Endocarditis (en-do-car-DY-tis) refers to inflammation of the lining of the heart, usually caused by an infection in a heart valve or the heart lining, called the endocardium (en-do-CAR-de-um). People at increased risk for endocarditis are sometimes given antibiotics to prevent it.
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The heart contains four chambers, each of which has a special function as the heart pumps blood through the body. The inner walls of these chambers are called the "endocardium" and are lined with small blood vessels and smooth muscle. Valves, like swinging doors between the chambers, open and close as the heart beats and as the blood flows. They keep the blood going in one direction, with no back flow.
Who Is at Risk for Endocarditis?
About 1 percent of people have defects in the endocardium or heart valves that are present since birth. Other people may develop defects from heart disease, rheumatic fever * , or use of intravenous * drugs. The defects can include tiny folds in the endocardium or a valve that does not open and close properly. Bacteria in the bloodstream sometimes settle into these malformed areas and cause an infection that swells the endocardium. This dangerous and often deadly condition is called "endocarditis," which strikes about 4 of every 100,000 Americans each year.
What Causes Endocarditis?
Bacteria cause endocarditis. Bacteria are present in normal amounts in different parts of the body, especially the mouth, throat, lungs, and intestines. They enter the body in many ways, such as by catching strep throat * or pneumonia * . Most times, the body's own defenses fight bacterial infections or doctors prescribe antibiotic medications to help rid the body of invading bacteria.
People who have normal hearts are rarely at risk for endocarditis. But when bacteria find a malformed heart valve or endocardium, they may settle in to reproduce. That can cause the heart to lose its ability to pump properly, as swollen valves start to stick partly open and blood clots form. The body and brain may fail to get enough oxygen, and heart failure or stroke * may result. The bacteria that cause endocarditis usually enter the bloodstream from an infection in another part of the body. Sometimes, however, the normal bacteria present in the mouth or intestines may become dislodged and settle in a damaged or abnormal heart. Surgery or dental procedures may cause such bacteria to get loose into the bloodstream, where they may start an infection in the endocardium.
* rheumatic fever is a disease that causes fever, joint pain, and inflammation affecting many parts of the body. It varies in severity and duration, and it may be followed by heart or kidney disease.
* intravenous (in-tra-VEEN-us) drugs are injected directly into the veins.
* strep throat is a contagious sore throat caused by a strain of bacteria known as Streptococcus.
* pneumonia is an inflammation of the lungs usually caused by bacteria, viruses, or chemical irritants.
* stroke may occur when a blood vessel bringing oxygen and nutrients to the brain bursts or becomes clogged by a blood clot or other particle. As a result nerve cells in the affected area of the brain, and the specific body parts they control, do not properly function.
What Happens to People with Endocarditis?
The symptoms of endocarditis can develop quickly. They may include:
- extreme weakness
- shortness of breath
- chills and excessive sweating
- swollen feet, ankles, and joints
- loss of appetite
It is very important for people at risk for endocarditis to see their doctors if they experience these symptoms.
It can be difficult for doctors to diagnose endocarditis, because its symptoms are similar to those of other conditions. But doctors may suspect that a person has endocarditis if they are aware of a recent infection or if they know a person has a history of heart abnormalities. Doctors also will listen for a heart murmur * and rapid heartbeat. They look at the skin, which may appear abnormally pale with small, red spots on the palms and soles of the feet. A sample of blood often can identify the organism causing the infection.
Antibiotics are used to treat the bacterial infection. Bed rest usually is necessary to allow time for recovery. If the infection has damaged a heart valve severely, surgery might be necessary to replace the damaged valve with an artificial one.
How Is Endocarditis Prevented?
Avoiding intravenous drugs is important for many reasons, including the fact that drug use puts people at risk for endocarditis. People with abnormal heart valves often are given antibiotics before surgery or before certain dental procedures. Although a recent study did not find a strong link between dental work and endocarditis, the American Dental Association and the American Heart Association continue to recommend that doctors give antibiotics to people with known heart defects before surgery or dental work.
* heart murmur is an extra sound heard during a heartbeat that is caused by turbulence in blood flow through the heart.
The U.S. National Heart, Lung, and Blood Institute posts a fact sheet
about endocarditis at its website.
American Heart Association National Center, 7272 Greenville Avenue,
Dallas, TX 75231. The American Heart Association posts fact sheets about
bacterial endocarditis and about dental care and heart disease at its