Update on Infective Endocarditis

Posted by e-Medical PPT
Pathogenesis
Disruption of the endocardial layer as a complication of abnormal blood flow associated with underlying cardiac defect
Bacterium-endothelium interaction with bacterial attachment and invasion of endothelial cells

Underlying valvular abnormality predisposing to infective endocarditis
rheumatic fever:a common cause in the past
mitral valve prolapse:currently represents the most common underlying cardiac abnormality

mitral valve prolapse
risk for infective ednocarditis is increased by 5x-8x
mitral regurgitation increases the risk
leaflet redundancy with myxomatous degeneration is a frequent finding

Coagulase-negative Staphylococci
can produce native-valve endocarditis in mitral valve prolapse
usually subacute, difficult to diagnose, and disregarded as a contaminant
delay in diagnosis and treatment may account for the severe complications
 myocardial abscess formation
 valvular insufficiency requiring valve surgery
 death

Prosthetic Heart Valve
positive blood culture in hospitalized patients with underlying prosthetic valves can be a harbinger of endocarditis
43% patients with nosocomial bacteremia or fungemia had prosthetic valve infection
a serious complication

Polymicrobial Infective Endocarditis clinical features
IV drug use is the predominant risk factor
younger age (mean 36.5 years)
right-sided cardiac involvement in > 60%
streptococci more frequent than S. aureus
mortality rate is 4x higher for pure left-sides vs pure right-sided endocarditis

Diagnostic (Duke) Criteria
Major criteria
 positive blood culture for IE
 evidence of endocardial involvement
Minor criteria
 predisposition (heart condition or IV drug use)
 fever of 100.40F or higher
 vascular or immunologic phenomena
 microbiologic or echocardiographic evidence not meeting major criteria

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