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The carotid artery is the large vertical artery in red. The blood supply to the common carotid artery starts at the arch of the aorta (left) or the subclavian artery (right). The common carotid artery divides into the internal carotid artery and the external carotid artery. Plaque often builds up at that division, and a carotid endarterectomy cuts open the artery and removes the plaque.
Section of carotid artery with plaque. Blood flows from the common carotid artery (bottom), and divides into the internal carotid artery (left) and external carotid artery (right). The atherosclerotic plaque is the dark mass on the left, which would be removed in an endarterectomy.

Carotid endarterectomy (CEA) is a surgical procedure used to prevent stroke, by correcting stenosis (narrowing) in the common carotid artery. Endarterectomy is the removal of material on the inside (end-) of an artery.

Atherosclerosis causes plaque to form in the carotid arteries, usually at the fork where the common carotid artery divides into the internal and external carotid artery. The plaque can build up in the inner surface of the artery (lumen), and narrow or constrict the artery. Pieces of the plaque emboli can break off and travel up the internal carotid artery to the brain, where it blocks circulation, and can cause death of the brain tissue.

Sometimes the plaque causes symptoms first. The symptoms are temporary or transitory strokes, known as transient ischemic attacks (TIAs). By definition, TIAs last less than 24 hours; after 24 hours they are called strokes. Symptomatic stenosis has a high risk of stroke within the next 2 days. National Institute for Health and Clinical Excellence (NICE) guidelines recommend that patients with moderate to severe (50-99% blockage) stenosis, and symptoms, should have "urgent" endarterectomy within 2 weeks.[1]

When the plaque doesn't cause symptoms, patients are still at higher risk of stroke than the general population, but not as high as patients with symptomatic stenosis. The incidence of stroke, including fatal stroke, is 1-2% per year. The surgical mortality of endarterectomy ranges from 1-2% to as much as 10%. Two large randomized clinical trials have demonstrated that carotid surgery done with a 30 day stroke and death risk of 3% or less will benefit asymptomatic patients with ≥60% stenosis who are expected to live at least 5 years after surgery. [2][3] Surgeons are divided over whether asymptomatic patients should be treated with medication alone or should have surgery.[4][5]

In endarterectomy, the surgeon simply opens the artery and removes the plaque. A newer procedure, endovascular angioplasty and stenting, threads a catheter up from the groin, around the aortic arch, and up the carotid artery. The catheter uses a balloon to expand the artery, and inserts a stent to hold the artery open. In several clinical trials,the 30-day incidence of heart attack, stroke, or death was significantly higher with stenting than with endarterectomy (9.6% vs. 3.9%) [6][7]

The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST)[8] funded by the National Institutes of Health (NIH) reported at the International Stroke Conference in San Antonio that the results of stents and endarterectomy were comparable. However, the European International Carotid Stenting Study (ICSS)[9] found that stents had almost double the rate of complications.[10]

Contents

Procedure

The internal, common and external carotid arteries are clamped, the lumen of the internal carotid artery is opened, and the atheromatous plaque substance removed. The artery is closed, hemostasis achieved, and the overlying layers closed. Many surgeons lay a temporary shunt to ensure blood supply to the brain during the procedure. The procedure may be performed under general or local anaesthesia. The latter allows for direct monitoring of neurological status by intra-operative verbal contact and testing of grip strength. With general anaesthesia indirect methods of assessing cerebral perfusion must be used, such as electroencephalography (EEG), transcranial doppler analysis and carotid artery stump pressure monitoring. At present there is no good evidence to show any major difference in outcome between local and general anaesthesia.

Non-invasive procedures have been developed, by threading catheters through the femoral artery, up through the aorta, then inflating a balloon to dilate the carotid artery, with a wire-mesh stent and a device to protect the brain from embolization of plaque material. The FDA has approved 5 carotid stent systems as safe and effective in patients at increased risk of complications for neck surgery. In the SAPPHIRE study, Yadav concluded that this procedure, known as carotid stenting, was non-inferior to carotid endarterectomy in total adverse events, and lowered event rates for major stroke, cranial nerve palsy, and myocardial infarction, in patients at high risk for surgery.[11] It is the consensus of experts in the field that carotid artery stenting should be considered an option for patients who require carotid artery revascularization to prevent stroke and who are at increased risk of having surgical complications. [12]

History

Surgical intervention to relieve atherosclerotic obstruction of the carotid arteries was first successfully performed by Dr. Michael DeBakey in 1953 at the Methodist Hospital in Houston, TX.[13] Since then, evidence for its effectiveness in different patient groups has accumulated. In 2003 nearly 140,000 carotid endarterectomies were performed in the USA (Halm).

Indications

The aim of CEA is to prevent the adverse sequelae of carotid artery stenosis secondary to atherosclerotic disease, i.e. stroke. As with any prophylactic operation, careful evaluation of the relative benefits and risks of the procedure is required on an individual patient basis. Peri-operative combined mortality and major stroke risk is 2 – 5%.

