Microporous Stent Coating for Tissue Interaction
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Solution Overview
Problem
Current stents face challenges in having varying characteristics along their surface area, leading to inconsistent performance, tissue granulation, and fluid stagnation, particularly when used in different anatomical lumens, where they often fail to accommodate unique radial forces and cilia function, resulting in complications like restenosis and infections.
Innovation Solution
A stent made from a single composite material, such as Ni, Co, Cu, Cr, H, Fe, Nb, O, and their combinations, with geometric modifications like laser-etched interstices and zones of varying hardness/softness, and a polyurethane coating that elevates struts above the surface to prevent epithelialization and promote cilia function, while minimizing granulation and infection risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a stent is covered with an elastomeric cover to prevent epithelialization, then epithelialization is reduced, but the cover is subject to bunching particularly about stenotic tissue which can lead to additional tissue granulation
Solution Approach 1:
The patent applies different surface properties to different regions of the stent. The external surface has a microporous structure that allows tissue ingrowth in specific areas while maintaining smooth coverage in other areas, preventing both epithelialization where needed and tissue granulation from bunching.
Solution Approach 2:
The stent incorporates a microporous external surface structure that allows controlled tissue interaction. This porous structure prevents epithelialization by allowing tissue ingrowth through the pores while maintaining structural integrity and preventing the bunching that causes granulation.
2Object-affected harmful factors
If a stent is dip coated to cover the scaffolding, then epithelialization is prevented, but the coating leads to uneven coating as well as inconsistency in stent performance from batch to batch
Solution Approach 1:
The patent replaces the mechanical dip-coating process with a controlled microporous structure formation process. This structure is created through precise manufacturing techniques that ensure uniformity without the variability inherent in dip-coating, eliminating batch-to-batch inconsistency while maintaining protection against epithelialization.
3Strength
If the ends of the stent are left exposed to encourage granulation tissue formation, then the stent is anchored in place, but direct metal to tissue contact accelerates tissue granulation and galvanic current generation
Solution Approach 1:
The patent applies different surface characteristics to different portions of the stent. The ends have a microporous structure that promotes controlled tissue ingrowth for anchoring while minimizing direct metal contact, reducing galvanic current generation compared to fully exposed metal ends.
Solution Approach 2:
The microporous structure acts as an intermediary between the metal stent and surrounding tissue. This intermediate layer allows tissue ingrowth for anchoring while reducing direct metal-tissue contact that causes galvanic currents, mediating the interaction between metal and biological tissue.
4Adaptability or versatility
If a stent is made from multiple materials to provide varying characteristics, then different shape-memories can be achieved, but the stent is vulnerable to premature obsolescence and leads to inconsistent characteristics along the surface area
Solution Approach 1:
The patent achieves varying characteristics along the stent surface by modifying the microporous structure in different regions rather than using multiple materials. This allows control over tissue interaction, flexibility, and radial force in specific zones while maintaining a uniform base material, ensuring consistency and reliability.
Solution Approach 2:
The patent creates a composite structure by combining a base metal material with a microporous surface layer. This composite approach provides varying characteristics through structural modification rather than material composition changes, maintaining material consistency while achieving functional diversity.
5Object-affected harmful factors
If a stent coating is made of a predominately hydrophilic polymer, then epithelialization is prevented, but it can lead to mucous formation and/or fluid stagnation
Solution Approach 1:
The microporous structure prevents epithelialization by allowing tissue penetration and integration rather than forming a continuous hydrophilic barrier. The pores facilitate fluid flow and prevent stagnation while still preventing epithelialization through controlled tissue ingrowth, eliminating the mucous formation issue associated with hydrophilic coatings.
Data Source
AI summary
The present invention, in an exemplary embodiment, provides a stent, which combines many of the excellent characteristics of both silicone and metal stents while eliminating the undesirable ones. In particular, a principal objective in accordance with the present invention is to provide a family of stents where the relative hardness/softness of regions of the stent can differ from other regions of the stent to provide additional patient comfort and resistance to compression forces. Exemplary embodiments provide a stent that is covered so as to provide certain predefined characteristics. In particular, a covered stent is provided that is coated internally such that the outer scaffolding surface of the stent has enhanced friction points while the internal surface exemplifies certain characteristics.