Future Balloon-Expandable Stents: High or Low-Strength Materials?

Area of Science:

• Biomaterials Science
• Mechanical Engineering
• Cardiovascular Research

Background:

• Advancements in material science enable novel coronary stent designs with improved biodegradability, strength, and flexibility.
• Understanding the impact of varying mechanical properties is essential for practical stent design, given the diverse material options.

Purpose of the Study:

• To investigate the sensitivity of coronary stent functional characteristics to variations in material plastic properties.
• To analyze the influence of mechanical properties on the performance of balloon-expandable coronary stent designs.

Main Methods:

• Finite Element Method (FEM) modeling was employed to simulate stent behavior.
• Two designs, Absorb BVS and Xience, were examined using polymeric and metallic materials.
• Simulations included crimping, implantation in atherosclerotic arteries, and three-point bending tests per ASTM standards.

Main Results:

• Higher yield stress materials showed similar deflection and bending force to PLLA in Absorb BVS, but not in Xience.
• Elevated yield stress reduced Xience stent flexibility and improved radial strength and stiffness for both stents.
• Increased stress enhanced mechanical performance by reducing arterial stress and plastic strain but also increased stent recoil.

Conclusions:

• High-strength materials have a dual effect on stent performance.
• Uncertainty in mechanical property estimation compromises the reliability of numerical model predictions for stent design.