Carotid Artery Stenosis

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Carotid atherosclerosis is one of the main risk factors for ischaemic cerebrovascular events (CVEs).

The area of the carotid artery most commonly affected by atherosclerosis is the bifurcation of the common carotid artery.

Carotid endarterectomy is strongly recommended for severe symptomatic stenosis but not routinely recommended for asymptomatic patients or lesser degrees of stenosis. Trials define symptomatic patients as those having transient ischaemic attacks (TIAs) or minor strokes within three months of entry into the trial.

  • Carotid stenosis is responsible for about 30% of CVEs.[1]
  • The prevalence of haemodynamically significant carotid stenosis varies with age and other risk factors, such as cigarette smoking and a high-fat diet.

Risk factors

  • Smoking.
  • Family history of CVE.
  • Ischaemic changes on electrocardiogram.
  • Obesity.
  • Raised blood pressure.
  • Elevated plasma glucose levels.

Aetiology

  • Atherosclerosis (90% of all cases).
  • Aneurysms.
  • Arteritis.
  • Carotid dissection.
  • Coils and kinks.
  • Fibromuscular dysplasia.
  • Vasospasm.

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  • Patients may present with TIAs or CVEs.
  • Typical symptoms are contralateral weakness or sensory disturbance, ipsilateral blindness, and (if the dominant hemisphere is involved) dysphasia, aphasia or speech apraxia.
  • Cognitive impairment and decline are associated with asymptomatic high-grade stenosis of the left internal carotid artery.[2]
  • Asymptomatic patients are most often identified when a carotid bruit is heard on physical examination.

Signs

  • Detection of a carotid bruit is a common physical examination finding that may lead to a referral for carotid duplex ultrasound.
  • Carotid bruits are not sensitive or specific enough to confirm or exclude significant carotid stenoses.[3] Lack of carotid bruits in patients with cardiovascular disease does not exclude a carotid stenosis.
  • A carotid 'bruit' may also be caused by a cardiac murmur transmitted to the neck or may be due to stiff, calcified or tortuous vessels in the absence of stenosis.
  • Echo colour Doppler ultrasonography is the screening method of choice. It is very accurate and non-invasive.
  • Carotid angiography is the gold standard for diagnosis but may be associated with a 1-2% risk of stroke. Less invasive techniques, such as MR angiography and angio-CT, are becoming increasingly commonly used.
  • One recent study comparing Doppler ultrasound, digital subtraction angiography (DSA) and the 3D CT volume rendering technique found that the decision to operate on an internal carotid artery stenosis may be strongly influenced by the diagnostic method used. DSA and 3D CT correlated well, whereas Doppler ultrasound tended to differ in higher degrees of stenosis, underestimating (compared with DSA) the degree of stenosis.[4]
  • Carotid magnetic resonance angiography: this is very sensitive and specific but its exact role is not clearly proven or well defined.[5]
  • Other investigations:
    • FBC, electrolytes, renal function, lipid profile.
    • Electrocardiogram: evidence of prior myocardial infarction (MI) and ischaemic changes (the most common cause of mortality following carotid endarterectomy is MI).
    • CT scan or MRI of the brain: for all symptomatic patients, in order to rule out other intracranial lesions and identify the presence of new and old cerebral infarcts.
  • Current guidance from the Royal College of Physicians (RCP) advises initial non-invasive carotid imaging with either duplex ultrasound or angiography (can be CT or MR). If significant stenosis is detected, a second imaging test should be performed. This should also be non-invasive - eg, MR angiography or a second ultrasound.[6]

The following are associated with an increased incidence of carotid arterial stenosis:

  • Best medical management of carotid stenosis includes lowering of blood pressure, treatment with statins and antiplatelet therapy in symptomatic patients.[7]
  • Treat associated cardiovascular risk factors - see separate articles Stroke Prevention and Prevention of Cardiovascular Disease.
  • Antiplatelet agents:
    • Low-dose aspirin.
    • Clopidogrel is an alternative to aspirin, in cases of intolerance of aspirin, in preventing recurrence of stroke.
  • Anticoagulation: the use of warfarin in patients with non-cardiac emboli is controversial.

