Duplex Ultrasound Remains a Reliable Test Even After Carotid Stenting

Transluminal arterial stenting reduces vessel compliance and may alter accurate interpretation of flow velocities. We reviewed duplex ultrasonography (DUS) following carotid stenting to identify criteria indicative of severe recurrent stenosis. This is a single-center retrospective review of 158 carotid stenoses treated with carotid angioplasty and stenting (CAS) from April 2001 to December 2004. DUS was obtained preoperatively, postoperatively, and at 3-month intervals thereafter. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were analyzed. Mean follow-up was 12 months (range 1-40). Mean age was 71 ± 9 years (range 51-91; 74% men, 26% women). Three patients (1.9%) developed restenosis and one (0.6%) developed an asymptomatic occlusion during follow-up. Average preoperative PSV was 373 ± 123 cm/sec (mean ± SD) and EDV was 148 ± 63 cm/sec. Immediate postoperative PSV and EDV decreased by an average of 70% (average 118 ± 45 cm/sec) and 72% (average 32 ± 15 cm/sec), respectively. In patients free from restenosis or occlusion, these reductions (range 65-80%) were maintained throughout follow-up and remained within 1-25% of immediate postoperative values. In patients suffering restenosis or occlusion, follow-up PSV and EDV increased 34% and 28%, respectively, compared to preoperative values. PSV and EDV increased by an average of 287% and 500%, respectively, compared to immediate postoperative values. Using criteria of PSV >170 cm/sec and a 50% increase of PSV over immediate postoperative values, restenosis or occlusion was detected with 100% sensitivity and specificity in our patients. Additionally, EDV >120 cm/sec and a 50% increase in EDV over immediate postoperative values detected restenosis and occlusion with 100% sensitivity and specificity. Presumed restenosis and occlusion detected by DUS were confirmed in all cases with angiography. Restenosis or occlusion after CAS at our institution can reliably be detected by carotid duplex using cut-off values of 170 cm/sec PSV, 120 cm/sec EDV, and >50% increase over immediate postoperative values. While these criteria are applied to patients undergoing CAS at our institution, they serve only as suggested guidelines for patient populations at other centers and must be customized to each Intersocietal Commission for the Accreditation of Vascular Laboratories-accredited vascular laboratory.