Carotid Disease Flashcards
blood supply to brain?
circle of willis
- left and right internal carotid arteries (no branches in neck, arise from common carotids)
- left and right vertebral arteries (arise from subclavian - 1st branch and travel within transverse foramina of C6-C1)
purpose of carotid endartectomy?
remove atherosclerostic plaque which is narrowing the carotid artery
reducing risk of ischaemic event (prophylactic procedure)
describe circle of willis?
..
how many strokes arise from asymptomatic ICA stenosis?
10-15%
…
medical management of carotid artery disease following TIA?
dual antiplatelet
statin
manage hypertension
definitive management of carotid artery disease after TIA?
urgent carotid artery duplex
if stenosis is 70-90% of vessel then urgent referral for carotid endartectomy within 2 weeks
indication for endartectomy?
> 70% stenosis in affected artery
should be done within 2 weeks
should have confirmed on 2 imaging methods (duplex + CT (or sometimes MRI)) but duplex alone can sometimes be enough
benefits and risks of doing carotid endartectomy after TIA?
there is a high risk of further stroke/TIA in the 2-4 weeks following TIA
procedure greatly reduces this risk
there is however a 3% risk of disabling stroke during the procedure (still less than otherwise though)
contraindication for carotid endartectomy?
100% eclusion
is procedure done if 50-70% occlusion in vessel?
grey area can be done depending on guideline, gender, time since event, surgeon and patient preference multiple TIA (crescendo TIAs) in a short time would be an indication for the procedure even if only 50% occluded
what type of anaesthetic is used?
depends on hospital
regional/local = can check for signs of ischaemia during operation
general = still surgical field
studies show no benefit of one over the other
how is procedure done?
incision along anterior margin of sternocleidomastoid
pull back sternocleidomastoid allowing exposure of carotid sheath
dissection and control of common, internal and external carotid arteries (maximal stenosis occurs at ostium/bifurcation)
clamp the artery
insert a shunt into common and internal carotid (if under GA) to bypass hole in artery and restore blood flow to brain
remove plaque, intima and media of vessel
closure with patch of bovine pericardium
complications of operation?
pain infection bleeding and haematoma (haematoma can lead to airway obstruction due to enclosed space in neck) damage to surrounding structures stroke death
how is bleeding/haematoma risk managed?
heparin during procedure as well as dual antiplatelets
what surrounding structures can be damaged?
hypoglassal (most common as it crosses over internal carotid), recurrent laryngeal and facial nerves
what causes carotid disease>
atherosclerosis
risk factors for carotid disease?
smoking
hypertension
diabetes
hyperlipidaemia
clinical features of carotid artery disease?
asymptomatic or symptoms of reduced blood flow
- contralateral motor/sensory deficit
- speech related deficit
- ipsilateral eye signs (amaurosis fugax)
investigations in carotid artery disease?
duplex US
CT (brain and carotids)
MRI (Brain and carotids)
management of carotid disease?
stop smoking and control risk factors
antiplatelet agents (aspirin, clopidogrel)
carotid endarterectomy
what is a stroke?
acute loss of focal cerebral function for over 24 hrs (can be global in case of coma and sub-arachnoid haemorrhage) with no possible cause other than vascular origin
causes of stroke?
emboli from an atherosclerosis in the internal carotid or other source
cardiac (A fib, valvular disease etc)
iatrogenic trauma to aortic arch (during endovascular surgery)
intra cranial vessel disease
carotid disease on which side can cause brocas/expressive dysphasia?
left (in most people) as brocas area is usually on the left side of brain
CVA vs TIA?
CVA = symptoms lasting >24 hrs or lead to death TIA = symptoms fully resolve within 24 hrs
what is amaurosis fugax?
transient visual disturbance in the eye on the same side as the carotid disease
often described as a curtain coming down
when is surgical intervention useful in carotid disease?
only when symptoms develop
most people are asymptomatic and medical management is more useful and surgery wont add much so not worth the risk
what investigations should all people with focal neurological deficit have?
duplex US of carotid and vertebral arteries
ECG ( to exclude dysrhythmia as a source of embolus)
full assessment of lipid profile
exclude diabetes
what will duplex US of carotids and vertebrals show?
whether stenosis is significant (>50%)
will show character of the plaque and whether it has an ends point which is within reach of surgeon (otherwise theres no point in surgery)
what is done if a duplex is not able to clarify lesion/plaque accurately?
CT/MRI scan of the brain +/- CT/MR angiogram of carotids
excludes intracranial haemorrhage (haemorrhagic infarct = contraindication to surgery), space occupying lesions or areas of infarct
what happens if stenosis >50% is seen on duplex after a TIA and the patient has made a good recovery with return to nearly normal activities?
may benefit from carotid surgery so should make urgent referral to vascular surgery for assessment
why urgent referral to vascular surgery?
carotid endarterectomy is prophylactic so reduces risk of further stroke/TIA
highest risk of another stroke/TIA within first 30 days, esp first 2 weeks so quicker surgery reduces risk the most
how fast should surgery be done after a TIA/stroke in patients with good recovery?
females = within 2 weeks of event (little benefit after 4 weeks) males = within 2 weeks (but still some benefit up to 12 weeks)
why dont patients suffer a reduction in cerebral blood flow during carotid endarterectomy even though the carotid is clamped above and below the plaque?
excellent collaterals at the base of the brain (circle of willis)
what is done if patient does experience reduced cerebral blood flow during surgery?
inert plastic shunt can be used to divert blood around the clamped artery while the operation continues
