Demonstrated are eight cases of carcinoid heart disease (7 females, 1 male; average age 63.4 y.). The primary tumor was localized in the ileum in 5, and in the cecal area in 3 patients, with liver metastases in each case. The characteristic heart lesion appears as an endocardial plaque composed of loose intercellular matrix with scattered smooth muscle cells, covered by an endothelial layer. The plaques are apposed on an otherwise normal valvular, or mural endocardium of the right heart. The resulting combined valvular lesions show a predominance of tricuspid incompetence, or of pulmonary stenosis. In one case with a widely patent foramen ovale there was involvement of left-heart valves in addition. Local effect of serotonin appears to play the main role in pathogenesis of the endocardial plaques.

        Key words: carcinoid – carcinoid syndrome – tricuspid incompetence – pulmonary stenosis