Carotid stenting

Carotid stenting (CAS) is a minimally-invasive surgical procedure available to correct carotid stenosis (narrowing of the carotid artery lumen by atheroma). Carotid stenosis can present with no symptoms (diagnosed incidentally) or through symptoms such as transient ischemic attacks (TIAs) or cerebrovascular accidents (CVAs, strokes). In a number of clinical trials, the rates of stroke and death have been noninferior or slightly lower than the current "gold standard" approach, carotid endarterectomy.

Over 14,000 patients have been enrolled in trials to evaluate the results of carotid stenting in patients at high risk for surgery. High risk characteristics include anatomical or medical co-morbid considerations. The most significant study to date has been the SAPPHIRE study, which in a randomized controlled study showed carotid stenting to be noninferior to endarterectomy in total major adverse event rates, but superior in rates of major procedural stroke, cranial nerve palsy, and myocardial infarction. (Yadav et al. "Protected Carotid-Artery Stenting versus Endarterectomy in High-Risk Patients". New England Journal of Medicine. October 7, 2004. pp 1493-1501)

The question of carotid stenting in non-high-risk patients has yet to be answered, with a few trials ongoing, including the Carotid Revsacularization Endarterectomy versus Stenting Trial (CREST)[1] funded by the National Institutes of Health (NIH.)

Additional recommended knowledge

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Procedure

• Informed consent obtained and local anaesthetic administered
• Preparation of both groins with antiseptic and draped
• Puncture into femoral artery and access through short sheath
• Guidewire passed through aorta and into arch
• Arch aortogram obtained if not previously performed to confirm suitability to continue
• Carotid and cerebral angiogram performed
• Long access sheath placed after cannulation of common carotid artery (CCA)
• Guidewire passed through area of carotid narrowing
• Placement of embolic protection device above the area of narrowing
• Angioplasty of carotid narrowing, but more commonly proceed straight to deployment of stent into area of narrowing
• Angioplasty post stent deployment
• Removal of protection device, guidewires and sheath
• Aftercare of groin puncture site

Indications

The aim of CAS is to prevent the adverse sequelae of carotid artery stenosis secondary to atherosclerotic disease, i.e. stroke.

Carotid stenting is currently indicated for the following patients:

Patients who are: Symptomatic with >50% stenosis Asymptomatic with >80% stenosis And at least one anatomic or co-morbid risk factor placing them at high-risk for adverse events from CEA:

Anatomic Contralateral carotid occlusion Contralateral laryngeal palsy Post-radiation treatment Previous CEA recurrent stenosis High cervical ICA lesions CCA lesions below the clavicle Severe tandem lesions

Co-morbid Congestive Heart Failure (Class III/IV), and/or known severe left ventricular dysfunction <30% Open-heart surgery within 6 weeks Recent myocardial infarction (>24 hours and <4 weeks) Unstable angina (CCS class III/IV) Synchronous severe cardiac and carotid disease requiring open heart surgery and carotid revascularization Severe pulmonary disease to include any of the following: Chronic oxygen therapy Resting P02 of < 60 mmHg Baseline hematocrit > 50% FEV1 or DLCO < 50% of normal Abnormal stress test Age greater than 80 years

Patient Selection Warnings:

Lesion Characteristics: Patients with evidence of intraluminal thrombus thought to increase the risk of plaque fragmentation and distal embolization. Patients whose lesion(s) may require more than two stents. Patients with total occlusion of the target vessel. Patients with lesions of the ostium of the common carotid. Patients with highly calcified lesions resistant to PTA. Concurrent treatment of bilateral lesions.

Access Characteristics: Patients with known peripheral vascular, supra-aortic or internal carotid artery tortuosity that would preclude the use of catheter-based techniques. Patients in whom femoral or brachial access is not possible

Patient Characteristics: Patients at low-to-moderate risk for adverse events from carotid endarterectomy. Patients experiencing acute ischemic neurologic stroke or who experienced a stroke within 48 hours. Patients with an intracranial mass lesion (i.e., abscess, tumor, or infection) or aneurysm (>9mm). Patients with arterio-venous malformations of the territory of the target carotid artery. Patients with coagulopathies. Patients with poor renal function, who, in the physician’s opinion, may be at high-risk for a reaction to contrast medium. Patients with perforated vessels evidenced by extravasation of contrast media. Patients with aneurysmal dilation immediately proximal or distal to the lesion. Pregnant patients or patients under the age of 18.

References

• Biller J, Feinberg WM, Castaldo JE, Whittemore AD, Harbaugh RE, Dempsey RJ, Caplan LR, Kresowik TF, Matchar DB, Toole JF, Easton JD, Adams HP Jr, Brass LM, Hobson RW 2nd, Brott TG, Sternau L. Guidelines for carotid endarterectomy: a statement for healthcare professionals from a Special Writing Group of the Stroke Council, American Heart Association. Circulation 1998;97:501-9. PMID 9490248.
• Golledge J, Mitchell A, Greenhalgh RM, Davies AH. Systematic comparison of the early outcome of angioplasty and endarterectomy for symptomatic carotid artery disease. Stroke 2000;31:1439-43. PMID 10835469. Full text,