9. Infective Endocarditis (IE) Flashcards
What is infective endocarditis (IE)?
Infection of the heart valves or other endocardial lined structure within the heart.
Name 4 types of IE.
- Left sided native IE.
- Left sided prosthetic IE.
- Right sided IE (rarely prosthetic).
- Device related IE e.g. pacemakers, defibrillators.
Which type of IE is more likely to spread systemically?
Left sided IE - these are more likely to cause thrombo-emboli.
(Right side IE could spread to the lungs).
Describe the pathogenesis of IE.
Microbial adherence (infection) -> vegetation on valve -> cardiac valve distortion -> cardiac failure and septic problems.
Name the most common causative organism in IE.
Streptococcus viridans
Give 3 risk factors for IE.
- Congenital - valve defects, VSD, PDA.
- Prosthetic or regurgitant valves.
- Intravenous drug use (IVDU).
- Poor dental hygiene.
- Soft tissue infections.
- Post heart surgery (If infectious material is introduced into the blood stream or during surgery).
Give 3 groups of people who are at risk of IE.
- Elderly.
- IVDU.
- Those with prosthetic valves.
- Those with rheumatic fever.
What bacteria are most likely to cause IE?
- Staph aureus.
- Staph epidermidis (coagulase negative staph).
- Strep viridans (alpha haemolytic).
Give 3 organisms (apart from Strep viridans) that can cause IE.
Enterococci, staph aureus/epidermidis, diphtheroids, Haemophilus, actinobacillus, Coxiella burnetii, chlamydia.
Fungi - Candida, aspergillus, histoplasma.
What is the hallmark of IE?
Vegetation - lumps of fibrin hanging off the heart valves.
Give 5 signs of IE.
- Splinter haemorrhages.
- Osler’s nodes.
- Janeway lesions.
- Roth spots.
- Heart murmurs.
Give 3 symptoms of IE.
- Signs of systemic infection e.g. fever, sweats.
- Embolisation e.g. stroke, PE, MI.
- Valve dysfunction e.g. HF, arrhythmia.
What is an IE patient at risk of?
- Stroke - vegetations.
- Destruction of valve - regurgitation - worsening heart failure.
Name 2 sites where vegetation is likely for IE.
- Atrial surface of AV valves.
- Ventricular surface of SL valves.
Why is it important to remove large vegetations?
To prevent them embolising and causing a stroke, MI etc.
Name the criteria that is used in the diagnosis of infective endocarditis.
Duke’s criteria.
Describe the Duke criteria for the diagnosis of IE.
Definite IE:
1. 2 major
2. 1 major + 3 minor
3. 5 minor
2 Major Criteria:
1. Pathogen grown from blood cultures
2. Evidence of endocarditis on echo, or new valve leak
5 Minor Criteria:
1. Predisposing factors
2. Fever
3. Vascular phenomena/signs
4. Immune phenomena/signs
5. Equivocal blood cultures
Give 2 major points in the Duke’s criteria that if present can confirm a diagnosis of IE.
- Positive blood culture with typical IE microorganism.
- Positive echo showing endocardial involvement.
Give 5 minor points in the Duke’s criteria that, if present, can confirm a diagnosis of IE.
- Predisposing factors
- Fever
- Vascular phenomena/signs
- Immune phenomena/signs
- Equivocal blood cultures
Investigations to confirm suspected infective endocarditis (IE).
- Blood cultures - essential
- 3 sets of blood cultures, at different times and sites. - Echocaardiogram - shows endocardial involvement e.g. TTE (transthoracic echo) or TOE
- Bloods - raised ESR/CRP.
- ECG.
Why might blood cultures be negative in a person with IE?
They may have previously received antibiotics.
Give 2 advantages and 1 disadvantage of a trans-thoracic echo (TTE).
Advantages:
1. Safe.
2. Non-invasive, no discomfort.
Disadvantage:
1. Often poor images so lower sensitivity.
Give 1 advantage and 2 disadvantages of a trans-oesophageal echo (TOE/TEE).
Advantage:
1. Excellent images.
Disadvantages:
1. More invasive, discomfort.
2. Small risk of perforation or aspiration.
Describe the treatment for IE.
- Antibiotics before results of culture
- IV benzylpenicillin + gentamicin. - Antiobiotics based on cultures
- Tailor to cultures + sensitivity - Treat any complications
- Arrhythmia, heart failure, heart block, embolisation, stroke rehab, abscess drainage - Surgery.
Give 4 indications for surgery in IE.
- Antibiotics not working.
- Complications.
- To remove infected devices.
- To replace the valve.
- To remove large vegetations before they embolise.
