Stent Anti-Migration Structure Resolves Removal Trade-Off
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Solution Overview
Problem
Existing stents face challenges in preventing migration and tissue ingrowth, making them difficult to remove after deployment, especially as they can lead to occlusion and increased migration rates.
Innovation Solution
A fully or partially covered stent with a three-dimensional anti-migration structure, either integrally formed or attached to the surface, which includes thin filaments or geometric patterns to enhance friction and prevent ingrowth, combined with a biocompatible material for secure placement and easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bare stent is used, then tissue ingrowth occurs in the openings between struts which prevents migration, but the stent becomes very difficult to remove after implantation and may cause lumen occlusion
Solution Approach 1:
The stent surface is segmented into different functional zones: covered portions that prevent tissue ingrowth and maintain removability, and uncovered portions that allow controlled tissue integration for anchoring. This segmentation resolves the contradiction by spatially separating the migration prevention function from the removal ease function.
Solution Approach 2:
Different regions of the stent are given different properties - some areas have covering material to prevent ingrowth while other areas remain bare to allow anchoring. This local differentiation enables the stent to simultaneously achieve migration resistance through anchored portions and ease of removal through covered portions.
2Object-affected harmful factors
If a partially covered stent is used, then tissue ingrowth is prevented or slowed in covered portions, but ingrowth still occurs in uncovered openings making removal difficult
Solution Approach 1:
Instead of partially covering the stent, the invention applies full covering to specific strategic zones (ends and selected portions) while leaving other portions uncovered. This partial but targeted application of covering material provides sufficient tissue ingrowth prevention in critical areas without causing widespread anchoring that would complicate removal.
3Ease of operation
If a fully covered stent is used, then tissue ingrowth is prevented along the entire length making removal easier, but the migration rate increases due to lack of friction-inducing structures
Solution Approach 1:
The stent employs local quality by providing covering material at specific locations (particularly at the ends and selected portions) rather than uniformly across the entire surface. This localized covering prevents tissue ingrowth in critical anchoring zones while maintaining smooth surfaces in other areas to reduce friction and enable easier removal.
Solution Approach 2:
The stent surface is divided into covered and uncovered segments, each serving distinct functions. The covered segments prevent tissue ingrowth and facilitate removal, while the uncovered segments provide friction and anchoring to resist migration, thus resolving the contradiction through functional segmentation.
4Reliability
If a stent with friction-inducing structure is used to prevent migration, then migration rate decreases, but tissue ingrowth increases making removal difficult
Solution Approach 1:
The stent is segmented into zones with different surface characteristics - covered portions that provide friction for migration resistance without promoting ingrowth, and uncovered portions that allow controlled tissue integration. This segmentation enables the stent to achieve migration resistance through friction from the covering material while preventing harmful tissue ingrowth.
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 effectively resists migration and minimizes tissue ingrowth, facilitating easier removal and maintaining lumen patency by providing enhanced frictional interaction with the body lumen.
Implementation Method 1
The anti-migration structure may function to lessen stent migration by roughening the outside surface of the stent, which is in contact with the inner surface of the body lumen into which it is placed.
Data Source
AI summary
An intraluminal prosthesis includes an outer three-dimensional (3D) anti-migration structure that is attached to the outer wall of a fully covered or partially covered stent to prevent migration and still allow stent removal at a later period of time. A method of manufacturing the intraluminal prosthesis includes attaching the anti-migration structure by usage of a polymer such as polyurethane.