The Histology of the Lung in Neonates with Tricuspid Valve Disease and Gross Cardiomegaly Due to Severe Regurgitation

Abstract

Lung autopsies from four neonates with Ebstein's anomaly or tricuspid valve dysplasia and gross cardiomegaly were examined. The mean cardiothoracic 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 diaphragmatic hernias. Lung and body weight ratios and radial alveolar counts, which reflect pulmonary hypoplasia and immaturity, were significantly decreased only in patients with diaphragmatic hernia. The thickness of the medical muscle layer in small pulmonary arteries was greater in patients with diaphragmatic hernia; however, in patients with tricuspid valve disease, it was relatively small. Abnormal vascular muscle extension was seen only in patients with diaphragmatic hernia. In the cases of tricuspid valve disease, although cardiomegaly and lung compression were severe, lung hypoplasia and immaturity were not, and neither abnormal medial thickening nor extension were found. Our results suggest that, at least in full-term infants with tricuspid valve disease, surgical relief of lung compression may improve respiratory function, even if the cardiomegaly is severe.

Tricuspid Valve Dysplasia with Severe Tricuspid Regurgitation: Fetal Pulmonary Artery Size Predicts Lung Viability in the Presence of Small Lung Volumes

“…In addition to lung volume, size of the hilar pulmonary arteries has been shown to be a strong prognostic factor in newborns with congenital diaphragmatic hernia, with smaller branch pulmonary artery being associated with severe pulmonary hypoplasia and higher mortality [18] . Though lung volume is reduced in the fetus with severe tricuspid regurgitation and cardiomegaly due to limited thoracic space and mechanical compression, the degree of co-existent lung hypoplasia, defined as lung immaturity and poor vascular development, may not be as great as suspected [19] . In such full-term infants with tricuspid valve disease, surgical relief of lung compression may therefore improve respiratory function.…”

Preoperative Physiology, Imaging, and Management of Ebstein’s Anomaly of the Tricuspid Valve

“…11,17,20 More recent histological data comparing the radial alveolar counts of EA patients with control patients suggest that despite the compressive effects of cardiomegaly, the histology of the lungs is not significantly altered. 21…”

The “wall-to-wall” heart in the patient with pulmonary atresia and intact ventricular septum

“…The compressed lungs appear underdeveloped and hypoplastic. 29,50,51 Although appearing grossly hypoplastic, it does not follow that the substance of the lungs is itself abnormal. Thus, Tanaka et al 50 failed to find any significant alveolar underdevelopment or immaturity of the parenchyma, nor were they able to recognize abnormal degrees or extent of muscularization of the pulmonary arteries.…”

“…29,50,51 Although appearing grossly hypoplastic, it does not follow that the substance of the lungs is itself abnormal. Thus, Tanaka et al 50 failed to find any significant alveolar underdevelopment or immaturity of the parenchyma, nor were they able to recognize abnormal degrees or extent of muscularization of the pulmonary arteries. Similar findings were reported by Lang et al 51 This knowledge is important for those seeking to manage and manipulate the flow of blood to the lungs in these patients.…”

“…27,28 The pulmonary veins connect in a normal fashion to the left atrium. 50,51 When compared to the gigantic right atrium, the left atrium appears small and under-filled. Mild dysplasia of the mitral valve, with functional prolapse, has been recorded in the older patient with isolated Ebstein's malformation of the tricuspid valve.…”