Infectious Endocarditis

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Overview, Causes, & Risk Factors

Infectious endocarditis is a type of inflammation (irritation with presence of extra immune cells) of the heart valves. It can affect the heart muscle (myocarditis) or the lining of the heart (pericarditis). Most people who develop infectious endocarditis have underlying heart disease.

Sources of the infection may be transient bacteremia (presence of bacteria in the blood), which is common during dental, upper respiratory, urologic, and lower gastrointestinal diagnostic and surgical procedures. The infection can cause growths on the heart valves, the lining of the heart, or the lining of the blood vessels. These growths may be dislodged and send clots to the brain, lungs, kidneys, or spleen.

Many bacteria can cause endocarditis, but an organism commonly found in the mouth, Streptococcus viridans, is responsible for approximately half of all bacterial endocarditis. Other common organisms include Staphylococcus and Group D streptococcus. Less common organisms include Pseudomonas, Serratia, Candida, and many others.

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 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.

Preexisting conditions that increase the likelihood of developing endocarditis include:

• congenital heart disease: ASD (atrial septal defect), PDA (patent ductus arteriosus), and others.
• prior rheumatic heart disease
• cardiac valve anomalies (such as mitral insufficiency)
• prosthetic (artificial) heart valves

Since Streptococcus viridans is often found in the mouth, dental procedures are the most common cause of bacterial endocarditis. This can put children with congenital heart conditions at risk. As a result, it is common practice for children with some forms of congenital heart disease to start on antibiotics prior to any dental work.