Finite element methods to analyze helical stent expansion.

Area of Science:

• Biomaterials Engineering
• Medical Device Design
• Computational Mechanics

Background:

• Helical polymeric stents offer potential for biodegradable drug-eluting applications.
• Nonuniform local expansion, or 'dog boning,' hinders full deployment of helical stents.
• Conventional stent expansion methods struggle with the unique geometry of helical designs.

Purpose of the Study:

• To investigate stent expansion methods for helical polymeric stents.
• To identify numerical analysis approaches suitable for complex helical stent geometries.
• To develop and validate a method for overcoming nonuniform stent expansion.

Main Methods:

• Finite element method (FEM) simulations, both explicit and implicit, were employed.
• Three common stent expansion approaches were modeled and compared.
• A coupled stent-balloon model was developed to simulate realistic deployment conditions.

Main Results:

• Standard displacement-controlled and uniform expansion methods failed to replicate observed nonuniform deformations.
• The coupled stent-balloon model successfully demonstrated characteristic local deformations.
• A progressive expansion approach was numerically investigated and verified.

Conclusions:

• Conventional expansion methods are inadequate for helical polymeric stents.
• A coupled stent-balloon model provides a more accurate simulation of helical stent deployment.
• The progressive expansion method offers a viable solution for nonuniform expansion, potentially reducing arterial damage.