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Cardiovascular System > Infective Endocarditis > Flashcards

Infective Endocarditis Flashcards

1
Q

What is the definition of Infective endocarditis?

A

Infection of the endocardium by bacteria

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2
Q

What does IE commonly affect

A 
Valvular structures (native or prosthetic) 
Chrodae tendineae 
Site of septal defects 
Mural endocardium
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3
Q

What are risk factors for native valve IE

A 
Mitral valve disease
Rheumatic heart dissease
Congenital heart disease 
Degenerative heart disease 
Assymetrical septal hypertrophy 
IVDA
Alcoholic cirrhosis 
Diabetes M 
Indwelling medical devices
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4
Q

Does IE have a worse prognosis in males or females?

A

Females

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5
Q

Which mitral valve disease increases the risk of IE?

A

Mitral valve prolapse

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6
Q

What congenital heart diseases increases the risk of IE?

A

Ventricular septal defect
Bicuspid aortic valve
Patent ductus arteriosus

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7
Q

What is the pathophysiology of IE from endothelial damage?

A
  1. Mechanical endothelial damage exposes ECM protein -> production of tissue factors
  2. Deposition of fibrin and platelets
  3. Forms non-bacterial thrombotic endocarditis (NBTE)

NBTE facilitate bacterial adherence and infection

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8
Q

What can cause damage to the endothelial valve?

A 
Turbulent blood flow 
Electrode 
Catheters 
Inflammation (rheumatic carditis)
Degenerative valve disease (seen with echo)
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9
Q

What is the venturi effect?

A

Constriction of part of vessel increase the velocity but reduces pressure, this can cause turbulent flow which can damage the endothelium

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10
Q

What is the pathophysiology of IE from endothelial inflammation?

A
  1. Endothelial inflammation -> expression of interns (B1 family)
    Integrins are transmembrane proteins that bind fibrin to endothelial surface
  2. IE pathogens carry fibronectin -> binding proteins on their surface
  3. Adhere to endothelium and organisms trigger active internalisation into valve endothelial cells
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11
Q

What is the pathophysiology of IE from bacteraemia?

A

Invasive procedure:
Dental procedures - perforation of oral mucosa
GU and GI surgery
IV catheters

Extra-cardiac infections
Non-invasive activities (chewing and teeth brushing)

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12
Q

Name 5 causative organisms

A 
Strep viridans 
Staph aureus 
Enterococci 
Staphylococci (coagulase-neg)
H influenzae
Actinobacillus 
Streptococcus bovis
Fungi
Coxiella burnetii, 
Brucella species, 
Culture-negative Haemphilus species, Actinobacillus,actinomycetemcomitans, Cardiobacterium hominis, eikenella corrodens and Kingella species (HACEK)
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13
Q

How can IE be classified?

A

Acute or subacute
Nidus (localisation) of infection +/- intra-cardiac material
Mode of acquisition (IVDU, healthcare or community)
Active infective endocarditis
Recurrence (relapse or reinfection)

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14
Q

What is an atypical presentation of IE?

A

Elderly or immunocompromised patients

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15
Q

What is an acute presentation of IE?

A

Fever
Embolic signs/symptoms
Decompensated HF

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16
Q

What is a subacute presentation of IE?

A

Fever
Palpitation
Immunologic/vascular phenomena
Non-specific constitutional symptoms

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17
Q

What are common symptoms of IE?

A 
Fever/chills 
Night sweats 
Malaise
Fatigue
Anorexia
Weight loss 
Non-specific:
Weakness
Arthralgia 
Headache 
SOB
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18
Q

What are clinical signs of IE?

A 
Cardiac murmur (regurgitant)
Janeway lesions 
Osler nodes 
Roth spot 
Meningeal signs 
Splinter haemorrhage 
Cutaneous infarcts 
Vasculitic rash
19
Q

What are Janeway lesions?

A

Haemorrhagic, macular, painless plaques with predilection for palms and soles

20
Q

What are Osler nodes?

A

Small, painful nodular lesions found on the pads of fingers or toes

21
Q

What investigations are carried out for IE?

A 
Blood culture 
FBC
U+Es
Urinalysis +ve for blood
ECG 
CXR
MRI
Leucocyte SPECT/CT
Echo (transthoracic (TTE) +/- transoesophageal (TOE))
22
Q

What do you look for in FBC?

