Structural Optimization and Finite Element Analysis of Variable-Stiffness Biodegradable Vascular Stents

Area of Science:

• Biomaterials Engineering
• Medical Device Design
• Corrosion Science

Background:

• Biodegradable vascular stents (BVSs) face premature structural failure due to stress corrosion cracking (SCC).
• Heterogeneous arterial plaques cause stent malapposition and stress concentration, worsening SCC.
• Current stent designs struggle with non-uniform degradation and inadequate radial support.

Purpose of the Study:

• To develop and evaluate variable-stiffness BVSs to enhance radial support and manage non-uniform degradation.
• To mitigate stress concentration and improve long-term performance in stenotic arterial environments.
• To investigate the impact of stent design modifications on immediate deployment and long-term degradation.

Main Methods:

• Variable-stiffness stents were designed with modified axial ring segments and selective strut widening.
• Virtual deployment in arteries with non-calcified and calcified plaques simulated immediate performance.
• Degradation simulations assessed long-term behavior under combined electrochemical corrosion and SCC effects.

Main Results:

• Variable-stiffness stents showed comparable residual stenosis to uniform-stiffness designs.
• Dual- and gradient-stiffness designs created smoother luminal profiles.
• Local strut widening extended recoil time and increased volume loss, mitigating non-uniform degradation. Widened gradient-stiffness designs prolonged stable support by 9.7%.

Conclusions:

• Variable-stiffness stents offer improved immediate and long-term performance compared to uniform-stiffness designs.
• Selective strut widening in gradient-stiffness designs effectively addresses non-uniform degradation and enhances stent stability.
• This novel stent design shows promise for overcoming critical challenges in BVS technology.