Infectious endocarditis (in-FEK-shus en-do-kar-DYE-tis) is an inflammation of the valves and internal lining of the chambers of the heart, known as the endocardium (en-doh-KAR-dee-um), caused by an infection.
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What Is Endocarditis?
The heart has four chambers and four valves that regulate the flow of blood through the heart. Each valve is made up of two or three smaller parts, known as leaflets, that swing open and shut. As the heart beats, it pumps blood through the chambers and out of the heart to the lungs and the rest of the body. The valves open to allow blood to pass through and out of the heart and then close to keep the blood from flowing backward.
In a normal heart, the swift, smooth movement of blood sweeps foreign material such as bacteria away from the heart. However, some people have defects in the heart's valves, the endocardium, or other parts of the heart's structure that disrupt the flow of blood. This disruption can allow bacteria or other germs that reach the heart through the bloodstream to lodge there and multiply, which results in an infection that inflames the heart's valves, muscles, and endocardium, producing endocarditis. The inflammation (in-flah-MAY-shun), which is the body's response to injury or infection, can be serious, and sometimes it damages or destroys heart valves.
What Causes Endocarditis?
Viruses, fungi, or other microscopic organisms can all cause infectious endocarditis, but the disease usually arises from a bacterial infection. A common bacterium that lives in the mouth, Streptococcus viridans (strep-tuh-KAH-kus VEER-ih-danz), is responsible for up to half of all cases of bacterial endocarditis. Other bacterial culprits include bacteria from the staphylococcus, streptococcus, and enterococcus families and, less commonly, other types.
In most cases of endocarditis, bacteria that normally live harmlessly on the body, such as in the mouth, on the skin, in the intestines * , or in the urinary tract * (YOOR-ih-nair-e TRAKT), enter the blood (a condition known as bacteremia, bak-tuh-REE-me-uh). The bacteria can enter through a cut or a tear, frequently caused by a dental or medical procedure, or they may come from an infection somewhere else in the body. Once in the bloodstream, the bacteria travel to the heart and become stuck to the endocardium or heart valves. As they grow and multiply, the bacteria may form vegetations, which are composed of clumps of bacteria, red and white blood cells, and fibrin, a protein that helps blood clot * .
Who Gets Endocarditis?
Endocarditis is not contagious, so there is no reason to avoid contact with someone who has it. The disease is not very common in people with normal hearts, but some people are more susceptible to it. Because bacteria can easily attach to a malformed part of the heart, people with an artificial or damaged heart valve or a heart defect are more likely to get endocarditis. Anyone who has had it before or who has a catheter * in a blood vessel also has a greater chance of becoming infected. Although many people with heart defects are born with them, other people develop defects during their lifetime, such as from intravenous * drug use or rheumatic fever * , which puts them at increased risk for endocarditis as well. Overall, between 1 and 4 cases per 100,000 people occur each year in the United States.
What Are the Signs and Symptoms
Flulike symptoms, such as fever and chills, are the most common symptoms of endocarditis. Some people experience weight loss, weakness, headache, tiredness, shortness of breath, joint and muscle pain, and excessive sweating at night (night sweats). A heart murmur * usually develops, and the person may look pale, have red spots on their skin, and see blood in their urine. An enlarged spleen * , small hemorrhages * on the nails and on the whites of the eyes, and swelling of the feet, legs, and abdomen also can occur with endocarditis.
* intestines are the muscular tubes that food passes through during digestion after it exits the stomach.
* urinary tract is the system of organs and channels that makes urine and removes it from the body. It consists of the urethra. bladder, ureters, and kidneys.
* clot is the process by which the body forms a thickened mass of blood cells and protein to stop bleeding.
* catheter (KAH-thuh-ter) is a small plastic tube placed through a body opening into an organ (such as the bladder) or through the skin directly into a blood vessel. It is used to give fluids to or drain fluids from a person.
* intravenous (in-tra-VEE-nus) means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.
* rheumatic (roo-MAH-tik) fever is a condition associated with fever, joint pain, and inflammation affecting many parts of the body, including the heart. It occurs following infection with certain types of strep bacteria.
* heart murmur is an abnormal sound from the heart, heard with a stethoscope, that is usually related to the flow of blood through the heart. Some murmurs indicate a problem with a heart valve or other part of the heart's structures, but many murmurs do not indicate any problem.
