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Endocarditis

Endocarditis

Definition

The endocardium is the inner lining of the heart muscle, which also covers the heart valves. When the endocardium becomes damaged, bacteria from the blood stream can become lodged on the heart valves or heart lining. The resulting infection is known as endocarditis.

Description

The endocardium lines all four chambers of the hearttwo at the top (the right and left atria) and two at the bottom (the right and left ventricles)through which blood passes as the heart beats. It also covers the four valves (the tricuspid valve, the pulmonary valve, the mitral valve, and the aortic valve), which normally open and close to allow the blood to flow in only one direction through the heart during each contraction.

For the heart to pump blood efficiently, the four chambers must contract and relax, and the four valves must open and close, in a well coordinated fashion. By damaging the valves or the walls of the heart chambers, endocarditis can interfere with the ability of the heart to do its job.

Endocarditis rarely occurs in people with healthy, normal hearts. Rather, it most commonly occurs when there is damage to the endocardium. The endocardium may be affected by a congenital heart defect, such as mitral valve prolapse, in which blood leaks through a poorly functioning mitral valve back into the heart. It may also be damaged by a prior scarring of the heart muscle, such as rheumatic fever, or replacement of a heart valve. Any of these conditions can damage the endocardium and make it more susceptible to infection.

Bacteria can get into the blood stream (a condition known as bacteremia ) in a number of different ways: It may spread from a localized infection such as a urinary tract infection, pneumonia, or skin infection or get into the blood stream as a result of certain medical conditions, such as severe periodontal disease, colon cancer, or inflammatory bowel disease. It can enter the blood stream during minor procedures, such as periodontal surgery, tooth extractions, teeth cleaning, tonsil removal, prostate removal, or endoscopic examination. It can also be introduced through in-dwelling catheters, which are used for intravenous medications, intravenous feeding, or dialysis. In people who use intravenous drugs, the bacteria can enter the blood stream through unsterilized, contaminated needles and syringes. (People who are prone to endocarditis generally need to take prescribed antibiotics before certain surgical or dental procedures to help prevent this infection.)

If not discovered and treated, infective endocarditis can permanently damage the heart muscle, especially the valves. For the heart to work properly, all four valves must be functioning well, opening at the right time to let blood flow in the right direction and closing at the right time to keep the blood from flowing in the wrong direction. If the valve is damaged, this may allow blood to flow backwarda condition known as regurgitation. As a result of a poorly functioning valve, the heart muscle has to work harder to pump blood and may become weakened, leading to heart failure. Heart failure is a chronic condition in which the heart is unable to pump blood well enough to supply blood adequately to the body.

Another danger associated with endocarditis is that the vegetation formed by bacteria colonizing on heart valves may break off, forming emboli. These emboli may travel through the circulation and become lodged in blood vessels. By blocking the flow of blood, emboli can starve various tissues of nutrients and oxygen, damaging them. For instance, an embolus lodged in the blood vessels of the lungs may cause pneumonia-like symptoms. An embolus may also affect the brain, damaging nerve tissue, or the kidneys, causing kidney disease. Emboli may also weaken the tiny blood vessels called capillaries, causing hemorrhages (leaking blood vessels) throughout the body.

Causes and symptoms

Most cases of infective endocarditis occur in people between the ages of 15 and 60, with a median age at onset of about 50 years. Men are affected about twice as often as women are. Other factors that put people at increased risk for endocarditis are congenital heart problems, heart surgery, previous episodes of endocarditis, and intravenous drug use.

While there is no single specific symptom of endocarditis, a number of symptoms may be present. The most common symptom is a mild fever, which rarely goes above 102°F (38.9°C). Other symptoms include chills, weakness, cough, trouble breathing, headaches, aching joints, and loss of appetite.

Emboli may also cause a variety of symptoms, depending on their location. Emboli throughout the body may cause Osler's nodes, small, reddish, painful bumps most commonly found on the inside of fingers and toes. Emboli may also cause petechiae, tiny purple or red spots on the skin, resulting from hemorrhages under the skin's surface. Tiny hemorrhages resembling splinters may also appear under the fingernails or toenails. If emboli become lodged in the blood vessels of the lungs, they may cause coughing or shortness of breath. Emboli lodged in the brain may cause symptoms of a mini-stroke, such as numbness, weakness, or paralysis on one side of the body or sudden vision loss or double vision. Emboli may also damage the kidneys, causing blood to appear in the urine. Sometimes the capillaries on the surface of the spleen rupture, causing the spleen to become enlarged and tender to the touch. Anyone experiencing any of these symptoms should seek medical help immediately.

