Infective Endocarditis Flashcards
Infective Endocarditis
•Infective endocarditis (IE) refers to infection of the endocardial surface of the heart. The cardiac valves are involved in the great majority of cases, but infection may also occur on the mural surface or on septal defects. IE has been extensively studied because its wide variety of manifestations can mimic other diseases, and because of its complex pathophysiology
Pathophysiology of IE
- Endothelial damage
- Bacteremia (septicemia)
- Formation of infected vegetation
- Inflammation
Endothelial Damage
- Aging valves
- Previously damaged valves (rheumatic fever or previous IE)
- Bicuspid aortic valve (1% of population)
- Prosthetic valves
- Turbulence (shunts, regurgitation)
- Mechanical trauma (catheter)
Inflammation
- Presence of intravascular bacteria leads to immune system activation
- Complement activation
- Production of autoantibodies: rheumatoid factor, antinuclear antibodies
- Immune complex formation
Clinical Manifestations are a Consequence of:
- Bacteremia
- Valvular vegetations
- Embolization
- Immune complex deposition
- Nonspecific immune stimulation
Signs and Symptoms
Fever of Unknown Origin (FUO)
- Illness of >3 weeks duration
- Fever greater than 101 F, (38.3 C) on several occasions
- No diagnosis despite one week of intensive evaluation
Cardiovascular Manifestations
A consequence of perivalvular abscess
Consequences of septic emboli Right sided
Consequences of septic emboli Left sided
Immune complexes in IE
- Nephritis
- Arthritis
- Vasculitis
Subcutaneous Nodules (Osler’s nodes)
Consequences of Bacteremia
Immune System Activation
- Circulating rheumatoid factor
- Hyperglobulinemia
- Splenomegaly
- Thrombocytopenia
Diagnosis
Duke Clinical Criteria: Major
Duke Clinical Criteria: Minor
Treatment of IE: Principles
- Bacteria in vegetations are relatively protected from antibiotic penetration AND immune system action
- High concentrations of bactericidal antibiotics and long duration of therapy are used
- Surgery may be needed for large vegetations or valvular damage
Antibiotic selection
- Cell wall active agents for Gram positive organisms
- Aminoglycoside or beta-lactam synergy especially for enterococci prosthetic valves
Prevention of IE with Antibiotics?
Principles:
- IE is uncommon but life threatening
- Certain cardiac conditions predispose to IE
- Bacteremia with IE-causing organisms occurs during certain invasive procedures
- Occasional cases of IE following procedures have been reported
Can antibiotic prophylaxis prior to invasive procedures prevent IE?
- Bacteremia occurs at least as commonly from daily activities as from procedures
- It is difficult to show that prophylaxis actually prevents IE
- On a population level, risk of antibiotic adverse effects may be greater than benefit of prophylaxis
- Cost effectiveness analyses are not favorable
IE Prevention
Antibiotic recommendations
- Amoxicillin 2 grams single dose
- PCN allergy: cephalexin 2 grams
- Anaphylactic PCN allergy: clindamycin 600 mg or azithromycin or clarithromycin 500 mg
