Stent Delivery System Rack and Pinion Control
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Solution Overview
Problem
The stent delivery system using self-expandable stents faces challenges in precise positioning and re-accommodation, with stents often jumping out of the delivery system, making it difficult to reposition them accurately and re-accommodate them after partial exposure.
Innovation Solution
A stent delivery system with a stent-accommodating tube body and an operation unit featuring a rack member and rotary roller mechanism, allowing for easy release and re-accommodation of the stent by moving the stent-accommodating tube body relative to the inner tube body, enabling precise control over the stent's placement and re-placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-expandable stent is used for treatment, then the stent can spontaneously return to its original expanded state to maintain the lumen shape, but it becomes difficult to position the stent accurately and control its release during the indwelling procedure
Solution Approach 1:
The delivery system is divided into multiple functional components: an inner catheter member for stent attachment and positioning, an outer restraining member for controlling stent release, and a control handle with thumbwheel for precise operation. This segmentation allows independent optimization of each component's function while maintaining overall system control.
Solution Approach 2:
The patent introduces a control handle with a thumbwheel as an intermediary device between the operator and the stent release mechanism. This intermediary translates rotational motion into precise linear displacement of the outer restraining member, enabling controlled stent release while maintaining positioning accuracy.
2Productivity
If the stent is released from the delivery system for deployment, then the stent can be expanded in the target part, but it becomes difficult to re-accommodate the stent into the delivery system for repositioning
Solution Approach 1:
The outer restraining member is designed to move dynamically between two states: a restrained state where it holds the stent within the delivery system, and a released state where it allows stent deployment. The control handle enables smooth transitions between these states, and the system can be reversed to re-accommodate the stent by rotating the thumbwheel in the opposite direction.
Solution Approach 2:
The delivery system is designed with multi-functionality to perform both stent release and stent re-accommodation using the same mechanical components. The outer restraining member and control handle mechanism can operate in reverse, allowing the system to both deploy and reposition the stent as needed during the procedure.
3Ease of operation
If the stent jumps out from the delivery system during insertion, then the stent may be deployed prematurely, but precise positioning at the target part becomes impossible
Solution Approach 1:
The control handle with thumbwheel provides mechanical feedback to the operator during stent release. The operator can feel the resistance and movement of the outer restraining member, allowing precise control of the release process. This tactile feedback ensures the stent is released only when intentionally commanded, preventing premature deployment while maintaining positioning accuracy.
Solution Approach 2:
The patent replaces simple mechanical release mechanisms with a more sophisticated control system involving a thumbwheel and threaded engagement. This mechanical substitution transforms an uncontrolled release into a precisely controllable process, where the operator can incrementally advance the outer restraining member to achieve accurate stent positioning before release.
Data Source
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AI summary
Disclosed is a stent delivery system (1) which includes a body and an operation unit (6) disposed at an proximal end of the body. The body includes a self-expanding stent (10), an inner tube body (3), and a stent-accommodating tube body (5) in which the stent (10) is accommodated. The inner tube body (3) has a stent-holding part enabling the stent (10) to be re-accommodated into the stent-accommodating tube body (5). The operation unit (6) includes: a rack member (43) which is fixed to a proximal end of the stent-accommodating tube body; an operation rotary roller (50) which has a working gear wheel (54) that engages with teeth (66) of the rack member (43), thereby causing the rack member to move forward and backward; and a connector (46) which is fixed to a proximal end portion of a proximal-side tube (34) that penetrates the stent-accommodating tube body and protrudes from the proximal end of the stent-accommodating tube body.