Infective Endocarditis

Question 1

General description of IE:

Answer 1

Infection of the inner layer of the heart (endocardium).
Can affect:
Heart valves (native, prosthetic)
Interventricular septum
Chordae tindineae
Endocardium (e.g E . faecalis)

Question 2

Aetiology/risk factors (cardiac and non-cardiac):

Answer 2

Aetiology:

• Streptococcus viridans
• Staphylococcus aureus (most common cause overall)
• Streptococcus bovis
• Enterococcus

Risk factors (cardiac):

• Previous episode of endocarditis
• Aortic stenosis
• Mitral valve prolapse with mitral regurgitation
• Prosthetic heart valve
• Rheumatic heart disease
• Surgical replacement of valves
• VSD

Risk factors (non-cardiac):

• Skin breaches (IV drug use, wounds, dermatitis)
• AIDS
• Immunocompromised patients
• Diabetes mellitus

Question 3

Pathology:

Answer 3

• Bacteraemia (bacteria in the blood) leads to colonisation, fibrin deposition and platelet aggregation
• This leads to a mature infected vegetation

Question 4

Symptoms:

Answer 4

• Fever
• Fatigue
• Malaise
• Rigors
• Night sweats
• Weight loss

Question 5

Signs:

Answer 5

• Pyrexia
• Splinter haemorrhages
• Splenomegaly
• Clubbing
• Roth spots (retinal haemorrhage)
• Osler nodes
• Janeway lesion

Question 6

Investigations:

Answer 6

• Blood culture - Before stating antibiotics, 3 sets at different times ( > 6 hours apart) from different sites
• Blood tests to include FBC, U+E, CRP and ESR (erythrocyte sedimentation rate)
• Urinalysis (to check for haemaruria, +ve blood)
• ECG (conduction delay, heart block)
• Chest x-ray (heart failure, cardiomegaly, pulmonary oedema)
• Echocardiogram (do a TTE- transthoracic echo)
• (CT scan to look for emboli in the spleen, brain etc)

Question 7

Treatment:

Answer 7

• Start IV antibiotics (as soon as all blood cultures have been taken)
• Surgery

Question 8

Complications:

Answer 8

• Heart failure
• Atrioventricular heart block
• Fistula formaiton
• Embolism