Stent Coating Separation Structure for Anti-Migration and Removal
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Solution Overview
Problem
Existing stents designed for body lumens face issues with migration due to flexibility and lubricious environments, and while anti-migration features enhance anchoring, they complicate removal and repositioning.
Innovation Solution
A stent design with a coating that includes a micro-pattern coating layer with preferential separation regions, allowing the coating to separate partially during expansion, maintaining anchoring while facilitating easy removal and repositioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stent is designed with compressible and flexible properties to assist delivery, then ease of delivery is improved, but the stent develops a tendency to migrate from its deployed position
Solution Approach 1:
The coating is segmented into distinct regions: a first region with anti-migration elements for anchoring, a second region for tissue contact, and a preferential separation region between them. This segmentation allows the stent to have both anchoring capability and ease of removal by separating these conflicting functions into different zones of the coating.
Solution Approach 2:
Different regions of the coating are given different properties: the first region has anti-migration elements protruding outward for anchoring, while the second region is designed for tissue contact. The preferential separation region has reduced adhesion to allow controlled separation. This local differentiation resolves the contradiction between stability and removable flexibility.
2Stability of the object's composition
If bare metal portions of the stent are exposed to promote tissue ingrowth and reduce migration, then position stability is improved, but the stent becomes more difficult to remove post-deployment
Solution Approach 1:
The coating is divided into a first region with anti-migration elements and a second region, with a preferential separation region between them. This allows the stent to promote tissue ingrowth for stability while maintaining a controlled separation zone that facilitates removal when needed.
Solution Approach 2:
The preferential separation region is extracted as a distinct functional zone with reduced adhesion properties, separating the anchoring function from the removal function. This allows the stent to be firmly anchored through tissue ingrowth in one region while having a designated area that facilitates controlled removal.
3Ease of operation
If the thickness and volume of anti-migration coatings are reduced to decrease stent stiffness, then ease of deployment is improved, but the anti-migration capability is compromised
Solution Approach 1:
Anti-migration elements are concentrated in the first region of the coating rather than being uniformly distributed. This local concentration provides effective anti-migration capability in a specific zone while allowing other regions to have reduced coating thickness for easier deployment.
Solution Approach 2:
The coating uses a composite structure with anti-migration elements (protrusions) integrated into the coating matrix. This composite design provides strong anti-migration capability in the first region while maintaining overall coating flexibility and reduced stiffness for easier deployment.
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 design reduces stent migration while enabling easy removal and repositioning by enhancing surface friction and maintaining mechanical properties.
Implementation Method 1
As discussed above, in some instances it may be desirable to design the stent 410 to include one or more 'preferential separation regions' 426... which permit one region of the micro-pattern coating layer 422 to separate from an adjacent region of the micro-pattern coating layer 422 as the stent 410 expands
Implementation Method 2
The micro-pattern coating layer 422 may include a plurality of anti-migration elements 424 extending radially outward from a base portion of the micro-pattern coating layer 422... The engagement of the textured surface of the micro-pattern coating layer 422 with the tissue of the body lumen 100 may initially prevent the stent from longitudinally shifting or migrating
Implementation Method 3
the expandable scaffold is configured to shift from a radially collapsed state to a radially expanded state... as the stent 410 expands from a collapsed, pre-deployment configuration to an expanded, deployed configuration
Data Source
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AI summary
A medical device for treating a body lumen, such as a medical stent, includes an expandable scaffold configured to shift from a radially collapsed state to a radially expanded state. The stent includes a coating disposed along the outer surface of the expandable scaffold in which a portion of the coating includes a plurality of anti-migration members and one or more preferential separation regions. Each preferential separation region is configured to permit first and second regions of the coating to separate from one another along the preferential separation region therebetween as the expandable scaffold shifts from the radially collapsed state to the radially expanded state.