Stent Delivery Device Stopper Design for Precise Placement
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Solution Overview
Problem
Conventional stent delivery devices face challenges in precisely delivering self-expanding stents due to longitudinal migration of the stent relative to the inner sheath, leading to imprecise placement and distortion, as they struggle to effectively combine the functions of restraining and releasing the stent during deployment and recapture.
Innovation Solution
A stent delivery device with a stent stopper having a circumferentially disposed main body and radially extending projections that securely engage the self-expanding stent, featuring a trapezoidal upper surface and recessed proximal end surface to prevent longitudinal displacement while allowing for smooth deployment and recapture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional stent stopper is used to restrain the stent on the inner sheath, then the stent can be retained during delivery, but the stent may be displaced longitudinally when the outer sheath is withdrawn, leading to imprecise delivery and distortion
Solution Approach 1:
The stent stopper is designed with a dynamic engagement mechanism where the distal end surface is inclined relative to the longitudinal axis, allowing the stent to be restrained during delivery through friction and geometric constraint, while enabling controlled longitudinal movement during deployment as the stent expands radially
Solution Approach 2:
The stopper features a localized inclined distal end surface that creates differential engagement: the inclined surface provides restraint during delivery, while the proximal end surface with recess allows controlled release during deployment, creating localized functional zones on the stopper structure
2Ease of operation
If the outer sheath is withdrawn to deploy the self-expanding stent, then the stent can be released, but the stent tends to migrate or jump longitudinally relative to the inner sheath, resulting in imprecise delivery and distortion
Solution Approach 1:
The inclined distal end surface of the stopper is configured to counteract the longitudinal migration tendency of the stent during outer sheath withdrawal, creating a preliminary restraining force that prevents jumping and maintains precise placement throughout the deployment process
3Adaptability or versatility
If the stent stopper is configured to restrain the stent during recapture, then recapture can be performed, but the stopper may hinder the stent's self-expansion behavior when fully deployed
Solution Approach 1:
The stopper is segmented into distinct functional surfaces: the distal end surface for restraint during recapture, and the proximal end surface with recess that allows controlled release during deployment, enabling the stopper to perform multiple functions without compromising stent expansion
Solution Approach 2:
The stopper acts as an intermediary mechanism between the inner sheath and stent, providing restrained engagement during recapture while allowing controlled disengagement during deployment, mediating between the conflicting requirements of retention and expansion
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
The solution effectively restrains the stent during deployment and recapture, ensuring precise placement and minimizing distortion, while allowing for seamless expansion and retraction, thereby improving the accuracy and reliability of stent delivery.
Implementation Method 1
a self-expanding stent constructed of shape memory material
Data Source
AI summary
A stent delivery device for delivering a self-expanding stent comprises an inner sheath including a proximal end portion and a distal end portion, a stent stopper including a stopper main body that is circumferentially disposed over at least a portion of the inner sheath at the proximal end portion, and at least one projection extending radially outward from the stopper main body for releasably engaging a portion of the self-expanding stent, and an outer sheath slidably disposed over the inner sheath and the stent stopper. The at least one projection includes a distal end surface and a proximal end surface, and the proximal end surface includes a recess extending into a body of the projection toward the distal end surface.