Vascular changes in pulmonic stenosis and tetralogy of Fallot studied in lung biopsies.

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