Right ventricular free wall biopsy specimens in 40 patients undergoing
surgery for relief of chronic thromboembolic pulmonary hypertension w
ere normal in 5%, disclosed only myocyte hypertrophy in 80%, mild foca
l fibrosis in 12.5%, and myocarditis in 2.5%. There was no relation be
tween postsurgical functional or hemodynamic outcomes and the presence
of focal fibrosis.