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 heart—two 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 backward—a 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 antibiotics—or even a combination of antibiotics—to 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〉.

Endocarditis

Definition

Endocarditis is an infection of the endocardium, the inner lining of the heart muscle and its four valves (tricuspid, pulmonary, mitral, and aortic). Abnormal or damaged endocardium is more likely to become infected when bacteria enter the bloodstream. When this happens, during surgical or dental procedures, for example, a condition called bacteremia results. The circulating bacteria can then enter the heart, where damaged tissue or other abnormalities allow them to multiply and cause an infection. Endocarditis is a life-threatening disease that interferes with the heart's ability to pump blood . Untreated, it is always fatal.

Description

Endocarditis most commonly occurs in people whose hearts have damaged valves. This may be the result of acquired valvular disease from rheumatic fever or other diseases. Patients with mitral valve prolapse, in which a poorly functioning mitral valve regurgitates blood back into the heart, allowing bacteria to multiply, are also at risk for endocarditis. Prosthetic (artificial) heart valves are more likely to become infected as well.

Bacteremia that causes endocarditis can occur in several ways:

• from a localized infection such as a urinary tract infection, pneumonia , skin infection, or dental infection
• as a result of certain medical conditions, such as severe periodontal disease, colon cancer , or inflammatory bowel disease
• during dental or surgical procedures, such as dental cleaning, tooth extractions, tonsil removal, or endoscopic examinations
• through in-dwelling catheters used for intravenous medications, intravenous feeding, or dialysis
• intravenous drug use using unsterilized, contaminated needles and syringes

The bacteria that cause most endocarditis are gram-positive cocci, such as Staphylococcus or Streptococcus. Staphylococcal endocarditis occurs most often among intravenous drug users and patients with in-dwelling venous catheters. Gram-negative bacterial endocarditis or fungal endocarditis is much less common; patients are usually intravenous drug users or those with prosthetic heart valves.

Endocarditis patients who appear critically ill are usually suffering from acute bacterial endocarditis, while those with subacute bacterial endocarditis have less severe but persistent symptoms such as weight loss, fatigue, and low-grade fever.

If not discovered and treated, endocarditis can permanently damage the heart valves. If a valve is damaged, it may allow blood to flow backward—a 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 congestive heart failure .

Another danger associated with endocarditis is that the overgrowth of bacteria colonizing heart valves may break off and form emboli that can become lodged in arteries. An embolism to an artery supplying the brain can cause a stroke; an embolus lodged in the blood vessels of the lungs may cause pneumonia.

Causes and symptoms

Most cases of infective endocarditis occur in patients 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. Other risk factors for endocarditis are congenital heart problems, heart surgery, past history of endocarditis, and intravenous drug use.

Patients with acute bacterial endocarditis are generally critically ill. Patients with subacute bacterial endocarditis tend to have a low-grade fever, which rarely rises above 102°F (38.9°C), chills, weakness, cough, difficulty breathing, headaches, arthralgias (aching joints), and loss of appetite, although these symptoms vary with individual patients.

Emboli may also cause a variety of symptoms, depending on their location. Emboli throughout the body may cause Osler's nodes, which are small, reddish, painful bumps most commonly found on the inside of fingers and toes. Emboli may also cause petechiae, which are 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 a stroke, with such symptoms as numbness, weakness, or paralysis on one side of the body or sudden blindness or double vision . Emboli may also damage the kidneys , causing nephritis. Sometimes the capillaries on the surface of the spleen rupture, causing it to become enlarged and tender. Patients with any of these symptoms require immediate medical attention.

Diagnosis

Clinicians diagnose endocarditis by taking a history and performing a physical examination , during which they may observe such signs as fever, an enlarged spleen, signs of kidney disease, or hemorrhaging. The clinician may also detect a heart murmur. A heart murmur may indicate abnormal flow of blood through one of the heart chambers or valves. Laboratory analysis of the patient's blood identifies the bacteria or other microorganisms that may be causing the infection.

The diagnostic workup also involves echocardiography to check for abnormalities in the structure of the heart wall or valves. Conventional echocardiography uses ultrasound to view the structures of the heart. This diagnostic procedure is transthoracic; the ultrasound transducer is placed on the chest wall.

