Infective endocarditis

Question 1

What is infective endocarditis?

Answer 1

Infection of endocarditis usually involving the heart valves, with ‘vegetation’ of the infectious agent.
Mitral valve is more commonly affected, but tricuspid valve is implicated in IV drug users.

Question 2

What are the risk factors for infective endocarditis?

Answer 2

IV drug abuse.
Cardiac lesions.
Rheumatic heart disease.
Dental treatment: requires antibiotic prophylaxis.

Question 3

What is the pathophysiology of infective endocarditis?

Answer 3

Rare infection that usually affects patients who already have a structural valve abnormality. The reason why heart valves are targeted is because the valves of the heart have limited blood supply and consequently white blood cells cannot reach the valves through the blood. Circulating bacteria adhere to the valve causing vegetations.

Question 4

What are the causative agents of infective endocarditis?

Answer 4

Streptococcus viridans.
Staphylococcus aureus.
Staphylococcus epidermidis.
Diphtheroids.
Microaerophilic streptococci.
HACEK group: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella and Kingella.

Question 5

What is the classification of infective endocarditis?

Answer 5

Duke criteria: 2 major criteria or 1 major and 3 minor criteria or 5 minor criteria.
Major criteria:
-2 separate positive blood cultures
-endocardial involvement
Minor criteria:
-fever >38 C
-IV drug user or predisposing heart condition, and
-immunological phenomena, e.g. Osler’s nodes or Roth’s spots
-vascular phenomena, e.g. mycotic aneurysm or Janeway lesions
-echocardiograph findings

Question 6

What investigations should be performed for suspected infective endocarditis?

Answer 6

Blood cultures: take 3 separate cultures from 3 peripheral sites.
Bloods for anaemia.
Urinalysis; microscopic haematuria.
CXR.
Transoesophageal/ transthoracic ECHO for vegetations.

Question 7

What are the signs and symptoms of infective endocarditis?

Answer 7

Fever
Roth's spots (seen on fundoscopy)
Osler's nodes (painful nodules on fingers and toes)
New murmur
Janeway lesions (painless papule on palms and plantars)
Anaemia
Nails: splinter haemorrhages
Emboli

Question 8

What are the complications of infective endocarditis?

Answer 8

Heart failure.
Arrhythmias.
Abscess formation in the cardiac muscle.
Emboli formation: may cause stroke, vision loss or spread the infection to other regions of the body.

Question 9

What is the conservative treatment of infective endocarditis?

Answer 9

Maintain good oral hygiene.

Question 10

What is the medical treatment of infective endocarditis?

Answer 10

Empirical therapy is benzylpenicillin and gentamicin.
Streptococci: benzylpenicillin and amoxicillin.
Staphylococci: flucloxacillin and gentamicin.
Aspergillus: miconazole.

Question 11

What is the surgical treatment of infective endocarditis?

Answer 11

Valve repair or replacement.