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Cardio > Infective endocarditis > Flashcards

Infective endocarditis Flashcards

1
Q

What is endocarditis?

A

Inflammation of the endocardium

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2
Q

What structures in the heart are especially at risk from infective endocarditis?

A

Heart valves

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3
Q

What gender is more at risk from infective endocarditis?

A

Men are twice as likely to get it than women

However, women have a worse prognosis

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4
Q

How does infective endocarditis occur?

A

Microbial infection of the endocardium, typically on the surface of the valves

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5
Q

What valves are typically infected in IE?

A

Mitral & aortic

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6
Q

Summarise the main factors that allow someone to get infective endocarditis

A

Well defined valvular disease (including previous IE)

Prosthetic valves

Congenital heart defects involving valves

IV drug abusers

Immunocompromised

Rheumatic heart disease

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7
Q

What valvular diseases put a patient at risk of getting infective endocarditis?

A

Mitral valve prolapse (regurgitation)

Aortic stenosis

Even if treated, replacement valves put the patient at risk

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8
Q

What congenital heart defect puts a patient at risk of getting infective endocarditis?

A

Bicuspid aortic valve (regurgitation)

VSD

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9
Q

What would cause an ‘at risk’ patient to get infective endocarditis?

A

Bacteraemia often through:

  • Surgical/dental procedure
  • Open wound
  • Intracardiac device
  • Injection with needle (IVDA)
  • Brushing teeth or gum disease (gingivitis)
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10
Q

What puts some elderly people at risk of getting infective endocarditis?

A

Degenerative aortic stenosis is common in the elderly

Aortic stenosis is one of the predisposing valvular defects

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11
Q

What microorganism is overall the commonest cause of infective endocarditis?

A

Strep viridans

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12
Q

What microorganism is the commonest cause of infective endocarditis in IV drug abusers?

A

Staph aureus

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13
Q

What microorganism is the commonest cause of infective endocarditis in those with prosthetic valve replacements?

A

Staph epidermis

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14
Q

What microorganism most commonly causes infective endocarditis in those with rheumatic heart disease?

A

Streptococcus pyogenes

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15
Q

IE caused by IV drug usage differs from other causes of IE. How is this?

A

IVDA tends to cause infective endocarditis at the tricuspid valve

Normally, the Mitral and Aortic valves tend to be the site of primary infection

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16
Q

Describe the mechanism by which infective endocarditis develops

A

Firstly, damage to the endocardium exposes underlying collagen & tissue factor

This causes platelet & fibrin adhesion - forming a small thrombus vegetation

This is called nonbacterial thrombotic endocarditis (NBTE)

The vegetation provides an easy attachment point for microorganisms to attach to - allowing mass adhesion and subsequent infection

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17
Q

The formation of NBTE’s on the endocardial surface leads to one of the key signs of infective endocarditis

What sign is this?

A

Splinter haemorrhages

These form under fingernails, due to small bits of the NBTE breaking off and embolising to the fingers

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18
Q

Where do NBTE’s tend to form?

A

At the edge of valves where the pressure is lowest due to the VENTURI effect

The low pressure is on the side of the valve facing in the direction of blood flow

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19
Q

What are the causes of endocardial damage that allow an NBTE to form?

A 
Turbulent flow 
Electrodes 
Catheters 
Inflammation (rheumatic endocarditis) 
Degenerative changes

25% of the time, can occur on normal endothelium though

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20
Q

What is the difference between ‘early’ and ‘late’ prosthetic valve IE?

A

Early means IE develops < 1 year after valve replacement surgery

Late means > 1 year

21
Q

What are the symptoms of Infective endocarditis?

A 
Fever 
 Headache 
Musculoskeletal pain 
Weight loss 
Malaise

(symptoms are fairly non-specific)

22
Q

What are the signs of infective endocarditis?

A

Murmurs

Splinter haemorrhages
Janeway lesions
Osler’s nodes
Vasculitic rash

Pyrexia
Splenomegaly

Signs of congestive heart failure

23
Q

Why might you look into someones eye if you suspect infective endocarditis?

