Low Radial Force Stents With Microstructured Surfaces
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Solution Overview
Problem
Minimally invasive stent implantation techniques face challenges with stent migration and lumenal wall damage due to the trade-off between radial force for anchoring and avoiding tissue damage, leading to complications like paravalvular leakage and tissue remodeling.
Innovation Solution
The development of low radial force stents with a microstructured surface, utilizing a Wenzel-Cassie interface that decouples radial force from localization, allowing for reduced contact with the lumenal surface and employing non-frictional forces for fixation, such as Van der Waal interactions, to minimize migration and tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stent radial force is increased to reduce stent migration, then stent localization is improved, but lumenal wall damage increases
Solution Approach 1:
The patent replaces the traditional friction-based mechanical anchoring system with a microstructured surface system that utilizes non-frictional forces (Van der Waal interactions, capillary forces) to achieve stent localization. The microstructured surface features (pillars, grooves, or other patterns at the micrometer scale) create these non-frictional adhesive forces between the stent and lumenal surface, allowing effective fixation without the high radial forces that cause tissue damage.
2Reliability
If stent radial force is increased to prevent stent migration, then stent fixation is improved, but tissue remodeling increases
Solution Approach 1:
The patent substitutes the high radial force mechanical anchoring system with a microstructured surface system that uses non-frictional adhesive forces. This substitution maintains reliable stent fixation through the microstructured surface's interaction with the lumenal surface, while avoiding the excessive radial forces that trigger adverse tissue remodeling processes such as thrombosis, in-stent restenosis, and neo intimal proliferation.
3Object-affected harmful factors
If stent radial force is reduced to minimize tissue damage, then lumenal wall damage decreases, but stent migration increases
Solution Approach 1:
The patent changes the physical parameters of the stent surface by introducing microstructured features at the micrometer scale. These structural parameter changes enable the stent to generate sufficient adhesive forces through non-frictional mechanisms (Van der Waal interactions, capillary forces) without requiring high radial forces, thus maintaining reliable localization while minimizing tissue damage.
4Reliability
If self-expandable stent is used to provide radial anchoring force, then stent fixation is improved, but chronic recoil and larger vessel size increase
Solution Approach 1:
The patent replaces the self-expandable stent's continuous radial outward force mechanism with a microstructured surface anchoring system. This substitution eliminates the need for continuous high radial forces to maintain fixation, thereby reducing chronic recoil and preventing excessive vessel enlargement while maintaining reliable stent fixation through non-frictional adhesive forces.
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 stents achieve effective localization and patency with reduced radial force, minimizing chronic complications and tissue damage, while maintaining stent fixation, thus improving the safety and efficacy of minimally invasive procedures.
Implementation Method 1
employing non-frictional forces for fixation, such as Van der Waal interactions, to minimize migration and tissue damage
Implementation Method 2
utilizing a Wenzel-Cassie interface that decouples radial force from localization, allowing for reduced contact with the lumenal surface
Data Source
AI summary
Low radial force stents with good resistance to migration are described comprising microstructured surfaces which generate inward radially directed grip to a lumen. In particular, stents are described for deployment within biological lumens where a novel combination of low outwardly directed radial force and resistance to shear slippage within the lumen is achieved by hierarchical microstructured surfaces which provide non-frictional grip to the luminal surface. Combinations of microstructured surfaces which combine low radial force frictional grip and non-frictional grip which do not rely on axially dependent changes in stent diameter or stent oversizing are described. These combinations of microstructured surfaces when placed on the outer surface of a stent provide a non-migrating stent. The hierarchical levels of the disclosed microstructures may themselves by composites of microstructures, which may or may not be self-similar to other hierarchical levels.