Final answer:
Vegetations are small masses made of fibrin and platelets that form on heart valve leaflets due to bacteremia, leading to complications like endocarditis.
Step-by-step explanation:
Small masses composed of fibrin and platelets that accumulate on the heart valve leaflets or their cords due to bacteremia are called vegetations. When bacteria enter the bloodstream, a condition known as bacteremia, they can cause endocarditis, an inflammation of the heart's inner lining. This can lead to heart valve damage when patches of tissue, associated with bacteria and protected by blood clots, form and accumulate vegetations. These are essentially clumps of platelets, fibrin, erythrocytes, and with bacterial colonization in cases of infectious endocarditis. Thrombi, on the other hand, are localized blood clots that can obstruct blood flow, while emboli are thrombi that have broken loose and travel through the bloodstream, potentially causing embolism. Myxomas are primary heart tumors, and varices are dilated blood vessels, usually in the esophagus or stomach.