Physical Properties of Venous Stents: An Experimental Comparison

Abstract

Purpose: Iliocaval obstruction is a substantial contributor to chronic venous insufficiency and is increasingly being treated endovascularly with angioplasty and stent placement. Utilization of an appropriate stent for treatment is pivotal; however, until today, mechanical properties of venous stents remain unknown.

Materials and methods: We analyzed the radial resistive force, the chronic outward force, as well as the crush resistance of seven stent models [Zilver Vena (Cook, Bjaeverskov, Denmark), Sinus Venous, Sinus Obliquus and Sinus XL Flex (Optimed, Ettlingen, Germany), Vici (Veniti; St. Louis, USA), Wallstent (Boston Scientific, Marlborough, USA), and Venovo (Bard, Tempe, USA)] in vitro using a radial force testing machine (RX-650, Machine Solutions Inc., Flagstaff, AZ, USA) and a hardness testing machine (zwickiLine, Zwick Roell, Ulm, Germany).

Results: The Sinus Obliquus revealed the highest radial resistive force (19.41 N/cm) and the highest chronic outward force at 50 and 30% nominal diameter (7.93 N/cm at 50%, 16.97 N/cm at 30%) while the Venovo revealed the highest chronic outward force at 90 and 80% nominal diameter (4.83 N/cm at 90%, 5.37 N/cm at 80%). The radial resistive force and the chronic outward force of the Wallstent greatly depended on whether the stent ends were fixated. The Wallstent revealed the highest crush resistance at nominal diameters of 90% (0.46 N/cm) to 60% (1.16 N/cm). The Sinus Obliquus revealed the highest crush resistance at a nominal diameter of 50% (1.41 N/cm).

Conclusion: Venous stents greatly differ regarding their mechanical properties. These results should be considered when choosing an appropriate stent for the treatment of venous obstruction.

Keywords: Iliocaval obstruction; Intervention; Physical properties; Stent; Venous.