Endocarditis

Infectious endocarditis results from a microbial infection of the endothelial surface of the heart. Risk factors include rheumatic and degenerative valve disease, mitral valve prolapse, hypertrophic cardiomyopathy, prosthetic valves and injecting drug use. The most common pathogens are viridans streptococci, Staphylococcus aureus, Streptococcus bovis and enterococci. Patients commonly present with fever and nonspecific symptoms such as myalgias and back pain. Most patients have heart murmurs, which usually represent the underlying heart pathology. Embolic phenomena can involve the spleen, kidneys, brain and skin. Diagnosis is usually on the basis of multiple positive blood cultures that grow typical pathogens, though serology may be necessary to detect unusual pathogens. Echocardiography enables visualization of vegetations and other complications of endocarditis (e.g. abscesses, valvular and ventricular dysfunction). Transoesophageal echocardiography is superior to transthoracic echocardiography for visualizing prosthetic valves and is more sensitive for the detection of vegetations on all valves. Bactericidal antimicrobial therapy is essential, and specific recommendations for therapy have been outlined by various working groups. Therapy often lasts 4-6 weeks, so monitoring for adverse events is essential. Surgery is indicated in patients who develop heart failure from valve dysfunction, who have partial dehiscence of a prosthetic valve, or in whom medical management is failing or very likely to fail (e.g. those with persistent bacteraemia or infection with resistant organisms). Antimicrobial prophylaxis is considered standard care in patients with high-to-moderate risk cardiac conditions undergoing procedures that are likely to lead to transient bacteraemia.