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Cardiovascular system > Infective Endocarditis > Flashcards

Infective Endocarditis Flashcards

1
Q

what can infective endocarditis affect?

A

> heart valves (native or prosthetic)
interventricular septum
chordae tendinae
intra-cardiac devices (pacemakers)

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2
Q

does it affect women or men more?

A

men

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3
Q

what creates a sterile fibrin-platelet vegetation?

A

adherence and invasion of nonbacterial thrombotic endocarditis

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4
Q

gives some examples of some mechanical disruption of valve endothelium

A 
> turbulent blood flow
> electrodes
> catheters
> inflammation
> degenerative changes
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5
Q

what is the venture effect?

A

when fluid goes through a constriction in a cylinder there is high velocity and low pressure. this can cause damage to endothelium.

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6
Q

describe colonisation of damaged epithelium

A

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.

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7
Q

describe the colonisation of inflamed valve tissue

A

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.

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8
Q

what can lead to bacteraemia?

A

> extra-cardiac infections
invasive procedures
gingival disease
activities of daily life )brushing teeth or bowel movement)

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9
Q

name three modes of acquisition

A

> health care related
community acquired
intra-venous drug abuse

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10
Q

describe non-nosocomial health care related endocarditis

A

signs and symptoms are less than 48 hours after admission/health care contact. could be from home based nursing, iv therapy or haemodialysis.

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11
Q

give three (specific) signs of infective endocarditis

A

> congestive heart failure
vascular/immunological phenomena
embolic phenomena

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12
Q

name some vascular/ immunological phenomena that arise from immune complex deposition

A 
> splinter haemorrhage
> vasculitic rash
> roth spots
> osler's nodes
> janeway nodes
> nephritis
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13
Q

describe a vasculitic rash

A

> diffuse
non-blanching
petechial
purpuric

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14
Q

describe roth spots

A

retinal haemorrhages with pale centres formed by coagulating fibrosis

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15
Q

describe osler’s nodes

A

painful raised deep red spots found on the fingers (and sometimes the palms and soles)

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16
Q

what are janeway lesions?

A

they are flat, macular, non tender echymotic lesions on the palms and soles that are pathognomonic for endocarditis

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17
Q

when should you have a high index of suspicion for infective endocarditis?

A 
> fever
> new murmur
> pyrexia of unknown origin
> prosthetic material
> previous IE
> congenital heart disorder
> immunocompromised
> intravenous drug abuser
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18
Q

when may signs of infective endocarditis be absent?

A

> elderly
after antibiotic treatment
immunocompromised
involving a less virulent/atypical organism

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19
Q

what investigations should you carry out?

A 
> 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
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20
Q

ideally describe how you would take blood cultures?

A

> prior to starting antibiotics

> 3 sets form different sites with more than 6 hours between each one

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21
Q

describe how you would take blood cultures from a patient in severe sepsis?

A

you would take 2 sets from different sites within an hour of each

22
Q

what does blood in the urine indicate?

A

nephritis

23
Q

would you do a trans oesophageal echocardiogram if:
> it the transthoracic echocardiogram was good quality and normal
> if there was low clinical suspicion

A

no

24
Q

when should you carry out a trans oesophageal echocardiogram?

A

> 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

25
Q

what should you do if the TTE and TOE are normal but the suspicion for infective endocarditis remains high?

A

repeat both the TTE and TOE at 70-10 days

26
Q

when should you repeat the TTE and TOE in infective endocarditis?

A

> if there is a new complication
to assess ongoing treatment in uncomplicated IE
to asses treatment success on completion

27
Q

when might infective endocarditis give negative blood cultures?

A

> prior antibiotics
fastidious organisms
intracellular bacteria

28
Q

what four groups of streptococci are there?

A

> oral (viridans)
s.milleri
nutritionally variant defective
group d (associated with the GI tract)

29
Q

name 3 species of enterococci

A

> E. faecalis
E. faecium
E. durans

30
Q

what 2 staphylococcus species are healthcare associated IE?

A

> staph. aureus

> coagulase negative staph. (epidermidis)

31
Q

why might blood cultures comes back falsely negative?

A

if the patient has had prior antibiotic treatment for an unexplained fever before the cultures were taken then the test is negative for many days after discontinuation of the antibiotics.

32
Q

name some fastidious organisms which might create a negative blood culture

A

> nutritionally variant streptococci
gram negative bacilli
brucella
fungi

33
Q

name three intracellular bacteria that can create a negative blood culture

A

> coxiella burnetii
bartonella
chlamydia

34
Q

describe the major modified duke criteria for diagnosing IE

A

> blood cultures positive for IE (typical organisms consistent with IE form 2 separate blood cultures. organisms consistent with IE from persistent positive blood cultures. single positive blood culture for coxiellaburnetii.)
evidence of endocardial involvement (positive echocardiogram or new valvular murmur.)

35
Q

described the minor modifies duke criteria for diagnosing IE

A 
> predisposition
> fever (>38)
> vascular phenomena
> immunological phenomena
> microbiological evidence
36
Q

what criteria need to be met for there to be a definite diagnosis of IE?

A

> 2 major
1 major and 3 minor
5 minor

37
Q

what criteria need to be met for there to be a possible diagnosis of IE?

A

> 1 major

> 3 minor

38
Q

what antibiotic treatment is given for IE?

A

intravenous antibiotic started as soon as blood cultures are taken

39
Q

what does the choice of antibiotics depend on?

A 
> prior antibiotics
> native/prosthetic valve
>  local epidemiology
> local resistance
> specific culturally negative pathogens
40
Q

what treatment is there for IE?

A

> antibiotics
surgery
aminoglycosides synergised with cell wall inhibitors

41
Q

what treatment is given if there is an IE infection to native valves?

A

> IV gentamicin
IV amoxicillin
(IV vancomycin)

42
Q

what antibiotic treatment is given to an IE infection where there are native valves and sepsis?

A

> gentamicin

> IV vancomycin

43
Q

what antibiotic treatment is given to an IE infection where prosthetic valves are involved with MSSA and MRSA infection?

A

> gentamicin
vancomycin
rifampicin

44
Q

what investigations are carried out daily with an IE case?

A

> full blood count
u and e’s
CRP

45
Q

how often is an ECG carried out in continuing treatment of IE?

A

every 1 to 2 days

46
Q

why is an echo carried out weekly when continuing treatment of IE?

A

to check that the growth is down

47
Q

what is the treatment for fungal infective endocarditis?

A

dual antifungals (often for life) with valve replacement.

48
Q

what complications indicate surgery?

A 
> heart failure
> fistula formation
> leaflet perforation
> uncontrolled infection
> abscess formation
> atrioventricular heart block
> embolism
> prosthetic valve dysfunction
49
Q

what high risk patients is prophylaxis limited to?

A

> highest incidence rate of IE

> highest risk of adverse outcomes of IE

50
Q

what cardiac conditions have the highest risk of IE?

A 
> acquired valvular heart disease
>valve replacement
> structural congenital heart disease
> hypertrophic cardiomyopathy
> previous IE

Cardiovascular system (34 decks)

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