Bow Stent with Nested Inner Outer Members for Removable Vessel Support
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Solution Overview
Problem
Current stents, especially metal expandable ones, are difficult to remove and often require replacement due to occlusion within a few months, limiting their effectiveness in treating benign strictures and maintaining vessel patency over time.
Innovation Solution
A bow-shaped stent design featuring a main linear strut with adjustable length and secondary struts that bow outward to apply radial force, allowing for expandable and removable support within a lumen, facilitated by a coaxial inner and outer member configuration and coupling elements for easy deployment and retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal expandable stents are used to provide wider lumen and reduce occlusion, then reliability is improved, but ease of removal deteriorates
Solution Approach 1:
The stent is divided into multiple expandable cells or struts that can be independently controlled. This segmentation allows the stent to be expanded and contracted in a controlled manner, enabling removal while maintaining structural integrity and resistance to occlusion when deployed.
Solution Approach 2:
The stent employs dynamic expandability where the structure can transition between compressed and expanded states. This dynamic characteristic allows the stent to provide reliable support when expanded (resisting occlusion) while enabling easy removal by compressing it back to its collapsed state for extraction.
2Duration of action of stationary object
If stents are designed to remain in patient for six months or more without replacement, then duration of action is improved, but reliability deteriorates due to occlusion
Solution Approach 1:
The stent's dynamic expandability allows it to be adjusted or removed after the treatment period, preventing long-term occlusion issues. The structure can maintain patency during the required duration while offering the option for removal if occlusion begins to occur, thus maintaining reliability throughout the retention period.
Solution Approach 2:
The stent is designed as a temporary implant that can be removed after serving its purpose. This approach allows the stent to maintain vessel patency for the required duration (six months or more) without the long-term occlusion problems associated with permanent stents, as it can be extracted once its supportive function is complete.
3Ease of operation
If stents are made expandable to provide support, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The stent employs a nested structure where the expandable struts are contained within a delivery catheter in a collapsed state. This nesting allows the complex expandable structure to be delivered through vessels in a compact form and then expanded at the target site, simplifying the deployment process while maintaining the necessary structural complexity for effective support.
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 maintains vessel patency for extended periods without occlusion, is readily removable, and can treat benign strictures, addressing the limitations of existing stent technologies by providing sustained support and ease of removal.
Implementation Method 1
an outer member and an inner member slidably disposed within a lumen of the outer member
Implementation Method 2
retracting the handle such that the second coupling element, first coupling element, and inner member are proximally withdrawn while the outer member remains stationary, shortening a length of the main linear strut thereby causing the first and second secondary struts to bow outward and apply radial force against a wall of the lumen
Data Source
AI summary
A stent having a main linear strut and at least two secondary struts. The main linear strut includes an outer member and an inner member. A distal end of one secondary strut may be attached to a distal end of the inner member. A proximal end of a secondary strut may be attached to a proximal end of the outer member. The ends of the secondary struts that are not attached to the inner and outer member may be joined. Methods of delivering such a stent and collapsing and withdrawing such a stent are also disclosed.