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What is the definition of infective endocarditis?
Infected thrombus (vegetation) on endocardial surface of valve
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What is the pathophysiology of infective endocarditis? What does it start with
- Damaged endocardium: turbulent flow
- Then platelet-fibrin THROMBUS deposition: chemotactic properties
- Transient BACTERAEMIA: adherence of bacteria to thrombus (eg on valve)
- Multiplication of bacteria: make VEGETATION
- Parts of vegetation EMBOLISE: brain, kidney, lung.. etc
- Immunological stimulation forms immune complexes
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Where can parts of vegetations embolise to and what are the consequences?
- If left heart:
- Brain: MCA – sudden onset hemiplegia
- Kidney: microemboli causing GN and microscopic haematuria or wedge shaped infarct
- Gut
- Liver
- Spleen
- If right heart: lung – pulmonary infarct
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How is the endocardium usually damaged?
Turbulent flow
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What are the predisposing factors for IE? Split into 2 categories
- 1. Damaged valves/turbulent blood flow:
- Congenital heart disease
- Degenerative/atherosclerotic aortic valve disease
- Chronic rheumatic heart disease
- Mitral valve prolapse
- Prostethic valve
- 2. Transient bacteraemia:
- Iv drug abuse
- Intravascular device eg central line
- Invasive procedures: dental, catheter, surgery..
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What are the symptoms of infective endocarditis? And explain them
- Acute cardiac failure (Staph Aureus)
- Fever
- Cough: backpressure of fluid
- Shortness of breath: cardiac failure, anaemia, toxins
- Abdo pain: emboli to liver/spleen/gut
- Mental deterioration: microemboli to brain
- Night sweats
- Symptoms of embolic and immunological sequelae
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What are the signs of IE?
- Hepatomegaly
- Splenomegaly
- Changing or new murmur
- Fever
- R/L ventricular failure
- Peripheral stigmata of IE: Janeway lesions (visible, painless), Oslers nodes (painful pulps), Splinter haemorrhages, Roth spots
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What are the vascular complications of IE?
- Embolic lesions
- Immune related vasculitis
- Mycotic aneurysms
- BRAIN: cerebral infarcts, SAH, cerebral abscess
- Spleen
- Renal lesions
- Right sided IE: pulmonary infiltrates, lung abscess
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What are the immunological sequelae of IE? And which sort of presentations are they more common in?
- Subacute presentation- strep viridans
- Ab-Ag complex form and deposit in peripheral vessels
- Roth spots: small rounded retinal haemorrhages with a white centre
- Oslers nodes: small painful lesions on pads of fingers and toes
- Splinter haemorrhages
- Glomerulonephritis
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What are the causative organisms for native valve endocarditis?
- Viridans streptococci: normal flora of oropharynx: strep mutans; gut flora: strep bovis. They have alpha haemolysis (turns agar green)
- Staph Aureus
- Enterococci
- Candida
- HACEK group (Haemophilus)
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Why are some IE culture negative?
- Previous antibiotic treatment
- Fastidious streptococci
- HACEK
- Fungal: Candida
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Which organisms cause prosthetic valve endocarditis?
- Early (6/12): Staph aureus, coagulase negative staph eg staph epidermidis
- Late: same as native: viridans strep, staph aureus, enterococci, candida
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How do you diagnose IE?
- 3 blood cultures before treatment is started
- if acutely ill: collect 2 sets in a 1-2hr period
- need 8-10mls in each bottle
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which other investigations are needed when managing IE?
FBC, U&Es, CRP, urine microscopy (haematuria as immune complexes to kidney), CXR, echo (TT/TOE-more invasive)
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What criteria is used to diagnose IE? And how do you use it?
- Modified Duke’s Criteria
- 2 major or 1 major+3minor or 5 minor
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what is the empirical treatment for native valve IE?
Amoxicillin + gentamicin
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what is the empirical treatment for prosthetic valve IE?
Vancmycin + gentamicin
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If IE is with viridans strep in a native valve, what is the treatment? Duration?
- Benzylpenicillin 7.2g daily in 6 divided doses + gentamicin 80mg bd iv
- 2 weeks
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how is MSSA or MSSE IE treated? Duration?
- Flucloxacillin 12g daily iv
- Gentamicin 80mg bd
- 4-6 weeks
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how is MRSA IE treated? Duration?
- Vancomycin 1g bd + gentamicin 80mg bd
- 4-6 weeks
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enterococcal endocarditis treatment? Duration?
- amoxicillin 12g daily iv
- gentamicin 80mg bd
- 4 weeks
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if strep and staph are gram +ve, why can we give gentamicin if it normally acts on gram –ve ?
give it with a penicillin which acts to open the cell wall, then gentamicin can go inside the cell and inhibit protein synthesis
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when does surgery need to be considered as a treatment for IE?
- Heart failure
- Persistent fever
- Recurrent embolism
- Large vegetations
- Cardiac abscess
- IE refractory to medical treatment
- Acute valvular regurgitation with pulm oedema
- Dehiscence of a prosthetic valve
- Infection with Candida, Coxiella burnetti, refractory enterococcal IE
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If a patient is allergic to penicillin or has used amoxicillin in last month, which drug is to be used instead?
Clindamycin
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Which valve is most likely to be affected?
Aortic>mitral>>tricuspid
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Which valve do IVDUs get IE on?
Tricuspid (right)
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What are non-bacterial thrombotic endocarditis associated with?
- Hypercoagulation states
- Pancreatic carcinoma
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What are the 2 main cardiac problems seen in SLE? What is the 2nd one also called?
- Pericarditis
- Endocarditis: Libman-Sacks endocarditis
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What is the pathogenesis of acute rheumatic fever?
- Post throat infection, starts 2-6wks after it
- Group A haemolytic strep
- Immunological cross reaction
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What are the signs and symptoms of acute rheumatic fever?
- Fever
- Flitting arthropathy: from joint to joint
- Sydenham’s chorea – cross reactivity of Ab in basal ganglia
- Skin nodules
- Rash – erythema marginatum: central pallor and erythema around it (serpentine rash)
- Pancarditis: pericarditis (audible rub), myocarditis, endocarditis which causes long term morb due to scarring and mitral valve stenosis
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What are the inflammatory lesions in the heart in acute rheumatic fever called and what do they contain?
Aschoff body: lympho, macro, degenerate collagen – small STERILE vegetations
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What is chronic rheumatic heart disease? And which valve?
- After recurrent and severe acute rheumatic fever
- Mitral valve > aortic
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Do you get regurgitation or stenosis in chronic rheumatic heart disease?
- Inflam lesion becomes organised and get fibrosis which leads to
- a) retraction: by shortening and thickening chordae – cause regurg
- b) cusp fusion causing stenosis
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what is the most common cause of mitral stenosis?
Chronic rheumatic heart disease
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what is the most common cause of aortic stenosis?
- Acquired calcification
- Calcification of congenital bicuspid valve (nb aortic normally has 3 cusps)
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what is the most common cause of mitral regurg?
Mitral valve prolapse
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What are the causes of aortic regurg?
- Chronic rheumatic heart disease
- IE
- RA
- SLE
- Aortic root disease: hypertension, dissection, seronegative arthropathies (ank spond, reiter’s syndrome, psoriatic arthropathy), Marfans, osteogenesis imperfecta, syphilitic aortitis
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What valvulopathies can infective endocarditis cause?
regurgitation
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