- Atherosclerosis is common at the bifurcation of the common carotid
artery
- Stenosis of the internal carotid artery is a potentially treatable
cause of:
- Ischaemic stroke
- Transient ischaemic attack
- Retinal infarction
- A patient with an asymptomatic 50% carotid stenosis has 1-2% per
year risk of a stroke
- The risk of stroke increases with the degree of stenosis
- Once a stenosis has become symptomatic the risk of a stroke is
further increased
- Once an ischaemic stroke has occurred the risk of further stroke is
~10% in the first year and ~5% in subsequent years
Assessment of stenosis
- Carotid bruits are an unreliable guide to severity of stenosis
- May be absent in patients with severe stenosis
Duplex ultrasound
- Doppler recordings allow assessment of flow at stenosis
- Also allows imaging of arterial anatomy
Carotid angiography
- Intra-arterial angiography is the traditional method of assessing
degree of stenosis
- 4% risk of inducing further neurological event
- 1% risk of permanent stroke
Magnetic resonance angiography
- An increasingly used non-invasive technique
Some surgeons will operate on the basis of non-invasive assessments
Medical management
- Stop smoking
- Pharmacological treatment of hypertension and diabetes
- Prophylactic aspirin
- Asprin prevents around 40 ‘vascular events’ per 1000 patients
treated for 3 years
- It should be started at 175-150 mg daily once ischaemic stroke
confirmed by CT
- It should also be given to those with asymptomatic stenoses
- The combination of aspirin and dipyridamole is no more effective
than aspirin alone.
Surgery for asymptomatic stenosis
Asymptomatic Carotid Atherosclerosis Study
- 1662 patients with more than 60% reduction in luminal diameter
- Randomised to either:
- Endarterectomy + medical treatment (aspirin 300 mg)
- Medical treatment alone
- Risk of ipsilateral stroke over 5 year period was reduced (5% vs.
11%) in surgery group
- 2.3% in surgery group had stroke within 30 days of surgery
- 0.4% in medical group had stroke in same time period
- Overall, benefit for those with asymptomatic stenosis but only the
presence of a low perioperative complication rate.
Asymptomatic Carotid Surgery Trial
- 3120 patients with more than 60% reduction in luminal diameter
- Randomised to either immediate or deferred carotid surgery
- Risk of stroke within 30 days of surgery was 3.1%
- Risk of stroke over 5 year period was reduced (3.8% vs. 11%) in
surgery group
- Results were similar to ACAS study
Surgery for symptomatic stenosis
Two large trials have been published
North American Symptomatic Carotid Endarterectomy Trial (NASCET)
- Compared endarterectomy plus medical treatment in those patients
with
- Non-disabling stroke in 4-6 months prior to surgery
- Severe (70-99%) ipsilateral stenosis
- The risk of stroke or death over 2 years was reduced (9% vs. 26%) in
surgery group
- 5.8% randomised to surgery had stroke within 30 days
- Benefit also seen in those with more than 50% stenosis but not to
same degree
European Carotid Surgery Trial (ECST)
- ECST risk of stroke or death over 3 years was reduced (12% vs. 22%)
in surgery group
- 7.5% randomised to surgery had stroke or died within 30 days of
operation
- In those with mild (0-30%) and moderate (30-60%) symptomatic
stenoses there was benefit from surgery
- Overall, In those with symptomatic stenoses
- Best results are seen in those with more severe stenosis
- Benefit only seen in institutions with low perioperative stroke and
death rate
- Surgery indicated in those with severe stenosis (more than 70%) that
have recently become symptomatic
- Operation should be performed by experienced surgeon
- Centres should audit their results and have a perioperative stroke
rate of less than 7%
- Angina and hypertension should be well controlled pre-operatively
- If patient selection is poor or complication rate high then there
will be no benefit from surgery.
Carotid Stenting
- Angioplasty and stenting is being increasingly used to dilate
stenoses
- Involves selective catheterisation of common carotid artery
- Wire advanced into external carotid artery
- Sheath placed in normal segment of common carotid artery
- Stenotic lesion negotiated with distal protection device
- This is placed in internal carotid artery and involves either
- Balloon occlusion system
- Polyurethane sac
- Requires patent contralateral internal carotid artery
- Angioplasty is then performed and stent deployed
- Distal protection devise is then retrieved
Results of carotid stenting
- Several large trials are in progress
- Two randomised trials have reported
Carotid Artery and Vertebral Artery Transluminal Angioplasty and
Stenting (CAVATAS) Study
- Started in 1992 before use of distal protection devices
- Not all patients undergoing angioplasty had a stent placed
- More than 500 patients randomised to either stenting or
endarterectomy
- Stroke rate about 10% in both groups
Study of Angioplasty with Protection in Patients at High Risk for
Endarterectomy (SAPPHIRE) Study
- Recruited more than 300 high risk patients
- 70% were asymptomatic with stenoses of more than 80%
- Results suggest that stenting may be safer than surgery
- Fewer earlier neurological events in stenting group
- Fewer major adverse events at one year
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