Fever and a New Murmur: Endocarditis Flashcards

1
Q

What are the 3 main requirements to diagnose/determine endocarditis?

A
  • Symptoms and signs of infection: fever
  • Embolic phenomena: splinter haemorrages
  • Abnormal heart valve: probably where the emboli have come from!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are splinter haemorrages and what do they look like?

A
  • Red black linear bleeds under the skin that look like splinter, where blood has seeped out of the arteriole
  • May be surrounding fresh bleeding
  • Due to a small clot blocking the arteriole in the nail bed, leading to damage and blood leakage.
  • Can also be in the conjunctiva; ‘conjunctival haemorrages
  • Larger ones cause larger areas of thrombosis and infarction → red and tender → black necrotic tissue (as seen on the feet)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

You can have abnormalities of the mitral and aortic sounds to produce a murmur. What are these caused?

A
  • Mitral valve stenosis (soft, long diastolic, hard to hear)
  • Aortic Valve stenosis (high pitched crescendo)
  • Aoortic valve regurgitation (soft, early diastolic)

These will all result in a murmur and are extremely common abnormalities in endocarditis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does an individuals with endocarditis’s heart valves look and why?

A

Abnormal vegetations of the surface of the valves due to infection, looks like warty/cauliflower lumps.

Bacterial colonisation → clumps of fibrin/platelets/bacterial species forming lumps → damaging/thickening/weakening of the heart valve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is it important to know what valves are more commonly affected?

A

aortic/mitral: common
Tricuspid/pulmonary: less common

Therefore if these break off they will be entering the arterial circulation causing embolic phenomena which you can see.

Or they may cause issues elsewhere;
eg; block a renal arteriole → area of renal infarction → blood in urinee
Into muscle of back → back pain
Up a carotid artery to block a brain blood vessel → temp. transient ischaemic event (until blood is restored and the person may have a perior of a few hours in which the have a neuro deficit
Up a carotid artery to block a brain blood vessel → permanent ischaemic effect → stroke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do valves perforate in endocarditis?

A

The multiplication and colonisation of the infectious organisms on the valve cna lead to weakening and eventual rupture/perforation of a valve leaflets.

ALso weakening and rupture of chordi tendini is a concern → inability to close → regurgitation from v to a → heart failure and death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is endocarditis such a catastrophic infection in comparison to other bodily infections?

A

Heart valves are avascular with no capillaries, and therefore no route of access for neutrophils. Neutrophils are only flowing past the valves throught the highly-pressured and fast-moving bloodstream of the heart.

Therefore the neutrophils can’t get out into the vegetation, and antibiotics are essential for survival, as our host-defence is invalid.

Has a 100% mortality rate!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Draw the flow diargram of pathogenesis of endocarditis.

A

The heart valve is always abnormal (for a variety of reasons).

It is normal to have abnormalities and fibrin/platelet clots but NOT to have bacteria present on these valves!

  • Those with poor dental care with loose rotting teeth (eg; the gingival cresent) that are very sticky to the clot will be a usual cause of endocarditis.
  • Therefore the agents that can stick to the thormbis are the ones to be nervous about!!! Usually are clear but there is a chance they will not!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Should you be concerned if your blood test came back with bacteria in it?

A

Not if these are in trace amounts, as we always have small amounts circulating that our immune system can fight off,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe continuous bacteraemia as a diagnostic method

A
  • high concentration of bacteria in and on vegetation, with bacteria continually shed from vegetation into blood
  • Constant bacteraemia; expect all blood cultures to be postive (with an organism likely to cause endocarditis)
  • Culture blood on 3 occasions at least 20mins apart (90-100% +ve)
    • Culture excised valve
    • normally with infections you have intermittant bacteraemia; but those with endocarditis have constant bacteraemia
    • expect they will all grow the same microbe

Organism identified in about 95% cases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do you need to form a diagnosis?

A
  • hear murmur
  • see embolic phenomena
  • ECG
  • 3x culture to find continuous bacteremia of the same individual microbe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Whats the difference between True bacteraemia, contaminant, or transient bacteraemia.

A

True Bacteraemia:

  • pathogen cultured (s. aureus, E.coli etc)
  • Sometime more then one set of cultures +
  • clinically compatible infective source identified

Contaminant bacteraemia from injection picking up bacteria missed by alcohol wipe

  • skin commensual cultured (staph epidermidis etc)
  • only one set of blood cultures +
  • No apparent infective source

Transient Bacteraemia

  • gut or mouth organism cultured
  • blood cultures only + briefly
  • no apparent infective source
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the treatment for endocarditis?

A

Luckily this is cause by infective agents that are relatively easy to treat. (mainly viridans streptococcil that turn the agar green; alpha haemolytic organisms, usually harmless, it’s just that they’re sticky)

Antibiotic: depends on organism
Method: always IV
Dose: always high dose
Duration: usually ~2-4 weeks
Cure rate: 70-90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why are rheumatic fever and endocarditis a common area of confusion, and how do we distinguish between!

A

These both involve heart valves:

Endocarditis:

  • caused mainly by streptococci in the mouth
  • ECG
  • Treat with penicillin

Rheumatic fever

  • streptococcuous pyogenes
  • doesn’t actually infect heart valves but is instead due to a immune response against the heart valves!!!
  • doesn’t require a blood culture as it’s only in the throat!!
  • ECG
  • Prevent with penicillin to treat throat infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

DIagnosis of Rheumatic Fever!

A
  • Inflammation (NOT infection) of heart, joints, skin, brain
  • Fever
  • Raised ESR and CRP
  • S.pyogenes
  • ANtibody repsonse to S.pyogenes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly