The Effects of Prolonged Neonatal Hypoxemia on the Pulmonary Vascular Bed and Heart

Changes in the blood vessels and heart were assessed in infants chronically hypoxemic during the neonatal period. The hypoxemia appears to arrest the relative involution of smooth muscle about the pulmonary arterial bed. This change is presumably related to persistent pulmonary arterial hypertension, as evidenced by a relative hypertrophy of the right ventricle in the hypoxemic infants. The small pulmonary arteries are identified as a possible site of hypoxemia-induced vasoconstriction. No abnormalities were found in the veins or capillaries of the pulmonary circulation or in any vessels of the systemic circulation.