Diagnosis

Doctors begin the diagnosis by taking a history, asking the patient about the symptoms mentioned above. During a physical examination, the doctor may also uncover signs such as fever, an enlarged spleen, signs of kidney disease, or hemor-rhaging. Listening to the patient's chest with a stethoscope, the doctor may also hear a heart murmur. A heart murmur may indicate abnormal flow of blood through one of the heart chambers or valves.

Doctors take a sample of the patient's blood to test it for bacteria and other microorganisms that may be causing the infection. They usually also use a test called echocardiography, which uses ultrasound waves to make images of the heart, to check for abnormalities in the structure of the heart wall or valves. One of the tell-tale signs they look for in echocardiography is vegetation, the abnormal growth of tissue around a valve composed of blood platelets, bacteria, and a clotting protein called fibrin. Another tell-tale sign is regurgitation, or the backward flow of blood, through one of the heart valves. A normal echocardiogram does not exclude the possibility of endocarditis, but an abnormal echocardiogram can confirm its presence. If an echocardiogram cannot be done or its results are inconclusive, a modified technique called transesophageal echocardiography is sometimes performed. Transesophageal echocardiography involves passing an ultrasound device into the esophagus to get a clearer image of the heart.

Treatment

When doctors suspect infective endocarditis, they will admit the patient to a hospital and begin treating the infection before they even have the results of the blood culture. Their choice of antibiotics depends on what the most likely infecting microorganism is. Once the results of the blood culture become available, the doctor can adjust the medications, using specific antibiotics known to be effective against the specific microorganism involved.

Unfortunately, in recent years, the treatment of endocarditis has become more complicated as a result of antibiotic resistance. Over the past few years, especially as antibiotics have been overprescribed, more and more strains of bacteria have become increasingly resistant to a wider range of antibiotics. For this reason, doctors may need to try a few different types of antibioticsor even a combination of antibioticsto successfully treat the infection. Antibiotics are usually given for about one month, but may need to be given for an even longer period of time if the infection is resistant to treatment.

Once the fever and the worst of the symptoms have gone away, the patient may be able to continue antibiotic therapy at home. During this time, the patient should make regular visits to the health care team for further testing and physical examination to make sure that the antibiotic therapy is working, that it is not causing adverse side effects, and that there are no complications such as emboli or heart failure. The patient should alert the health-care team to any symptoms that could indicate serious complications: For instance, trouble breathing or swelling in the legs could indicate congestive heart failure. Headache, joint pain, blood in the urine, or stroke symptoms could indicate an embolus, and fever and chills could indicate that the treatment is not working and the infection is worsening. Finally, diarrhea, rash, itching, or joint pain may suggest a bad reaction to the antibiotics. Anyone experiencing any of these symptoms should alert the health care team immediately.

In some cases, surgery may be needed. These include cases of congestive heart failure, recurring emboli, infection that doesn't respond to treatment, poorly functioning heart valves, and endocarditis involving prosthetic (artificial) valves. The most common surgical treatment involves cutting away (debriding) damaged tissue and replacing the damaged valve.

KEY TERMS

Aortic valve The valve between the left ventricle of the heart and the aorta.

Bacteremia An infection caused by bacteria in the blood.

Congestive heart failure A condition in which the heart muscle cannot pump blood as efficiently as it should.

Echocardiography A diagnostic test using reflected sound waves to study the structure and motion of the heart muscle.

Embolus A bit of foreign material, such as gas, a piece of tissue, or tiny clot, that travels in the circulation until it becomes lodged in a blood vessel.

Endocardium The inner wall of the heart muscle, which also covers the heart valves.

Mitral valve The valve between the left atrium and the left ventricle of the heart.

Osler's nodes Small, raised, reddish, tender areas associated with endocarditis, commonly found inside the fingers or toes.

Petechiae Tiny purple or red spots on the skin associated with endocarditis, resulting from hemorrhages under the skin's surface.

Pulmonary valve The valve between the right ventricle of the heart and the pulmonary artery.

Transducer A device that converts electrical signals into ultrasound waves and ultrasound waves back into electrical impulses.

