Stent Delivery System Locking Mechanism for Precision Placement
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Solution Overview
Problem
Self-expandable stents are difficult to correctly implant at desired portions due to movement issues during expansion, as they are restricted between inner and outer tubes, leading to potential restenosis and complications during stent delivery.
Innovation Solution
A stent delivery system with a distal-side tube, proximal-side tube, stent accommodation tubular member, and pulling wire mechanism that allows controlled movement and expansion of the stent, preventing twist transmission and facilitating precise placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stent is restricted between inner tube and outer tube during delivery, then the stent can be safely transported to the target location, but the stent may move forward during expansion due to friction and loosening, compromising implantation precision
Solution Approach 1:
A locking mechanism acts as an intermediary between the stent and the delivery system. This locking portion engages with the stent during transport to prevent movement, then releases at the target location to allow controlled expansion, thus mediating between the need for secure transport and precise implantation
Solution Approach 2:
The delivery system transitions from a static restricted state during transport to a dynamic release state during implantation. The locking mechanism is designed to be temporarily engaged during delivery and then released to allow stent expansion, enabling the system to adapt its constraints based on the operational phase
2Ease of operation
If the outer tube is pulled to release the stent for expansion, then the stent can be deployed, but friction between the outer tube and catheter or introducer valve may cause unwanted movement
Solution Approach 1:
The locking mechanism serves as an intermediary that decouples the release operation from friction-dependent tube movement. By using a dedicated locking portion that directly engages and releases the stent, the system eliminates reliance on friction between the outer tube and other components, ensuring precise placement during the release operation
3Length of moving object
If the stent is accommodated in a sheath with smaller diameter than the lumen, then the stent can be delivered through narrow passages, but the stent may not expand correctly at the desired portion
Solution Approach 1:
The locking mechanism acts as an intermediary that ensures the stent remains at the correct location during delivery through narrow passages, then releases to allow proper expansion. The locking portion prevents premature expansion while navigating constricted areas, and its release at the target site ensures expansion occurs only at the desired location
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 secure and precise implantation of self-expandable stents by minimizing twist transmission and movement during expansion, reducing the risk of restenosis and improving stent delivery efficiency.
Implementation Method 1
the stent itself has contracting and expanding functions... the stent is pressed out of the sheath. Because the stent is released from the sheath, the applied stress is removed. The stent thus returns to the original configuration.
Data Source
AI summary
A stent delivery system includes a distal-side tube having a guide wire lumen, a proximal-side tube, a fixing tube at which a proximal portion of the distal-side tube and a distal portion of the proximal-side tube are fixed and which has an opening communicating with the guide wire lumen, a stent accommodation tubular member which encloses a distal side of the distal-side tube and is slidable toward a proximal end of the distal-side tube, a stent accommodated inside the stent accommodation tubular member, and a pulling wire whose one end portion is fixed to the stent accommodation tubular member and which extends inside the proximal-side tube for moving the stent accommodation tubular member toward a proximal side by being pulled toward the proximal side.