Pusher Guide Wire With Variable Friction Stent Holding Portion
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Solution Overview
Problem
Conventional pusher guide wires lack the ability to retrieve a self-expandable stent once it has been partially released from a catheter due to uniform frictional resistance, making it difficult to correct placement errors without risking stent deformation.
Innovation Solution
A pusher guide wire design with varying frictional resistance between the stent and the stent holding portion, where the proximal end side has higher frictional resistance than the distal end side, allowing for controlled retrieval of the stent into the catheter by adjusting the pitch intervals or shapes of the stent holding portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform frictional resistance is used between stent and stent holding portion, then the stent can be easily released to target site, but the stent cannot be retrieved into catheter once more
Solution Approach 1:
The stent holding portion is designed with different frictional resistance characteristics at different locations: the distal end side has a smooth surface with small frictional resistance to facilitate stent release, while the proximal end side has a rough surface with large frictional resistance to enable stent retrieval. This local differentiation of surface properties resolves the contradiction between easy release and retrievability.
2Adaptability or versatility
If frictional resistance is increased on proximal end side, then stent retrieval becomes possible, but stent may become deformed during retrieval
Solution Approach 1:
The rough surface treatment is applied only to the proximal end side of the stent holding portion, creating localized high friction zones that engage the stent bars without affecting the entire stent structure. This localized approach provides sufficient friction for retrieval while minimizing the risk of deformation.
Solution Approach 2:
The stent holding portion is segmented into distinct functional zones: a distal end side for easy release and a proximal end side for secure retrieval. This segmentation allows each zone to perform its specific function optimally without interfering with the other.
3Ease of operation
If frictional resistance is decreased on distal end side, then stent release is facilitated, but stent may be caught by stent holding portion
Solution Approach 1:
The smooth surface treatment is applied specifically to the distal end side of the stent holding portion, creating a localized low-friction zone that facilitates stent release without compromising the overall holding capability. This localized smooth surface allows the stent to slide off easily while the proximal end side maintains its rough, high-friction characteristics for secure retrieval if needed.
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
Enables the retrieval of the stent into the catheter, reducing the risk of deformation and allowing for repeated attempts to achieve precise placement of the stent at the target site.
Implementation Method 1
frictional resistance between the stent and the stent holding portion is larger on the proximal end side than on the distal end side
Data Source
AI summary
A pusher guide wire for delivering a stent to a target site includes a core shaft, a coil body that covers a distal end portion of the core shaft, a pusher portion that is fixed to the core shaft and on a proximal end side with respect to the coil body, and a stent holding portion that is fixed to the core shaft and between the coil body and the pusher portion. In the pusher guide wire, frictional resistance between the stent and the stent holding portion is larger on the proximal end side than on the distal end side.