Indium-111 leukocyte scintigraphy for detection of valvular abscesses and vegetations

Abstract

Infective endocarditis results from colonization and invasion of the endothelial surfaces of the heart by bacterial or fungal organisms. Infection usually follows an episode of transient bacteremia from a distant source of acute infection or as a result of dental or surgical manipulation. Rheumatic heart disease, congenital cardiac abnormalities, prosthetic valves, and age-related atherosclerosis and fibrocalcification are predisposing factors. Bacterial endocarditis is classified on the basis of the infecting organism and histologic appearance into subacute and acute forms. Subacute endocarditis is histologically characterized by invasion through the endothelium and formation of vegetations consisting of a meshwork of platelets, fibrin, and bacteria, but there are usually few polymorphonuclear leukocytes. Lesions typically occur in areas of endothelial damage caused by a jet or Venturi effect that forms a sterile thrombus that becomes infected following transient bacteremia. Acute endocarditis is usually caused by highly invasive organisms that attach to endothelial surfaces and may not require a sterile platelet-fibrin thrombus for initial endothelial invasion. Histologically, there is marked destruction of the myocardium with infiltration by large numbers of polymorphonuclear leukocytes.