Stent Delivery Sheath Segmentation for Reduced Deployment Force
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Solution Overview
Problem
Current stent delivery devices face challenges in deploying self-expanding stents in narrower body lumens due to increased force requirements, necessitating improvements in catheters and systems that facilitate easier stent deployment.
Innovation Solution
The stent delivery device incorporates an outer sheath with a distal portion featuring longitudinal strips that radially expand, allowing the stent to deploy by releasing the radially outward force exerted against the sheath, reducing the force needed for deployment and enabling repositioning of the stent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the outer sheath is made smaller to accommodate use in narrower body lumens, then the device can be used in narrower lumens, but the force required to deploy the stent increases
Solution Approach 1:
The outer sheath is segmented into multiple longitudinal strips that can radially expand. This segmentation allows the distal portion of the sheath to expand outward, creating additional space for stent deployment while maintaining a small overall catheter profile for navigation through narrow lumens.
Solution Approach 2:
The outer sheath transitions from a constrained cylindrical state during delivery to an expanded radial state at the deployment site. By utilizing the radial dimension for expansion, the device creates deployment space without increasing the axial or circumferential dimensions that would prevent navigation through narrow body lumens.
2Ease of operation
If the outer sheath is removed completely to allow stent expansion, then the stent can deploy freely, but the ability to reposition the stent is lost
Solution Approach 1:
The outer sheath is designed with dynamic expandability, allowing it to transition between a constrained delivery state and an expanded deployment state. This dynamic characteristic enables the sheath to maintain engagement with the stent during positioning while allowing controlled release for deployment, facilitating both repositioning and stable deployment.
Solution Approach 2:
The self-expanding stent utilizes its own elastic memory to expand when released from the outer sheath. The stent's intrinsic properties allow it to self-deploy without requiring additional external forces or mechanisms, ensuring reliable expansion while the expandable sheath provides controlled retention and release capability.
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
This configuration reduces the force required for stent deployment and allows for easier repositioning by maintaining a proximal portion of the stent within the sheath, enhancing the deployment process in narrower lumens.
Implementation Method 1
The outer sheath may include a distal portion including a plurality of longitudinal strips that are radially expandable
Implementation Method 2
Once unconstrained by the outer sheath, the self-expanding stent can expand to force itself against the luminal wall of the body lumen
Data Source
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Figure 2B
AI summary
A stent delivery device having a delivery configuration for delivering a stent to a treatment location and a deployment configuration for deploying the stent at the treatment location may include an outer sheath, an inner shaft slidably disposed within a lumen of the outer sheath, and a distal tip member fixedly attached to a distal end of the inner shaft. A distal portion of the outer sheath may include a plurality of longitudinal strips circumferentially disposed about the lumen of the outer sheath. At least a portion of the distal tip member may be configured to slide over a distal end of the outer sheath in the delivery configuration.