Infective Endocarditis Flashcards
What is Infective Endocarditis?
Infection of part of the endocardial surface of a valve.
Risk Factors of Infective Endocarditis (6).
- Previous Episode.
- Rheumatic Valve Disease.
- Prosthetic Valves.
- Congenital Heart Defects.
- IVDUs.
- Recent Piercings.
Which valve is most commonly affected generally?
Mitral valve.
Which valve is most commonly affected in IVDUs?
Tricuspid valve.
Commonest Causative Organisms of infective Endocarditis (4).
- S. aureus (commonest) - IVDU.
- S. viridians (S. minis and S. sanguinis - both associated with poor dental hygiene and dental procedures).
- S. bovis (link : colorectal cancer).
- S. epidermidis - coagulate negative (< 2 months post-surgery e.g. indwelling lines).
Non-Infective Causes of Endocarditis (2).
- SLE - Libman-Sacks.
- Malignancy - Marantic Endocarditis.
Pathophysiology of Infective Endocarditis (3).
- Bacteraemia.
- Invasion and Adhesion to Valve.
- Replication of Pathogens, Enmeshment within Layers of Platelets and Fibrin to Form Vegetations.
What is a Vegetation?
Thrombus containing micro-organisms.
Consequences of Endocarditis (3).
- Disturbance of Valve Function.
- Embolism (Septic) and Aneurysm (Mycotic).
- Antigen-Antibody Immune Complex Formation.
Clinical Signs of Infective Endocarditis (6).
- Janeway Lesions - Non-Tender Macules on Palms/Soles.
- Osler nodes - Tender Subcutaneous Nodules on Finger Pads/Toes.
- Roth Spots - Exudative Haemorrhage Retinal Lesions with Pale Centres.
- Microscopic Haematuria (Glomerulonephritis).
- Splinter Haemorrhages.
- PR Prolongation/Complete AV Block (Aortic Root Abscess).
What combination of signs should raise suspicion of Infective Endocarditis?
Fever and New Murmur.
Investigations of Infective Endocarditis (3).
- 3 Sets of Blood Cultures 1 hour apart from Various Sites.
- 1st Line Imaging : Transthoracic Echo.
- Most Sensitive : TOE.
Diagnostic Criteria of Infective Endocarditis (4)
DUKES :
1. Pathological Criteria -
2. 2 Major Criteria.
3. 1 Major + 3 Minor Criteria.
4. 5 Minor Criteria.
What is Pathological Criteria?
Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery.
What are the Major Criteria? (2)
- Positive Blood Cultures.
- Evidence of Endocardial Involvement e.g. Echo or new Regurgitation.
What are the Minor Criteria? (5)
- Predisposing Heart Condition or IVDU.
- Positive Microbiology but does not meet major criteria.
- Pyrexia.
- Vascular Phenomena.
- Immunological Phenomena.
Management of Infective Endocarditis (2).
- Long-Term (Minimum 6 Weeks) IV Antibiotics - initially Broad-Spectrum, but then sensitive.
- Surgical Repair.
Initial Blind Antibiotic Therapy in Infective Endocarditis (3).
- Native Valve : Amoxicillin +/- Low-Dose Gentamicin.
- Penicillin Allergy, MRSA, Sepsis : Vancomycin + Low-Dose Gentamicin.
- Prosthetic Valve : Vancomycin + Rifampicin + Low-Dose Gentamicin.
Indications for Surgical Repair in Infective Endocarditis (7).
- Haemodynamically Unstable.
- Severe HF.
- Severe Sepsis.
- Valvular Obstruction or Infected Prosthetic Valve.
- Persistent Bacteraemia.
- Repeated Emboli.
- Aortic Root Abscess +/- PR Interval Prolongation.
When is IE Prophylaxis not required? (4)
- Dental Procedures.
- Upper and Lower GI Procedures.
- GU tract procedures.
- Upper and Lower Respiratory Tract Procedures.
Complications of Infective Endocarditis (4).
- Acute Valvular Insufficiency - HF.
- Neurological Complications e.g. Stroke, Abscess, Haemorrhage.
- Embolic Complications.
- Infection e.g. Osteomyelitis, Septic Arthritis.
Poor Prognostic Factors of Infective Endocarditis (4).
- S. aureus.
- Prosthetic Valve - especially if early.
- Culture Negative.
- Low Complement.
