Endovascular Stent with Abraded Surface for Drug Loading
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Solution Overview
Problem
Stents used for treating atherosclerosis complications such as restenosis and thrombosis face challenges in maximizing drug loading capacity while maintaining structural integrity and minimizing the stent-catheter crossing profile thickness, particularly due to issues with polymer coatings that can lead to thrombosis and increased risk of restenosis.
Innovation Solution
A nonpolymeric therapeutic agent eluting stent with a textured or abraded microstructure is developed, where the stent is crimped into a hydrocarbon film layer, treated with abrasives, and then passivated to increase surface area for drug coating without compromising structural integrity, allowing for increased drug loading and reduced risk of thrombosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a polymer coating is applied to the stent surface to enable controlled drug release, then drug loading capacity is improved, but the risk of thrombosis increases due to delamination and sharp edges
Solution Approach 1:
The patent removes the polymer coating layer entirely from the stent surface. Instead of using a polymer-based drug delivery system, the invention employs a metal-based porous coating that eliminates delamination issues while maintaining controlled drug release capability through the porous metal structure.
Solution Approach 2:
The patent applies a porous metal coating to the stent surface, which provides controlled drug release through the porous structure without requiring a polymer layer. The porous metal structure allows drug diffusion while maintaining structural integrity and eliminating the delamination problem associated with polymer coatings.
2Quantity of substance
If the stent surface is roughened to increase drug loading capacity, then the total surface area increases, but the crossing profile thickness increases which limits passage through occluded arteries
Solution Approach 1:
The patent uses a porous metal coating that increases surface area and drug loading capacity without significantly increasing the overall crossing profile thickness. The porous structure provides extensive surface area for drug attachment while maintaining a thin profile that can pass through occluded arteries.
Solution Approach 2:
The patent creates a composite structure combining the base stent material with a porous metal coating. This composite approach allows the stent to have enhanced drug loading capacity through the porous coating while maintaining the original stent's thin profile for successful catheter passage.
3Reliability
If a polymer coating is used for controlled drug release, then restenosis is reduced, but structural integrity is compromised due to delamination and edge formation
Solution Approach 1:
The patent eliminates the polymer coating that causes delamination and structural integrity issues. By removing the polymer layer entirely and using a porous metal coating instead, the invention maintains restenosis prevention capability while preserving the structural strength of the stent.
Solution Approach 2:
The patent employs a porous metal coating that provides controlled drug release for restenosis prevention without compromising structural integrity. The porous metal structure maintains strength while enabling drug diffusion, eliminating the delamination problem that weakens polymer-coated stents.
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 solution effectively decreases the stent's crossing profile thickness, enhances drug loading capacity, and increases fatigue resistance, while minimizing the risk of restenosis and thrombosis by ensuring controlled drug release and maintaining structural integrity.
Implementation Method 1
the stent is crimped into a hydrocarbon film layer, treated with abrasives
Implementation Method 2
crimped into a hydrocarbon film layer which creates a mask for at least one of the inner layer and sides of the stent
Data Source
Figure 1
Figure 2A
Figure 2B~2C
AI summary
A radially expandable, endovascular stent designed for placement at a site of vascular injury, for inhibiting restenosis at the site, a method of using, and a method of making the stent. The stent includes a radially expandable body formed of one or more metallic filaments where at least one surface of the filaments has a roughened or abraded surface. The stent may include a therapeutic agent on the abraded surface.