One of the hallmarks of endocarditis that may be observed during echocardiography is vegetation, which is the abnormal growth of tissue, composed of blood platelets, bacteria, and a clotting protein called fibrin, that grows around a valve. Another indicator 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 performed or its results are inconclusive, a modified technique called transesophageal echocardiography is sometimes performed. This technique involves passing an ultrasound device into the esophagus to get a clearer image of the heart.

Treatment

When infective endocarditis is suspected, the patient is admitted to the hospital and antibiotic treatment is started before the results of the blood culture are available. The choice of antibiotics depends on which infecting microorganism is suspected. Once the results of the blood culture become available, the physician will prescribe specific antibiotics known to be effective against the specific microorganism involved.

Today the treatment of endocarditis is 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, a few different types of antibiotics—or even a combination of antibiotics—may be necessary to treat the infection successfully. Antibiotics are usually prescribed for about six weeks but may be given for an even longer period of time if the infection is resistant to treatment.

Once the fever and acute symptoms have resolved, most patients are able to continue antibiotic therapy at home. During this time, patients make regular visits to the health care team to ensure that the antibiotic therapy is working, that it is not causing adverse side effects, and that there are no complications such as emboli or congestive heart failure.

Patients must be advised to alert the health care team to any symptoms that could indicate serious complications. For instance, difficulty breathing or edema (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 an adverse reaction to the antibiotics. Patients experiencing any of these symptoms should be advised to seek immediate medical attention.

In some cases surgical intervention may be needed to treat congestive heart failure, recurring emboli, infection that does not respond to treatment, poorly functioning heart valves, and endocarditis involving prosthetic (artificial) valves. The most common surgical treatment involves debriding (cutting away) damaged tissue and replacing the damaged valve.

Prognosis

Untreated infective endocarditis progresses and is always fatal. However, when 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 the nature of the complications.

KEY TERMS

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

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 circulates in the bloodstream 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 that can develop following a bacteremia. Vegetation is composed of blood platelets, the infecting bacteria, a few white blood cells, and fibrin, a protein involved in clotting.

Health care team roles

Endocarditis is generally diagnosed by a primary care physician, emergency medicine physician, or cardiologist. Nurses, ECG technicians, laboratory technologists and other allied health professionals have important roles in the diagnosis of endocarditis as well as institution of timely treatment. Nurses and other practitioners involved in triage or screening in the emergency department, clinic, office, or other treatment setting must accurately assess patients with indications of endocarditis.

ECG technicians and laboratory technologists are responsible for performing the diagnostic tests, ECG, and blood cultures to confirm the diagnosis and causative microorganism. In the hospital, nurses and allied health professionals are responsible for closely monitoring patients for complications.

Prevention

Some individuals are especially prone to endocarditis. These include patients with past history of endocarditis, those with congenital heart problems or heart damage from rheumatic fever, and patients with prosthetic heart valves. Intravenous drug users are also at increased risk. Patients at high risk for endocarditis need to take a dose of prophylactic antibiotics before undergoing procedures likely to cause bacteria to enter the bloodstream, such as most dental procedures. The American Heart Association recommends two grams of amoxicillin (children: 50 mg/kg) taken by mouth one hour before dental appointments. Patients who are allergic to penicillin can take clindamycin, cephalexin, or azithromycin instead.

Resources

BOOKS

Ahya, Shubhada N., Kellie Flood, and Subramanian Paranjothi. The Washington Manual of Medical Therapeutics, 30th Edition. Philadelphia: Lippincott Williams & Wilkins, 2001.

Faculty Members of the Yale University School of Medicine. The Patient's Book of Medical Tests. Boston, New York: Houghton Mifflin Company, 1997.

ORGANIZATIONS

American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (214) 373-6300. <http://www.amhrt.org.>.

National Heart, Lung, and Blood Institute. Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. (301) 951-3260. <http://www.nhlbi.gov>.

OTHER

"Infective Endocarditis." The Merck Manual. <http://www.merck.com/pubs/mmanual/section16/chapter208/208a.htm>.

"Medical and Dental Perspectives on Infective Endocarditis: A Tale of Two Professions." <http://www.hsdm.med.harvard.edu/pages/srg/Seminars/endohtml.html#Anchor5>.

