Bioresorbable Stent Radial Strength via Molecular Orientation
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Solution Overview
Problem
Current bioresorbable stents face challenges with insufficient radial strength, higher recoil, strut fracturing, and increased stent-to-artery coverage, which can lead to restenosis and thrombosis, while also being difficult to manufacture with precise dimensional tolerances and radiopacity.
Innovation Solution
A bioresorbable stent with enhanced radial strength and controlled degradation rate, achieved by orienting molecular chains during processing and using preformed configurations like fibers or films in the stent's wall thickness, which also includes coatings for delayed degradation and improved radiopacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer materials are used for stent struts, then the stent can be manufactured with standard processes, but the radial strength is insufficient and strut fracturing occurs
Solution Approach 1:
The patent uses a composite wall thickness comprising a polymer matrix material reinforced with preformed configurations (fibers, films, or particles) that are aligned in the radial direction. This composite structure provides both the required radial strength and resistance to strut fracturing while maintaining the bioresorbable properties of the polymer matrix.
Solution Approach 2:
The patent applies different material properties to different regions of the stent wall thickness. The preformed configurations are specifically oriented in the radial direction where strength is needed, while the polymer matrix provides overall structural integrity. This localized reinforcement approach ensures high radial strength without requiring excessive overall wall thickness.
2Strength
If the stent wall thickness is increased to improve radial strength, then strength is improved, but the manufacturing precision of dimensional tolerances becomes more difficult to achieve
Solution Approach 1:
The wall thickness is segmented into distinct functional layers: a polymer matrix material and embedded preformed configurations. This segmentation allows independent control of each component's properties and dimensions, making it easier to achieve precise overall dimensional tolerances while maintaining enhanced radial strength through the reinforced structure.
3Strength
If the stent is designed with higher radial strength, then strut fracturing is reduced, but the stent-to-artery coverage increases which can lead to restenosis
Solution Approach 1:
The reinforcement with preformed configurations is applied locally in the radial direction where strength is needed, rather than increasing the overall stent-to-artery coverage. This localized reinforcement approach provides high radial strength to prevent strut fracturing while maintaining appropriate stent coverage that minimizes restenosis risk.
4Strength
If conventional polymer processing is used, then the manufacturing process is simple, but the molecular chains are not oriented which results in insufficient strength
Solution Approach 1:
The preformed configurations (fibers, films, or particles) are prepared and aligned in the radial direction before being incorporated into the polymer matrix during the molding process. This preliminary alignment action ensures that the reinforcement is optimally oriented to provide radial strength, while the integration step remains a standard part of the manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The stent maintains increased radial strength and luminal capacity, reduces strut fracturing, and provides controlled resorption, improving clinical outcomes by minimizing restenosis and thrombosis risks while being easier to manufacture with precise dimensions and enhanced visibility during deployment.
Implementation Method 1
The wall thickness is drawn and/or expanded to strengthen the tubular precursor construct
Implementation Method 2
The stent is bioresorbable, degrading and/or resorbing through hydrolysis of the stent material
Data Source
AI summary
Disclosed herein is a high strength, bioresorbable wall thickness suitable for use in an endoprosthesis such as a stent that is produced by first forming a wall thickness by melt processing or solution processing one or more bioresorbable materials into a tubular shape; drawing the shape from shorter length to an optimum longer length and reducing the diameter from a larger diameter to a smaller diameter to orient the molecular chains of the material; fabricating a stent from the tube formed of the oriented material by cutting a strut pattern in its wall thickness; covering the stent's struts with at least one coating to delay degradation of the bioresorbable material; covering the stent's struts with one or more controlled release active ingredients to minimize the risk of restenosis or other side effects; crimping the stent onto a balloon catheter assembly; delivering the stent into an anatomical lumen via percutaneous methods to a treatment location; radially expanding the stent from a smaller size to a larger size at the treatment location wherein the stent temporarily supports the anatomical lumen; and removing the catheter from the lumen.