Infectious endocarditis

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Heart, front view

Heart, section through the middle

Infective endocarditis

Janeway lesion on the finger

Infectious endocarditis is an infection of the lining of the heart chambers and heart valves, caused by bacteria, fungi, or other infectious agents.

Endocarditis - infectious

Infectious endocarditis is an inflammation of the heart valves. Endocarditis is distinguished from infections of heart muscle (myocarditis) or the lining of the heart (pericarditis). Most people who develop infectious endocarditis have underlying heart disease.

Endocarditis is usually a result of bacteremia (bacteria in the blood), which is common during dental, upper respiratory, urologic, and lower gastrointestinal diagnostic and surgical procedures. The bacteria in the bloodstream can settle on damaged heart valves, and grow to create a “vegetation” or clump of live bacteria. These growths may form infected clots that break off and travel to the brain, lungs, kidneys, or spleen.

Many bacteria can cause endocarditis in patients with underlying valve problems, but an organism commonly found in the mouth, Streptococcus viridans, is responsible for approximately half of all bacterial endocarditis. Other common organisms include Staphylococcus aureus and enterococcus. Less common organisms include pseudomonas, serratia, and candida. Staphylococcus aureus can infect normal heart valves, and is the most common cause of infectious endocarditis in intravenous drug users.

Symptoms of endocarditis may develop slowly (subacute) or suddenly (acute). Fever is a hallmark of both. In the slower form, fever may be present on a daily basis for months before other symptoms appear. Other symptoms are nonspecific, such as fatigue, malaise (general discomfort), headache, and night sweats. As the illness progresses, small dark lines, called splinter hemorrhages, may appear under the fingernails.

The health care provider may hear changing murmurs in the heart and detect an enlarged spleen and mild anemia. Murmurs result from changes in blood flow across valves when clumps of bacteria, fibrin and cellular debris, called vegetations, collect on the heart valves. The mitral valve is most commonly affected, followed by the aortic valve.