Infective Endocarditis (IE)

Question 1

Definition of IE

Answer 1

• IE is an infection involving the endocardial surface of the heart, including the valvular structures, the chordae tendineae, sites of septal defects, or the mural endocardium.

Question 2

Aetiology of IE

Answer 2

• Viridans group streptococci most common in native valves
• S. aureus most common in IVDUs
• Coagulase negative staphylococci most common in prosthetic valves

Question 3

Signs and Symptoms of IE (FROM JANE)

Answer 3

• Signs/symptoms include:
  
  • Fever, fatigue
  • Roth’s spots
  • Osler’s nodes
  • Murmur, malaise, myalgia
  • Janeway lesions
  • Anaemia, anorexia, arthralgia
  • Nail haemorrhage, night sweats
  • Emboli
  • Weight loss, weakness, headache and SOB
• Risk factors include Hx of endocarditis, presence of prosthetic valves, some congenital heart disease (unrepaired cyanotic disease, repaired congenital disease with prosthetic material, repaired congenital heart disease adjacent to site of prosthetic device) and transplant.

Question 4

Pathophysiology of IE

Answer 4

• Usually develops on the valvular surfaces of the heart which have sustained endothelial damage secondary to turbulent blood flow.
• As a result, platelets and fibrin adhere to the underlying collagen surface and create a prothrombotic milieu.
• Bacteraemia leads to colonisation of the thrombus and perpetuates further fibrin deposition and platelet aggregation, which develops into a mature infected vegetation.

Question 5

Investigation of IE

Answer 5

• Blood cultures
  
  • Bacteraemia
  • Fungaemia
• 12-lead ECG
  
  • Prolonged PR interval
  • Non-specific ST/T wave abnormalities
  • AV block
• ECHO
  
  • Valvular/mobile vegetations

Question 6

Diagnostic Criteria of IE (BE FEVER)

Answer 6

• Dukes Criteria
• BE FEVER
  
  • Blood cultures – typical organism in 2 cultures
  • Evidence of endocardial involvement on echocardiography
  • Fever
  • Echocardiography findings (that don’t fit major criteria)
  • Vascular phenomena (i.e. emboli, haemorrhages)
  • Evidence from microbiology (that don’t fit major criteria)
  • Risk factors (i.e. drug abuse, valvular diseases)

Question 7

Treatment of IE

Answer 7

• IV antibiotics
• Once culture results back from microbiology adjust antibiotics appropriately
• NVE for 4 weeks
• PVE for 6 weeks
• Surgery indicated if:
  
  • HF
  • Uncontrollable intervention
  • Prevention of embolism

Question 8

Complications of IE

Answer 8

• CHF
• Systemic embolization
• Anterior mitral valve vegetation >10mm
• Valvular dehiscence, rupture or fistula
• Splenic abscess
• Mycotic aneurysms

Question 9

Prevention and Prognosis of IE

Answer 9

• Primary prevention
  
  • Antibiotic prophylazis during dental procedures reserved for patients with highest life-time risk (i.e. Hx of endocarditis, prosthetic valves)
• Secondary prevention
  
  • Antibiotic prophylaxis for patients undergoing dental procedures, invasive procedures of the respiratory tract or invasive treatment for infected skin or MSK tissues
• Prognosis
  
  • Worse in elderly patients