Bacterial Endocarditis


by Ernest G. Brookfield, M.D.
Division of Pediatric Cardiology
Medical College of Ohio
Toledo, Ohio

From CHASER News V.2-No.1; 2/94 - © Copyrighted Material
Bacterial endocarditis is an infection of the inner surface of the heart or the heart valves caused by bacteria usually found in the mouth, intestinal tract or urinary tract. This infection results in a serious illness which requires prolonged treatment and on occasion produces injury to the heart or even death. Endocarditis is a major concern in almost all unrepaired congenital heart defects as well as in most repaired defects with a few exceptions. Endocarditis is generally preventable with simple measures, but the implementation of these measures is often confusing for the parents of thechild, the physician, and the dentist. Hopefully this brief article will decrease some of that confusion.

Endocarditis occurs when bacteria grow on the edges of a heart defect or on the surface of an abnormal valve after the bacteria enter the blood stream, most commonly from dental procedures but also from procedures involving the gastrointestinal or urinary tract. Once the bacteria infect the inner surfaceof the heart, they continue to grow producing large particles called vegetation that may then break off and travel to the lungs, brain, kidneys andskin. The continuing infection may also seriously damage the heart valve on which the vegetations have grown. Symptoms and signs of endocarditis vary butprolonged fever (more then 2-3 days) without an obvious cause is a most important sign and should always be investigated in a child with congenital heart disease. Other signs and symptoms include poor appetite, feeling weak or tired, joint pains, skin rashes, and changes in the nature of a previously present heart murmur. The chance that these signs and symptoms are caused by endocarditis is more likely if they occur soon after a dental cleaning or procedure involving the gastrointestinal or urinary tract.

Bacterial endocarditis can usually be diagnosed if the physician suspects its presence in a child with a congenital heart defect and a prolonged fever. Blood tests show signs of inflammation such as an elevated sedimentation rate,while anemia and blood cells in the urine are often present. The most important diagnostic test for endocarditis involves a positive blood culture. A blood culture is a small sample of blood drawn from the vein which is grown in a special solution so that bacteria can be detected. Three to five blood cultures are obtained in a 24 hour period and will generally confirm the diagnosis. Previous antibiotic may result in negative cultures.

Bacterial endocarditis can occur with many heart defects but is most common inaortic valve lesions, a patent ductus arteriosus (unrepaired), Tetralogy of Fallot, ventricular septal defects, coarctation of the aorta, and mitral valveprolapse with mitral regurgitation. Endocarditis rarely occurs in an isolatedsecundum atrial septal defect or pulmonic stenosis. Endocarditis may occur inmost congenital heart lesions after surgical repair with the exception of completely repaired ventricular septal defects and patent ductus arteriosus (after 6 months have elapsed from the time of surgery).

Endocarditis is usually prevented by giving your child an antibiotic just prior to a procedure that would release bacteria into the blood stream, and repeating a smaller dose of the antibiotic six hours after the procedure. Themost common procedure causing endocarditis is dental cleaning where bacteria in the gums are released into the blood stream. Tonsillectomy and adenoidectomy may also be a source of bacteria producing endocarditis as well as previously mentioned urinary and gastrointestinal tract procedures. On the other hand ear tube insertion, the most common surgical procedure in children, presents less risk of endocarditis and does not require preventive antibiotics. Orthodontic procedures generally do not present a risk, but the decision to use antibiotics is up to the orthodontist and related to the degree of manipulation during an orthodontic visit. The most common antibiotic used to prevent endocarditis is Amoxicillin but in the case of penicillin allergy Erythromycin is used. Other antibiotics or combinations may be appropriate for high risk patients or in procedures involving the intestinal or urinary tract.

Parents of children with a heart defect, repaired or unrepaired, should ask their cardiologist or primary physician whether their particular child requires protection from endocarditis and inform the dentist or physician performing a procedure of this requirement. All dentists should be aware of the type and dose of antibiotic from standardized recommendations by the American Heart Association and the American Dental Association. The American Heart Association provides a small card for parents listing the child's name, diagnosis, prescribing physician and explaining the type and dose of antibiotics to prevent endocarditis. The dentist or operating physician should be able to prescribe the antibiotic but if there is confusion the parent should check with the child's cardiologist or primary physician and they will be able to clarify the situation. Since the most common cause of bacterial endocarditis is bacteria from gums (alpha-Hemolytic streptococci), good dental and gum hygiene is particularly important for children with congenital heart disease. This dental hygiene should be implemented by periodic dental checks and by following your dentist's instructions in caring for your child's teeth and gums.

Once endocarditis is diagnosed, treatment consists of a period of intravenous doses of appropriate antibiotics determined from blood tests under the supervision of an infectious disease specialist and cardiologist. After four to six weeks most children recover from endocarditis, but there is a significant risk of further damage to a heart valve and on occasion there is apoor outcome, so the emphasis should be on the prevention of endocarditis rather then the treatment. After reading this article if you have any questions regarding endocarditis, contact your child's cardiologist or primaryphysician. They will also help you to determine if a specific procedure places your child at risk for the infection.