THE HISTOLOGY OF THE LUNG IN NEONATES WITH TRICUSPID-VALVE DISEASE AND GROSS CARDIOMEGALY DUE TO SEVERE REGURGITATION

Lung autopsies from four neonates with Ebstein's anomaly or tricuspid valve dysplasia and gross cardiomegaly were examined. The mean cardiot horacic ratio was 92 +/- 0.5%. The degrees of pulmonary hypoplasia and pulmonary artery muscularization were assessed and were compared with those in lungs from four controls and four patients with diaphragmati c hernias. Lung and body weight ratios and radial alveolar counts, whi ch reflect pulmonary hypoplasia and immaturity, were significantly dec reased only in patients with diaphragmatic hernia. The thickness of th e medial muscle layer in small pulmonary arteries was greater in patie nts with diaphragmatic hernia; however, in patients with tricuspid val ve disease, it was relatively small. Abnormal vascular muscle extensio n was seen only in patients with diaphragmatic hernia. In the cases of tricuspid valve disease, although cardiomegaly and lung compression w ere severe, lung hypoplasia and immaturity were not, and neither abnor mal medial thickening nor extension were found. Our results suggest th at, at least in full-term infants with tricuspid valve disease, surgic al relief of lung compression may improve respiratory function, even i f the cardiomegaly is severe.