A 48-year-old male with a history of hypertension, patent foramen ovale, coronary artery disease, and diabetes mellitus presents with increasing shortness of breath, wheezing, peripheral edema, diarrhea, and headache. Transthoracic echocardiography shows severe tricuspid regurgitation, severe mitral regurgitation, and evidence of right ventricular failure. The subvalvular apparatus of the tricuspid and mitral valves appear thickened.
What is the likely etiology?
A. Carcinoid heart diseaseCorrect Answer: A
Neuroendocrine tumors are rare tumors arising primarily in the gastrointestinal tract (67.5%) and the bronchopulmonary system (25.3%). These tumors may secrete many different products, including 5- hydroxytryptamine (5-HT, serotonin), prostaglandins, histamine, substance P, and transforming growth factor-β. These vasoactive substances are typically metabolized in the liver; however, when metastasis form and bypass this metabolism, systemic symptoms can develop. Approximately half of patients with neuroendocrine tumors will develop carcinoid syndrome, characterized by cutaneous flushing, diarrhea, and bronchospasm, and only 20% to 30% of those patients will develop carcinoid heart disease. The neuroendocrine products cause deposition of plaques along the endocardial surfaces of the valve leaflets, chordae tendinae, papillary muscles, and walls of the heart. These deposits primarily form on the ventricular aspect of the valves. The most common valve involved is the tricuspid valve because of the metabolism of the products in the pulmonary circulation. This can result in tricuspid regurgitation or a combination of tricuspid regurgitation and stenosis. The mitral valve can be involved in the setting of a patent foramen ovale, in which case the vasoactive substances bypass the lung. Carcinoid heart disease can present with signs and symptoms of right ventricular failure including dyspnea, peripheral edema, and liver disease; however, not all patients with carcinoid heart disease present with symptoms. The most common cause of death in these patients is right ventricular failure, and the second most common cause is tumor progression.
Mild tricuspid regurgitation is common in patients with a normal right ventricle and tricuspid valve. However, various pathologies can contribute to an increased severity of tricuspid regurgitation. The most common cause of tricuspid regurgitation is right ventricular dilation, which causes dilation of the tricuspid annulus (secondary/functional tricuspid regurgitation). Typically, a right ventricular systolic pressure of 55 mm Hg or greater will cause functional tricuspid regurgitation. Other causes include rheumatic and carcinoid heart disease, endocarditis, Ebstein anomaly, connective tissue disease (Marfan), and rheumatoid arthritis. Tricuspid regurgitation is well tolerated in patients with no evidence of pulmonary hypertension or right ventricular failure; however, tricuspid regurgitation in the setting of pulmonary hypertension can lead to heart failure and is associated with poor survival. Management of carcinoid heart disease involves diuretics and salt and water restriction. When severe, tricuspid valve replacement is the operation of choice. Because of the tricuspid valve restriction in addition to the calcified and diseased subvalvular apparatus, a tricuspid valve repair is not an option.
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