Duplex Ultrasound Velocity Criteria in Carotid Artery Stenting Patients

Abstract

Carotid artery stenting (CAS), performed either by transfemoral or by trans-carotid artery revascularization (TCAR) technique, is a less invasive alternative to carotid endarterectomy (CEA). Carotid stenting has been demonstrated to be technically feasible and safe in high-risk patients. It has been approved as an acceptable method for revascularization in circumstances where CEA yields suboptimal results. While the role of CAS in carotid revascularization is still in evolution, stenting will continue to be performed in an increasing number of patients with carotid stenosis. Therefore, it is anticipated that there will be a corresponding increase in the number of in-stent restenosis cases. There is still controversy regarding the clinical significance and appropriate diagnostic criteria for recurrent carotid stenosis after CAS. Placing a stent in the carotid artery alters its biomechanical properties and renders it less compliant. This in turn leads to elevations in velocities that do not necessarily reflect a clinically relevant stenosis. If the thresholds to define normal arteries are revised upward, then duplex ultrasonography has been found to be a highly effective method of post CAS surveillance. This chapter analyzes current information on this important clinical problem and presents evidence-based recommendations for the diagnosis of recurrent carotid stenosis after CAS.