Self-Expanding Stent Deployment Catheter with Nested Tube Control
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Solution Overview
Problem
Conventional systems for inserting braided self-expanding stents into blood vessels struggle with precise positioning due to significant expansion and length changes during deployment, leading to potential dislocation and inability to maintain intended position.
Innovation Solution
A catheter system comprising an inner tube, a middle tube, and an outer tube, where the stent is radially compressed between the inner and outer tubes, allowing controlled release by displacing the outer tube proximally and the central tube distally to maintain the stent's intended position, with a drive unit enabling precise movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a braided self-expanding stent is compressed radially for insertion, then the stent can be inserted easily into the blood vessel, but the stent length increases significantly during compression
Solution Approach 1:
The catheter system employs a nested tube structure with an inner tube, middle tube, and outer tube, where each tube can move independently within the others. The compressed stent is positioned between the inner and outer tubes, allowing the tubes to nest within each other while providing independent movement control to manage stent length changes during deployment
2Reliability
If the stent is released from the catheter, then the stent expands radially to open the blood vessel, but the stent position changes due to length and diameter changes
Solution Approach 1:
The system transitions from a static catheter to a dynamic one where the outer tube can move independently relative to the inner tube. During stent release, the outer tube moves distally to compensate for the stent's expansion, dynamically adjusting the delivery system's length to maintain the stent's distal end position while allowing radial expansion
Solution Approach 2:
The outer tube acts as an intermediary element between the operator's release action and the stent's expansion. By moving the outer tube distally during release, it compensates for the stent's length increase, ensuring the distal end position remains accurate while still allowing the stent to expand radially to open the vessel
3Device complexity
If conventional catheter systems are used to deploy the stent, then the deployment process is simple, but millimeter precision positioning cannot be achieved
Solution Approach 1:
The catheter is segmented into three independently movable tubes (inner, middle, outer) rather than a single unified structure. This segmentation allows precise control over the stent release process, enabling millimeter precision positioning by coordinating the movement of each tube while maintaining a relatively simple overall catheter design
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
Ensures that both the distal and proximal ends of the stent assume their intended positions after release, maintaining target length and position, thereby preventing dislocation and ensuring accurate placement.
Implementation Method 1
If the stent is a self-expanding stent, then due to its elasticity or spring effect, it expands itself back into its original shape when it is released and in the process expands its lateral surface
Implementation Method 2
catheters, in which the compressed stents are arranged in a sleeve-like tube which, due to its elastic properties, presses the stent radially inwards
Data Source
Figure 1a~1f
Figure 2
Figure 3
AI summary
System for insertion of a compressed, self-expansible stent into in particular a blood vessel and for release of the stent in particular in the blood vessel, comprising a catheter with an inner tube, a middle tube and an outer tube, wherein the middle tube extends through the outer tube, and the inner tube extends through the middle tube, wherein the compressed stent, in a distal end portion of the catheter, is arranged radially compressed between the inner tube and the outer tube, running radially around the inner tube, and the middle tube ends distally at the proximal end of the stent, wherein, in order to release the stent, the outer tube is displaceable in the proximal direction and the middle tube in the distal direction, in such a way that the distal end of the stent maintains its intended position during the release.