Stents optimization and validation

Stent optimization

IDENTIFY PROBLEMS

The following issues can cause stents to be optimized:

Stent does not expand properly in the vessel
Too little radial force
Stent is not flexible enough
Stent is difficult to push through the catheter
Stent breaks at implantation
Proximal and distal areas appear weak
etc..

The following international standards and regulations are used in this context:

ISO 25539-1: Cardiovascular implants – Endovascular devices – Part 1: Endovascular prostheses

ISO 25539-2: Cardiovascular implants – Endovascular devices – Part 2: Vascular stents

ISO 25539-3: Cardiovascular implants – Endovascular devices – Part 3: Vena cava filters

ASTM F2514: Finite Element Analysis (FEA) of Metallic Vascular Stents Subjected to Uniform Radial Loading

ASTM F2477: Standard Test Methods for in vitro Pulsatile Durability Testing of Vascular Stents

ASTM F2942: Standard Guide for in vitro Axial, Bending, and Torsional Durability Testing of Vascular Stents

ASTM F3067: Guide for Radial Loading of Balloon Expandable and Self Expanding Vascular Stents

ASTM F2079: Elastic Recoil of Balloon-Expandable Stents

ASTM F3211: Fatigue-to-Fracture (FtF) Methodology for Cardiovascular Medical Devices.

FDA Guidance for Industry and FDA Staff: Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems. April 18, 2010

FDA Guidance for Industry and FDA Staff: Reporting of Computational Modeling Studies in Medical Device Submissions. September 21, 2016

Heart Valves:

ISO 5840-3: Cardiovascular implants – Cardiac valve prostheses – Part 3: Heart valve substitutes implanted by transcatheter techniques

ISO 5910: Cardiovascular implants and extracorporeal systems – Cardiac valve repair devices

Stent validation (numerical)

The following requirements should be fulfilled:

Fatigue strength (at least 1 million cycles)
flexibility test
Crimp Simulatiom
Expansion simulation
Virtual stenting