Definition
The endocardium is a thin membrane that covers the inner surface of the heart. Bacterial endocarditis is an infection of this membrane. Infection occurs when bacteria attach to the membrane and grow.
The infection is most common when the heart or heart valves have already been damaged. It can be life-threatening, and it can permanently impair the heart valves. This can lead to serious health problems, such as congestive heart failure.
The infection can also cause growths on the valves or other areas of the heart. Pieces of these growths can break off and travel to other parts of the body. This can cause serious complications.
Causes
Bacteria can travel to the heart through the blood. They can enter the blood
from an infection elsewhere in the body. They can also enter through breaks in the
skin or mucous membranes caused by dental work, surgery, or IV (intravenous) drug
use. Only certain bacteria cause this infection, the most common of which are
streptococci, staphylococci, and enterococci.
The bacteria may then be able to attach to the endocardium. Some heart conditions can increase the chance of infections. These conditions may cause blood flow to be obstructed or to pool, providing a place for the bacteria to build up.
Risk Factors
The following conditions place a person at greater risk for bacterial endocarditis during certain procedures: heart valve scarring from rheumatic fever or other conditions; artificial heart valve; congenital heart defect; cardiomyopathy; prior episode of endocarditis; and mitral valve prolapse, with significant regurgitation (abnormal backflow of blood).
The foregoing conditions increase the risk of the infection with certain activities, including IV drug use (risk is extremely high when needles are shared); any dental procedure, even cleanings; removal of tonsils or adenoids, and other procedures involving the ears, nose, and throat; bronchoscopy (viewing the airways through a thin, lighted tube); and surgery on the gastrointestinal or urinary tracks, including the gallbladder and prostate.
Symptoms
Symptoms of bacterial endocarditis vary from mild to severe, depending on the bacteria causing the infection, the amount of bacteria in the bloodstream, the extent of structural heart defects, the body’s ability to fight infection, and overall health. The symptoms, which can begin within two weeks of the bacteria entering the bloodstream, include fever, chills, fatigue, weakness, malaise, unexplained weight loss, poor appetite, muscle aches, joint pain, coughing, shortness of breath, bumps on the fingers and toes, and little red dots on the skin, inside the mouth, or under the nails. The first symptom may be caused by a piece of the infected heart growth breaking off.
Screening and Diagnosis
A doctor will ask about symptoms and medical history and will perform a
physical exam, which includes listening to the patient’s heart for a murmur. Tests
may include blood cultures to check for the presence of bacteria; blood tests to
look for signs of infections and complications related to endocarditis; a
computed
tomography (CT) scan (a detailed X-ray picture that
identifies abnormalities of fine tissue structure); an electrocardiogram (ECG or
EKG), which is a test that records the heart’s activity by
measuring electrical currents through the heart muscle; an echocardiogram, which is a test that uses high-frequency
sound waves (ultrasound) to examine the size, shape, and motion of the heart; and
a transesophageal echocardiogram, in which ultrasound is passed through the
patient’s mouth and then into the esophagus to better visualize the heart
valves.
Treatment and Therapy
Treatment, including medications and possible surgery, focuses on getting rid
of the infection from the blood and heart. Antibiotics
are given through an IV into a vein. The patient must be admitted to the hospital
for this treatment, which could take four to six weeks to complete. If the
antibiotics fail to remove the bacteria, or if the infection returns, surgery may
be needed. Surgery may also be necessary if the infection has damaged the heart or
valves.
Prevention and Outcomes
The best way to prevent endocarditis is to avoid the use of illegal IV drugs.
Certain heart conditions may increase the risk, too. To find out if the patient is
at increased risk for this condition, the doctor should be consulted.
The American Heart Association (AHA) recommends that people with high and moderate risk should take antibiotics before and after certain dental and nondental medical procedures. In addition, the AHA recommends taking an antibiotic just before and after any procedure that may put a person at risk.
The patient should tell his or her dentist and other health professionals about the heart condition. Other preventive measures include maintaining good oral hygiene, brushing teeth twice daily, flossing daily, visiting a dentist for a cleaning at least every six months, and seeing a dentist if dentures cause discomfort. Finally, people should seek medical care immediately for symptoms of an infection.
Bibliography
Bonow, R. O., et al. “ACC/AHA 2006 Guidelines for the Management of Patients with Valvular Heart Disease.” Journal of the American College of Cardiology 48 (2006).
Durack, David T., and Michael H. Crawford, eds. Infective Endocarditis. Philadelphia: W. B. Saunders, 2003.
Fauci, Anthony, et al., eds. Harrison’s Principles of InternalMedicine. 17th ed. New York: McGraw-Hill, 2008.
Giessel, Barton E., Clint J. Koenig, and Robert L. Blake, Jr. “Information from Your Family Doctor: Bacterial Endocarditis, a Heart at Risk.” American Family Physician 61, no. 6 (March 15, 2000): 1705.
Hoen, B. “Epidemiology and Antibiotic Treatment of Infective Endocarditis: An Update.” Heart 92 (2006): 1694-1700.
Rakel, Robert E., Edward T. Bope, and Rick D. Kellerman, eds. Conn’s Current Therapy 2011. Philadelphia: Saunders/Elsevier, 2010.
Zipes, Douglas P., et al., eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia: Saunders/Elsevier, 2008.
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