Off-Center Support Member Anchors Self-Expanding Stent
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Solution Overview
Problem
Self-expanding stents often experience 'stent jumping' during deployment due to stored energy, leading to inaccurate placement, which can render stent deployment ineffective in treating stenosis.
Innovation Solution
A stent delivery system with an off-center support member that expands non-coaxially relative to the inner shaft, applying a counterforce to the vessel wall to anchor the stent initially, preventing the stent from jumping and ensuring accurate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-expanding stent is deployed by retracting the outer sheath, then the stent expands to treat stenosis, but the stored energy causes the stent to jump and move from the desired position
Solution Approach 1:
The distal tip is designed to engage the vessel wall before the stent fully expands, creating a counteracting force that prevents the stent from jumping forward due to stored energy. This preliminary engagement establishes a stable anchor point that counteracts the harmful jumping motion.
Solution Approach 2:
The distal tip performs a preliminary anchoring action by engaging the vessel wall prior to complete stent deployment. This preliminary engagement ensures the stent remains at the desired position during the expansion process, preventing inaccurate placement.
2Measurement precision
If frictional force acts on the stent during sheath retraction, then the stent is pushed forward, but this causes the stent to jump and lose placement accuracy
Solution Approach 1:
The distal tip engages the vessel wall before the stent fully expands, creating a counteracting force that prevents the stent from jumping forward due to stored energy. This preliminary engagement establishes a stable anchor point that counteracts the harmful jumping motion.
3Ease of operation
If the outer sheath is retracted to deploy the stent, then the stent expands, but the sheath develops slack causing the inner member to move forward
Solution Approach 1:
The distal tip performs a preliminary anchoring action by engaging the vessel wall prior to complete stent deployment. This preliminary engagement ensures the stent remains at the desired position during the expansion process, preventing inaccurate placement.
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 off-center support member facilitates accurate and stable deployment of self-expanding stents by anchoring them to the vessel walls, reducing or eliminating stent jumping and improving placement accuracy.
Implementation Method 1
Self-expanding stents exhibit spring-like characteristics, so care must be taken to reduce, if not eliminate, the phenomenon of 'stent jumping'. That is, self-expanding stents can store energy. Frictional force generated as the outer sheath is retracted can cause the stent perform like a spring, storing energy as the frictional force acts on the stent.
Implementation Method 2
A self-expanding stent possesses a spring force that causes the stent to expand following its implacement in the vessel when a restraining sheath is retracted from the compressed stent.
Implementation Method 3
Frictional force generated as the outer sheath is retracted can cause the stent perform like a spring, storing energy as the frictional force acts on the stent.
Data Source
Figure 1~2
Figure 3~4
AI summary
A delivery device for delivering and deploying a medical device comprises: an inner shaft (10) which is coaxial with a sheath (1), a self-expanding stent (50) retained on the inner shaft and retained within the outer sheath prior to stent deployment, an off center support member in engagement with the shaft that is disposed interior the outer sheath at a location distal to the stent, wherein said off center support member is comprised of a self expanding material and engaged to the shaft non coaxially, relative to the longitudinal axis of the shaft, wherein the off center support member is in an initial state of relative compression, and expands when a restraining force is removed, such that when the device is inserted in the patient's body, the off center support member, when expanded, deploys against the vessel walls to displace the shaft into an off center arrangement prior to deployment of the stent.