Endokarditis

Endokarditis, also known as infective endocarditis, is an infection of the endocardial surface of the heart, most often involving the heart valves. It can present acutely with rapid illness or subacutely with a more prolonged course. The condition carries substantial risk of complications if not treated promptly.

Risk factors include pre-existing valvular disease, prosthetic valves, congenital heart disease, implanted cardiac devices, and intravenous drug use. Bacteremia from dental work, surgery, or other procedures can introduce pathogens into the bloodstream and contribute to infection.

Pathophysiology involves microorganisms adhering to damaged or abnormal endocardium and forming vegetations composed of bacteria, fibrin, and platelets. Common causative organisms are Staphylococcus aureus, viridans group streptococci, Enterococcus species, and HACEK organisms; fungi are less frequent but more difficult to treat.

Clinical features typically include fever and a new or changing heart murmur, with signs of systemic infection. Embolic phenomena (such as stroke or limb ischemia) and immune phenomena (such as Osler nodes or Roth spots) may occur.

Diagnosis relies on microbiology and imaging. Multiple blood cultures before antibiotics are recommended. Echocardiography, especially transesophageal, detects vegetations and abscesses. The Duke criteria combine microbiologic evidence, imaging findings, and clinical features to establish the diagnosis.

Treatment requires prolonged intravenous antibiotics, usually four to six weeks, tailored to the responsible organism and susceptibility. Empiric regimens cover common pathogens; prosthetic valve endocarditis may require additional agents. Surgery is considered for heart failure, uncontrolled infection, perivalvular complications, or prevention of embolism.

Prognosis varies with organism, timing of therapy, and comorbidities; mortality remains a concern in certain cases. Prevention focuses on antibiotic prophylaxis in high-risk patients undergoing selected procedures according to local guidelines.