Anti-migration Stent Nested Design Resolves Migration Contradiction
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Solution Overview
Problem
Conventional stents for expanding narrowed or blocked lumens in the body are prone to migration due to external forces such as moving body fluids, food pressure, or body shaking, and are difficult to remove after a procedure.
Innovation Solution
An anti-migration stent design featuring a first stent with a hollow cylindrical shape made of super elastic shape memory alloy and PTFE film parts, combined with a second stent that is shorter and fitted over the first stent, with a connection part and bent portion made of silicone, which prevents migration and facilitates easy removal by allowing the second stent to be turned over when pulled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional stent is used to expand a narrowed lumen, then the lesion area is expanded, but the stent migrates due to external forces from body fluids, food pressure, or body shaking
Solution Approach 1:
The patent employs a nested structure where a second stent is fitted over the first stent. The first stent expands the narrowed lumen while the second stent, with its bent portion, resists migration forces. This nested configuration allows both stents to work together, with the inner stent providing expansion and the outer stent providing migration resistance, thereby resolving the contradiction between stability and migration resistance.
Solution Approach 2:
The second stent incorporates a bent portion that creates an asymmetric structure. This bent portion engages with the lumen wall in a non-symmetric manner, providing directional resistance to migration forces. The asymmetric design allows the stent to maintain position against external forces while still permitting controlled expansion of the lesion area, addressing both stability and migration resistance requirements.
2Strength
If a conventional stent is used to expand a narrowed lumen, then the lesion area is expanded, but the stent is difficult to remove after the procedure
Solution Approach 1:
The stent system is segmented into two separate stents that can be independently managed. The first stent performs the lesion expansion function, while the second stent with its bent portion can be deliberately positioned and engaged for removal. During removal, the bent portion of the second stent can be manipulated to disengage from the lumen wall, allowing controlled extraction of the entire stent assembly. This segmentation enables the removal operation to be performed more easily by targeting the second stent for disengagement.
3Reliability
If the second stent is made shorter and fitted over the first stent, then migration is prevented, but the structure becomes more complex
Solution Approach 1:
The nested stent configuration, while adding structural complexity, provides effective migration prevention through the interaction of the two stents. The second stent fitted over the first stent creates a layered structure where the bent portion of the outer stent engages with the lumen wall to prevent migration. This nested design, though more complex than a single stent, achieves superior migration resistance by combining the expansion capability of the inner stent with the anchoring capability of the outer stent.
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 anti-migration stent effectively prevents deformation and migration during external forces, while its design allows for easy removal from the lumen by turning over the second stent, reducing the risk of damage to the lumen and simplifying the removal process.
Implementation Method 1
a first cylindrical body formed in a hollow cylindrical shape by weaving or crossing wires made of a super elastic shape memory alloy in a mesh shape
Implementation Method 2
a first film part made of polytetrafluoroethylene (PTFE) formed on an inner surface of the first cylindrical body
Implementation Method 3
a bent portion formed at an angle between the second cylindrical body and the connection part, with the second cylindrical body, the connection part, and the bent portion having a third film part made of silicone formed thereon
Data Source
AI summary
Proposed is an anti-migration stent which expands a lesion area occurring in a lumen and is prevented from migrating, is deformed to fit the lumen of a curved shape, and can be easily removed from the lumen. More specifically, the anti-migration stent includes a first stent including a first cylindrical body, a first film part, and a second film part, and a second stent including a second cylindrical body, a connection part formed to be inclined by bending at one side of the second cylindrical body inward, a bent portion formed at an angle between the second cylindrical body and the connection part, and a third film part, wherein after the second stent is fitted over one side of the first stent, the one side of the first stent and the connection part are connected to each other, and the second stent is held in the lumen.