The development of the pulmonary circulation in pulmonary atresia

Abstract

In pulmonary atresia the intrapulmonary arterial circulation fails to grow and develop normally. When the ductus arteriosus is the only source of blood supply, the reduction in blood flow before birth impairs fetal development and such children die at birth, if untreated, with abnormally small pre- and intra-acinar arteries and a reduction in intra-acinar arterial number. The muscle coat is abnormally thin although the distribution of muscle along the arterial pathway is normal. An aortopulmonary anastomosis increases arterial size and if too large arterial medial hypertrophy develops rapidly in the first days of life, but peripheral arterial number remains low.