A

Elevated acute inflammatory markers:
Erythrocyte sedimentation rate (ESR)
C-reactive protein (CRP)

23
Q

What can an ECG show for IE?

A

PR interval prolongation > 0.2s

24
Q

What can an CXR show for IE?

A

Pulmonary congestion or abscess

25
Q

When to carry out TOE after a TTE echo?

A

If has prosthetic valve or intracardiac device
Non-diagnosis TTE
Postive TTE

If TOE negative but high suspicion, repeat TTE and/or TOE with 5-7days

26
Q

What investigations for IE should be carried out if patient have a native valve?

A
  1. Repeat echo
  2. Imaging for embolic events
  3. Cardiac CT
27
Q

What investigations for IE should be carried out if patient have a prosthetic valve?

A
  1. Repeat echo
  2. Leucocyte SPECT/CT
  3. Cardiac CT
  4. Imaging for embolic events
28
Q

What are the 3 categories of IE after investigation?

A

Definite
Possible
Rejected

29
Q

What are the 2 major criterias for 2015 Modified Duke’s Criteria?

A

Blood cultures positive for IE

Imaging positive for IE

30
Q

What are the critierias that determine positive IE blood cultures?

A

Typical microorganisms of IE from 2 separate blood cultures: Strep viridans, strep bovis, HACEK grow, staph aureus

Microorganisms of IE from perisistently positive blood cultures: >2 pos. from samples 12hr apart OR all 3 or most of cultures > 4 taken 1 hr apart

Single positive blood culture for coxiella burnetti or phase I IgG antibody titre > 1:800

31
Q

What are the critierias that determine positive IE in imaging?

A

A. Echocardiogram positive for IE: vegetation, abscess, pseudo aneurysm, valvular perforation

B: Abnormal activity around the site of prosthetic valve implantation detected by PET/CT or radiolabelled leukocytes SPECT/CT

C. Paravalvular lesions by cardiac CT

32
Q

What are the 5 minor criteria?

A
  1. Prediposing heart conditions or IVDA
  2. Pyrexia >38
  3. Vascular phenomena: major arterial emolbi, intracranial haemorrhage, conjunctival haemorrhage and janeways lesions
  4. Immunological phenomena: oilers nodes, roth spots and rheumatoid factor
  5. Microbiological evidence; positive blood culture but does not meet a major
33
Q

What criteria is required to diagnose definite IE?

A

2 major
1 major and 3 minor
5 minor

34
Q

What criteria is required to diagnose possible IE?

A

1 major and 1 minor

3 minor

35
Q

What criteria is required to diagnose rejection IE?

A

Resolution of endocarditis with antibiotics therapy <= 4 days

36
Q

What does does treatment of IE depend on?

A

Whether patient has received previous antibiotic therapy

Whether the infection affects a native valve or a prosthesis (if so, was surgery early or late PVE)

The place of infection (community, nosocomial, healthcare related) and knowledge of the local epidemiology, especially for antibiotic resistance and specific culture-neg pathogens

37
Q

What antibiotics are used to treat community-acquired native valves or late prosthetic valves?

A

Ampicillin
Flucloxacillin or oxacillin
Gentamicin

38
Q

What antibiotics are used to treat early PVE or nosocomial and non-nosocomial healthcare related endocarditis?

A

Vancomycin
Gentamicin
Rifampin

39
Q

What are patient characteristics that are poor predictors of IE?

A

Old
Prosthetic valve IE
Diabetes M
Comorbidity

40
Q

What are clinical complications of IE which suggests poor prognosis?

A 
Heart failure 
Renal failure 
> moderate area of ischaemic stroke 
Brain haemorrhage 
Septic shock
41
Q

What are microorganisms of IE which suggest poor prognosis?

A

Staph aureus
Fungi
Non-HACEK

42
Q

What are the preventive measures?

A 
Strict dental hygiene 
Disinfection of wounds 
Eradication or decrease of chronic bacterial carriage: skin, urine 
Curative antibiotics for infection
No self-medication with antibiotics 
Strict infection control 
Discourage piercing and tattooing 
Limit use of infusion catheters and invasive procedures
43
Q

What are echocardiographic findings that are poor predictors?

A 
L sided valve regurgitation
Low LV EF
PHT 
Large vegetations 
Prosthetic dysfunction 
Premature mitral valve closure

Cardiovascular System (37 decks)

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