Pulmonary hypertension following neonatal shock

Five neonates, aged between 3 and 14 days, had pulmonary hypertension two or more days following an episode of postnatal hypotensive shock. Unlike most previously described infants with "persistence of fetal circulation," prenatal and perinatal histories were normal, with Apgar scores of 8 to 10. Significantly, no infant was cyanotic or apparently hypoxic (PaO₂<50). After resuscitation and successful medical or surgical therapy for the underlying disorder, heart failure developed in each infant, with x-ray signs of pulmonary edema, as well as electrocardiographic signs of right ventricular hypertrophy. Cardiac catheterization revealed moderate to severe pulmonary hypertension but no anatomic heart disease. Heart failure requiring digitalis persisted for four to 12 months; electrocardiographic signs of right ventricular hypertrophy persisted for one to 21/2 years, but resolved in each case. All five children were asymptomatic by the age of 2 years, and the four children who had follow-up catheterization were found to have normal intracardiac pressures. Previous reports of neonatal pulmonary hypertension have focused on the possible etiologic roles of perinatal acidosis or hypoxia. The clinical pictures in our five infants are different from those previously reported and support the hypothesis that severe shock or its sequelae may result in prolonged but reversible pulmonary hypertension.