Massimo Fioranelli
 
 
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Prevention of infective endocarditis
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INTRODUCTION Many people are told that they need to take an antibiotic before having a dental, surgical, or other invasive medical procedure. Certain procedures, such as a root canal or tooth extraction, may allow bacteria from the mouth to enter the bloodstream. These bacteria can infect the heart valves and lining of the heart, causing them to become inflamed. This inflammation is called infective endocarditis. Infective endocarditis has the potential to cause catastrophic medical problems, including heart failure and leakage of the heart valves. When taken before a procedure, antibiotics may prevent bacteria from being released into the bloodstream. This is known as antibiotic prophylaxis.

INFECTIVE ENDOCARDITIS Infective endocarditis (IE) is an infection of the lining of heart chambers or valves with bacteria, fungi, or other organisms that are released into the bloodstream. IE occurs most commonly in people who have abnormal heart valves or had previous heart surgery; less commonly, it can occur in otherwise healthy people who have do not have heart disease. Infective endocarditis may develop following a sequence of events: Bacteria circulate in the bloodstream and become lodged in the blood clot on the lining or valves of the heart. The bacteria grow, forming an abnormal structure (called a vegetation) on the heart valves or lining. IE can develop in a small percentage of people who undergo dental or other procedures. Antibiotics are commonly given to people who are at high risk of developing IE to reduce the likelihood of developing the infection. However, studies of antibiotics to prevent infective endocarditis have shown mixed results. Some studies show that antibiotics can help to prevent IE while others show no benefit. Guidelines for antibiotic prophylaxis The American Heart Association has issued recommendations for who should receive antibiotics to prevent IE. These recommendations are based upon a review of studies peformed between 1950 and 2006, which included hundreds of thousands of patients. Analysis of these data showed that there was no benefit of using preventive antibiotics, except in the highest risk patient.

Highest risk People with the following conditions are considered to be at the highest risk of developing infectious endocarditis. Antibiotic prophylaxis is generally recommended before certain procedures for people with the following conditions: Mechanical prosthetic heart valves Natural prosthetic heart valves obtained from animals or cadavers A prior history of infective endocarditis Most congenital (from birth) heart abnormalities such as single ventricle states, transposition of the great arteries, and tetralogy of Fallot, even if the abnormality has been repaired

Moderate risk People with the following conditions are considered to be at moderate risk of developing infective endocarditis. Antibiotic prophylaxis is NOT generally recommended for people with moderate risk conditions. This is an important change from prior recommendations . Valve repair surgery Hypertrophic cardiomyopathy Mitral valve prolapse with valvular regurgitation and/or valvular thickening Most other congenital cardiac abnormalities not listed above Unrepaired ventricular septal defect, unrepaired patent ductus arteriosus Acquired valvular dysfunction (eg, mitral or aortic regurgitation or stenosis) Atrial septal defect, ventricular septal defect, or patent ductus arteriosus that was successfully closed (either surgically or with a catheter based procedure) within the past six months

Low risk People with the following conditions are thought to have a low risk of infective endocarditis. Antibiotics have never been recommended for people with these conditions: Physiologic, functional, or innocent heart murmurs Mitral valve prolapse without regurgitation or valvular leaflet thickening Mild tricuspid regurgitation Coronary artery disease (including previous coronary artery bypass graft surgery) Simple atrial septal defect Atrial septal defect, ventricular septal defect, or patent ductus arteriosus that was successfully closed (either surgically or with a catheter based procedure) more than six months previously Previous rheumatic fever or Kawasaki disease without valvular dysfunction People with pacemakers or defibrillators

Dental care recommendations Anyone who is at risk of developing infective endocarditis should follow a program of careful mouth and tooth care. This includes a professional cleaning every six months, twice daily tooth brushing, and once daily use of dental floss. These measures can help to prevent plaque-forming bacteria from adhering to the gums and teeth.


ANTIBIOTIC RECOMMENDATIONS The antibiotic type, dose, and regimen recommended before a procedure varies, depending upon the procedure being performed. The following treatment suggestions come from the American Heart Association's guidelines on antibiotic prophylaxis.

Dental, oral, or upper respiratory tract procedures
The primary antibiotic regimen for most people, including those with prosthetic heart valves, is 2 grams of amoxicillin by mouth (pills or liquid) one hour before the procedure; a second dose is not necessary. Children should receive 50 mg/kg, up to a maximum of 2 grams.

People allergic to penicillin
People who are allergic to penicillin can be treated one hour before the procedure with clindamycin, cephalexin, cefadroxil, or azithromycin. People unable to take oral medications People who are unable to take oral medications can be treated with ampicillin injected into a muscle or vein 30 minutes before the procedure. Patients allergic to penicillin can be given clindamycin or cefazolin 30 minutes before the procedure.

Genitourinary or gastrointestinal procedures
The American Heart Association does not consider gastrointestinal or urinary procedures to present a high risk of causing infective endocarditis, and therefore, no longer recommends the routine use of antibiotics before these procedures, even in people with the highest risk heart condition

Pregnancy
Pregnant women with high risk conditions should be given antibiotic prophylaxis . The antibiotics mentioned above are considered to be safe in pregnancy. A pregnant woman who has a high risk of IE does not usually need antibiotic prophylaxis before a normal vaginal delivery or cesarean section. Antibiotics may be recommended before labor or cesarean section for other reasons, including prevention of infection due to group B streptococcus.

Children
Children with a moderate or high risk of developing infective endocarditis are usually given antibiotics before selected dental and surgical procedures.

No treatment
The guidelines provided above may not apply to all patients in all situations. There may be instances in which an individual has a condition that is associated with a high or moderate risk of IE and antibiotics are not recommended. In such cases, it is important to understand the risks and benefits of taking versus not taking preventive antibiotics. Patients should discuss these issues with their healthcare provider in advance of the procedure.

REFERENCES
Wilson, W, Taubert, KA, Gewitz, M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007; 116:1736. Bonow, RO, Carabello, BA, Chatterjee, K, et al. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing committee to revise the 1998 guidelines for the management of patients with valvular heart disease). J Am Coll Cardiol 2006; 48:e1. Duval, X, Alla, F, Hoen, B, et al. Estimated risk of endocarditis in adults with predisposing cardiac conditions undergoing dental procedures with or without antibiotic prophylaxis. Clin Infect Dis 2006; 42:e102.

 



 

 
 
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