Infective Endocarditis

Question 1

What is infective endocarditis?

Answer 1

Infection of part of the endocardium, usually the endocardial surface of a valve.

Question 2

What should you consider in a fever and a new murmur until proven otherwise?

Answer 2

Infective endocarditis

Question 3

What are the typical causes of infective endocarditis?

Answer 3

Usually bacterial:

1. Streptococci (S. viridans 40-50%) - originates in mouth, weakly pathogenic.
2. Staphylococci (S. aureus 20-30%) - highly pathogenic.
3. E. coli and less commonly fungi (immunocompromised).

Question 4

What are the risk factors for developing infective endocarditis?

Answer 4

Skin breaches, renal failure, immunosuppression, diabetes mellitus.

Question 5

What is the pathogenesis of infective endocarditis?

Answer 5

1. Bacteria delivered to heart during episode of bacteraemia - from tooth brushing to surgery.
2. Highly pathogenic organism or abnormal valve allows infection.
3. Organisms replicate and become enmeshed with layers of platelets, fibrin and inflammatory cells on valve surface (vegetations)

Question 6

What is a vegetation?

Answer 6

A thrombus containing microorganisms.

Question 7

What are the signs of infective endocarditis in these areas?

1. Septic
2. Cardiac
3. Immune complex
4. Embolic

Answer 7

1. Fever, rigors, night sweats, malaise, weight loss, anaemia, splenomegaly, clubbing.
2. New murmur, change in existing murmur.
3. Vasculitis, microscopic haematuria, AKI
4. Various sites for embolisation with varying presentations, Jane way lesions, Osler’s nodes, splinter haemorrhages.

Question 8

How is infective endocarditis diagnosed?

Answer 8

1. Modified Duke’s criteria - 2 major/1 major 3 minor/5 minor.
2. 3 sets of blood cultures 1 hour apart from different sites at peak fever (major)
3. Positive finding on transoesophageal echo (major)

Question 9

What is the treatment for infective endocarditis?

Answer 9

1. Consult antibiotic guidelines
2. Surgery if - heart failure, valvular obstruction, repeated emboli, myocardial abscess.
3. 50% require surgery

Question 10

What are the complications of infective endocarditis?

Answer 10

1. Disturbance of valvular function - underlying structure destroyed (regurgitation)
2. Embolism - part of vegetation breaks away (stroke)
3. Formation of Ag-Ab immune complexes - deposit in glomeruli (glomerulonephritis)