Distribution of arterial lesions and collateral pathways in the pulmonary hypertension of congenital heart disease: a computer aided reconstruction study.

Three dimensional computer aided reconstructions of pulmonary vessels were used to investigate the distribution of vascular changes and the formation of collateral channels in 11 patients with congenital heart disease. In the patients with less severe grades of hypertensive pulmonary vascular disease obstructive changes were unevenly distributed, whereas in those with disease of grade 4 or more distribution became more even. Plexiform lesions occurred rather more frequently in supernumerary arteries arising laterally from a large parent vessel, whereas cellular or fibrous intimal thickening tended to affect dichotomous branches at the periphery. Hypertensive changes were confined to arteries of 100-150 microns diameter running along the necks of acini. Various types of collateral channels were found. In particular, the reconstructions suggest that pulmonary arterial blood at high pressure could flow into bronchial arteries via proximal bronchopulmonary arterial anastomoses, and thence by way of dilatation lesions to the alveolar capillaries.