Persistence of the fetal cardiopulmonary circulatory pathway: survival of an infant after a prolonged course;

The first case of "idiopathic" persistence of the fetal cardiopulmonary circulatory pathway with survival after a prolonged course is documented by serial cardiac catheterizations. All previously reported infants have either markedly improved within the first week of life or subsequently died. This entity has been described in term infants with prenatal or perinatal distress who present with tachypnea and cyanosis from birth. The chest radiograph is remarkable for the absence of pulmonary parenchymal pathology and the hemoglobin and hematocrit are normal. Blood gas determinations indicate hypoxia and acidosis with or without hypercarbia. Cardiac catheterization and angiography reveal an anatomically normal heart with severe pulmonary hypertension, left ventricular pressure lower than right ventricular pressure, and right-to-left venoarterial shunting through the fetal channels (atrial and or ductal levels). It is postulated that this entity may result from antenatal factors that affect the pulmonary vasculature and its subsequent adjustment to extrauterine life. These factors may include abnormal intrauterine stress resulting in excessive hypertrophy of the pulmonary arteriolar smooth muscle, or abnormal pulmonary vascular responsiveness to the usual vasoactive stimuli before or after birth, or an immature or dysfunctioning enzyme system necessary for the normal decrease in pulmonary artery pressure.