Stent Delivery System With Delayed-Release Position Restraint
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Solution Overview
Problem
Existing stent delivery systems face challenges in achieving precise positional accuracy during deployment due to displacement of the stent under blood flow forces, often leading to incomplete closure of the entry tear or complete closure of branch vessels, which can result in organ ischemia or endoleak.
Innovation Solution
A stent delivery system comprising a handle, outer tube, restraining member, and delayed-release member, which includes restraining threads and a control guidewire to maintain stent position, ensuring accurate release by securing the proximal end to the delayed-release member and using fixed coils to stabilize the distal end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stent is released without positional restraint mechanisms, then the release process is simpler, but the stent may move backward under blood flow forces, compromising deployment accuracy
Solution Approach 1:
The restraining member is divided into multiple restraining threads (first restraining thread, second restraining thread, etc.) that are distributed around the stent. Each thread independently restrains the stent at different locations, allowing the system to maintain positional accuracy through multiple discrete restraint points rather than a single complex restraint mechanism.
Solution Approach 2:
The restraining threads are pre-configured in a closed-loop structure around the stent before delivery. This preliminary configuration ensures that the stent is already restrained against backward movement when deployed, eliminating the need for complex real-time adjustment mechanisms during the deployment process.
2Measurement precision
If restraining threads are used to prevent stent movement, then positional accuracy is improved, but the structure of the delivery system becomes more complex
Solution Approach 1:
The restraining threads serve multiple functions: they restrain the stent from moving backward during deployment, maintain the stent in a compressed state within the outer tube, and can be controlled to release in a specific sequence. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The control guidewire acts as an intermediary element that controls the restraining threads. By manipulating the control guidewire, the operator can simultaneously control multiple restraining threads, simplifying the control interface despite the presence of multiple restraining elements.
3Reliability
If the stent is allowed to move during release, then the release process is faster, but the entry tear may not be completely closed or branch vessels may be blocked
Solution Approach 1:
The restraining threads are designed to release in a periodic or sequential manner rather than all at once. The control guidewire enables sequential release of different restraining threads, allowing the stent to expand in a controlled, step-by-step process that ensures proper positioning and complete closure of the entry tear and branch vessels.
Solution Approach 2:
The restraining threads provide preliminary counter-action against the natural tendency of the stent to move backward during release. By pre-positioning these restraining elements, the system counteracts the harmful backward movement before it can compromise the closure of the entry tear or blockage of branch vessels.
Data Source
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AI summary
A stent delivery system and a method for mounting a stent (1) are disclosed. The stent delivery system includes a handle, an outer tube (52), a restraining member and delayed-release member (4) and is structurally simple and easy to use. During the release of a stent (1) from the restraining member, a proximal end of the stent (1) is always secured to the delayed-release member (4), avoiding the stent (1) from moving backward under the action of forces from the blood and thus resulting in improved positional accuracy of the release of the stent (1). Additionally, during the release of the stent (1) from the restraining member, a distal end of the stent (1) can be secured to an inner tube (51) by means of a fixed coil (32), and the proximal end of the stent (1) can remain fixed on the delayed-release member (4). This can avoid the stent (1) from moving forward or backward during the release of a middle section of the stent (1), allowing the stent (1) to be released under true accurate positional control.