A

Roth’s spots

Sign of IE

24
Q

Describe what murmurs could be found on someone at risk of IE

A

Mitral prolapse would cause late systolic murmur

  • 5th ic space in MCL
  • Radiation to left axilla

Bicuspid aortic valve can cause aortic regurgitation = diastolic murmur

  • left sternal edge with patient leaning forward
  • held expiration

VSD can cause systolic murmur

Mechanical valves have ‘clicks’

25
Q

How is infective endocarditis investigated?

A

Blood cultures!

+ FBC, CRP, ESR, U&E’s

Urinalysis - if blood culture +ve
ECG
ECHO (TTE ± TOE)
CXR

26
Q

Describe the rules for blood cultures for IE

A

Take 3 sets of blood from different sites

At least 6 hours between

Wait until results are back before starting antibiotic treatment

(If patient septic, 2 sites within 1 hour)

27
Q

What ECG finding will help confirm a diagnosis of IE?

A

Conduction delay

28
Q

A Transthoracic ECHO (TTE) looks normal, but there is high clinical suspicion of IE

What do you do next?

A

TOE

29
Q

Both a TTE & TOE scan look normal, but there remains high clinical suspicion of IE

What do you do?

A

Repeat TTE/TOE at 7-10 days

30
Q

A TTE shows obvious signs of infective endocarditis, making you sure of a diagnosis.

What do you do?

A

Still need to do a TOE

Both TTE & TOE needed for diagnosis

TOE visualises complications, abscesses and can be used to measure size of vegetations

31
Q

Aside from diagnosis, what other uses of ECHO imaging is there?

A

Investigate new complications

Asses ongoing treatment

Assess treatment success

32
Q

Does a negative blood culture result rule out bacterial IE?

A

No - can be negative result if:

  • Prior antibiotic treatment
  • Fastidious bacteria
  • Intracellular bacteria
33
Q

What 3 genus of bacteria are responsible for most (85%) of IE?

A

Strep

Enterococci

Staph

34
Q

S. sanguis, S. mitis, S. salivarius, S. mutans, Germella morbillorum are examples of what?

A

Strep viridans

‘Oral streptococci’

35
Q

Group D streptococci, such as S. bovis / equinus complex cause infective endocarditis relating to illnesses of where?

A

GI tract

ulcerative collitis etc

36
Q

What 2 bacteria are commonly found in Health care associated IE?

A

Staph Aureus

Coagulase negative staph (CNS), Staph epidermidis

37
Q

Why would HACEK group bacteria, nutritionally variant streptococci, Brucella spp and fungi cause problems when using blood cultures to investigate IE?

A

Fastidious

Would cause -ve result on blood culture

38
Q

Why would Coxiella burnetii, Bartonella & Chlamydia cause problems with blood cultures?

A

Intracellular bacteria so would give negative blood test

39
Q

Summarise what you would do if a patient gave a negative blood culture, but you still had high suspicion they had IE

A

serological testing
cell culture
gene amplification
PCR

40
Q

What criteria are used to diagnose IE?

A

Modified duke criteria

41
Q

What major criteria would mean a definite diagnosis of infective endocarditis?

A

2 or more of:

  • Typical organisms of IE from 2 blood cultures
  • Persistently positive blood cultures that have typical organisms of IE
  • Single +ve culture for Coxiella burnetii
  • Positive ECHO
  • New valvular regurgitation / murmur
42
Q

What is the treatment route for Infective endocarditis?

A

IV Antibiotics

treatment can be started as soon as all blood cultures have been taken

± surgery

43
Q

What antibiotics are given together to treat a IE patient with native valves?

A

Gentamicin + Amoxycillin

Or Gentamicin + Vancomycin

44
Q

If a patient has native valves & is septic, what antibiotics should they be given for IE?

A

Gentamicin + Vancomycin

45
Q

How is the antibiotic treatment of Infective endocarditis different for those with prosthetic valves?

A

Gentamicin
Vancomycin
Rifamipicin

46
Q

What investigations are done to monitor how a patient is recovering from IE?

A

Daily - FBC, U&Es, CRP

ECG every 1 or 2 days

Weekly ECHO

47
Q

How is fungal infective endocarditis treated?

A

Dual anti-fungals (long term)

Valve replacement surgery

48
Q

What complications are associated with IE?

A 
heart failure
fistula formation
leaflet perforation
uncontrolled infection
abscess formation
atrioventricular heart block
embolism
prosthetic valve dysfunction /dehiscence

Cardio (41 decks)

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