Endocarditis prophylaxis

• Certain congenital heart lesions are believed to have a low enough risk for developing endocarditis that the small risks associated with high-dose antibiotic prophylaxis prior to dental and other procedures seem unwarranted:
  • Secundum ASD: unrepaired OR successfully repaired
    • In the secundum type of atrial septal defect, the fossa ovalis can be closed, and there is no residual flow turbulence.
    • An ostium primum atrial septal defect is a type of endocardial cushion defect (atrioventricular septal defect) that always involves some malformation of the left component of the atrioventricular valve ("cleft mitral valve"). After repair of this type of atrial defect, patients have an endocarditis risk equal to that of patients who have chronic mitral valve regurgitation. They require antibiotic prophylaxis.
  • Ligated PDA
  • successfully repaired ventricular septal defect.
    • some patients who have repaired VSD are at risk for endocarditis because of residual small patch leaks, mild subaortic turbulence, or aortic valve incompetence due to prolapse of the aortic sinuses into the area of the patched ventricular septal defect. Patients who have such hemodynamic abnormalities require antibiotic prophylaxis.
• In contrast, repaired coarctation of the aorta requires lifelong administration of antibiotic prophylaxis
  • there almost always is some residual turbulent jet of blood flow in the area of coarctation repair.
  • bacterial endarteritis is possible in patients who have both repaired and unrepaired coarctation of the aorta.
• In addition, minor aortic valve abnormalities, especially bicuspid aortic valve, are common in the presence of coarctation of the aorta. Although such valvular abnormalities may have no hemodynamic importance, they do represent a risk for endocarditis.

Oral amoxicillin (50 mg/kg in children; 2 g in adults) should be given 1 hour prior to anticipated procedures that can cause transient bacteremia, such as professional dental cleanings. A second dose following the procedure is no longer recommended. Intravenous ampicillin can be substituted for the patient unable to take the oral regimen, and alternative  regimens with clindamycin, cephalexin, and azithromycin are suggested for patients who are allergic to penicillins. The specific regimens along with patient information  handouts are available at the AHA Web site noted in the references.

Endocarditis may occur after procedures deemed to have a risk for causing bacteremia, but many cases of bacterial endocarditis occur with no prior history of such procedures. Therefore, endocarditis always must be considered in the differential diagnosis of the febrile patient who has an at-risk cardiac lesion.

References:
Bonow RO, Carabello B, de Leon AC Jr, et al. ACC/AHA 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 (Committee on Management of Patients With
Valvular Heart Disease). J Am Coll Cardiol. 1998;32:1486-1588
Dajani AS, Taubert KA, Wilson W, et al. Prevention of bacterial
endocarditis. Recommendations by the American Heart Association. AHA
medical/scientific statement. Available at: