For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/endo/

What Causes Endocarditis?

Infective endocarditis (IE) occurs if bacteria, fungi, or other germs invade your bloodstream and attach to abnormal areas of your heart. Certain factors increase the risk of this happening.

A common underlying factor in IE is a structural heart defect, especially faulty heart valves. Usually your immune system will kill germs in your bloodstream. However, if your heart has a rough lining or abnormal valves, the invading germs can attach and multiply in the heart.

Other factors also can play a role in causing IE. Common activities, such as brushing your teeth or having certain dental procedures, can allow bacteria to enter your bloodstream. This is even more likely to happen if your teeth and gums are in poor condition.

Having a catheter (tube) or another medical device inserted through your skin, especially for long periods, also can allow bacteria to enter your bloodstream. People who use intravenous (IV) drugs also are at risk for IE because of the germs on needles and syringes.

Bacteria also may spread to the blood and heart from infections in other parts of the body, such as the gut, skin, or genitals.

Endocarditis Complications

As the bacteria or other germs multiply in your heart, they form clumps with other cells and matter found in the blood. These clumps are called vegetations (vej-eh-TA-shuns).

As IE worsens, pieces of the vegetations can break off and travel to almost any other organ or tissue in the body. There, the pieces can block blood flow or cause a new infection. As a result, IE can cause a range of complications.

Heart Complications

Heart problems are the most common complication of IE. They occur in one-third to one-half of all people who have the infection. These problems may include a new heart murmur, heart failure, heart valve damage, heart block, or, rarely, a heart attack.

Central Nervous System Complications

These complications occur in as many as 20 to 40 percent of people who have IE. Central nervous system complications most often occur when bits of the vegetation, called emboli (EM-bo-li), break away and lodge in the brain.

The emboli can cause local infections called brain abscesses. Or, they can cause a more widespread brain infection called meningitis (men-in-JI-tis).

Emboli also can cause strokes or seizures. This happens if they block blood vessels or affect the brain's electrical signals. These complications can cause long-term damage to the brain and may even be fatal.

Complications in Other Organs

IE also can affect other organs in the body, such as the lungs, kidneys, and spleen.

Lungs. The lungs are especially at risk when IE affects the right side of the heart. This is called right-sided infective endocarditis.

A vegetation or blood clot going to the lungs can cause a pulmonary embolism (PE) and lung damage. A PE is a sudden blockage in a lung artery.

Other lung complications include pneumonia and a buildup of fluid or pus around the lungs.

Kidneys. IE can cause kidney abscesses and kidney damage. The infection also can inflame the internal filtering structures of the kidneys.

Signs and symptoms of kidney complications include back or side pain, blood in the urine, or a change in the color or amount of urine. In some cases, IE can cause kidney failure.

Spleen. The spleen is an organ located in the left upper part of the abdomen near the stomach. In some people who have IE, the spleen enlarges (especially in people who have long-term IE). Sometimes emboli also can damage the spleen.

Signs and symptoms of spleen problems include pain or discomfort in the upper left abdomen and/or left shoulder, a feeling of fullness or the inability to eat large meals, and hiccups.

Who Is At Risk for Endocarditis?

Infective endocarditis (IE) is an uncommon condition that can affect both children and adults. It's more common in men than women.

IE typically affects people who have abnormal hearts or other conditions that put them at risk for the infection. Sometimes IE does affect people who were healthy before the infection.

Major Risk Factors

The germs that cause IE tend to attach and multiply on damaged, malformed, or artificial (man-made) heart valves and implanted medical devices. Certain conditions put you at higher risk for IE. These include:

• Congenital heart defects (defects that are present at birth). Examples include a malformed heart or abnormal heart valves.
• Artificial heart valves, an implanted medical device in the heart (such as a pacemaker wire), or an intravenous (IV) catheter (tube) in a blood vessel for a long time.
• Heart valves damaged by rheumatic fever or calcium deposits that cause age-related valve thickening. Scars in the heart from a previous case of IE also can damage heart valves.
• IV drug use, especially if needles are shared or reused, contaminated substances are injected, or the skin isn't properly cleaned before injection.

What Are the Signs and Symptoms of Endocarditis?

Infective endocarditis (IE) can cause a range of signs and symptoms that can vary from person to person. Signs and symptoms also can vary over time in the same person.

Signs and symptoms differ depending on whether you have an underlying heart problem, the type of germ causing the infection, and whether you have acute or subacute IE.

Signs and symptoms of IE may include:

• Flu-like symptoms, such as fever, chills, fatigue (tiredness), aching muscles and joints, night sweats, and headaches.
• Shortness of breath or a cough that won't go away.
• A new heart murmur or a change in an existing heart murmur.
• Skin changes such as:
  • Overall paleness.
  • Small, painful, red or purplish bumps under the skin on the fingers or toes.
  • Small, dark, painless flat spots on the palms of the hands or the soles of the feet.
  • Tiny spots under the fingernails, on the whites of the eyes, on the roof of the mouth and inside of the cheeks, or on the chest. These spots are from broken blood vessels.
• Nausea (feeling sick to your stomach), vomiting, a decrease in appetite, a sense of fullness with discomfort on the upper left side of the abdomen, or weight loss with or without a change in appetite.
• Blood in the urine.
• Swelling in the feet, legs, or abdomen.

