Uncaging Stent with Degradable Metallic Coating
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Solution Overview
Problem
Existing stents, both metallic and biodegradable, face challenges such as inward recoil, limited ability to further expand after implantation, and reduced vascular compliance, leading to issues like re-occlusion and impaired vessel function.
Innovation Solution
The development of stents with modified radial strength and compliance characteristics, featuring circumferential rings with separation regions that form discontinuities over time, allowing for increased compliance and reduced radial strength post-implantation, thereby mimicking natural vessel behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic stents are used to provide high radial strength and hold the vessel open, then the vessel remains open with sufficient crush resistance, but the stent jails the lumen preventing further expansion and inhibits positive remodeling
Solution Approach 1:
The stent transitions from a static high-strength structure to a dynamic system where radial strength decreases over time. The metallic coating degrades progressively, allowing the stent to evolve from providing rigid support to allowing natural vessel remodeling while maintaining adequate support throughout the healing process
Solution Approach 2:
The radial strength parameter of the stent is intentionally designed to change over time through controlled degradation of the metallic coating. This time-dependent parameter change allows the stent to provide high initial strength for vessel stabilization followed by progressive strength reduction to enable vessel remodeling and expansion
2Strength
If high radial strength stents are used to prevent lumen recoil, then the lumen remains open, but the stent inhibits vasodilation and vaso-motion important for vessel healing
Solution Approach 1:
The stent's radial strength is designed as a time-dependent parameter that decreases through controlled metallic coating degradation. This allows the stent to provide high initial strength for preventing recoil while progressively reducing strength to restore vasodilation and vaso-motion capabilities essential for vessel healing
Solution Approach 2:
The stent system transitions from a static high-strength configuration to a dynamic system that adapts its mechanical properties over time. The progressive degradation of the metallic coating creates a temporal profile of radial strength that matches the vessel healing timeline, enabling both immediate structural support and long-term physiological function
3Ease of operation
If shape memory self expandable alloys are used, then the stent can be delivered in a compressed state, but these stents do not exhibit high radial strength and the lumen becomes smaller after implantation
Solution Approach 1:
The stent combines a shape memory alloy core structure with a degradable metallic coating layer. The core provides superelasticity and deliverability, while the coating provides additional radial strength that degrades over time. This composite structure integrates the advantages of both material systems while mitigating their individual limitations
Solution Approach 2:
The stent system uses the dynamic degradation of the metallic coating to progressively increase radial strength after implantation. The shape memory alloy provides initial structural integrity during delivery and implantation, while the degradable coating adds temporary radial strength that evolves over time to support the vessel during the critical healing period
Data Source
AI summary
A stent (scaffold) or other luminal prosthesis comprising circumferential structural elements which provide high strength after deployment and allows for scaffold to uncage, and/or allow for scaffold or luminal expansion thereafter. The circumferential scaffold is typically formed from non-degradable material and will be modified to expand and/or uncage after deployment.