Hypoplasia of the intrapulmonary arteries in children with right ventricular outflow tract obstruction, ventricular septal defect, and major aortopulmonary collateral arteries.

Postmortem injection studies have been carried out on the pulmonary vasculature of four children dying with pulmonary atresia and ventricular septal defect or severe tetralogy of Fallot with major aortopulmonary collateral arteries, in which nearly all bronchopulmonary segments had more than one source of blood supply. Despite regional variations in the source of blood supply, there was remarkable uniformity of arterial size and number within the respiratory unit throughout each case. In all cases, there was a normal number of arterial pathways, but both pre- and intraacinar arteries were considerably smaller than normal. The need for early operative intervention to ensure growth of pre- and particularly intraacinar arteries is emphasized.