* spleen is an organ in the upper left part of the abdomen that stores and filters blood. As part of the immune system, the spleen also plays a role in fighting infection.
How Do Doctors Diagnose and
Doctors may suspect endocarditis if someone with a known heart abnormality develops an unexplained long-lasting fever, an abnormal heart sound (a murmur), or symptoms of heart failure such as shortness of breath or swelling of the legs.
Certain tests can help doctors diagnose endocarditis, including blood cultures to detect bacteria in the bloodstream, a complete blood count, and laboratory tests that look for inflammation. For example, checking a patient's erythrocyte sedimentation rate (ESR) shows how quickly the person's red blood cells, or erythrocytes (eh-RITH-ruh-sites), settle to the bottom of a test tube, which is a measure of inflammation in the body. Another blood test identifies levels of C-reactive protein, which is increased in the blood when there is significant inflammation in the body. Doctors may also use an echocardiogram to look for signs of infection on the heart valves or in the heart. An echocardiogram (eh-ko-KAR-dee-uh-gram) is a diagnostic test that uses sound waves to produce images of the heart's chambers and valves and observe blood flow through the heart.
Doctors treat infectious endocarditis with antibiotics. The medication is given intravenously in the hospital at first, but sometimes patients finish treatment at home. Several weeks of antibiotic treatment may be necessary to eliminate the infection. In more serious cases, patients may need oxygen and medications to support heart function while hospitalized, and some people require surgery to repair damage to the heart caused by inflammation.
Do People Recover from Endocarditis?
The infection can start suddenly or come on gradually over weeks to months. Left untreated, endocarditis is often fatal. However, when treated successfully with antibiotics and when there has been little damage done to the heart valves, patients usually begin to feel better within a few days. If the infection does not improve with antibiotics, or if there is evidence that the heart valves have been damaged significantly, surgery may be required to replace the valve to clear the infection from the body and restore heart function.
Endocarditis can cause other complications. In some people with the disease, pieces of the infected material (vegetations) in the heart may break off and travel through the blood to other organs. If these pieces travel to the brain and block a blood vessel there, for example, the person may develop a stroke * . If they reach other organs, they may cause serious infections there. Endocarditis can also cause an irregular heartbeat, jaundice * , and kidney failure, as well as heart failure.
* hemorrhages (HEH-muh-rih-jes) are areas of uncontrolled or abnormal bleeding.
* stroke is a brain-damaging event usually caused by interference with blood flow to the brain. A stroke may occur when a blood vessel supplying the brain becomes clogged or bursts, depriving brain tissue of oxygen. As a result, nerve cells in the affected area of the brain, and the specific body parts they control, do not properly function.
* jaundice (JON-dis) is a yellowing of the skin, and sometimes the whites of the eyes, caused by a buildup in the body of bilirubin, a chemical produced in and released by the liver. An increase in bilirubin may indicate disease of the liver or certain blood disorders,
* respiratory tract includes the nose, mouth, throat, and lungs. It is the pathway through which air and gases are transported down into the lungs and back out of the body.
* urethra (yoo-REE-thra) is the tube through which urine passes from the bladder to the outside of the body,
* gastrointestinal (gas-tro-in-TES-tih-nuhl) means having to do with the organs of the digestive system, the system that processes food. It includes the mouth, esophagus, stomach, intestines, colon, and rectum and other organs involved in digestion, including the liver and pancreas.
How Is Endocarditis Prevented?
Doctors give antibiotics to people who are at risk for infectious endocarditis before they undergo procedures that could introduce bacteria into the bloodstream. For example, simple dental work, removal of the tonsils, or medical procedures involving parts of the upper respiratory tract * (such as the mouth and throat), urinary tract (such as the urethra * ), or lower gastrointestinal * tract can all provide an avenue for bacteria to enter the bloodstream and travel to the heart.
American Heart Association, National Center, 7272 Greenville Avenue,
Dallas, TX 75231. The American Heart Association posts a fact sheet
about bacterial endocarditis at its website.
U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD
20894. The National Library of Medicine has a website packed with
information on diseases (including endocarditis) and drugs, consumer
resources, dictionaries and encyclopedias of medical terms, and
directories of doctors and helpful organizations.