Barbara Wexler

Endocarditis

Definition

Endocarditis is an infection of the endocardium, the inner lining of the heart muscle and its four valves (tricuspid, pulmonary, mitral, and aortic). Abnormal or damaged endocardium is more likely to become infected when bacteria enter the bloodstream. When this happens, during surgical or dental procedures, for example, a condition called bacteremia results. The circulating bacteria can then enter the heart, where damaged tissue or other abnormalities allow them to multiply and cause an infection. Endocarditis is a life-threatening disease that interferes with the heart's ability to pump blood. Untreated, it is always fatal.

Description

Endocarditis most commonly occurs in people whose hearts have damaged valves. This may be the result of acquired valvular disease from rheumatic fever or other diseases. Patients with mitral valve prolapse, in which a poorly functioning mitral valve regurgitates blood back into the heart, allowing bacteria to multiply, are also at risk for endocarditis. Prosthetic (artificial) heart valves are more likely to become infected as well.

Bacteremia that causes endocarditis can occur in several ways:

• from a localized infection such as a urinary tract infection, pneumonia, skin infection, or dental infection

• as a result of certain medical conditions, such as severe periodontal disease, colon cancer, or inflammatory bowel disease
• during dental or surgical procedures, such as dental cleaning, tooth extractions, tonsil removal, or endoscopic examinations
• through in-dwelling catheters, used for intravenous medications, intravenous feeding, or dialysis
• intravenous drug use using unsterilized, contaminated needles and syringes

The bacteria that cause most endocarditis are gram-positive cocci, such as Staphylococcus or Streptococcus. Staphylococcal endocarditis occurs most often among intravenous drug users and patients with in-dwelling venous catheters. Gram-negative bacterial endocarditis or fungal endocarditis is much less common; patients are usually intravenous drug users or those with prosthetic heart valves.

Endocarditis patients who appear critically ill are usually suffering from acute bacterial endocarditis, while those with subacute bacterial endocarditis have less severe, but persistent symptoms such as weight loss, fatigue, and low-grade fever.

If not discovered and treated, endocarditis can permanently damage the heart valves. If a valve is damaged, it may allow blood to flow backward—a 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 congestive heart failure.

Another danger associated with endocarditis is that the overgrowth of bacteria colonizing heart valves may break off and form emboli that can become lodged in arteries. An embolism to an artery supplying the brain can cause a stroke; an embolus lodged in the blood vessels of the lungs may cause pneumonia.

Causes and symptoms

Most cases of infective endocarditis occur in patients 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. Other risk factors for endocarditis are congenital heart problems, heart surgery, past history of endocarditis, and intravenous drug use.

Patients with acute bacterial endocarditis are generally critically ill. Patients with subacute bacterial endocarditis tend to have a low-grad fever, which rarely rises above 102°F (38.9°C), chills, weakness, cough, difficulty breathing, headaches, arthralgias (aching joints), and loss of appetite, although these symptoms vary with individual patients.

Emboli may also cause a variety of symptoms, depending on their location. Emboli throughout the body may cause Osler's nodes, which are small, reddish, painful bumps most commonly found on the inside of fingers and toes. Emboli may also cause petechiae, which are 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 a stroke, with symptoms such as numbness, weakness, or paralysis on one side of the body or sudden blindness or double vision. Emboli may also damage the kidneys, causing nephritis. Sometimes the capillaries on the surface of the spleen rupture, causing it to become enlarged and tender. Patients with any of these symptoms require immediate medical attention.

Diagnosis

Clinicians diagnose endocarditis by taking a history, and performing a physical examination, during which they may observe signs such as fever, an enlarged spleen, signs of kidney disease, or hemorrhaging. The clinician may also detect a heart murmur. A heart murmur may indicate abnormal flow of blood through one of the heart chambers or valves. Laboratory analysis of the patient's blood identifies the bacteria or other microorganisms that may be causing the infection.

The diagnostic workup also involves echocardiography to check for abnormalities in the structure of the heart wall or valves. Conventional echocardiography uses ultrasound to view the structures of the heart. This diagnostic procedure is transthoracic; the ultrasound transducer is placed on the chest wall.

