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YR6: CARDIAC > Infective Endocarditis > Flashcards

Infective Endocarditis Flashcards

1
Q

What is infective endocarditis?

A

Infection of the endocardium (inner lining of heart, mainly valves)

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2
Q

List 5 cardiac risk factors for infective endocarditis

A

Acquired valvular disease: rheumatic heart disease, AS, degenerative valve disease
Prosthetic heart valves
Congenital heart defects: VSD, bicuspid aortic valve
Previous endocarditis
Implantation of cardiac device

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3
Q

List 4 non-cardiac risk factors for infective endocarditis

A

IV drug use
Poor dental hygiene/ Recent dental work
IV catheter
Immunosuppression

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4
Q

List 5 causative organisms of infective endocarditis

A

Staphylococcus aureus (most common)
Streptococcus Viridans
Coagulase -ve Staph e.g. S. epidermis
Streptococcus bovis
Non-infective

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5
Q

In which patients is staphylococcus aureus IE particularly common?

A

Acute presentations
IVDU

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6
Q

What is the most common cause of IE in developing countries?

A

Streptococcus viridians: S. mitis + S. sanguinis

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7
Q

Which organisms are found in the mouth and thus linked to poor dental hygiene or following a dental procedure?

A

Streptococcus viridians: S. mitis + S. sanguinis

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8
Q

What is the most common cause of IE following prosthetic valve surgery? Why?

A

Staphylococcus epidermidis
Commonly colonize indwelling lines, usually the result of peri-operative contamination.
After 2 months the spectrum of organisms which cause endocarditis return to normal

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9
Q

Which cause of IE is associated with colorectal cancer?

A

Streptococcus bovis
Subtype S. gallolyticus is most linked with colorectal cancer

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10
Q

Name 2 non-infective causes of IE

A

SLE: Libman-Sacks
Malignancy: Marantic endocarditis

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11
Q

List 5 causes of culture negative IE

A

Prior abx therapy
Coxiella burnetii
Bartonella
Brucella
HACEK: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella

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12
Q

Describe the pathogenesis of infective endocarditis

A
  1. Damaged valvular endothelium; exposure of subendothelial layer
    → adherence of platelets + fibrin
    → sterile vegetation (microthrombus)
  2. Localized infection/ contamination
    → bacteremia
    → bacterial colonization of vegetation
    → formation of fibrin clots encasing the vegetation
    → valve destruction with loss of function (valve regurgitation)
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13
Q

Describe valve involvement in IE

A

Mitral > Aortic > Tricuspid > Pulmonary

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14
Q

Which valve is most commonly affected in IVDU with IE?

A

Tricuspid

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15
Q

List 3 clinical consequences of bacterial colonisation of vegetation in IE

A

Bacterial vegetation→ bacterial thromboemboli→ vessel occlusion→ Infarctions

Emboli can lead to metastatic infections of other organs.

Formation of immune complexes + antibodies against tissue antigens → glomerulonephritis, Osler nodes

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16
Q

List 3 symptoms of infective endocarditis

A

Fever + chills (most common)
FLAWS
Arthralgias + myalgias

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17
Q

How may sub-acute IE differ in presentation to acute IE?

A

Sub-acute: nonspecific flu-like Sx
Acute: signs of acute sepsis.

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18
Q

List 3 cardiac manifestations of IE

A

New murmur
HF: due to valve insufficiency
Arrhythmias: due to perivalvular abscess causing conduction delay

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19
Q

Depending on the valve affected, which murmur may be heard in IE

A

TR: pansystolic, loudest at LSB
AR: Early diastolic loudest at 3rd ICS, LSB
MR: Pansystolic loudest at apex

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20
Q

List 4 extra-cardiac manifestations of IE

A

Peripheral embolic + immunologic phenomena
Emboli to intra-abdominal organs
Neurological manifestations
Pulmonary manifestations

21
Q

List 4 peripheral embolic and immunologic phenomena in IE

A

Petechiae, esp. splinter haemorrhages
Janeway lesions (non-tender macules on palms + soles)
Osler nodes (painful nodules on pads of fingers + toes)
Roth spots (retinal haemorrhages)

22
Q

Give 2 examples of where IE may emboli to intra-abdominal organs

A

AKI: haematuria + anuria
Splenomegaly + LUQ pain

23
Q

What may cause neurological manifestations in IE?

A

Septic embolic stroke
Hemorrhage
Meningitis
Encephalitis
Abscess

24
Q

What do pulmonary manifestations of IE result from? What does this cause?

