Birge, Richard F.

A case is reported of a 20-day-old infant with origin of the right pulmonary artery from the ascending aorta. Besides its abnormal origin, the artery was stenotic in its proximal half. We believe the malformation results from persistence of the distal (instead of the proximal) part of the primitive sixth aortic arch and of a portion of the right dorsal aorta. The presence of ductal tissue in the wall of the right pulmonary artery supports this concept. The pulmonary vasculature in the two lungs showed great differences in medial and intimal characteristics. A second case of origin of the right pulmonary artery from the aorta, deseribed elsewhere, provided material for comparative study of the structure of the right main pulmonary arteries and the intrapulmonary branches.