Structural Optimization and Fatigue Performance Evaluation of Balloon-Expandable Aortic Valve Stents

Transcatheter aortic valve implantation (TAVI) is a critical therapy for aortic stenosis, but most existing valve stents are designed for Western patients, whose aortic root anatomy differs from Chinese patients characterized by smaller annulus diameters, heavier calcification, and a higher prevalence of bicuspid valves. To address this mismatch, we designed a balloon-expandable aortic valve stent tailored for Chinese patients and systematically evaluated its performance. Four structural schemes were considered; a diamond-hexagonal composite mesh was selected based on radial strength, expansion uniformity, anchoring stability, sealing, and coronary access. Material properties of MP35N were obtained via tensile tests, and finite element models simulated crimping, recoil, and expansion. Among three end-corner geometries, the U-shaped design showed superior mechanical behavior with lower stress/strain concentrations. For stents crimped to 6.5 mm, maximum equivalent stress ranged from 1030 to 1076 MPa and plastic strain from 0.221 to 0.259; upon expansion to 20-29 mm, stress reached 1417-1493 MPa and strain 0.447-0.544, with strain concentrated at the corner ends. Simulated recoil matched experimental results within 7% relative error. Accelerated fatigue testing (4 × 10⁸ cycles) of the bare stents revealed no fractures, displacements, or surface damage. These findings demonstrate that the optimized bare stent structure exhibits good mechanical feasibility, durability, and improved anatomical compatibility for Chinese TAVI patients, providing a promising device solution for domestic clinical application.