Pulmonary vascular changes associated with hypoplastic left ventricle syndrome

Abstract

The lungs of ten newborn infants who died of hypoplastic left ventricle syndrome were studied by a morphometric technique that (1) determined the percentage wall thickness of injected pulmonary arteries, (2) determined the ratio between the number of alveoli per high-power field and the number of corresponding arteries, and (3) examined in detail the extension of medial smooth muscle to the vessels at the periphery of the acinus. The findings in the lung were related to the gross cardiac morphological changes and to echocardiographic and hemodynamic findings. The echocardiograms of eight neonates demonstrated small left ventricles. The aortic root was hypoplastic in seven and the left atrium was small in three of the eight. Pulmonary artery hypertension and elevation of the left atrial pressure were present in all infants in whom measurements were obtained. The mean percentage wall thickness of all vessels was greater in afflicted infants than in normal age-matched control subjects. There was a normal ratio between the number of alveoli per high-power field and the number of corresponding arteries, and all infants had extension of muscle to the peripheral vessels at the alveolar duct and alveolar wall levels. The pulmonary vascular abnormalities observed in the neonate with hypoplastic left ventricle syndrome may represent persistence of fetal vascular abnormalities associated with the abnormal fetal circulatory hemodynamics resulting from the malformation. These abnormalities may influence the success of surgery proposed for hypoplastic left ventricle syndrome.