• Transcranial doppler counts of micro-embolic signals in the ipsilateral middle cerebral artery. [ Time Frame: First 24 hours after implantation of carotid stent ] [ Designated as safety issue: No ]
  

• Composite of any stroke, myocardial infarction or death [ Time Frame: within 30 days after the carotid stenting procedure ] [ Designated as safety issue: No ]
  
• Subclinical cerebral embolization [ Time Frame: within 24 hours after carotid artery stenting ] [ Designated as safety issue: No ]
  

Stroke is responsible for more than 10% of all deaths and much severe disability in developed countries. In the United States, approximately 600,000 new strokes are reported annually, of which 150,000 are fatal, and more than 4,000,000 surviving stroke victims are affected by significant disability. Seventy-five percent of strokes occur in the distribution of the carotid arteries and are considered of a thromboembolic etiology, most of which originate in carotid lesions. Carotid artery stenting (CAS) with cerebral embolic protection is currently the preferred treatment of carotid stenosis in high risk surgical patients, i.e., those with significant comorbidities or a hostile neck from previous surgical procedures or radiation. Although several predictors of adverse outcomes after CAS have been identified, the effects of device characteristics, including stent design, on neurologic adverse events have not been established.

The proposed study will be a randomized prospective controlled trial designed to test the hypothesis that the implantation of closed-cell stents for carotid lesions in high-risk patients will be associated with a reduced perioperative cerebral microembolization as detected by transcranial Doppler, and reduced 30-day stroke, myocardial infarction, and death rates when compared with the implantation of open-cell stents.