Endocarditis: causes, signs, diagnosis, treatment, and prevention

Structure and why valves are vulnerable

Valves are integral parts of the heart and the human body, but their leaflets receive relatively little direct blood supply. Because of this limited vascularity, infectious organisms that settle on a valve are harder for the immune system to clear. When a valve becomes infected, organisms such as bacteria or even protozoa may create masses called vegetations that impair normal valve motion. The condition most commonly affects the heart valves.

Causes and pathogenesis

Most cases are caused by bacteria entering the bloodstream and attaching to a damaged or prosthetic valve. Staphylococci and streptococci species are frequent culprits; fungi are less common but can produce severe disease. Risk factors include preexisting valve disease, prosthetic heart valves, recent invasive procedures, and intravenous drug use. Once organisms adhere, they multiply and incite clotting and inflammation, producing vegetations that may erode tissue or break off and embolize.

Clinical features and diagnosis

Patients commonly have fever, fatigue, a new or changing heart murmur, and signs of systemic infection. Vascular phenomena such as embolic stroke, splinter hemorrhages, Janeway lesions, and immune-mediated signs such as Osler nodes may occur. Diagnosis rests on blood cultures to identify the organism and cardiac imaging—especially transesophageal echocardiography—to visualize vegetations. Clinical algorithms that combine microbiology and imaging help guide diagnosis and management.

Treatment, prevention and prognosis

Treatment usually requires prolonged, targeted intravenous antibiotics based on culture results; some cases need surgical repair or valve replacement when there is severe valve destruction, persistent infection, or recurrent emboli. Preventive measures include maintaining good dental hygiene and, for selected high‑risk patients, targeted antibiotic prophylaxis before particular invasive procedures. Early recognition and specialist care improve outcomes, but endocarditis remains a serious illness with potential complications such as heart failure, abscess formation, and conduction disturbances.

History and notable facts

Descriptions of endocardial disease date back to the era when clinicians first correlated fevers, murmurs, and embolic events with valve lesions. Clinical signs like Osler nodes and Janeway lesions are named after physicians who characterized them. The pattern of disease has evolved with modern medicine: prosthetic devices and intravenous drug use have changed who is at greatest risk, while advances in microbiology, imaging, and surgery have improved survival.

• Key terms: endocardium, heart valves, bacteria
• Risk examples: prosthetic valves, dental infections, IV drug use (infected bloodstream)
• Less common agents: protozoa and fungi may be involved in rare cases

For more clinical details and practice guidance see specialized resources: patient information, professional summaries, and diagnostic pathway outlines at relevant clinical pages.