Infective Endocarditis Flashcards
(50 cards)
what can infective endocarditis affect?
> heart valves (native or prosthetic)
interventricular septum
chordae tendinae
intra-cardiac devices (pacemakers)
does it affect women or men more?
men
what creates a sterile fibrin-platelet vegetation?
adherence and invasion of nonbacterial thrombotic endocarditis
gives some examples of some mechanical disruption of valve endothelium
> turbulent blood flow > electrodes > catheters > inflammation > degenerative changes
what is the venture effect?
when fluid goes through a constriction in a cylinder there is high velocity and low pressure. this can cause damage to endothelium.
describe colonisation of damaged epithelium
exposed stromal cells and extracellular proteins trigger deposition of fibrin-platelet clots to which streptococci bind. these fibrin adhered streptococci attract monocytes and induce them to produce tissue factor activity and cytokines . this encourages vegetation growth by inducing cytokine, integrin and TFA production from neighbouring endothelial cells.
describe the colonisation of inflamed valve tissue
in response to local inflammation endothelial cells express integrins that bind plasma fibronectin to which microorganisms adhere. this results in endothelial internalisation of bacteria. in response to invasion endothelial cells produce TFA and cytokines triggering blood clotting and extension of inflammation promoting formation of the vegetation. internalised bacteria eventually lyse endothelial cells by secreting membrane active proteins such as haemolysins.
what can lead to bacteraemia?
> extra-cardiac infections
invasive procedures
gingival disease
activities of daily life )brushing teeth or bowel movement)
name three modes of acquisition
> health care related
community acquired
intra-venous drug abuse
describe non-nosocomial health care related endocarditis
signs and symptoms are less than 48 hours after admission/health care contact. could be from home based nursing, iv therapy or haemodialysis.
give three (specific) signs of infective endocarditis
> congestive heart failure
vascular/immunological phenomena
embolic phenomena
name some vascular/ immunological phenomena that arise from immune complex deposition
> splinter haemorrhage > vasculitic rash > roth spots > osler's nodes > janeway nodes > nephritis
describe a vasculitic rash
> diffuse
non-blanching
petechial
purpuric
describe roth spots
retinal haemorrhages with pale centres formed by coagulating fibrosis
describe osler’s nodes
painful raised deep red spots found on the fingers (and sometimes the palms and soles)
what are janeway lesions?
they are flat, macular, non tender echymotic lesions on the palms and soles that are pathognomonic for endocarditis
when should you have a high index of suspicion for infective endocarditis?
> fever > new murmur > pyrexia of unknown origin > prosthetic material > previous IE > congenital heart disorder > immunocompromised > intravenous drug abuser
when may signs of infective endocarditis be absent?
> elderly
after antibiotic treatment
immunocompromised
involving a less virulent/atypical organism
what investigations should you carry out?
> full blood count > U and E's (urea and electrolytes) > CRP (c-reactive protein test) > ESR (erythrocyte sedimentation rate) > urin-analysis > blood culture > ECG > CXR > echocardiogram
ideally describe how you would take blood cultures?
> prior to starting antibiotics
> 3 sets form different sites with more than 6 hours between each one
describe how you would take blood cultures from a patient in severe sepsis?
you would take 2 sets from different sites within an hour of each
what does blood in the urine indicate?
nephritis
would you do a trans oesophageal echocardiogram if:
> it the transthoracic echocardiogram was good quality and normal
> if there was low clinical suspicion
no
when should you carry out a trans oesophageal echocardiogram?
> if the TTE is normal but there is a high clinical suspicion
if the TTE was positive to show complications/abscesses/to measure size of vegatation
