Heart Valves and Infective Endocarditis

What is infective endocarditis?

Endocarditis illustration

Infective endocarditis (IE), also called bacterial endocarditis (BE), is an infection caused by bacteria that enter the bloodstream and settle in the heart lining, a heart valve or a blood vessel. IE is uncommon, but people with some heart conditions have a greater risk of developing it.

Infective endocarditis refers specifically to infection in the lining of the heart, but IE also affects the valves and often affects the muscles of the heart.

View an illustration of endocarditis.

There are two forms of IE:

  1. Acute IE — develops suddenly and may become life threatening within days
  2. Subacute or Chronic IE (or subacute bacterial endocarditis) — develops slowly over a period of weeks to several months.

How do people contract infective endocarditis?

The infection can be caused by bacteria introduced into the blood stream, usually through normal activity such as tooth brushing which causes minor injury to the lining of the mouth or gums. These bacteria can lodge on heart valves and cause infection of the endocardium. One study found that people with poor dental health or who bleed during tooth brushing had a higher risk of developing bacteria in the blood (bacteremia).

Why does endocarditis pose a threat to the heart valves?

The heart valves are not supplied directly with blood. Therefore, the body’s immune response system, such as the infection-fighting white blood cells, cannot directly reach the valves through the bloodstream. If bacteria begins to grow on the valves (this occurs most often in people with already diseased heart valves), it is difficult to fight the infection, whether through the body’s own immune system or through medications that rely on the blood system for delivery.

Who is at risk for infective endocarditis?

Risk factors for children and young adults include birth defects of the heart such as malformed valves or a hole in the septum, which allow blood to leak from one part of the heart to another.

Risk factors for adults include previous valve surgeries or transplants, calcium deposits in the mitral valve or in the aortic valve, congenital heart defects or a history of endocarditis.

Illegal drug use and IE

If the cause of IE is injection of illicit drugs or prolonged use of I.V. drugs, the tricuspid valve is most often affected. Street drugs, including narcotics, can also affect the mitral or aortic valve.

What are the symptoms of infective endocarditis?

The symptoms of acute IE usually begin with fever (102°–104°F), chills, fast heart rate, fatigue, night sweats, aching joints and muscles, persistent cough or swelling in the feet, legs or abdomen.

The symptoms of chronic IE may be such things as fatigue, mild fever (99°–101°F), a moderately fast heart rate, weight loss, sweating, a low red blood cell count (anemia) and can take place over as much as a period of months.

Treatment usually consists of at least two weeks and as much as six weeks of high doses of I.V. antibiotics.

Prevention for those at risk usually involves awareness of the risks, and preventative antibiotics prior to certain surgical, dental and medical procedures.

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