Infective Endocarditis - February 2006

Infective endocarditis (IE) has been known since the early 1500s but still presents physicians with major diagnostic and management dilemmas. It is relatively rare in children but its incidence is increasing. Because of the increased survival rate of children with congenital heart disease and other risk factors such as indwelling vascular lines and IV drug use, there has been an increase in the “at risk” population. Additionally, the increasing popularity of body piercing and tattooing has led to a marked rise of cases of IE directly attributable to these practices.

IE is a rare but serious, non-contagious infection associated with significant morbidity and mortality. Infection may involve a native, previously normal heart valve or a prosthetic device (e.g., valve, conduit, patch, graft, shunt, or pacemaker) in a post-operative patient. Endocarditis may affect congenital heart lesions (most commonly, tetralogy of Fallot, VSD, aortic stenosis, PDA and transposition of the great arteries), valves affected by rheumatic heart disease and mitral valve prolapse.

Endocarditis is the result of a bacteremia occurring at the time of trauma, surgery, gynecologic procedures and other potentially high-risk activities. In a normal host, this bacteremia is usually transient, asymptomatic and without sequelae. If there is a damaged valve, endothelial injury from blood flow turbulence or a foreign body, platelet-fibrin aggregates accumulate at the site of the injury or on the foreign body in an attempt to repair the damage. Bacteria can grow in these small thrombi, creating a nidus of infection that is sequestered from normal host defense mechanisms. Bacterial vegetations grow and produce cardiovascular, embolic or immune complex-mediated signs and symptoms.

Staphylococcus aureus, α-hemolytic oral mucosa-derived streptococci and enterococcus are the dominant pathogens in native normal and unoperated anomalous valves. Staphylococcus epidermidis and S. aureus are common pathogens in the postoperative patient and in patients with prosthetic devices.

Fever is a dominant clinical feature in 95% of cases. Heart murmurs, if not previously present, usually develop at some point during the course of the disease. Other presenting signs and symptoms include fatigue, weakness, anorexia, weight loss and night sweats. Embolization of vegetation occurs in 50% of all cases and may be to the brain, liver, spleen, kidneys, peripheral limbs, and/or lungs. Petechiae, splinter hemorrhages and Janeway lesions (flat, painless, red to bluish red spots on the palms and soles) result from embolization. Other manifestations of IE are related to the body’s immune response to the infection. Musculoskeletal symptoms (myalgia and arthralgia), splenomegaly, Osler’s nodes (painful subcutaneous nodules on fingers and toes) and Roth’s spots (pale oval lesions on the retina) are immunological responses that develop slowly.

Definitive diagnosis of IE includes recovery of a microorganism from culture or histologic study of the heart, an embolized vegetation or an intra-cardiac abscess. Persistently positive blood cultures with a pathogen compatible with IE; echocardiographic evidence of an intra-cardiac mass, vegetations, perivalvular abscess, or new partial dehiscence of a prosthetic valve; and/or a new valvular murmur (regurgitation, or worsening or changing of a preexisting murmur) all support the diagnosis of IE. The Duke criteria for IE divides pathological and clinical findings into major and minor categories, and can help in the diagnosis of endocarditis.

Once the diagnosis of IE is established, treatment with IV antibiotics for six to eight weeks is recommended, based on the specific causative pathogen. Consultation with an infectious disease expert is advised. With appropriate therapy, the blood should be culture negative within 72-96 hours and fever should subside in one to two weeks. Persistent fever could be due to the presence of resistant organisms, metastatic foci of infection, an infected clot, a myocardial abscess, pulmonary emboli or drug fever.

Prognosis depends on the development of complications. Congestive heart failure secondary to valvular insufficiency is potentially life-threatening and is an indication for surgical intervention. Valvular or myocardial abscesses and cardiac arrhythmias, such as heart block, are also serious complications.

To prevent IE, high-risk patients, procedures and factors that predispose to bacteremia must be identified. Patients needing IE prophylaxis include those with intracardiac foreign bodies (prosthetic valve, grafts), prior episodes of infective endocarditis, most congenital heart lesions (except isolated secundum ASD, a repaired secundum ASD, VSD, or PDA after six months of operation, and pulmonary valve stenosis), hypertrophic cardiomyopathy, rheumatic or other acquired valve disease, and mitral valve prolapse with regurgitation. Specific antibiotic regimens for prophylaxis have been recommended by the American Heart Association and approved by the American Dental Association (www.americanheart.org; Searchword: Endocarditis prophylaxis). Chewable tablets and antibiotic suspensions may be indicated in children who have difficulty swallowing tablets.

Body piercing and, to a lesser degree, tattooing should be considered high risk procedures in relation to the possible acquisition of IE for several reasons including 1) the physical invasiveness of the procedure; 2) the piercing site may be a reservoir for IE-causing organisms; 3) prolonged healing times associated with mucosal trauma around the piercing site, (e.g. up to six weeks for healing of the tongue and up to 12 months for healing of the navel); and 4) procedures may not be carried out under adequate hygienic conditions. Evidence is mounting to support the use of antibiotic prophylaxis after body piercing and tattooing. Patients with known cardiac abnormalities in particular should be strongly advised against these practices and educated on the potentially life-threatening results that follow.

References

1. Practical Strategies in Pediatric Diagnosis and Therapy. Editors Robert M. Kliegman, Larry A. Greenbaum, Patricia S. Lye. – 2nd edition, 2004. Elsevier Inc.

2. Unique Features of Infective Endocarditis in Childhood. Ferrieri, P., Gewitz, MH., et al. Circulation 2002;105:2115-2127.

3. Victims of Fashion: Endocarditis after Oral Piercing. Dubose, J and Pratt, JW. Curr Surg 2004 Sept/Oct 61(5) 474-477.

4. Antibiotic prophylaxis, body piercing and infective endocarditis. Millar B and Moore J. J Antimicrob Chemother. 2004 Feb, 53 (2) 123-6.


This information provided by California Pacific Medical Center's Division of Pediatric Cardiology
John Coulson, M.D. and Nikola Tede, M.D.
(415) 600-3477