Carotid stenosis is diagnosed with ultrasound doppler studies of the neck arteries, magnetic resonance angiography (MRA) or computed tomography angiography (CTA). The circle of Willis typically provides a collateral blood supply. Surgical management of symptomatic stenoses has a much higher therapeutic index with regard to asymptomatic lesions.

The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) are both large randomized class 1 studies which have helped define current indications for carotid endarterectomy. The NASCET found that for every six patients treated, one major stroke would be prevented at two years (i.e. a number needed to treat (NNT) of six) for symptomatic patients with a 70 – 99% stenosis, where percent stenosis was defined as:[14]

percent stenosis = ( 1 - ( minimal diameter ) / ( poststenotic diameter ) ) x 100%.

Symptomatic patients with less severe carotid occlusion (50 – 69%) had a smaller benefit, with a NNT of 22 at five years (Barclay). In addition, co-morbidity adversely affects the outcome; patients with multiple medical problems have a higher post-operative mortality rate and hence benefit less from the procedure. For asymptomatic patients (those without TIA or strokes) the European asymptomatic carotid surgery trial (ACST) found that asymptomatic patients may also benefit from the procedure, but only the group with a high grade stenosis (60% or more). For maximum benefit patients should be operated on soon after a TIA or stroke, preferably within the first month.

Contra-indications

The procedure cannot be performed in case of:

  • Complete internal carotid artery obstruction (because there is no benefit to treating chronic occlusion).
  • Previous stroke on the ipsilateral side with heavy sequelae, because there is no point in preventing what has already happened, or risking making it worse.
  • Patient deemed unfit for the operation by the anaesthesiologist.

Complications

About 3% of asymptomatic and 6% of symptomatic patients are expected to suffer stroke or death as a result of either the surgery or carotid stenting. Other surgical complications include Hemorrhage of the wound bed which is potentially life-threatening, as swelling of the neck due to hematoma could compress the trachea. Rarely, the hypoglossal nerve can be damaged during surgery. This is likely to result in fasciculations developing on the tongue and paralysis of the affected side: on sticking it out, the patients tongue will deviate toward the affected side. Another rare but potentially serious complication is hyperperfusion syndrome due to the sudden increase in perfusion of the vasculature distal to stenosis.[15]

References

  1. ^ Sharon Swain, Claire Turner, Pippa Tyrrell, Anthony Rudd on behalf of the Guideline Development Group, Diagnosis and initial management of acute stroke and transient ischaemic attack: summary of NICE guidance, BMJ 2008;337:a786, doi:10.1136/bmj.a786 (Published 24 July 2008)
  2. ^ Executive Committee for the Asymptomatic Carotid Atherosclerosis Study (ACAS). Endarterectomy for asymptomatic carotid artery stenosis. Jama. 1995;273:1421-1428.
  3. ^ Halliday A, Mansfield A, Marro J, Peto C, Peto R, Potter J, Thomas D. Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial. Lancet. 2004;363:1491-1502.
  4. ^ Clinical Decisions: Management of Carotid Stenosis, N Engl J Med 358:1617-1621
  5. ^ Drug Therapy Gains Favor to Avert Stroke, By THOMAS M. BURTON, Wall Street Journal, MARCH 3, 2009. Layman's summary of surgery vs. medication-only debate.
  6. ^ Carotid Stenting vs. Endarterectomy: Longer-Term Outcomes JournalWatch General Medicine
  7. ^ Risk-Adjusted 30-Day Outcomes of Carotid Stenting and Endarterectomy: Results From the SVS Vascular Registry, Sidawy AN, Zwolak RM, White RA, Siami FS, Schermerhorn ML, Sicard GA, on behalf of the Outcomes Committee for the Society for Vascular Surgery. J Vasc Surg 2009;49:71-9.
  8. ^ Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) ClinicalTrials.gov.
  9. ^ Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial International Carotid Stenting Study investigators The Lancet, 26 February 2010 doi:10.1016/S0140-6736(10)60239-5Cite
  10. ^ Study Finds Stents Effective in Preventing Strokes By RONI CARYN RABIN, New York Times, February 26, 2010.
  11. ^ Yadav JS, Wholey MH, Kuntz RE, et al. (October 2004). "Protected carotid-artery stenting versus endarterectomy in high-risk patients". N. Engl. J. Med. 351 (15): 1493–501. doi:10.1056/NEJMoa040127. PMID 15470212. 
  12. ^ White CJ, Beckman JA, Cambria RP, Comerota AJ, Gray WA, Hobson RW, 2nd, Iyer SS. Atherosclerotic Peripheral Vascular Disease Symposium II: controversies in carotid artery revascularization. Circulation. 2008;118:2852-2859.
  13. ^ Debakey Bio
  14. ^ Barnett HJ, Taylor DW, Eliasziw M, et al. (November 1998). "Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators". The New England Journal of Medicine 339 (20): 1415–25. PMID 9811916. http://content.nejm.org/cgi/pmidlookup?view=short&pmid=9811916&promo=ONFLNS19. 
  15. ^ van Mook WN, Rennenberg RJ, Schurink GW, et al. (2005). "Cerebral hyperperfusion syndrome". Lancet Neurol 4 (12): 877–88. doi:10.1016/S1474-4422(05)70251-9. PMID 16297845. 

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