Infective Endocarditis Flashcards
What is infective endocarditis
Infection of the endothelial surface of the heart. Heart valves are most commonly affected
What is the pathophysiology of infective endocarditis
It develops on surfaces of the heart which have sustained endothelial damage secondary to turbulent blood flow.
Prosthetic material are also a potential target.
If bacteraemia occurs, these areas can become infected
Bacteraemia can result from procedures (eg. dental) or peripheral infection
What organisms are responsible for IE
S. viridans - prosthetic valve
Staph aureus - IVDA
Enterococci
What criteria are used to diagnose infective endocarditis
Duke criteria
2 major criteria OR
1 major and 3 minor criteria OR
5 minor criteria
What are the major criteria according to Duke criteria
Evidence of endocardial involvement:- Vegetations/abscess on echo New murmur (valvular regurgitation)
Positive blood culture for IE:-
Typical microorganisms from 2 separate blood cultures
What are the minor criteria
Predisposition - heart condition or IV drug user
Fever > 38
Vascular phenomena - arterial emboli, Janeway lesions
Immunological phenomena - glomerulonephritis, Osler nodes, Roth spots, RF
Positive blood cultures but not sufficient to fit major criteria
What are the symptoms of IE
Common symptoms:- Fever Sweats Anorexia and weight loss General malaise
Less common:-
New heart failure
Embolic phenomena eg. stroke
What signs would you expect to see on examination of a patient with IE
Regurgitant murmur Splenomegaly Clubbing - after a few weeks of IE Splinter haemorrhages - >4 is pathological Osler nodes Janeway lesions Roth spots - retinal haemorrhages Microscopic haematuria Features of CVA
*My be evidence of aetiology
What conditions predispose to infective endocarditis
Acquired valvular heart disease Valve replacement Congenital heart disease - not including isolated ASD or fully repaired VSD or PDA Previous IE Hypertrophic cardiomyopathy
What is the most important investigation in a patient with IE
Blood cultures
Multiple (3+) from different sites at different times
What other investigations would you do on a patient with IE
FBC - anaemia of chronic disease
Inflammatory markers - repeated measures provide info on patients response to treatment
Renal function - may be impaired due to infarction glomerulonephritis
Echo - detect vegetation supporting diagnosis of IE as well as complications of IE
How do you manage IE
Broad spectrum IV antibiotics after cultures taken
At least 6 weeks
*Involve microbiologist
Full dental exam and remove and infected teeth
What are the complications of IE
Local destructive effect:- Valve incompetence Abscesses Prosthetic valve dehiscence Myocardial rupture
Embolization:-
Stroke
Ischaemic bowel
Renal infarcts
Autoimmune reaction to the organism:-
Glomerulonephritis
Cerebral vasculitis
Arthritis
What are the indications for valve replacement in IE
Heart failure
Uncontrolled infection
Prevention of embolism from large vegetations
Prosthetic valve endocarditis
What is the prognosis of IE
Mortality around 20%
The following have a worse prognosis:-
Infection of prosthetic valve
Embolic phenomena
Staph aureus as causative organism
