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Week 12: Infective Endocarditis > Infective Endocarditis > Flashcards

Infective Endocarditis Flashcards

1
Q

Pathophysiology of IE: What are the steps in the development of IE lesions?

A
  1. Endothelial injury
  2. Platelet deposition
  3. Adherence of microbials to platelets which occurs via MSCRAMMS
  4. Incorporation of microbials into vegetation which then multiplies
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2
Q

Clinical criteria for definite IE?

A
  • 2 major criteria; OR
  • 1 major criterion and 3 minor criteria; OR
  • 5 minor criteria
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3
Q

What are the major criteria for IE?

A
  1. Blood culture positive for IE
  2. Echo positive for IE
  3. New valvular regurgitation
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4
Q

What are the minor criteria for IE?

A
  1. Predisposition for IE (e.g. pre-existing heart condition, IV drug use)
  2. Fever
  3. Valvular phenomena (e.g. major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages and Janeway lesions)
  4. Immunological phenomena (e.g. Osler nodes, Roth spots, and rheumatoid factor)
  5. Micro or serological evidence (e.g. positive blood culture that does not meet major criterion, or serological evidence of active infection with an organism consistent with IE)
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5
Q

Clinical criteria for possible IE?

A
  • 1 major criterion and 1 minor criterion; OR

- 3 minor criteria

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6
Q

When is the possibility of IE rejected?

A
  • Firm alternate diagnosis explaining evidence of IE; OR
  • Resolution of IE syndrome with antibiotic therapy for < 4 days; OR
  • No pathologic evidence of IE at surgery or autopsy, with antibiotic therapy for < 4 days; OR
  • Does not meet criteria for possible IE
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7
Q

What are Roth Spots?

A
  • Oral retinal haemorrhages with pale centers
  • Infrequent findings
  • Also noted in patients with collagen vascular disease and haematologic disorders
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8
Q

What are Osler Nodes?

A
  • Small painful reddish nodules

- Most common on pads of fingers and toes

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9
Q

What are Janeway Lesions?

A
  • Non-tender, reddish nodular lesions

- Most commonly found on palms of hands and soles of feet

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10
Q

What are Splinter Haemorhages?

A

Small, linear haemorhages under the finger and/or toenails (resemble splinters of wood under the nails)

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11
Q

What are Petechiae?

A

Reddish-brown, pinpoint, haemorrhagic spots on the skin, conjunctivae, or oral mucosa

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12
Q

What are the three echo positive signs of IE?

A
  1. Oscillating mass (vegetation)
  2. Abscess
  3. New partial dehiscence with prosthetic valve
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13
Q

Where can vegetations occur?

A
  • Form at sites of endothelial injury located upstream of infected valve: eg. atrial surface of atrio-ventricular valves, ventricular surface of semilunar valves
  • Satellite vegetations or jet lesions present along infected flow path: eg. IE of MV with MR => MR might hit LA wall and a vegetation can occur at this site // IE of AV with AR => infected AR jet may hit amvl resulting in jet lesion on MV leaflet
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14
Q

What is an abscess?

A
  • Complication of IE
  • Extension and penetration of infection into surrounding tissues
  • Contain phlegmon (puss)
  • DO NOT communicate with circulation (no flow within abscess cavity)
  • Most common with PrV and AV IE (in paravalvular region); abscesses may form in anterior aortic root or mitral-aortic intravalvular fossa (MAIF)
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15
Q

What is new partial dehiscence of PrV due to IE?

A
  • Dehiscence = rocking of PrV at an angle far in excess of normal excursion
  • Clue to dehiscence: paravalvular regurgitation
  • In IE: due to weakening of infected valve annulus
  • Partial separation of prosthetic sewing ring from native annulus (“pulling away” of PrV from annulus)
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16
Q

TTE vs TOE in IE

A
  • TOE has a higher sensitivity and specificity in diagnosis of vegetations and abscess cavities in native and prosthetic valves
  • Sensitivity of TTE in detecting abscesses is very low
17
Q

TTE vs TOE in Prosthetic AVR

A
  • Anterior aortic annulus: best seen with TTE (acoustic shadow present with TOE - anterior annulus obscured by AVR artifact)
  • Posterior aortic annulus: best seen with TOE (in TTE, AVR shadows posterior aortic annulus)
18
Q

In what clinical contexts is there zero probability of IE?

