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Yr 3 cardio > infectious endocarditis > Flashcards

infectious endocarditis Flashcards

1
Q

definition of infectious endocarditis

A

infection of the intracardiac, endocardial structures - mainly heart valves

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2
Q

aetiology of IE

A

endocardium can be colonised by any organism

vegetations form as a result of lodging of the organisms on the heart valves during a period of bacteraemia

vegetations made of platelets, fibrin, and infective organisms - poorly penetrated by cellular/humoral immune system

= vegetations destroy the valve leaflets, invade the myocardium or aortic wall = abscess cavities

Activation of the immune system also causes formation of immune complexes leading to cutaneous vasculitis, glomerulonephritis or arthritis.

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3
Q

most common IE organisms

A

streptococci - a-haemolytic Streptococcus viridans or Streptococcus bovis.

staphylococci: staph aureus, staph epidermidis (in IV drug users)

enterococci - enteroccus faecalis

other organisms HACEK (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella), Coxiella burnetii, histoplasma, diphtheroids, chlamydia

fungi - candida, aspergillus, histoplasma

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4
Q

RF for IE

A
  • abnromal valves - congenital, post-rheumaticm, calcification/degeneration
  • prosthetic valves
  • turbulent flow eg patent ductus arteriosus or VSD
  • recent dental work and bacteraemia
  • S bovis may be associated with GI malignancy
  • IV drug users
  • immunocomprimised patients
  • SLE
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5
Q

acute IE

A

occurs on normal valves - commonest organism is Staph aureus

  • skin breaches (dermatitis, IV lines, wounds)
  • renal failure
  • immunosuppression
  • DM
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6
Q

subacute IE

A

endocarditis on abnormal valves

  • aortic/mitral valve disease
  • tricuspid valves in IV drug users
  • coarctation
  • patent ductus arteriosus
  • VSD
  • prosthetic valves

Endocarditis on prosthetic valves may be ‘early’ (within 60d of surgery, usually Staph. epidermidis, poor prognosis) or ‘late’.

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7
Q

epidemiology of IE

A

16-22/million/yr

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8
Q

sx of IE

A

fever with sweats/chills/rigors - may be relapsing remitting

malaise, arthraluigua, myalgia, confusion - particularly in elderly

skin lesions

inquire about recent dental surgery or IV drug abuse

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9
Q

signs of IE

A

pyrexia, tachycardia, signs of anaemia

night sweats

weight loss

clubbing - if long standing

New regurgitant murmur or muffled heart sounds (right-sided lesions may imply IV drug use). - vegetation may cause valve destruction and severe regurg or valve obstruction

aortic root abscess causes prolongation of the PR interval, and may lead to complete AV block

LVF is a common cause of death

Frequency: Mitral>aortic>tricuspid>pulmonary.

splenomegaly

vasculitis

microscopic haematuria

glomerulonephritis and AKI

vasculitic lesions:

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10
Q

vasculitic lesions in IE

A

petechiae particularly on retinae (Roth’s spots)

pharyngeal and conjunctival mucosa

janeway lesions - painless palmar macules, which blanch on pressure

osler’s nodes - tender nodules on finger/toe pads

splinter haemorrhages

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11
Q

Ix for IE

A

bloods

urinalysis - microscopic haematuria, proteinuria

blood culture

echo

ECG (abscesses = conductive changes) look for heart block

CXR (septic pul emboli: focal lung infiltrates +- central cavitation, particualrly in tricuspid valve endocarditis) cardiomegaly, pulmonary oedema

CT to look for emboli

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12
Q

blood culture for IE

A

at least 3sets 1hr apart

Culture and sensitivity is vital, but empirical treatment should be started first.

Cultures remainnegative in 2–5%.

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13
Q

bloods for IE

A

FBC - raised neutrophils, normocytic anaemia

raised ESR, CRP UE

rheumatic fever +ve

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14
Q

echo for IE

A

transthoracic

Transoesophageal echocardiography is much more sensitive for the detection of endocarditis; especially useful for the detection of vegetations and valve abscess, diagnosis of prosthetic valve endocarditis and assessment of embolic risk.

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15
Q

classification for IE

A

Dukes

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16
Q

duke’s classification

A

(2 major, 1 major + 3 minor or all minor).

major

  • posutive blood culture in 3 separate samples (?2 of same organism)
  • +ve echo (vegetation, abscess, prosthetic valve dehiscence, new valve regurgitation)

minor

  • high grade pyrexia (temp >38degrees)
  • RF (abnormal valves, IVdrug use, dental surgery).
  • +ve blood culture, but not major criteria
  • +ve echo, but not major criteria
  • vascular signs
17
Q

Mx of IE

A

Antibiotics for 4–6 weeks (at least 6 weeks for prosthetic valve endocarditis).

On clinical suspicion: Benzylpenicillin +- gentamicin (empirical treatment); gentamicin dosage adjusted for peak serum level of 3–4mg/ml, trough<1mg/ml

Streptococci: Continue as above (alternatives – ceftriaxone, vancomycin).

Staphylococci: Flucloxacillin/vancomycin +gentamicin (for prosthetic valves: vancomycin + gentamicin + rifampin)

Enterococci: Ampicillin + gentamicin

Culture negative: Vancomycin + gentamicin

Surgery: If poor response or deterioration, urgent valve replacement is indicated. Surgical replacement of the prostheses. In ‘kissing’ mitral valve vegetations, the mitral valve maybe salvageable.

surgery if: Heart failure, valvular obstruction; repeated emboli; fungal IE; persistent bacteraemia; myocardial abscess; unstable infected prosthetic valve.

18
Q

IE prophylaxis

A

history of IE undergoing high risk procedures

  • Dental, incision or biopsy of respiratory mucosa, procedures in patients with GI/GU tract infection, procedures on infected skin or musculoskeletal tissue, prosthetic heart valve placement. For patients undergoing a dental procedure: 2 g oral amoxicillin30–60 min before the procedure.
19
Q

advice for IE

A

clear info about prevention:

  • importance of maintaining good oral health,
  • symptoms that indicate IE and when to seek expert advice,
  • the risks of invasive procedures, including non-medical procedures eg body piercing/tattoo
20
Q

complications of IE

A

Valve incompetence,

intracardiac fistulae or abscesses,

aneurysm formation,

heart failure.

Renal failure, glomerulonephritis.

Arterial emboli from the vegetations (brain, kidneys, lungs, spleen).

21
Q

Px of IE

A

Fatal if untreated. Even when treated, 15–30% mortality

50% require surgery. 20% in hospital mortality (Staphs 30%; bowel bacteria 14%; Streps 6%). 15% recurrence at 2yrs.

Yr 3 cardio (38 decks)

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