis of accelerated pulmonary vascular disease.

Hemodynamic and angiograhic data from 209 patients with d-transposition of the great arteries were reviewed to estimate the incidence of prominent bronchopulmonary circulation and to explore its role in the genesis of accelerated pulmonary vascular disease in these patients. The degree of bronchopulmonary circulation was assessed visually by considering the extent of the pulmonary arterial opacification and the circulation to the left atrium. An initial survey study revealed a marked degree of collateral circulation in 20 of 138 patients with d-transposition having cardiac catheterization before age 2 years at the Hospital for Sick Children, Toronto, between 1967 and 1972. Detailed analysis of 71 additional patients with d-transposition aged 1 week to 72 months (mean 17 months) studied at Children's Memorial Hospital, Chicago, between 1967 and 1974 showed collateral circulation of marked degree in 23 and of mild degree in 14. The bronchopulmonary collateral vessels were more freqently demonstrated in the patients with intact ventricular septum than in those with ventricular septal defect or left ventricular outflow tract stenosis. In a prospective study in 12 of 15 patients during cardiac catheterization the functional patency of the bronchopulmonary collateral circulation was demonstrated by obstructing pulmonary blood flow in the right or left pulmonary artery, or both, with an inflated balloon and obtaining from the pulmonary arterial segment distal to the occlusion blood with an oxygen saturation similar to that of the aorta. A hypothesis is presented concerning the role of systemic hypoxemia and local pulmonary hypoxemia induced by way of the bronchopulmonary collateral vessels and the bronchial arterial vasovasorum in promoting pulmonary vasoconstriction. It is suggested that increased pulmonary blood flow and pressure due to the physiologic features of ventricular septal defect, patent ductus arteriosus or transposition of the great vessels, in the face of this regionally increased hypoxemia results in accelerated pulmonary vascular disease.