Infective endocarditis Flashcards
What is infective endocarditis?
Infection of endocardium, affecting the:
- Heart valves
- Inteventricular septum
- chordae tendinae
- intra-cardiac devices
Describe the epidemiology of IE
Older patients Degenerative aortic stenosis Rheumatic heart disease Invasive procedures Intracardiac devices Valve disease Prosthetic valves CHD IV drug abuse (usually affects R side) Immunocompromised patients
Name some cardiac risk factors for IE
MVP VSD AS RHD Prosthetic valves Cardiac surgery for native IE Prior native IE Surgery for prosthetic IE
Name some non-cardiac risk factors for IE
IV drug use Indwelling medical devices DM AIDS Chronic skin infections or burns Genitourinary infections Pregnancy/abortion/delivery Alcoholic cirrhosis GI lesions Solid organ transplant Homeless, lice Pneumonia and meningitis Infected farm animals Dog/cat exposure
Describe the pathophysiology of IE
Damage to epithelium:
- Nonbacterial thrombotic endocarditis, sterile vegetation
- Mechanical disruption of valve endo.
Bacterial colonisation
What can cause bacteraemia?
Extracardiac infections
Invasive procedures
Gingival disease
Activities of daily living e.g. brushing teeth
What organism is most associated with acute onset IE?
Staph Aureus
What organism is most associated with sub-acute onset IE?
Streptococci
Describe some modes of acquisition of IE
Health care related - nosocomial/idiopathic (hospital) - non-nosocomial (home based care) Community acquired IVDA
State some symptoms of IE
Fever Fatigue Malaise weight loss headache Musculoskeletal pain Altered mentation (mental activity) Murmur Immune complex deposition e.g. splinter haemorrhages, vasculitic rash, Roth spots, Oslers nodes, Janeway lesions Nephritis Signs of HF
Describe vasculitis rash
Diffuse, non-blanching red/purple (petechial) spots, purpuric
What does purpuric mean?
Rash caused by internal bleeding from small vessels
Describe Roth’s spots
Retinal haemorrhages, spots with a white pale centre at the back of the eye due to coagulated fibrosis
Describe Oslers nodes
Deep red spots, painful, raised, tend to be on finger pulps but can be on the palms or soles of the feet
Describe Janeway lesions
Flat, echymotic (like bruises) on palms or soles of feet, non-tender
What clinical sign is pathognomonic for IE?
Janeway lesions
When might some clinical signs be absent in patients?
Immunocompromised
Elderly
After antibiotic treatment
IE evolving less virulent/atypical organism
When should you be very suspicious of IE?
New murmur Pyrexia of unknown origin Known IE causative organism Prosthetic material Previous IE CHD New conduction disorder Immunocompromised IVDA
What investigations would be used for IE?
Full blood count e.g. CRP, ESR, U+Es Urinalysis - blood = nephritis ECG CXR ECG - TTE and TOE Blood cultures
How should blood cultures be taken?
3 sets taken 6 hours apart from different sites of the body
If in septic shock, this is accelerated to only 2 sets taken an hour apart
Describe ECG taking when investigating IE
TTE first only
- if positive straight to TOE
- if negative no TOE unless clinical suspicion is high, and then repeat after 7/10 days
Why is TOE taken?
When suspicion is high, to find:
- complications
- abscesses
- measure size of vegetation
When should ECG (TTE/TOE) be repeated?
If suspicion is still high
New complication e.g. murmur, fever, embolism, HF
To assess treatment efficacy
What % of IE cultures show positive blood cultures?
85%
