Mechanical behaviour modelling of balloon-expandable stents

Area of Science:

• Biomaterials Engineering
• Medical Device Design
• Computational Mechanics

Background:

• Endoprostheses, or stents, are crucial for restoring vascular lumen and blood flow.
• Evaluating the mechanical properties of stents is essential for ensuring their long-term efficacy and safety.

Purpose of the Study:

• To develop and apply finite element method (FEM) models for characterizing the mechanical behavior of balloon-expandable stents.
• To analyze the expansion mechanisms, long-term behavior, and failure modes of the P308 Palmaz stent.

Main Methods:

• Construction of multiple FEM models to simulate stent dilation and predict post-expansion shape.
• Assessment of stress and strain fields within the stent wall during expansion.
• Investigation of factors contributing to stent crushing under external pressure and sensitivity to geometric imperfections.
• Evaluation of stent fatigue life for long-term performance prediction.

Main Results:

• Quantification of stent shortening, radial and longitudinal recoil post-dilation.
• Identification of structural weaknesses and critical pressures for stent crushing.
• Analysis of fatigue life, providing insights into long-term durability.
• Demonstration of FEM's capability to predict mechanical properties difficult to obtain experimentally.

Conclusions:

• FEM provides valuable mechanical characterization data for stents, complementing experimental methods.
• This analysis aids in understanding stent performance, failure mechanisms, and optimizing designs.
• Informed prosthesis selection based on mechanical properties can improve clinical outcomes.