Radial Force Measurements in Carotid Stents: Influence of Stent Design and Length of the Lesion

Purpose: To assess the differences in radial force of carotid stents and whether the length of the lesion influences the measurements. Materials and Methods: Different models of tapered stents of similar size (length, 30 mm) were used. The tapered nitinol Acculink, Prot g, and Cristallo Ideale carotid artery stents and the straight, braided Elgiloy carotid Wallstent were compared. A measurement device consisting of three film loops along the stent body connected to aluminium rods with copper strain gauges was developed. Five stents of each type were deployed within 3-mm stenoses in simulated long (26 mm) and short (8 mm) stenoses. Results: In the short stenosis simulation, the greatest radial force was seen in the Prot g stent, at 3.14 N +/- 0.45, followed by the Cristallo Ideale stent (1.73 N +/- 0.51), Acculink (1.16 N +/- 0.21), and Wallstent (0.84 N +/- 0.10; P < .001). In the long stenosis simulation, peak radial force again was highest in the Protege stent (1.67 N +/- 0.37), but the Acculink stent was second (0.95 N +/- 0.12) and the Wallstent third (0.80 N +/- 0.06). The Cristallo Ideale stent, in contrast to the short stenosis simulation, produced the least radial force (0.44 N +/- 0.13) in the long stenosis simulation (P=.001). Conclusions: Radial forces exerted by carotid stents vary significantly among stent designs. Differences between stent types are dependent on the length of the stenosis. An understanding of radial force is necessary for a well-considered choice of stent type in each individual patient.