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What is the definition of infective endocarditis?
Infected thrombus (vegetation) on endocardial surface of valve
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
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
- If right heart: lung – pulmonary infarct
How is the endocardium usually damaged?
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..
What are the symptoms of infective endocarditis? And explain them
- Acute cardiac failure (Staph Aureus)
- 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
What are the signs of IE?
- Changing or new murmur
- R/L ventricular failure
- Peripheral stigmata of IE: Janeway lesions (visible, painless), Oslers nodes (painful pulps), Splinter haemorrhages, Roth spots
What are the vascular complications of IE?
- Embolic lesions
- Immune related vasculitis
- Mycotic aneurysms
- BRAIN: cerebral infarcts, SAH, cerebral abscess
- Renal lesions
- Right sided IE: pulmonary infiltrates, lung abscess
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
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
- HACEK group (Haemophilus)
Why are some IE culture negative?
- Previous antibiotic treatment
- Fastidious streptococci
- Fungal: Candida
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
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
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)
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
what is the empirical treatment for native valve IE?
Amoxicillin + gentamicin
what is the empirical treatment for prosthetic valve IE?
Vancmycin + gentamicin
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
how is MSSA or MSSE IE treated? Duration?
- Flucloxacillin 12g daily iv
- Gentamicin 80mg bd
- 4-6 weeks
how is MRSA IE treated? Duration?
- Vancomycin 1g bd + gentamicin 80mg bd
- 4-6 weeks
enterococcal endocarditis treatment? Duration?
- amoxicillin 12g daily iv
- gentamicin 80mg bd
- 4 weeks
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
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
If a patient is allergic to penicillin or has used amoxicillin in last month, which drug is to be used instead?
Which valve is most likely to be affected?
Which valve do IVDUs get IE on?
What are non-bacterial thrombotic endocarditis associated with?
- Hypercoagulation states
- Pancreatic carcinoma
What are the 2 main cardiac problems seen in SLE? What is the 2nd one also called?
- Endocarditis: Libman-Sacks endocarditis
What is the pathogenesis of acute rheumatic fever?
- Post throat infection, starts 2-6wks after it
- Group A haemolytic strep
- Immunological cross reaction
What are the signs and symptoms of acute rheumatic 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
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
What is chronic rheumatic heart disease? And which valve?
- After recurrent and severe acute rheumatic fever
- Mitral valve > aortic
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
what is the most common cause of mitral stenosis?
Chronic rheumatic heart disease
what is the most common cause of aortic stenosis?
- Acquired calcification
- Calcification of congenital bicuspid valve (nb aortic normally has 3 cusps)
what is the most common cause of mitral regurg?
Mitral valve prolapse
What are the causes of aortic regurg?
- Chronic rheumatic heart disease
- Aortic root disease: hypertension, dissection, seronegative arthropathies (ank spond, reiter’s syndrome, psoriatic arthropathy), Marfans, osteogenesis imperfecta, syphilitic aortitis
What valvulopathies can infective endocarditis cause?