Carotid Angioplasty and Stenting

Historical Background

Balloon angioplasty of the carotid artery was first described in the late 1970s as an intervention for carotid artery stenosis. It was proposed as an alternative to carotid endarterectomy (CEA) in medically high-risk patients and those with hostile neck anatomy. Early trials demonstrated the feasibility of the technique but were not widely accepted because of small study size, high complication rates, and only occasional use of stenting. Carotid angioplasty and stenting (CAS) has evolved to its current form with improvements in equipment and technique, increased operator experience, and standard use of cerebral protection during carotid stent placement.

Indications

Key trials have helped to determine which patients are best treated with CAS, but this issue is not yet resolved. The current indication for CAS is high anatomic or physiologic risk for CEA ( Table 8-1 ).

Preoperative Care

• Obtain an understanding of the arch, carotid, and cerebral arterial anatomy before the procedure by arteriogram, computed tomography (CT) angiography, or magnetic resonance angiography. This enhances patient selection and procedural planning.

• A CT or magnetic resonance imaging (MRI) scan of the brain is obtained in symptomatic patients and in those older than 80 years to evaluate for preprocedural cerebral pathology. Patients older than 80 years are at higher risk for stroke after CAS.

• Antiplatelet therapy is initiated with aspirin at 325 mg/day and clopidogrel at 75 mg/day for 5 days before the procedure. In all cases patients should have received clopidogrel (total dose of 300 mg) before the intervention. Patients are asked to discontinue beta-blockers on the day of the stent procedure to help avoid poststent bradycardia.

• A neurologic examination is performed and a stroke scale is completed.

• The procedure is performed under local anesthesia with minimal or no sedation to facilitate patient cooperation and neurologic monitoring. An arterial line is placed for continuous blood pressure monitoring. External pacer pads should be readily available. Patients with severe aortic stenosis undergo placement of a temporary venous pacemaker. Because of the minimal use of sedation, patients may be apprehensive and hypertensive. Avoid acutely reducing the blood pressure during the intervention with pharmacologic agents because poststent hypotension or bradycardia is not uncommon. If antihypertensive medication is required, it is best to use a short-acting agent.

Pitfalls and Danger Points

• Stroke. Stroke may occur with CAS. The perioperative risk of stroke, ipsilateral postprocedural stroke, and death in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) was 2.5% for asymptomatic patients and 6.0% for symptomatic patients. Although minor stroke was higher with CAS than with CEA, the incidence of major stroke and death was similar between the two procedures.

• Difficult access of the carotid artery. Tortuous aortic arch or great vessel anatomy must be analyzed and the appropriate steps must be taken to achieve access safely. A reverse-curved catheter may be required for common carotid artery cannulation. A variety of stiff exchange wires may be used to support a carotid access sheath. In some patients with a diseased arch CAS should be avoided.

• Unable to cross the lesion. The curve at the tip of the guidewire may be altered or the crossing wire may be supported with a directional catheter. The patient’s neck position may be changed to make the course into the lesion less angulated. The residual lumen of a complex lesion is most likely to be just posterior to the flow divider. A buddy wire may also be used to facilitate crossing of the lesion.

• Spasm of the distal internal carotid artery (ICA). If ICA spasm is identified during the CAS procedure, small doses of nitroglycerine may be administered into the carotid sheath. Spasm resolves after the filter and wire are removed.

• No flow after stenting. The filter may be full of obstructive debris and should be aspirated before removal.

• Hypotension, bradycardia, or both. Hypotension and bradycardia occur regularly with CAS but are rarely sustained. They are supported with the appropriate pharmacologic agent.

• In-stent restenosis. Recurrent in-stent stenosis appears to occur with a similar frequency after CAS as it does after CEA. It is usually treated with repeat balloon angioplasty and occasionally with repeat stenting. It is rare for carotid stent patients to require arterial replacement.

Endovascular Strategy

Favorable Versus Unfavorable Aortic Arch Anatomy

Arch tortuosity is a significant deterrent to safe and simple access sheath placement. The arch is considered type I if the branches originate at the top of the arch, type II if the arch vessels arise between the parallel planes delineated by the outer and the inner curves of the arch (moderate angulation), and type III if the branches originate along the upslope of the arch, proximal or caudal to the lesser curvature of the arch, or off the ascending aorta (severe angulation; Fig. 8-1 ).