Surgical

  • Carotid endarterectomy (surgical removal of the fatty deposits and blood clots from inside the carotid artery wall):
    • Reduces the risk of disabling stroke or death by 48% in a person with severe symptomatic carotid stenosis (more than 70% stenosis) who has had a TIA.[8]
    • In trials of carotid endarterectomy in people with TIA, the perioperative risk of disabling stroke or of death is less than 5%.
    • Carotid endarterectomy should be performed as soon as the patient is fit for surgery - preferably within two weeks of developing symptoms.[6]
    • Despite a 3% perioperative stroke or death rate, carotid endarterectomy for asymptomatic carotid stenosis reduces the risk of any stroke by approximately 30% over three years. However, the absolute risk reduction is small (1% per annum over the first few years of follow-up in trials).[9]
    • Indications include:
      • Symptomatic patients with greater than 70% stenosis: clear benefit was found in the North American Symptomatic Carotid Endarterectomy Trial (NASCET).[10]
      • Symptomatic patients with 50-69% stenosis: benefit is marginal and appears to be greater for male patients.[9]
      • Asymptomatic patients with greater than 60% stenosis: benefit is significantly less than symptomatic patients with greater than 70% stenosis.[9]
      • In general, symptomatic patients with greater than 50% stenosis and healthy, asymptomatic patients with greater than 60% stenosis warrant consideration for carotid endarterectomy.[9]
  • Carotid angioplasty and stenting:
    • Stenting with the use of an emboli protection device is a less invasive revascularisation strategy than endarterectomy in carotid artery disease. For patients with severe carotid artery stenosis and co-existing conditions, carotid stenting with the use of an emboli protection device appears to be as safe and as effective as carotid endarterectomy.[6][11]
    • One meta-analysis has reported that carotid endarterectomy is superior to endovascular treatment for short-term outcomes. However, stenting was associated with significantly fewer cranial nerve and myocardial complications.[12]
    • However, one study has shown that angioplasty can be as effective as carotid endarterectomy over three years at preventing stroke, with similar major risks.[13]
    • This procedure is currently indicated in selected cases such as restenosis and stenoses, located both proximally and distally to the carotid bifurcation.[14]
  • Carotid atherosclerosis is one of the main risk factors for ischaemic stroke. The annual risk of ipsilateral stroke for asymptomatic severe stenoses is as low as 1-2%, but increases to 13% in patients with recent ischaemic symptoms. The risk decreases after the first 2-3 years from the symptomatic episode, dropping to 3%.[14]
  • Patients with carotid artery stenosis are also at increased risk of MI and sudden death.
  • Following endarterectomy, recurrent stenosis occurs in 1-20% of cases, and re-operation is necessary in 1-3% of cases.[15]
  • Ipsilateral stroke was found to occur in 9% treated with surgery and 26% with medical management after two years of follow-up.[15]

Further reading & references

  1. Henry M, Polydorou A, Klonaris C, et al; Carotid angioplasty and stenting under protection. State of the art. Minerva Cardioangiol. 2007 Feb;55(1):19-56.
  2. Johnston SC, O'Meara ES, Manolio TA, et al; Cognitive impairment and decline are associated with carotid artery disease in patients without clinically evident cerebrovascular disease. Ann Intern Med. 2004 Feb 17;140(4):237-47.
  3. Johansson EP, Wester P; Carotid bruits as predictor for carotid stenoses detected by ultrasonography: an observational study. BMC Neurol. 2008 Jun 24;8:23.
  4. Flis V, Tetickovic E, Breznik S, et al; The measurement of stenosis of the internal carotid artery: comparison of doppler ultrasound, digital subtraction angiography and the 3D CT volume rendering technique. Wien Klin Wochenschr. 2004;116 Suppl 2:51-5.
  5. Westwood ME, Kelly S, Berry E, et al; Use of magnetic resonance angiography to select candidates with recently symptomatic carotid stenosis for surgery: systematic review. BMJ. 2002 Jan 26;324(7331):198.
  6. National clinical guidelines for stroke (fourth edition); Royal College of Physicians (2012)
  7. Ederle J, Brown MM; The evidence for medicine versus surgery for carotid stenosis. Eur J Radiol. 2006 Oct;60(1):3-7. Epub 2006 Aug 21.
  8. Cina CS, Clase CM, Haynes RB; Carotid endarterectomy for symptomatic carotid stenosis. Cochrane Database Syst Rev. 2000;(2):CD001081.
  9. Chambers BR, Donnan GA; Carotid endarterectomy for asymptomatic carotid stenosis. Cochrane Database Syst Rev. 2005 Oct 19;(4):CD001923.
  10. Barnett HJ, Meldrum HE, Eliasziw M; The appropriate use of carotid endarterectomy. CMAJ. 2002 Apr 30;166(9):1169-79.
  11. Yadav JS, Wholey MH, Kuntz RE, et al; Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004 Oct 7;351(15):1493-501.
  12. Meier P, Knapp G, Tamhane U, et al; Short term and intermediate term comparison of endarterectomy versus stenting for BMJ. 2010 Feb 12;340:c467. doi: 10.1136/bmj.c467.
  13. McCabe DJ, Pereira AC, Clifton A, et al; Restenosis after carotid angioplasty, stenting, or endarterectomy in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS). Stroke. 2005 Feb;36(2):281-6. Epub 2005 Jan 13.
  14. De Fabritiis A, Conti E, Coccheri S; Management of patients with carotid stenosis. Pathophysiol Haemost Thromb. 2002 Sep-Dec;32(5-6):381-5.
  15. Barnett HJ, Taylor DW, Eliasziw M, et al; Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med. 1998 Nov 12;339(20):1415-25.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Colin Tidy
Current Version:
Peer Reviewer:
Dr Helen Huins
Last Checked:
28/02/2013
Document ID:
1915 (v22)
© EMIS