What You Should Know
What does infective endocarditis look like?
When endocarditis occurs, masses called vegetations form at the site of infection whether on a heart valve, other heart structures, or implanted devices. When vegetations are viewed under a microscope, one sees the microorganism causing the infection embedded in a meshwork of fibrin and other cellular material similar to that used by the body to form blood clots. Cells that the body uses to fight infection are uncommon, a finding which explains the need to use antibiotics over many weeks to kill the infecting organism.
Who gets endocarditis?
Endocarditis occurs when bacteria enter the bloodstream (bacteremia) and attach to a damaged portion of the inner lining of the heart or abnormal heart valves. Not all bacteria entering the bloodstream are capable of causing endocarditis. Only those bacteria that are able to stick to the surface lining the heart and abnormal valves tend to cause endocarditis.
Endocarditis most often occurs in people with preexisting heart disease (which may or may not be known by patients or their physicians) and less commonly in people with normal hearts.
Preexisting heart conditions associated with endocarditis include:
- Previous cardiac valve surgery
- Previous infective endocarditis
- Mitral valve prolapse
- Abnormal valves due to rheumatic fever
- Certain congenital heart diseases
Some congenital heart defects (e.g. ventricular septal defect, atrial septal defect, or patent ductus arteriosus) can be repaired surgically and, once repaired, are not associated with an increase in the risk of subsequent endocarditis.
How does bacteremia occur?
Bacteremia occurs as part of our daily living when bacteria normally living on the skin, the lining of the mouth, or the lining of the intestinal tract enter the bloodstream through small cuts, abrasions or breakdowns. Bacteria can enter the bloodstream as a result of minor trauma during typical daily activities such as brushing teeth or chewing. Thus the mouth is a common daily source of bacteremia and good oral hygiene appears to lower the risk for the development of bacteremia and subsequent endocarditis.
Certain invasive medical procedures are also known to cause bacteremia, particularly if they injure sites where bacteria are normally found. For people with heart conditions associated with endocarditis undergoing some of these procedures, it has been recommended that antibiotics be given before the procedure to limit or prevent bacteremia and protect against endocarditis. However, as discussed below, there is controversy about the value of this common practice.
These procedures include:
- Dental procedures likely to cause significant bleeding, including professional teeth cleaning
- Tonsillectomy or adenoidectomy
- Certain types of surgery on the respiratory passageways, the gastrointestinal tract or the urinary tract
- Surgery on infected tissues or structures
What symptoms should lead to evaluation?
The presenting signs and symptoms of infective endocarditis are highly variable and the severity of illness ranges from mild to severe. The presenting features may be highly suggestive of the diagnosis, but in many the illness is non-specific. In almost all, fever is found. Other findings include loss of appetite, unexplained weight loss, new rashes (both painful and painless), headache, backache, joint pain, confusion, shortness of breath, or sudden weakness in the face or limbs suggestive of a stroke.
Once seen by a doctor, a new heart murmur may be heard, and new skin, fingernail, or eye changes noted. The combination of certain symptoms with particular findings on physical examination will prompt the treating physician to consider endocarditis as the source of the problem. The next steps will be to draw blood for culture and to perform an echocardiogram to evaluate the heart.
What can happen to patients with endocarditis?
Untreated, most patients with infective endocarditis will die. The infection can lead to damage of the heart valve(s) that in turn causes severe leaking (regurgitation) of blood back through the valve(s) and an inability of the heart to efficiently pump blood to the body. This may lead to congestive heart failure and causes symptoms such as shortness of breath or swelling of the ankles. In addition, small pieces of the vegetation can break off and travel through the blood vessels to other parts of the body. These pieces, called "emboli" can cause damage to organs such as the brain (a stroke), eyes, lungs, kidneys, spleen, liver, and intestines. Endocarditis can also cause heart rhythm changes that may require a pacemaker for correction.
How is endocarditis treated?
Treatment of endocarditis requires antimicrobial therapy, sometimes for two, but often for 4-6 weeks. In some, surgery is required to remove the infection from the heart, to correct pre-existing heart disease, or to repair the heart or valve damage caused by the infection. To accomplish these goals, replacement of an infected heart valve with an artificial valve may be needed. The common reasons for cardiac surgery during endocarditis include:
- Heart failure
- Uncontrolled infection
- Significant valve dysfunction
- Artificial valve infection
- Extension of the infection into the heart (abscess formation)
- Recurrent emboli
Can endocarditis be prevented?
Since infective endocarditis can have serious consequences it is important to try and prevent the development of the disease, if possible. A recent study has shown that people with good oral hygiene, including daily flossing, may be less likely to develop endocarditis.
Doctors have also used antibiotics to prevent this disease. Many organizations have published guidelines on the use of antibiotics for this purpose (prevention or prophylaxis). These guidelines target patients with a known heart abnormality that is subject to infection who are having a medical procedure associated with bacteremia from organisms that commonly cause endocarditis. In the United States, the American Heart Association guidelines, last published in 1997, are widely followed. The scientific rationale for this practice can be found in the guidelines. Unfortunately, there are no studies in humans proving that antibiotic prophylaxis prevents endocarditis nor are such studies likely to be performed.
Prophylaxis for the prevention of endocarditis, however, has become more controversial because recently published studies provide evidence that questions the benefit of this practice. Moreover, there is a concern that widespread use of antibiotics for this purpose might contribute to promoting antibiotic resistance, an important issue today, as well as needlessly expose patients to antibiotic side effects such as allergic reactions.
It is important to recognize that even if antibiotics effectively prevented infective endocarditis and were used according to current guidelines, only a small percentage of cases could be prevented. This is because most people with endocarditis have not had an invasive procedure for which antibiotics could have been given; some have unrecognized heart disease and would not have been recognized as candidates for antibiotic prophylaxis; and occasionally patients are infected with organisms not treated by the antibiotics recommended for use.
The medical and dental communities await future publication of newly revised guidelines that consider the issues outlined above.
Despite these concerns, it is important for patients to talk to their physicians, dentists, and other health care providers, if there is a concern for the development of infective endocarditis. These professionals can work with patients to assess individual risk and develop an appropriate management plan. Nothing is better than close communication between patients and providers.
Endocarditis is a serious disease. Good oral hygiene, including daily flossing, is an important preventative measure that all patients should employ. If you have a history of structural heart disease or believe that you are at risk for the development of endocarditis, you should discuss this with your primary care physician. In addition, it is important to discuss this potential risk with your dentist or other health care providers that may be performing invasive procedures.