Endocarditis

Question 1

Define endocarditis

What are the classifications of endocarditis?

Answer 1

Endocarditis is inflammation of the endocardium of the heart.

1. Endocarditis on normal valves - acute course
2. Endocarditis on abnormal valves - subacute course

Question 2

What is the pathophysiology of infective endocarditis?

Answer 2

• Bacteraemia (or fungi, SLE, malignancy)
• Microorganisms adhere to endocardium & valve
• Microorganism grows and multiplys
• Forms a fibrin-platelet vegetation
  
  • Fibrin thrombosis → embolization
  • Calcification of valves → destruction

Question 3

What are the risk factors for infective endocarditis?

Answer 3

• Previous IE
• Valves with congenital/ acquired disease or prosthetics
• CV disease, especially
• IV drug use
• Immunosuppressed patients
• Indwelling IV catheter
• Rheumatic heart disease

Question 4

What are the main causes of infective endocarditis?

Outline the course & chief cause of acute & subacute IE?

Answer 4

Causes;

• Bacteraemia; Strep. viridans and Staph. aureus
• Fungi, SLE (Libman-Sacks endocarditis) & malignancy

Acute (on normal valves);

• Acute HF +/- emboli
• Staph. aureus

Subacute (on abnormal valves);

• Between acute & chronic
• Any valve abnormality

Question 5

What are the signs of infective endocarditis?

Answer 5

SECI - Septic, Embolic, Cardiac, Immunological

Septic signs;

• Fever, rigors, night sweats, malaise, weight loss, anaemia, splenomegaly, clubbing
• Can cause sepsis

Embolic phenomena;

• Emboli break off

Cardiac lesions;

• Any new murmur, regurgitation (vegetations destroy valve), valve obstruction
• Long PR interval (aortic root abscess)
  
  • May lead to AV block
• LVF

Immune complex deposition;

• Vasculitis
• Microscopic haematuria, GN, acute renal failure
• Roth spots (boat shaped retinal haemorrhage with pale centre)
• Oslers nodes (painful pulp infarcts in fingers/toes due to clots)
• Janeway lesions (painless palmer or plantar macules)
• Splinter haemorrhages (small clots)

Question 6

How would you investigate and diagnose infective endocarditis?

Answer 6

Duke criteria;

Major;

• Positive blood culture;
  
  1. Typical organism in 2 separate culures or
  2. Persistently +ve blood cultures (3 >12hrs apart)
• Endocardium involved;
  
  1. Positive echocardiogram (vegetation, abscess, dehiscence of prosthetic valve)
  2. New valvular regurg (chang in murmur not sufficient)

Minor;

• Predisposition (cardiac lesion; IV drug abuse)
• Fever >38C
• Vascular/ immunological signs
• Positive blood culture that doesnt meet major criteria
• Positive echocardiogram that does not meet major criteria

Requires 2 major, 1 major/ 3 minor, 5 minor

• FBC & differential WCC
• ESR
• CRP
• Complement C3, C4, CH50
• ECG, look for conduction defects
• Urinalysis (protein & microscopic haematuria)
• Echocardiogram (normal does not exclude)

Question 7

How would you treat IE?

Answer 7

• Antibiotics
• Surgery for destructed valve
• Prevent complications; warfarin