How Is Endocarditis Diagnosed?

Your doctor will diagnose infective endocarditis (IE) based on your risk factors, your medical history and signs and symptoms, and test results.

Diagnosis of IE often is based on many factors, rather than a single positive test result, sign, or symptom.

Diagnostic Tests

Blood Tests

Blood cultures are the most important blood tests used to diagnose IE. Blood is drawn several times over a 24-hour period. It's put in special culture bottles that allow bacteria to grow.

Doctors then identify and test the bacteria to see which antibiotics will kill them. Sometimes the blood cultures don't grow any bacteria, even if a person has IE. This is called culture-negative endocarditis, and it requires antibiotic treatment.

Other blood tests also are used to diagnose IE. For example, a complete blood count may be used to check the number of red and white blood cells in your blood. Blood tests also may be used to check your immune system and to check for inflammation.

Echocardiography

Echocardiography (echo) is a painless test that uses sound waves to create pictures of your heart. Two types of echo are useful in diagnosing IE.

Transthoracic (tranz-thor-AS-ik) echo. For this painless test, gel is applied to the skin on your chest. A device called a transducer is moved around on the outside of your chest.

This device sends sound waves called ultrasound through your chest. As the ultrasound waves bounce off your heart, a computer converts them into pictures on a screen.

Your doctor uses the pictures to look for vegetations, areas of infected tissue (such as an abscess), and signs of heart damage.

Because the sound waves have to pass through skin, muscle, tissue, bone, and lungs, the pictures may not have enough detail. Thus, your doctor may recommend transesophageal (tranz-ih-sof-uh-JEE-ul) echo (TEE).

Transesophageal echo. For TEE, a much smaller transducer is attached to the end of a long, narrow, flexible tube. The tube is passed down your throat. Before the procedure, you're given medicine to help you relax, and your throat is sprayed with numbing medicine.

The doctor then passes the transducer down your esophagus (the passage from your mouth to your stomach). Because this passage is right behind the heart, the transducer can get detailed pictures of the heart's structures.

EKG

An EKG is a simple, painless test that detects your heart's electrical activity. The test shows how fast your heart is beating, whether your heart rhythm is steady or irregular, and the strength and timing of electrical signals as they pass through your heart.

An EKG typically isn't used to diagnose IE. However, it may be done to see whether IE is affecting your heart's electrical activity.

For this test, soft, sticky patches called electrodes are attached to your chest, arms, and legs. You lie still while the electrodes detect your heart's electrical signals. A machine records these signals on graph paper or shows them on a computer screen. The entire test usually takes about 10 minutes.

How Is Endocarditis Treated?

Infective endocarditis (IE) is treated with antibiotics and sometimes with heart surgery.

Antibiotics

Antibiotics usually are given for 2 to 6 weeks through an intravenous (IV) line inserted into a vein. You're often in a hospital for at least the first week or more of treatment. This allows your doctor to make sure the medicine is helping.

If you're allowed to go home before the treatment is done, the antibiotics are almost always continued by vein at home. You'll need special care if you get IV antibiotic treatment at home. Before you leave the hospital, your medical team will arrange for you to receive home-based care so you can continue your treatment.

You also will need close medical followup, usually by a team of doctors. This team often includes a doctor who specializes in infectious diseases, a cardiologist (heart specialist), and a heart surgeon.

Surgery

Sometimes surgery is needed to repair or replace a damaged heart valve or to help clear up IE. For example, IE caused by fungi often requires surgery. This is because this type of IE is harder to treat than IE caused by bacteria.

How Can Endocarditis Be Prevented?

If you're at risk for infective endocarditis (IE), you can take steps to prevent the infection and its complications.

• Be alert to the signs and symptoms of IE. Contact your doctor right away if you have any of these signs or symptoms, especially a persistent fever or unexplained fatigue (tiredness).
• Brush and floss your teeth regularly, and have regular dental checkups. Germs from a gum infection can enter your bloodstream.
• Avoid body piercing, tattoos, and other procedures that may allow germs to enter your bloodstream.

Research shows that not everyone at risk for IE needs to take antibiotics before routine dental exams and certain other dental and medical procedures.

Let your health care providers, including your dentist, know if you're at risk for IE. They can tell you whether you need antibiotics before exams and procedures.

Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. Often, these advances depend on the willingness of volunteers to take part in clinical trials.

Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions. For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to infective endocarditis, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

• http://clinicalresearch.nih.gov
• www.clinicaltrials.gov
• www.nhlbi.nih.gov/studies/index.htm
• www.researchmatch.org

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.

Links to Other Information About Endocarditis

NHLBI Resources

• Congenital Heart Defects (Health Topics)
• Heart Surgery (Health Topics)
• Heart Valve Disease (Health Topics)

Non-NHLBI Resources

• Endocarditis (MedlinePlus)

Clinical Trials

• Children and Clinical Studies
• Clinical Trials (Health Topics)
• Current Research (ClinicalTrials.gov)
• NHLBI Clinical Trials
• NIH Clinical Research Trials and You (National Institutes of Health)
• ResearchMatch (funded by the National Institutes of Health)