One of the hallmarks of endocarditis that may be observed during echocardiography is vegetation, which is the abnormal growth of tissue, composed of blood platelets, bacteria, and a clotting protein called fibrin, that grows around a valve. Another indicator 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 performed or its results are inconclusive, a modified technique called transesophageal echocardiography is sometimes performed. This technique involves passing an ultrasound device into the esophagus to get a clearer image of the heart.

Treatment

When infective endocarditis is suspected, the patient is admitted to the hospital and antibiotic treatment is started before the results of the blood culture are available. The choice of antibiotics depends on which infecting microorganism is suspected. Once the results of the blood culture become available, the physician will prescribe specific antibiotics known to be effective against the specific microorganism involved.

Today the treatment of endocarditis is 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, a few different types of antibiotics—or even a combination of antibiotics—may be necessary to treat the infection successfully. Antibiotics are usually prescribed for about six weeks but may be given for an even longer period of time if the infection is resistant to treatment.

Once the fever and acute symptoms have resolved, most patients are able to continue antibiotic therapy at home. During this time, patients make regular visits to the health care team to ensure that the antibiotic therapy is working, that it is not causing adverse side effects, and that there are no complications such as emboli or congestive heart failure.

Patients must be advised to alert the health care team to any symptoms that could indicate serious complications. For instance, difficulty breathing or edema (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 an adverse reaction to the antibiotics. Patients experiencing any of these symptoms should be advised to seek immediate medical attention.

In some cases surgical intervention may be needed to treat congestive heart failure, recurring emboli, infection that does not respond to treatment, poorly functioning heart valves, and endocarditis involving prosthetic (artificial) valves. The most common surgical treatment involves debriding (cutting away) damaged tissue and replacing the damaged valve.

Prognosis

Untreated infective endocarditis progresses and is always fatal. However, when 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 the nature of the complications.

Health care team roles

Endocarditis is generally diagnosed by a primary care physician, emergency medicine physician, or cardiologist. Nurses, ECG technicians, laboratory technologists and other allied health professionals have important roles in the diagnosis of endocarditis as well as institution of timely treatment. Nurses and other practitioners involved in triage or screening in the emergency department, clinic, office, or other treatment setting must accurately assess patients with indications of endocarditis.

ECG technicians and laboratory technologists are responsible for performing the diagnostic tests, ECG, and blood cultures to confirm the diagnosis and causative microorganism. In the hospital, nurses and allied health professionals are responsible for closely monitoring patients for complications.

KEY TERMS

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

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 circulates in the bloodstream 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 that can develop following a bacteremia. Vegetation is composed of blood platelets, the infecting bacteria, a few white blood cells, and fibrin, a protein involved in clotting.

Prevention

Some individuals are especially prone to endocarditis. These include patients with past history of endocarditis, those with congenital heart problems or heart damage from rheumatic fever, and patients with prosthetic heart valves. Intravenous drug users are also at increased risk. Patients at high risk for endocarditis need to take a dose of prophylactic antibiotics before undergoing procedures likely to cause bacteria to enter the bloodstream, such as most dental procedures. The American Heart Association recommends two grams of amoxicillin (children: 50 mg/kg) taken by mouth one hour before dental appointments. Patients who are allergic to penicillin can take clindamycin, cephalexin, or azithromycin instead.

Resources

BOOKS

Ahya, Shubhada N., Kellie Flood, and Subramanian Paranjothi. The Washington Manual of Medical Therapeutics, 30th Edition. Philadelphia: Lippincott Williams & Wilkins, 2001.

Faculty Members of the Yale University School of Medicine. The Patient's Book of Medical Tests. Boston, New York: Houghton Mifflin Company, 1997.

ORGANIZATIONS

American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (214) 373-6300. 〈http://www.amhrt.org〉.

National Heart, Lung, and Blood Institute. Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. (301) 951-3260. 〈http://www.nhlbi.gov〉.

OTHER

"Infective Endocarditis." The Merck Manual. 〈http://www.merck.com/pubs/mmanual/section16/chapter208/208a.htm〉.

"Medical and Dental Perspectives on Infective Endocarditis: A Tale of Two Professions." 〈http://www.hsdm.med.harvard.edu/pages/srg/Seminars/endohtml.html#Anchor5〉.

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

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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 body’s 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

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