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21st World Congress of the World Society of Cardio-Thoracic Surgeons


Anyone with a structural abnormality of the heart is susceptible to developing an invasive infection of the heart valves called Subacute Bacterial Endocarditis or SBE Whenever the normal flow patterns of blood within the heart chambers are altered in anyway areas of both turbulence and stasis may result. Bacteria which transiently enter the blood stream tend to adhere to the heart structures near these areas of abnormal blood flow. This causes a serious infection of the heart valves which can be deadly. Once established, endocarditis can cause many dangerous complications, including stroke, multiple abscesses throughout the body, destruction of the heart valve tissue with severe congestive heart failure, kidney failure, and death. Endocarditis is notoriously hard to cure, even with antibiotics. Prevention is the most effect way to reduce a patients risk of serious consequences from heart valve infection.

It has been shown that pre-treatment with antibiotics in patients at risk can prevent this infection from taking hold. Pretreatment is called antibiotic prophylaxis and there are now standard drug regimens recommended for persons at increased risk. The guidelines for antibiotic prophylaxis have been formulated and endorsed by The American Heart Association and The American Dental Association.

Patients at risk for developing endoarditis include (but are not limited to) those with:

  • Implanted heart valves (mechanical or tissue) as a replacement for their own heart valve
  • Abnormal native heart valves (leakage, blockage)
  • Any congenital heart defect (VSD, ASD, PDA, complex anomaly)
  • Dacron or Teflon vascular grafts or patches over cardiac defects.
  • Mitral Valve Prolapse - only if there is significant valve leakage.
  • Pacemakers

Patients with newly replaced heart valves are at high risk for SBE. For this reason, the patients are usually counseled to avoid elective dentistry for 3 months following a new heart valve implant. This allows time for the body to layer the new valve with some native healing tissue. Even after this initial healing phase, the patient with a replacement heart valve continues to have a lower, but definitely significant, risk of endocarditis throughout their remaining lifespan.

Any procedure on the human being which causes bacteria to transiently enter the blood stream can cause SBE in a susceptible patient. The most likely procedure to cause SBE is dental work, even cleaning of the teeth by the technologist. Dental procedures frequently cause transient bacteremia (where bacteria from the mouth to enter the bloodstream briefly). If the patient also has a structurally abnormal heart valve or abnormal chamber flow patterns (like those seen in congenital heart defects), the bacteria are prone to take up residence on the heart valves and cause endocarditis. Other procedures such as manipulation of urinary tract, bowel, or gall bladder can also transiently release bacteria into the blood stream. Although elective surgery is not known for bacterial invasion of the blood stream, it is probably wise to follow the recommendations below if you have any heart murmurs or implanted cardiovascular devices. After the completion of the invasive procedure, the risk of SBE falls back down to baseline. For this reason patients with coronary artery disease who receive bypass surgery with coronary vein or mammary artery bypass grafts are not included in this group and do not need any coverage.

Current standard guidelines for antibiotic prophylaxis of SBE are published by The American Heart Association and are reviewed in the sections below.

Disclaimers

  • Antibiotic regimens used to prevent recurrences of acute rheumatic fever are inadequate for the prevention of bacterial endocarditis.
  • In patients with markedly compromised renal function, it may be necessary to modify or omit the second dose of gentamicin or vancomycin.
  • Intramuscular injections may be contraindicated in patients receiving anticoagulants.


Dental/Oral/Upper Respiratory Tract Procedures

I. Standard Regimen in Patients at Risk (including those with prosthetic heart valves and other high risk patients):

  • For Penicillin/Ampicillin/Amoxicillin allergic patients:

    Erythromycin ethylsuccinate 800 mg or erythromycin stearate 1.0 gm orally 2 hours before a procedure, then one-half the original dose 6 hours after the initial administration...OR...

    Clindamycin 300 mg orally 1 hour before a procedure and 150 mg 6 hours after the initial dose.

  • For Non-Allergic patients:

    Amoxicillin 3.0 gm orally one hour before procedure, then 1.5 gm six hours after initial dose.

II. Alternate Prophylactic Regimens in Patients at Risk

  • For Patients who cannot take oral medications

    • For Penicillin/Ampicillin/Amoxicillin allergic patients:

      Clindamycin 300 mg IV 30 minutes before a procedure and 150 mg IV (or orally) 6 hours after the initial dose.

    • For Non-Allergic patients:

      Ampicillin 2.0 gm IV (or IM) 30 minutes before a procedure, then ampicillin 1.0 gm IV (or IM) OR amoxicillin 1.5 gm orally 6 hours after the initial dose.
  • For high risk patients who are not candidates for the standard regimen:

    • For Penicillin/Ampicillin/Amoxicillin allergic patients:

      Vancomycin 1.0 gm IV administered over 1 hour, starting one hour before the procedure. No repeat dose is necessary.

    • For Non-Allergic patients:

      Ampicillin 2.0 gm IV (or IM) plus gentamicin 1.5 mg/kg IV (or IM) (not to exceed 80 mg) 30 minutes before the procedure, followed by amoxicillin 1.5 gm orally 6 hours after the initial dose. Alternatively, the parenteral regimen my be repeated 8 hours after the initial dose.


Genitourinary Procedures

I. Standard Regimen:

  • For Penicillin/Ampicillin/Amoxicillin allergic patients:

    Vancomycin 1.0 gm IV administered over 1 hour plus gentamicin 1.5 mg/kg IV (or IM) (not to exceed 80 mg) one hour before the procedure. May be repeated once 8 hours after the initial dose.
  • For Non-Allergic patients:
    Ampicillin 2.0 gm IV (or IM) plus gentamicin 1.5 mg/kg IV (or IM) (not to exceed 80 mg) 30 minutes before the procedure, followed by amoxicillin 1.5 gm orally 6 hours after the initial dose. Alternatively, the parenteral regimen may be repeated once 8 hours after the initial dose.

II. Alternative oral regimen for low risk patients:

  • For Non-Allergic patients:

    Amoxicillin 3.0 gm orally one hour before the procedure, then 1.5 gm 6 hours after the initial dose.


Pediatric Drug Doses

  • For Children, the doses are:

    • Amoxicillin: 50 mg/kg initial then 25 mg/kg subsequently
    • Ampicillin 50 mg/kg initially then 25 mg/kg subsequently
    • Clindamycin: 10mg/kg initially and 5 mg/kg subsequently
    • Erythromycin ethylsuccinate and stearate: 20 mg/kg initially then 10 mg/kg subsequently
    • Gentamicin 2.0 mg/kg initially then 1.0 mg/kg subsequently
    • Vancomycin 20 mg/kg initially and 10 mg/kg subsequently

    • The following weight ranges may also be used for the initial pediatric dose of Amoxicillin

      • <15 kg (33 lbs) ... 750 mg of Amoxicillin orally
      • 15-30 kg (33-66 lbs) ... 1.5 gm of Amoxicillin orally
      • >30 kg (66 lbs) ... 3.0 gms (full adult dose)


    Adapted from Prevention of Bacterial Endocarditis: Recommendations by the American Heart Association by the Committee of Rheumatic Fever, Endocarditis, and Kawasaki Disease. JAMA 1990; 264:2919-2922. Please refer to these joint American Heart Association - American Dental Association recommendations for more complete information as to which patients and which procedures require prophylaxis.

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