Antibiotic prophylaxis for patients with certain types of heart disease (e.g., rheumatic heart disease, infective endocarditis, and congenital heart disease [CHD])ispartofstandardmedicaltherapyinmostdevelopednations.Infective endocarditis(IE)is lesscommon inchildrenthan inadults. Althoughthe incidence of rheumatic heart disease in developed countries has decreased, it appears that the incidence of IE in children has been increasing, due to, in part, improved survival of potentially at-risk children, such as those with CHD and those with indwelling venous catheters. In the developed world, CHD is the most common risk factor for IE.
Cardiac endothelial damage is the initiating factor for IE. In children with CHD, shear forces from high-velocity aberrant blood flow can damage the cardiac endothelium. Alternatively, damage may be caused by catheter- induced trauma. A thrombus can form at the site of damage. If a child subsequently has transient bacteremia with an organism capable of causing endocarditis, the thrombus may become infected. The most common etiologic organisms for IE in children are streptococci and staphylococci, especially viridans group streptococci and Staphylococcus aureus. Bacterial proliferation results in the formation of vegetations. The goal of antibiotic prophylaxis is to prevent or quickly treat bacteremia and prevent IE in susceptible patients. Despite its widespread practice, no study has ever demonstrated that antimicrobial prophylaxis in at-risk individuals prior to invasive procedures definitively prevents IE.
BecausethepresentationofIEisgenerallyinsidiouswithfeverandother
nonspecific systemic complaints (e.g., weakness, fatigue and weight loss)
physicians must have a high degree of suspicion in the appropriate clinical
circumstance. Once suspected, the Duke criteria, comprised of major and
minor criteria, can be used to assist in diagnosing IE in children. The major
Duke criteria are as follows:
• Two separate positive blood cultures with a typical etiologic agent for IE
• Evidence of cardiac involvement (e.g., a positive finding on echocardiography or new valvular regurgitation).
The minor Duke criteria include:
• A predisposing condition (i.e., CHD, indwelling catheter)
• Fever
• Vascular complications (i.e., Janeway lesions)
• Immunologic complications (i.e., Osler nodes, Roth spots)
• Microbiologic evidence that does not meet major criteria
• Echocardiographic evidence that does not meet major criteria.
Using these clinical criteria, definite IE is diagnosed with two major criteria, one major criterion and three minor criteria, or five minor criteria. Echocardiography is the primary imaging modality used in the diagnosis of IE.
The American College of Cardiology and the American Heart Association have established guidelines to assist physicians with deciding when to prescribe antibiotic prophylaxis for IE. Patients are stratified into high-risk, moderate-risk, and low-risk groups. Antimicrobial prophylaxis is recommended for high-and moderate-risk groups prior to an invasive procedure. Common invasive procedures requiring antibiotic prophylaxis include oral and dental procedures, including routine dental cleanings, and genitourinary and gastrointestinal procedures. As the risk of bacteremia is highest for oral and dental procedures, maintaining good dental hygiene is especially important in children at risk for IE.
Children's risk for IE can be determined using the American College of Cardiology and the American Heart Association guidelines. Those at high risk for IE are those with prosthetic heart valves, a previous history of IE, complex cyanotic CHD (i.e., tetralogy of Fallot) and surgically constructed systemic or pulmonary conduits. Children at moderate risk for IE include those with other types of CHD, excluding children older than 6 months aftersurgicalrepairofatrialseptaldefect,ventricularseptaldefectandpatent ductusarteriosus,andisolatedsecundumatrialseptaldefect;acquiredvalvular dysfunction or prior valvular repair; hypertrophic cardiomyopathy with obstruction; mitral valve prolapse with regurgitation or thickened leaflets; and intracardiac defects repaired within the last 6 months.
Recommended antibiotic prophylaxis regimens vary with the type of invasive procedure. For oral, dental, and upper respiratory tract procedures, one dose of amoxicillin (50 mg/kg/dose, maximum 2 g/dose) 1 hour prior to the procedure is suggested. For genitourinary and gastrointestinal procedures, ampicillin (50 mg/kg/dose, maximum 2 g/dose) and gentamicin (1.5 mg/kg/dose) 30 minutes prior to the procedure, followed by a second dose of ampicillin or amoxicillin 6 hours later is suggested for high- risk patients. For moderate-risk individuals, ampicillin or amoxicillin within 30 minutes of starting the procedure is suggested. Physicians should be alert totheneedforantimicrobialprophylaxisagainstIEintheappropriateclinical scenario, such as children with CHD prior to dental procedures.
Bonow RO, Carabello BA, Chattergee K, et al. ACC/AHA 2006 guidelines for the management
of patients with valvular heart disease: a report from the American College of Cardiology/
AmericanHeartAssociationTaskForceonPracticeGuidelines(writingcommitteetorevise
the 1998 guidelines forthe managementof patients with valvular heart disease) developed in
collaboration with the Society of Cardiovascular Anesthesiologists endorsed by the Society
for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons.
J Am Coll Cardiol. 2006;48:e1–e148.
FerrieriP,GewitzMH,GerberMA,etal.Uniquefeaturesofinfectiveendocarditisinchildhood.
Pediatrics. 2002;109:931–943.
Review other book chapters online related to Congenital heart defects:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Avoiding Common Pediatric Errors Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7489-6 
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