Duplex Ultrasound Follow-up of Carotid Stents

Endovascular treatment of carotid disease continues to evolve. There have been few published reports describing the ultrasound follow-up of stented carotid arteries. It is the purpose of this study to evaluate the duplex ultrasound characteristics of carotid stents including comparing hemodynamic to B-mode and color-flow imaging data. During the past 5 years, 40 carotid stents have been placed in the common or internal carotid arteries of 37 patients. There were 21 males and 16 females with an average age of 67 ± 9 years. Duplex ultrasound examinations included peak systolic velocity (PSV) and end diastolic velocity (EDV) taken proximal to the stent (pre-stent), at the proximal, mid, and distal regions of the stent, and distal to the stent (post-stent). The stents were evaluated at 1 day, 3, 6, and 12 months postprocedure and yearly thereafter. The average follow-up interval was 6 ± 1 months from stent placement. In 31 patent internal carotid artery stents, the PSV proximally within the stent was 92 ± 6 cm/sec with an EDV of 24 ± 2 cm/sec (all velocity data expressed as mean ± SEM). The mid stent PSV was 86 ± 5 cm/sec with an EDV of 24 ± 2 cm/sec. The distal stent PSV was 90 ± 4 with an EDV of 26 ± 2 cm/sec. Proximal to the stent, the PSV was 70 ± 3 cm/sec with an EDV of 17 ± 1 cm/sec. Distal to the stent, the PSV was 77 ± 4 cm/sec with an EDV of 25 ± 2 cm/sec. There were no defects observed on B-mode image and no areas of color turbulence. Three stents developed stenotic areas with PSVs of 251, 383, and 512 cm/sec. The EDV was 50, 131, and 365 cm/sec, respectively. Poststenotic turbulence was present in each of these stents. An elevated PSV of greater than 125 cm/sec was found in 32% of the stents (9 of 28) without evidence of stenosis on B-mode image or poststenotic turbulence. These data demonstrate that velocities within stented carotid arteries can be elevated above established ranges for normal. In conclusion, velocity criteria may need to be adjusted when applied to stented carotid arteries.