What condition commonly affects the tricuspid valve in patients with carcinoid syndrome?

Carcinoid syndrome is associated with neuroendocrine tumors that often secrete serotonin and other vasoactive substances. These substances can lead to fibrous plaque formation on right-sided heart structures, and this is most prominently seen in the tricuspid valve. In carcinoid syndrome, the excessive serotonin levels induce a fibrotic reaction, resulting in thickening and retraction of the tricuspid valve leaflets.

The involvement of the tricuspid valve can lead to dysfunction, primarily manifesting as regurgitation, which contributes to right-sided heart failure. This condition represents a classic example of right-sided cardiac valvular disease associated with carcinoid syndrome.

Other conditions listed, such as left-sided heart failure, myocardial infarction, and endocarditis, do not directly relate to the effects of carcinoid syndrome on cardiac structures. Left-sided heart failure is predominantly influenced by factors affecting the left side of the heart and systemic circulation, while myocardial infarction pertains more to coronary artery disease and not to valvular disease itself. Endocarditis refers to an infection of the heart valves which does not typically result from the fibrous changes seen in carcinoid syndrome. Therefore, the correct condition that commonly affects the tricuspid