Pulmonary hypertension in scimitar syndrome in infancy

Abstract

Four infants with the scimitar syndrome presented with failure to thrive, cardiac failure, and pulmonary hypertension. In all cases systemic arteries arose from the upper abdominal aorta to perfuse the lower part of the right lung, and a large unobstructed anomalous pulmonary vein drained venous blood from almost the entire right lung to the inferior vena cava. An additional small pulmonary vein joined the inferior vena cava or right atrium and in three of the four cases angiography showed intrapulmonary connections between the two anomalous veins. At necropsy, in all four cases the right lung was hypoplastic. The bronchi were abnormal in size or number in three cases, but there was no sequestrated tissue. Microscopical examination showed normal peripheral airway and alveolar development. The pulmonary arterial branching pattern was deficient in three patients. Postmortem arteriography, dissection, and microscopical studies showed that in areas of lung not perfused by branches of the right pulmonary artery the systemic arteries anastomosed with intrapulmonary arteries to distribute blood to a dilated capillary bed. In all tissue examined arterial medial thickness was increased in both lungs while vein wall thickness was normal. For comparison a fifth patient, more typical of the syndrome, was included; this patient did not have pulmonary hypertension and died from septicaemia at 2 years of age. Symptomatic infants with pulmonary hypertension probably have the most severe form of the scimitar syndrome. It is recommended that sick infants should have a two stage correction, systemic arteries being ligated at the first procedure and the anomalous vein being reimplanted in the left atrium at a second and later procedure, with closure of an atrial septal defect if present.