Surgical & Heart Information

Acute or Subacute Bacterial Endocarditis is an infection of the heart's endocardium. The endocardium is the inner lining of the heart muscle, which also covers the heart valves. Bacterial Endocarditis can damage or even destroy your heart valves. The difference between acute and subacute bacterial endocarditis is acute bacterial endocarditis is a sudden onset, whereas subacute bacterial endocarditis is a gradual onset.

Acute endocarditis most often occurs when an aggressive species of skin bacteria, especially a staphylococcus (staph), enters the bloodstream and attacks a normal, undamaged heart valve. Once staph bacteria begin to multiply inside the heart, they may send small clumps of bacteria called septic emboli into the bloodstream to spread the infection to other organs, especially to the kidneys, lungs and brain. Intravenous (IV) drug users are at very high risk of acute endocarditis, because numerous needle punctures give aggressive staph bacteria many opportunities to enter the blood through broken skin. Dirty drug paraphernalia increases the risk. If untreated, this form of endocarditis can be fatal in less than six weeks.

Subacute endocarditis is caused by one of the viridans group of streptococci (Streptococcus sanguis, mutans, mitis or milleri) that normally live in the mouth and throat. Streptococcus bovis or Streptococcus equinus also can cause subacute endocarditis, typically in patients who have some form of gastrointestinal cancer, usually colon cancer. Subacute endocarditis tends to involve heart valves that already are damaged in some way, and it usually is less likely to cause septic emboli than acute endocarditis. If untreated, subacute bacterial endocarditis can worsen for as long as one year before it is fatal.

Acute or Subacute Bacterial Endocarditis occurs when bacteria in the bloodstream (bacteremia) lodge on abnormal heart valves or other damaged heart tissue. Certain bacteria normally live on parts of your body, such as the mouth and upper respiratory system, the intestinal and urinary tracts, and the skin. Some surgical and dental procedures cause a brief bacteremia. Bacteremia is common after many invasive procedures, but only certain bacteria commonly cause endocarditis.

Endocarditis rarely occurs in people with normal hearts. However, if you have certain preexisting heart conditions, you're at increased risk for endocarditis.
*Some of these conditions include having:

• an artificial (prosthetic) heart valve
• a history of previous endocarditis
• heart valves damaged (scarred) by conditions such as rheumatic fever
• various kinds of congenital heart defects
• hypertrophic cardiomyopathy (hi"per-TRO'fik kar"de-o-mi-OP'ah-the)
• people who have had a heart transplant who develop a heart valve abnormality

Some congenital heart defects, including a ventricular septal defect, an atrial septal defect, or a patent ductus arteriosus, can be successfully repaired surgically. After this you'll no longer be at increased risk for endocarditis.

Although endocarditis is a very serious disease, and many people may be at increased risk for developing it, most of these people do not contract it. According to the American Heart Association, there are about 29,000 cases of endocarditis diagnosed a year.

Endocarditis is much more likely to result from frequent exposure to random bacteremias associated with daily activities than from bacteremia caused by a dental, gastrointestinal (GI) tract, or genitourinary (GU) tract procedure. Prophylaxis may prevent an exceedingly small number of cases of endocarditis, if any, in individuals who undergo a dental, GI tract, or GU tract procedure.

The risk of antibiotic-associated adverse events exceeds the benefit, if any, from prophylactic antibiotic therapy. Maintenance of optimal oral health and hygiene may reduce the incidence of bacteremia from daily activities and is more important than prophylactic antibiotics for a dental procedure to reduce the risk of endocarditis.

Not all cases of endocarditis can be prevented, because we don't always know when a bacteremia occurs. In past years, the American Heart Association has recommended that patients at increased risk for endocarditis take prophylactic antibiotics before certain dental, GI and GU procedures. Recently, the American Heart Association’s Endocarditis Committee, together with national and international experts on endocarditis, extensively reviewed published studies in order to determine whether dental, GI or GU tract procedures are possible causes of endocarditis. These experts concluded that there is no conclusive evidence linking dental, GI or GU tract procedures with the development of endocarditis. They also concluded that endocarditis is much more likely to result from frequent exposure to random bacteremias associated with daily activities than from bacteremia caused by a dental, GI or GU tract procedure.

Therefore, the current practice of giving patients antibiotics prior to a dental procedure is no longer recommended EXCEPT for patients with the highest risk of adverse outcome resulting from endocarditis. Those people at highest risk include those with:

• Prosthetic cardiac valve or prosthetic material used for cardiac valve repair
• Previous endocarditis
• Congenital heart disease for these conditions:
  
  Unrepaired cyanotic congenital heart disease, including palliative shunts and conduits
  Completely repaired congenital heart defect with prosthetic material or device, whether placed by surgery or by catheter intervention, during the first six months after the procedure
  Repaired congenital heart disease with residual defects (persisting leaks or abnormal flow) at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endothelialization)
  
  
• Cardiac transplantation recipients who develop cardiac valve abnormalities