Evaluation of mechanical properties of self-expanding metal stents for optimization of tracheal collapse in dogs.

The objective of this study was to compare the mechanical properties, including radial, axial, and bending forces, of various self-expanding metal stents with different wire diameters. The radial forces generated through longitudinal and cylindrical compression, along with axial and bending forces, were measured and used to evaluate the mechanical properties of 3 types of self-expanding metal stents (n = 3); the most suitable type was further assessed with 4 different wire diameters (n = 3). The D-type stent (double-wire woven uncovered nitinol stent) had the highest radial force and the lowest axial force and hence, was the most suitable for clinical use; however, its bending force was the lowest, corroborating the results of the axial force measurements. Therefore, the D-type stent was further evaluated using the following wire diameters: i) 0.127, ii) 0.152, iii) 0.178, and iv) 0.203 mm. When the wire diameter was increased by 0.025 mm, the measured radial, axial, and bending forces increased significantly. Thus, the adequate wire diameter should be determined based on the anatomical structure of stents. The mechanical properties of self-expanding stents should be considered in selecting the optimal design for tracheal collapse in dogs.