Elastic Stent for Temporary Vessel Support and Safe Retrieval
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Solution Overview
Problem
Current stents used to treat peripheral vessel stenosis face challenges such as high recurrence rates due to mechanical stress and irritation, leading to restenosis, and difficulties in safe removal without causing tissue injury or leaving behind decomposition products that can obstruct blood vessels.
Innovation Solution
A stent with an elastic wall that decreases in diameter under tensile force, allowing for temporary implantation to prevent intima delamination and subsequent removal without causing vascular injury, using materials like woven or braided wire with shape memory properties and a non-adhesive coating to prevent vascularization and facilitate easy retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stent is implanted in peripheral vessels to prevent intima delamination, then vascular occlusion and infarction are prevented, but the stent becomes subject to high mechanical loads leading to destruction and restenosis
Solution Approach 1:
The patent applies the disposable principle by designing a stent intended for temporary use only. The stent is implanted to provide immediate structural support and prevent intima delamination, then systematically removed after a predetermined period (typically 1-4 weeks) before the vessel can be permanently damaged or restenosis occurs. This resolves the contradiction by accepting the stent's temporary nature rather than expecting long-term durability in high-stress peripheral vessels.
Solution Approach 2:
The patent applies preliminary action by providing instructional material that specifies a predetermined removal time before the stent is actually removed. The instructional material guides the user to remove the stent at an optimal time point that balances the need for vascular support with the risk of mechanical destruction, enabling timely intervention before restenosis or vessel damage occurs.
2Reliability
If a stent is left in place long-term to prevent restenosis, then vascular patency is maintained, but the stent causes constant irritation leading to restenosis and may impede surgical bypass
Solution Approach 1:
The patent applies the disposable principle by designing a stent for temporary use only. The stent provides immediate structural support to maintain vascular patency during the critical healing period, then is removed before long-term irritation can cause restenosis or interfere with potential surgical bypass procedures. This resolves the contradiction by limiting the stent's presence to the minimum necessary duration.
Solution Approach 2:
The patent applies the dynamics principle by transitioning the stent from a permanent to a temporary implant. The stent's function is dynamic rather than static—it provides support when needed most (immediately after intima delamination) and is then removed to allow the vessel to heal without foreign body irritation. This dynamic approach optimizes the balance between maintaining patency and preventing irritation-induced restenosis.
3Ease of operation
If a stent is removed from a vascularized vessel wall, then the stent can be retrieved, but tissue injury and decomposition product obstruction may occur
Solution Approach 1:
The patent applies preliminary action by providing instructional material that specifies a predetermined removal time, ensuring the stent is removed before significant vascularization occurs. This timing guidance enables safe removal by extracting the stent while minimizing adhesion to the vessel wall, thereby reducing tissue injury and preventing decomposition product obstruction. The instructional material guides users to remove the stent at an optimal time point that balances retrievability with tissue safety.
Solution Approach 2:
The patent applies the disposable principle by designing a stent for temporary use with systematic removal planned from the outset. The stent is intended to be removed after a predetermined period (1-4 weeks) before extensive vascularization occurs, making retrieval safe and minimizing tissue injury. This resolves the contradiction by planning for removal before the stent becomes permanently integrated into the vessel wall.
4Volume of moving object
If extreme overdilation is performed to expand stenosis in leg vessels, then adequate vessel expansion is achieved, but dissection of the vessel wall layers occurs
Solution Approach 1:
The patent applies parameter changes by transitioning from a permanent to a temporary stent implantation strategy. The temporary stent allows for adequate lumen expansion to treat stenosis but is removed before the high mechanical loads of peripheral circulation can cause mechanical destruction or restenosis. This parameter change (temporary versus permanent implantation) resolves the contradiction by accepting the need for expansion while avoiding the long-term consequences of wall dissection and restenosis.
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 prevents restenosis and allows for safe removal, reducing the risk of vascular occlusion and amputation, while minimizing tissue damage and avoiding long-term vascularization, thus addressing the limitations of existing stent technologies.
Implementation Method 1
The wall (12) is designed so as to be elastic under tension and is designed so that on exertion of a tensile force (15), which acts on one of the ends (13, 14) of the stent in the longitudinal direction, the diameter of the stent decreases
Implementation Method 2
using materials like woven or braided wire with shape memory properties and a non-adhesive coating to prevent vascularization and facilitate easy retrieval
Data Source
AI summary
A stent for positioning in a body lumen having a cylindrical shape extending along a longitudinal axis surrounded by a stent wall which defines a diameter of an axial passage communicating with openings on two opposite ends of the stent. The wall is configured so as to be elastic under tension whereupon an exertion of a tensile force acting on one of the ends of the stent in a longitudinal direction decreases the diameter of the stent, such that the stent may be removed.