Self-Expanding Drug Eluting Stent with Composite Polymer Coating
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Solution Overview
Problem
Conventional medical implants, particularly self-expanding stents, face limitations such as thrombosis, restenosis, and vascular remodeling, and biodegradable polymeric materials exhibit poor expandability and mechanical properties, making them inadequate for effective medical treatments.
Innovation Solution
The development of tubular, self-expanding medical devices with a combination of polymeric materials and conformal coatings, including poly(lactic acid-co-caprolactone) and paclitaxel, which enhance expansion characteristics and mechanical properties, allowing for high radial strength and controlled drug release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biodegradable polymeric materials are used for stents, then long-term effects of permanent implants are eliminated, but expandability and mechanical properties deteriorate
Solution Approach 1:
The patent applies composite materials by combining biodegradable polymeric materials with metallic components (such as shape memory alloys or other metals) to create a stent structure that exhibits both the biocompatibility and biodegradability of polymers and the mechanical strength and expandability of metals. This composite approach allows the device to achieve adequate radial strength while maintaining the advantage of being biodegradable over time.
2Ease of operation
If low-profile devices with small diameter fibers are used, then device size is reduced for easier delivery, but expansion characteristics and radial strength deteriorate
Solution Approach 1:
The patent uses composite materials combining biodegradable polymers with metallic elements to create low-profile stents that maintain adequate radial strength despite using small diameter fibers. The metallic components provide the necessary mechanical reinforcement while allowing the overall device to be crimped to smaller delivery profiles.
Solution Approach 2:
The patent employs parameter changes by utilizing shape memory alloys or other materials with phase transition properties that allow the stent to be delivered in a compressed state and then expand to full diameter upon deployment. This enables low-profile delivery while achieving full expansion characteristics at the target site.
3Strength
If conventional metallic stents are used, then mechanical strength is maintained, but thrombosis, restenosis and vascular remodeling occur
Solution Approach 1:
The patent extracts the harmful metallic components from the stent structure and replaces them with biodegradable polymeric materials that do not cause thrombosis or restenosis. The metallic reinforcement is either completely removed or minimized to only essential structural elements, allowing the device to maintain adequate strength while eliminating the biological complications associated with permanent metal implants.
Solution Approach 2:
The patent uses composite materials to create a stent that combines the mechanical strength needed for structural support with biodegradable components that eliminate thrombogenicity. The composite structure allows gradual degradation of the polymeric portion while maintaining mechanical integrity during the critical healing period.
4Reliability
If drug eluting coatings are added to stents, then restenosis risk is decreased, but device complexity increases
Solution Approach 1:
The patent merges the drug delivery function with the structural components of the stent by incorporating therapeutic agents directly into the biodegradable polymeric material or coating layers. This integration approach delivers the beneficial effect of drug-eluting coatings for restenosis prevention while minimizing additional complexity through combined functionality.
Data Source
AI summary
Disclosed are self-expanding medical implants for placement within a lumen of a patient. The implants comprise a woven or non-woven structure having a substantially tubular configuration, and are designed to be low-profile such that they are deliverable with a small diameter catheter. The implants have a high recoverability and desired mechanical properties.