What is infective endocarditis?

Infective endocarditis (IE) [also called bacterial endocarditis (BE), or subacute bacterial endocarditis (SBE) ] occurs when germs (especially bacteria) enter the bloodstream and attack the lining of the heart valves. Infective endocarditis causes growths or holes on the valve or scarring of the valve tissue, most often resulting in a leaky heart valve. Without treatment, endocarditis is a fatal disease.

Bacteria get into the bloodstream regularly when eating, during teeth brushing and when passing stools. Normal heart valves are very resistant to infection, but diseased valves have defects on the surface where bacteria may attach. The bacteria rapidly form colonies, grow vegetations and produce enzymes, destroying the surrounding tissue and opening the path for invasion. Dental procedures (particularly tooth extractions) and endoscopic examinations are associated with bacteria in the blood, so prophylactic (preventative) antibiotics are advised for patients with valve disease. Intravenous drug abusers are at high risk for developing IE. Learn more about endocarditis.

In many cases of endocarditis, antibiotics alone can cure the infection. However, in about 25-30 percent of patients with IE, surgery is needed during the early acute phase of infection due to severe valve leakage or failure to control the infection with antibiotics. Another 20-40 percent of patients will require surgery later. Patients who have had a prior valve replacement, and have an infected prosthetic valve (prosthetic valve endocarditis or PVE), are more likely to need surgery than those with their original valves (native valve endocarditis).

The timing of surgery, the type of surgery, and the antibiotics used to treat the endocarditis are based on several issues:

  • The diagnosis of IE
  • The microorganisms involved and their presence in the blood or tissues of the valve
  • The location of the IE and the extent of heart and valve damage
  • Presence of complications, such as heart failure, sepsis, emboli (blood clots or stroke), and other organ involvement
  • History of previous IE

Evaluation of infective endocarditis includes:

  • Evaluation of symptoms
  • Blood cultures - blood tests for microorganisms
  • Echocardiogram

Patients who require surgery more urgently include those with:

  • Moderate to severe or progressive heart failure due to valve regurgitation (leaky heart valve), caused by the infection
  • Vegetation or blood clots blocking the valve
  • Abscesses or an aneurysm around the aortic valve. This occurs more often with IE of the aortic valve and PVE and can be difficult to diagnosis.
  • Emboli (blood clots or stroke), that continue to occur, even after antibiotic therapy. Some patients have large attached, but mobile vegetations (growths), likely to break loose from the valve.
  • Certain fungal infections with extensive valve damage
  • An unstable prosthetic valve

Other patients who may require surgical treatment for IE include patients with:

  • Infective endocarditis, persistent fever, and other signs of uncontrolled infection, even after adequate antibiotic therapy has been given
  • An infection on a new prosthetic valve, supported by positive blood cultures and an echocardiogram showing vegetation on the valve
  • Certain types of difficult to treat bacteria such as non-candida fungal endocarditis or pseudomonas infection
  • Very large vegetations, or growths on the valve leaflets and risk of embolism

These patients should be evaluated by the surgeon. After the surgeon reviews the particular risk factors and extent of infection, an individualized decision is made on how and when to proceed with surgery.

Along with the type of microorganism, complications related to IE, and the extent of valve damage, the surgeon also looks at other factors when determining if and when to have surgery and the risks involved. These include transient ischemic events or stroke, the age of the patient, and intravenous drug abuse.

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