Infective Endocarditis Flashcards
What is endocarditis?
an endovascular infection of cardiovascular structures including cardiac valves, atrial and ventricular endocardium, large intrathoracic vessels and intracardiac foreign bodies
What is the approx. mortality of untreated endocarditis?
100%
True or false: fever + new murmur = infective endocarditis until proven otherwise
true
What is infective endocarditis?
Infective endocarditis is when the heart’s inner lining (the endocardium) becomes inflamed secondary to an infection.
Is infective endocarditis more common in men or women?
Men
What are the 3 layers of the heart?
An outer epicardium (connective tissue and fat)
A middle muscular myocardium
An inner endocardium
Give 6 potential causes of bacteraemia that may lead to endocarditis:
1) poor dental hygiene
2) IV drug use
3) soft tissue infection
4) dental treatments
5) intravascular cannulae infection
6) cardiac surgery or permanent pacemakers
How does damaged endothelium increase endocarditis risk?
damaged endothelium promotes platelet and fibrin deposition which allows organisms to adhere and grow, leaving to the formation of an infected vegetation
Give two reasons for abnormal cardiac endothelium:
1) valvular lesions creating non-laminar flow
2) septal defects or a patent ductus arteriosus
What two cardiac structures are most commonly affected by infective endocarditis?
1) mitral valve
2) aortic valve
Is endocarditis most commonly left-sided or right-sided?
Left-sided
Only 5-10% are right-sided
What cardiac region is most commonly affected by infective endocarditis in IV drug users?
right-sided chambers
What is the most causative bacteria for infective endocarditis?
Staphylococcus aureus
Give three ways in which S. aureus can reach the heart:
1) infection of prosthetic valves
2) IV drug user contamination
3) infected indwelling catheters
What % of infective endocarditis is caused by Streptococcus viridans in developing countries?
50%
Give two examples of S. viridans bacteria:
1) Streptococcus mitis
2) Streptococcus sanguinis
Where is S. viridans usually found?
Mouth (particularly in dental plaque)
Give 2 factors that increase risk of S. viridans infective endocarditis?
1) poor dental hygiene
2) dental procedure
Give two ways in which Staph. epidermidis can reach the heart:
1) colonising indwelling lines
2) colonising prosthetic valves
What bacteria is the most common cause of infective endocarditis immediately after surgery?
Staphylococcus epidermidis
What bacteria associated with colorectal cancer causes infective endocarditis?
Streptococcus bovis
Give two examples of non-infective endocarditis:
1) Libman-Sacks endocarditis
2) Non-bacterial thrombotic endocarditis
What is Libman-Sacks endocarditis?
endocarditis associated with SLE
What is non-bacteria thrombotic endocarditis?
small, sterile vegetations deposited on valve leaflets causing inflammation of the endocardium
Give the overall framework of the Modified Duke criteria
either of the following confirms infective endocarditis diagnosis
1) positive microbiology/histology test on vegetations
2) patient fits two points of the major criteria
3) patient fits one point of the major and 3 points of the minor criteria
4) patient fits five points of the minor criteria
Give 4 examples of major points from the Modified Duke criteria:
1) two positive blood cultures consistent with endocarditis bacteria
2) positive molecular assays for gene targets
3) positive echocardiogram (e.g. abscess, vegetation, new valvular regurgitation)
4) new valvular regurgitation
Give 4 examples of minor points listed in the Modified Duke criteria:
1) predisposing heart condition or IV drug user
2) fever >38 degrees C
3) vascular signs e.g. splinter haemorrhages
4) immunological signs e.g. Osler’s nodes
Give 8 potential clinical features of infective endocarditis:
1) fever
2) heart murmur (new)
3) petechiae
4) Janeway lesions
5) Osler’s nodes
6) splinter haemorrhages
7) Roth spots
8) haematuria, glomerulonephritis and suspected renal infarction
What is petechiae?
small red/purple spots due to capillary haemorrhage
What are Janeway lesions?
irregular, painless erythematous macules found on the thenar and hypothenar eminence
What are Osler’s nodes?
small, tender, red/purple nodules on the pulp of finger tips
What are roth spots?
Retinal hemorrhages with pale centers
How many blood cultures should be taken when investigating infective endocarditis?
three (all from different sites)
Give the 4 key investigations that should be carried out for suspected infective endocarditis:
1) blood cultures
2) echocardiography
3) FBC
4) serology for culture negative endocarditis
What are 5 intrinsic risk factors for infective endocarditis?
- Valvular stenosis or regurgitation
- Hypertrophic cardiomyopathy
- Structural heart disease with turbulent flow
- Prosthetic heart valves
- Previous infection
What are 3 extrinsic risk factors?
Intravenous drug use (right-sided endocarditis)
Invasive vascular procedures (e.g. central lines)
Poor oral hygiene/dental infections
How long should antibiotics be given for to treat infective endocarditis?
4-6 weeks
Give 4 antibiotics given to treat Staphylococcal endocarditis:
1) vancomycin
2) gentamicin
3) flucloxacillin
4) benzylpenicillin