Transesophageal echocardiography A diagnostic test using an ultrasound device, passed into the esophagus of the patient, to create a clear image of the heart muscle.

Tricuspid valve The valve between the right atrium and the right ventricle of the heart.

Vegetation An abnormal growth of tissue around a valve, composed of blood platelets, bacteria, and a protein involved in clotting.

Prognosis

If left untreated, infective endocarditis continues to progress and is always fatal. However, if it is diagnosed and properly treated within the first six weeks of infection, the infection can be completely cured in about 90% of the cases. The prognosis depends on a number of factors, such as the patient's age and overall physical condition, the severity of the diseases involved, the exact site of the infection, how vulnerable the microorganisms are to antibiotics, and what kind of complications the endocarditis may be causing.

Prevention

Some people are especially prone to endocarditis. These include people with past episodes of endocarditis, those with congenital heart problems or heart damage from rheumatic fever, and those with artificial heart valves. Intravenous drug users are also at increased risk. Anyone who falls into a high-risk category should alert his or her health-care professionals before undergoing any surgical or dental procedures. High-risk patients must be treated in advance with antibiotics before these procedures to minimize the risk of infection.

Resources

BOOKS

Zaret, Barry L., et al., editors. The Patient's Guide to Medical Tests. Boston: Houghton Mifflin, 1997.

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.

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endocarditis

endocarditis (ĕn´dōkärdī´tĬs), bacterial or fungal infection of the endocardium (inner lining of the heart) that can be either acute or subacute. In the acute form the symptoms (fever, malaise, fatigue, weight loss, anemia) are directly related to the presence of an active infection that runs its course within a few weeks. Acute endocarditis may follow respiratory infection, surgery, or other trauma; but in some cases the source of infection is unknown. A major cause of endocarditis is the use of contaminated intravenous needles by drug addicts. Bacterial endocarditis is an insidious, often progressive, disease that can lead to kidney failure and congestive heart failure. The causative agent in many cases of subacute disease is Streptococcus viridans. Endocarditis is often a complication of Lyme disease. A previously damaged valve increases the risk of infection tenfold. The most common diseases causing these predisposing valvular deformities are rheumatic fever and congenital heart disease. Thrombi associated with the infection on the valve often dislodge and spread septic emboli throughout the body that may damage the kidney. Primary diagnostic symptoms are fever and a changing heart murmur. Physical diagnosis can be confirmed by the use of echocardiography (ultrasound). Treatment with high doses of antibiotics often kills the bacteria, but the damage to the valve may put an additional strain on the heart that can eventually lead to cardiac failure. However, it is sometimes possible through follow-up corrective surgery to repair or replace valves damaged by endocarditis.

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Endocarditis

Endocarditis

Who Is at Risk for Endocarditis?

What Causes Endocarditis?

What Happens to People with Endocarditis?

How Is Endocarditis Prevented?

Resources

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.

KEYWORDS

for searching the Internet and other reference sources

Antibiotic therapy

Bacteremia

Cardiovascular system

Circulatory system

Inflammation

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.

* 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.

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 bodys own defenses fight bacterial infections or doctors prescribe antibiotic medications to help rid the body of invading bacteria.

* 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.

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.

* 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:

  • fever
  • 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.

Diagnosis

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.

* heart murmur
is an extra sound heard during a heartbeat that is caused by turbulence in blood flow through the heart.

Treatment

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.

See also

Bacterial Infections

Heart Disease

Heart Murmur

Rheumatic Fever

Substance Abuse

Resources

The U.S. National Heart, Lung, and Blood Institute posts a fact sheet about endocarditis at its website. http://www.nhlbi.nih.gov/nhlbi/infcentr/topics/endocard.htm

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 website. Telephone 1-800-AHA-USA1 http://www.amhrt.org/Heart_and_Stroke_A_Z_Guide/bend.html

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endocarditis

endocarditis (en-doh-kar-dy-tis) n. inflammation of the endocardium and heart valves. It is most often due to rheumatic fever or bacterial infection (bacterial e.). The main features are fever, changing heart murmurs, heart failure, and embolism. See also subacute bacterial endocarditis.

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endocarditis

en·do·car·di·tis / ˌendōˌkärˈdītis/ • n. Med. inflammation of the endocardium. DERIVATIVES: en·do·car·dit·ic / -ˈditik/ adj.

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