Cardiac manifestation of gastrointestinal CARCINOID TUMOR that metastasizes to the liver. Substances secreted by the tumor cells, including SEROTONIN, promote fibrous plaque formation in ENDOCARDIUM and its underlying layers. These deposits cause distortion of the TRICUSPID VALVE and the PULMONARY VALVE eventually leading to STENOSIS and valve regurgitation. [ MESH:D002275 ]