A

Zero probability of IE in the absence of:

  1. Vasculitic/embolic phenomena
  2. Central venous access of pacing wires
  3. Recent IV drug use
  4. Prosthetic Valve
  5. Positive blood cultures
19
Q

Texture of a likely vegetation vs an unlikely vegetation?

A
  • Likely vegetation: reflectance of myocardium (grey)

- Unlikely vegetation: hyper-reflective (white or echo-bright)

20
Q

Location of a likely vegetation vs an unlikely vegetation?

A
  • Likely vegetation: upstream side of valves; along jet pathway; on prosthetic material
  • Unlikely vegetation: downstream side of valves
21
Q

Motion of a likely vegetation vs an unlikely vegetation?

A
  • Likely vegetation: independently mobile, high frequency motion
  • Unlikely vegetation: fixed and immobile
22
Q

Shape of a likely vegetation vs an unlikely vegetation?

A
  • Likely vegetation: irregular and lobulated, may be multiple
  • Unlikely vegetation: filamentous or ‘stringy’; discrete nodule
23
Q

Accompanying abnormalities of a likely vegetation vs an unlikely vegetation?

A
  • Likely vegetation: regurgitation, abscess, pseudoaneurysm, fistula, PrV dehiscence, valve aneurysm
  • Unlikely vegetation: none
24
Q

What are other clues to the presence of IE?

A
  1. Perivalvular complications (eg. pseudoaneurysms, fistulas)
  2. Leaflet perforation
  3. Chordal ruputre
  4. Valve aneurysms
  5. Significant valve dysfunction (eg. regurgitation and/or obstruction)
25
Q

What are pseudoaneurysms?

A

Perivalvular cavity (abscess) that communicates with the cardiovascular lumen

26
Q

Abscess vs Pesudoaneurysm

A

Abscess:

  1. Non-pulsatile
  2. No communication with circulation

Pseudoaneurysm:

  1. Pulsatile
  2. Communicates with circulation
27
Q

What are fistulas?

A
  • Communication between two neighbouring cavities through a perforation
  • Occur when weakened and necrotic tissue breaks through valve annulus resulting in a direct communication between 2 cardiac chambers OR a cardiac chamber and a great vessel
  • Eg. abnormal flow from aorta to RA (flow is continuous over cardiac cycle)
28
Q

What is leaflet perforation?

A
  • Complication of valve aneurysm

- Interruption of leaflet tissue continuity => essentially a hole in the leaflet itself

29
Q

What are valve aneurysms?

A
  • Occur as a consequence of valvular infection => saccular out-pouching of valvular tissue
  • IE = weakening of valve tissue, loss of elastic components
30
Q

When to refer for TOE in native valve IE?

A
  • TOE recommended; proven higher diagnostic yield

- Exception: negative TTE and exceptional TTE images and low probability

31
Q

When to refer for TOE in prosthetic valve IE?

A
  • TOE mandatory (if no contrary indications); marked diagnostic superiority
  • Consider CMR; if TOE equivocal (ambiguous) or if periaortic abscess suspected
32
Q

When to refer for TOE in right sided IE?

A
  • TOE recommended in selected cases: clinical complications or left-sided disease
33
Q

When to refer for TOE in cardiac device related IE?

A
  • TOE recommended in selected cases; TTE negative or ambiguous
  • Consider ICE (intracardiac echo); if TOE negative and high clinical probability
34
Q

What are possible complications of IE?

A
  1. Heart failure
  2. Perivalvular extension of infection
  3. Embolic events
35
Q

What echo parameters are associated with increased risk of embolism?

A
  1. Large mobile vegetations (>10mm)
  2. Located on MV
  3. Increased size while on antibiotic therapy
  4. Multivalvular infection

Week 12: Infective Endocarditis (1 decks)

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