Endocarditis Flashcards
What is endocarditis ?
- inflammation of the inner layer of the heart
What are the 2 different etiologies that can lead to endocarditis
- Bacterial infection -> (usually) valvular damage -> thrombi -> bacterial adhesion -> endocarditis
- Non-bacterial -> Lupus (autoimmune disease) -> LIBMAN-SACKS -> endocarditis
Endocarditis of bacterial origin: what is the starting mechanism leading to bacterial adhesion on the cardiac valves
- Bacterial endocarditis, usually involves the endocardium lining the cardiac valves
- valves have microvasculature supplying them, and microbial invasion of the valves can occur by 2 mechanisms:
1) valve damage -> microbe escapes vasculature -> goes on valve tissue
2) Valve damage -> microbes adhere to valve + enters small vessels
Either ways, micro needs first to get into the bloodstream, occurs either by:
- open wound / abscess
- dental / surgical procedure
- infected needle / substance
Most common valve involved in infective endocarditis ?
- Left side valves: Aortic, mitral valve more common
Sometimes occurs due to aortic valve (bicuspid), mitral valve prolapse
RF for either valves for endocarditis ?
- prosthetic valves
- congenital heart defects
- rheumatic heart disease
- intravenous drug use (mostly affects tricuspid valve)
Endocarditis: Pathomechanism:
- first, endothelium gets damaged, either by injury or previous inflammation
- exposes underlying collagen + tissue factor -> causes platelets and fibrin to adhere -> formation of thrombosis, called Non-bacterial thrombotic endocarditis (NBTE)
Different ways through which bacterias get into the body: brushing teeth (gets in the gums), gut, lungs -> ends up in the blood.
If it’s a small amount, usually gets killer by the immune system, but if it travels long enough -> finds the NTBE -> adheres to it -> causes an infection called vegetation.
Usually they attach to lower pressure parts (easier to adhere), so usually on top of the valves, or just below the valves in case of aortic regurgitation (High to low P)
State the different classifications of infective endocarditis:
- acute
- subacute
Based on how fast the infection develops.
State the different causes of infective endocarditis:
- Strept viridans: most common cause of subacute bacterial endocarditis, found in mouth, attacks valves that had previously been damaged
- Staph aureus: found on skin, often affects the tricuspid valve, due to IV drug use.
- Staph epidermidis: a nosocomial infection, get either through prosthetic valves during valve surgery, or intravenous catheter
- Enterococcus faecalis + Strept Bovis: both found in normal flora, which, during colorectal diseases, like colorectal cancer/ulcerative colitis -> migrates through the wall
- HACEK organisms: gram - bacterias of normal flora in mouth/throat
Infective endocarditis: symptoms
- fever: most common symptom, but non-specific. Other non-specific symptoms: lethargy, musculoskeletal signs, night sweats, paleness, dyspnea, weight loss
- murmur: results from turbulent flow
- splinter hemorrhages: results from septic emboli -> goes under the nails
- Janeway lesions: painless, flat erythematous lesions found in palms on hands or feet, also due to septic emboli
- Osler’s nodes: painful lesions, antigen-antibody complex deposition on fingers and toes
- Roth spots: antigen-antibody Complex deposition in the eyes
- Glomerulonephritis: due to antigen-antibody complex deposition in the kidney
Infective endocarditis: Diagnosis
Important to find the cause:
- blood culture: grow bacteria from blood sample
- echocardiography: visualize the heart, look for vegetations, look for the movement of the valves
Infective endocarditis: Diagnosis: What is minor and Major DUKE criteria
- Major: + culture, + echo
- Minor: predisposing condition, fever, vascular and immune phenomenon, microbial evidence
Define when:
- 2 major, or
- 1 major + 3 minor, or
- 5 minor
Infective endocarditis: Lab signs
- normocytic anemia
- leukocytosis
- CRP and ESR increased
- Immunocomplexes
- Cryoglobulins
- micro hematuria
Infective endocarditis: complications
- HF: Valve destruction (regurgitation), ruptured chordae tendinae, intracranial fistula, shunts, coronary embolism, sepsis
- renal failure: immune-mediated glomerulonephritis, renal embolism, antibiotic nephtotoxic
- Embolism: cerebral, spleen, lungs
- Other: uncontrolled infection, abscess formation
Infective endocarditis: Treatment
- Antibiotics: depending on the microorganism
- If Native valve staph, without complication: high dose beta lactam + amino glycoside for 2-6 weeks
- if complication/prosthetic valve: beta lactam, aminoglycoside, rifampin, for 6 weeks
- surgery in severe cases, if it causes a valve dysfunction -> and possible heart failure
Infective endocarditis: Prevention
- Prophylaxis needed for dental procedures (amoxicillin)
- prophylaxis in: respiratory tract procedures, GI, dermatological and musculoskeletal
