Infective Endocarditis

Question 1

What is Infective Endocarditis?

Answer 1

• Infection part of the endocardium, usually the surface of a valve

Question 2

What are the causes of infective endocarditis?

Answer 2

=> Bacterial (more common):

• Streptococci, weakly pathogenic (Strep Epidermis common in those with indwelling lines, Strept bovis can also cause colorectal cancer)
• Staphloccoci, highly pathogenic (Staph Aureus common in of IV drug users)

=> Fungal
- Typically in immunocompromised

Question 3

What is the pathophysiology of Infective Endocarditis?

Answer 3

• Bacteria delivered to the heart in an episode of bacteraemia
• Organisms adhere to and invade valve

=> Endocardium is usually resistant to infection, but infection can occur in one of two ways:

• Highly pathogenic organism invading a normal valve
• Weakly pathogenic organism invading an abnormal valve
• As organism replicates, it gets buried in platelets and fibrin, forming a vegetation
• Vegetation is a thrombus containing microorganisms

Question 4

What are the complications of infective endocarditis?

Answer 4

=> Disturbance of valve function
=> Embolism
=> Formation of antigen-antibody immune complexes (clinical features depend on where these immune complexes are deposited)

Question 5

What are the investigations in suspected Infective Endocarditis?

Answer 5

=> Blood cultures
- At least 3 sets of blood cultures taken from different sites, minimum 1 hour apart

=> Transoesophageal Echocardiography

=> Dukes Criteria

• 2 major criteria
• 1 major and 3 minor criteria
• 5 minor criteria

=> Urinalysis
- Microscopic haematuria

Question 6

What are the major and minor criteria of Dukes Criteria?

Answer 6

=> Major Criteria:
- Positive blood cultures
(typical microorganisms from 2 blood cultures)
(persistent positive blood cultures taken >12 hours apart)
(3 or more positive cultUres taken >1 hour apart)
- Evidence of endocardial involvement noted on echocardiography

=> Minor Criteria:

• Predisposing valvular or cardiac abnormality
• Fever
• Vasculitic phenomena
• Embolic phenomena
• Positive blood cultures that do not meet major criteria
• Suggestive echocardiographic findings

Question 7

What valve is most commonly affected by Infective Endocarditis?

Answer 7

Mitral valve but in cases where Infective Endocarditis is causes by IV drug use, its the Tricuspid Valve

Question 8

What are the common signs of infective Endocarditis?

Answer 8

• Janeway lesions (painless)
• Oslers nodes (painfull)
• Splinter haemorrhages

Question 9

What are the indications of surgery in cases of Infective Endocarditis?

Answer 9

• Decompensated Heart Failure
• Failed antibiotic use
• Severe Sepsis
• Perivalvular abscess