Pulmonary hypertension complicating portal hypertension.

We report 9 patients with pulmonary hypertension complicating portal hypertension. The cause of portal hypertension was cirrhosis in 7 patients, nodular regenerative hyperplasia of the liver in 1, and portal vein obstruction in 1. Six patients had been treated by portal-systemic shunting before the clinical onset of pulmonary hypertension. The interval between the first manifestation of portal hypertension and the recognition of pulmonary hypertension ranged from 2 to 15 years. Histologic examination in 1 of these patients revealed medial hypertrophy, concentric intimal proliferation, and plexiform lesions affecting the small pulmonary arteries. Pulmonary hypertension might result from the effect of a vasoconstrictive agent on the small pulmonary arteries or of a substance toxic to the walls of these vessels that is produced in the splanchnic territory, destroyed by the liver in normal subjects, and reaches the pulmonary arteries through portal-systemic shunts in these patients.