A

Septic emboli from tricuspid involvement
Signs of PE e.g. dyspnoea
Signs of pulmonary infection

25
Q

What criteria is used to diagnose infective endocarditis?

A

Modified Duke criteria

26
Q

What defines the Modified Duke Criteria?

A

Pathological criteria positive
OR
2 major criteria
OR
1 major + 3 minor criteria
OR
5 minor criteria

27
Q

What constitutes positive pathological criteria for IE?

A

+ve histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content)

28
Q

What are the majors in the modified duke criteria?

A

+ve blood cultures
Evidence of endocardial involvement

29
Q

What constitutes positive blood cultures in the major criteria for IE?

A

2 +ve blood cultures with typical organisms for IE
OR
Persistent bacteraemia from 2 blood cultures taken > 12h apart or >,3 +ve blood cultures
OR
+ve serology for Coxiella burnetii, Bartonella species or Chlamydia psittaci

30
Q

What constitutes evidence of endocardial involvement in IE?

A

+ve echo: oscillating structures, abscess formation, new valvular regurg or dehiscence of prosthetic valves
OR
New valvular regurgitation

31
Q

What are the minor criteria for IE?

A

Predisposing heart condition or IVDU

Fever > 38ºC

Vascular phenomena: major arterial emboli, splenomegaly, splinter haemorrhages, Janeway lesions

Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots

Microbiological evidence:
+ve blood cultures not meeting major criteria or serological evidence of active infection with organism consistent with IE.

32
Q

Describe investigations for infective endocarditis

A

3 separate sets of blood cultures from 3 different sites
ECG
TTE (possible TOE if inconclusive)

Bloods: FBC, CRP, U+Es, LFTs
Urinalysis

33
Q

Why is urinalysis performed in IE? What may be found?

A

Septic emboli are common complication
Haematuria + nephritic sediment

34
Q

What investigation would be performed in patients with S. gallolyticus?

A

Colonoscopy to r/o colorectal cancer

35
Q

What investigation should be performed in all patients with IE once stable and receiving therapy?

A

Dental assessment

36
Q

What may be seen on ECG in infective endocarditis?

A

Progression of infection can lead conduction abnormalities
Prolonged PR interval, non-specific ST/T wave abnormalities, AV block

37
Q

What is seen on echocardiography in IE?

A

Valvular vegetations
New valvular regurgitation
+/- Abscess (e.g., perivalvular abscess)

38
Q

List 4 poor prognostic factors in IE

A

S. aureus infection
Prosthetic valve (esp. ‘early’, acquired during surgery)
Culture -ve endocarditis
Low complement levels

39
Q

Describe the mortality of IE according to organism

A

Staphylococci - 30%
Bowel organisms - 15%
Streptococci - 5%

40
Q

What is the initial blind therapy for suspected infective endocarditis in patients with a native valve?

A

Amoxicillin
+/- low dose Gentamicin

If pen allergy, MRSA or severe infection: Vancomycin + low dose Gentamicin

41
Q

What is the initial blind therapy for suspected infective endocarditis in patients with a prosthetic valve?

A

Vancomycin + Rifampicin + low-dose Gentamicin

42
Q

Tx of native valve endocarditis caused by staphylococci

A

Flucloxacillin

If pen allergy or MRSA: Vancomycin + Rifampicin

43
Q

Tx of prosthetic valve endocarditis caused by staphylococci

A

Flucloxacillin + Rifampicin + low-dose Gentamicin

If pen allergy or MRSA: Vancomycin + Rifampicin + low-dose Gentamicin

44
Q

Tx of endocarditis caused by fully-sensitive streptococci (e.g. viridans)

A

Benzylpenicillin

If pen allergy: Vancomycin + low-dose Gentamicin

45
Q

Tx of endocarditis caused by less sensitive streptococci

A

Benzylpenicillin + low-dose Gentamicin

If pen allergy: Vancomycin + low-dose Gentamicin

46
Q

When may surgical treatment be needed in infective endocarditis?

A

Severe valvular incompetence
Aortic abscess (often indicated by a lengthening PR interval)
Infections resistant to abx /fungal infections
Cardiac failure refractory to standard medical Tx
Recurrent emboli after abx therapy

47
Q

List 4 complications of infective endocarditis

A

Acute HF
Systemic embolisation inc. Stroke
AKI
Valvlar dehiscence, rupture or fistula

48
Q

What is the prognosis in infective endocarditis?

A

FATAL if untreated
15-30% mortality even WITH treatment

49
Q

Do dental, upper and lower GI tract,
GU tract, O+G or resp procedures require IE prophylaxis?

A

NO

YR6: CARDIAC (41 decks)

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