Pathophysiology
Endothelial injury + transient bacteraemia allow platelet-fibrin thrombus formation on valves, colonised by circulating organisms. Common pathogens: Staph aureus (most common overall and in IVDU), viridans streptococci (dental), Enterococcus (GU procedures), Strep gallolyticus (colon cancer), HACEK organisms, Coxiella and Bartonella in culture-negative disease.
Sources: AHA Infective Endocarditis Guideline (Circulation 2023;148:e1); ESC 2023 Endocarditis Guidelines (Eur Heart J 2023;44:3948)
Clinical presentation
Fever, new/changed regurgitant murmur, embolic phenomena (stroke, splinter haemorrhages, Janeway lesions, mycotic aneurysm), immune features (Roth spots, Osler nodes, glomerulonephritis). Right-sided IE in IVDU: septic pulmonary emboli.
Sources: AHA Infective Endocarditis Guideline (Circulation 2023;148:e1); ESC 2023 Endocarditis Guidelines (Eur Heart J 2023;44:3948)
Diagnosis
Duke criteria: 2 major, 1 major + 3 minor, or 5 minor. Major - typical organism on 2 separate blood cultures; imaging evidence of endocardial involvement (vegetation, abscess, dehiscence). TTE first-line, TOE if prosthetic valve, suspected complications, or negative TTE with high clinical suspicion.
Sources: AHA Infective Endocarditis Guideline (Circulation 2023;148:e1); ESC 2023 Endocarditis Guidelines (Eur Heart J 2023;44:3948)
Management
Empiric IV antibiotics after >=3 blood culture sets: vancomycin + ceftriaxone (native valve) or vancomycin + gentamicin + rifampicin (prosthetic). Refine when cultures return. 4-6 weeks total. Surgical indications: heart failure from valve dysfunction, uncontrolled infection or abscess, recurrent embolism with large vegetation, prosthetic dehiscence.
Sources: AHA Infective Endocarditis Guideline (Circulation 2023;148:e1); ESC 2023 Endocarditis Guidelines (Eur Heart J 2023;44:3948)
