Carcinoid heart disease.

Carcinoid tumors are relatively rare neuroendocrine malignancies most commonly originating from enterochromaffin cells in the gastrointestinal tract. The incidence is 1 in 100 000 of the general population.1 They usually grow slowly over years, commonly causing no symptoms at all until they become large or have metastasized. Carcinoid tumors of midgut origin may secrete large amounts of vasoactive substances, including 5-hydroxytryptamine (5HT), tachykinins, and prostaglandins. These are largely inactivated by the liver. Carcinoid syndrome occurs when tumor cells metastasize to the liver as the vasoactive substances produced are able to reach the systemic circulation via the hepatic vein. Clinically, this is characterized by flushing, diarrhea, and bronchospasm. Over the past decade, several new therapies for carcinoid tumors have emerged to reduce symptoms and cause tumor regression. Most notably, the development of somatostatin analogs, which inhibit the release of various biogenic amines and peptides, including serotonin, has resulted in a marked improvement in symptoms.2 These may also have contributed to increased survival, although this has not been proved.2,3 Rarely, surgical resection is curative for nonmetastatic disease. Otherwise, reduction of symptoms, improvement in quality of life, and improvement in survival by inhibition of tumor hormones or reduction of tumor load are the main goals. Metastatic disease of the liver may be debulked either surgically or by hepatic artery embolization in selected patients. Interferon therapy and targeted radionuclide therapy may stabilize or reduce the tumor. Chemotherapy is rarely an option except for pancreatic, bronchial, and high-grade neuroendocrine tumors. Carcinoid heart disease (CHD) was first reported in 1954.4 Several series have reported CHD in up to 70% of cases of carcinoid syndrome.5,6 Development is thought to relate to the vasoactive substances secreted by the metastatic tumor cells in the liver, reaching the right heart. This is associated with deposition of fibrous tissue on the endocardial surfaces of the heart. More recent reports have suggested that this number has reduced, perhaps as a result of the introduction of somatostatin analogs and other antitumor therapies designed to reduce the tumor load and the production of tumor secretory products.7 Exceptionally, CHD may present in carcinoid tumors without liver metastases or in primary ovarian carcinoid tumors in which 5-HT is thought to reach the systemic circulation directly, bypassing portal circulation and the liver.8,9