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Infective endocarditis is a serious infection of the heart's inner lining (endocardium) and heart valves, typically caused by bacteria, fungi, or other microorganisms that enter the bloodstream. The condition can be acute or subacute, with acute cases progressing rapidly and potentially becoming life-threatening within days to weeks. Risk factors include pre-existing valve disease, prosthetic valves, intravenous drug use, and certain congenital heart defects.
The infection begins when microorganisms in the bloodstream adhere to abnormal or damaged endocardial surfaces, particularly heart valves, where they multiply and form vegetations composed of fibrin, platelets, and inflammatory cells. These vegetations can cause valve dysfunction, embolize to distant organs, or lead to abscess formation. The most commonly affected valves are the mitral and aortic valves in native valve endocarditis, while tricuspid valve involvement is more common in intravenous drug users.
Diagnosis requires clinical suspicion based on predisposing factors, symptoms (fever, new heart murmur, embolic phenomena), and laboratory findings including positive blood cultures and elevated inflammatory markers. The Duke criteria provide a standardized approach combining major criteria (positive blood cultures, echocardiographic evidence of vegetations) and minor criteria (fever, predisposing conditions, vascular phenomena) for diagnosis. Early recognition and treatment with appropriate antimicrobial therapy is crucial, as complications can include heart failure, stroke, systemic embolization, and death.
Key imaging focus: Vegetations, abscess, valve perforation, new regurgitation