Vascular Changes in Pulmonic Stenosis and Tetralogy of Fallot Studied in Lung Biopsies

Abstract

The present study deals with the results of the histological investigation of lung biopsies from 44 patients with pulmonic stenosis and 117 with tetralogy of Fallot in correlation with their clinical and hemodynamic data. Particularly cases without additional complicating malformations have been considered. Medial atrophy and luminal widening of the muscular pulmonary arteries and veins were confirmed in both isolated pulmonary stenosis and tetralogy of Fallot but were more marked in pulmonic stenosis. Intimal fibrosis in the pulmonary vessels on the other hand gave the impression of being greater in the cases of tetralogy of Fallot than in pulmonic stenosis even within the same age group, but this difference is not statistically significant. Intimal fibrosis was even more pronounced in tetralogy of Fallot with a previous shunt operation. The intimal fibrosis is thought to be based on organization of thrombi. The explanations for the medial atrophy and the widening of the arterial lumen are unknown, but it is thought likely that the flatness of the pressure curve in the pulmonary artery plays a role in causation.