Stent Delivery System Segmented Sheath Catheter Repositioning
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Solution Overview
Problem
Conventional sheathed stent delivery systems face challenges such as difficulty in repositioning or removing the stent after deployment, inaccurate placement due to frictional forces and the sheath obstructing direct visualization, and require high force to overcome friction, leading to potential malpositioning and increased complexity and cost.
Innovation Solution
A stent delivery system with an elongate shaft, constraining members, and a release wire mechanism that allows for controlled deployment and repositioning of the stent, enabling precise placement and retraction by manipulating the constraining members and release wire, reducing frictional forces and improving visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional sheathed stent delivery system is used, then the stent can be delivered to the target location, but the stent cannot be repositioned or removed after deployment and requires high force to overcome friction
Solution Approach 1:
The delivery system is divided into separate components: an outer introducer sheath and an inner catheter assembly. The stent is segmented between these two components, held compressed by the outer sheath and positioned on the inner catheter. This segmentation allows independent movement of components, enabling controlled stent deployment and repositioning by manipulating the relative positions of the outer sheath and inner catheter.
Solution Approach 2:
The inner catheter acts as an intermediary component between the operator and the stent. It provides a stable platform for stent positioning while allowing the outer sheath to be manipulated independently. The interaction between the outer sheath and inner catheter serves as a mechanical intermediary system that controls stent deployment forces and reduces friction through distributed contact.
2Manufacturing precision
If the outer sheath is proximally withdrawn to deploy the stent, then the stent can be expanded, but accurate placement of the proximal portion becomes difficult
Solution Approach 1:
The stent deployment process is segmented into two independent controllable actions: outer sheath retraction and inner catheter manipulation. This allows the distal portion of the stent to be deployed first through sheath retraction while the proximal portion remains constrained on the inner catheter, enabling precise placement of the proximal end without affecting the already-deployed distal end.
Solution Approach 2:
The inner catheter is pre-positioned with the stent in the desired final location before deployment begins. This preliminary positioning ensures that when the stent is deployed, the proximal portion is already at the correct location, eliminating the need for complex real-time adjustments during the deployment process.
3Measurement precision
If direct visualization of the stent is required for accurate placement, then the sheath obscures the stent location making placement more difficult
Solution Approach 1:
The delivery system separates the visualization function from the deployment function. The inner catheter provides a stable platform that maintains stent position while the outer sheath can be manipulated for deployment. This segmentation allows continuous visualization of the stent through the more transparent inner catheter while using the outer sheath for controlled deployment actions.
Data Source
AI summary
A stent delivery system includes an elongate shaft including a proximal portion, a distal portion, at least one lumen extending at least partially therethrough, and a stent receiving portion on the distal portion of the elongate shaft. A stent is positioned on the stent receiving portion of the elongate shaft. A proximal constraining arrangement is engaged with a proximal end of the stent. A distal constraining arrangement is engaged with a distal end of the stent. A release wire is disposed through the elongate shaft and releasably engaged with portion of the proximal constraining arrangement and the distal constraining arrangement member. A handle assembly comprising a shuttle and a spring arrangement is positioned therein. A first brake assembly is disposed within the handle assembly and a second brake assembly is disposed within the handle assembly proximal to the first brake assembly.