Stent Deployment System with Segmented Sheath Flaps
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Solution Overview
Problem
Existing deployment systems for expandable stents often cause deformation, such as stretching or twisting, due to friction between the sheath and the stent during expansion, leading to inaccurate placement at the treatment site.
Innovation Solution
A deployment system featuring a tubular sheath with flaps that overlie longitudinal portions of the stent, allowing for partial and controlled expansion to minimize deformation, comprising multiple sheaths with flaps that are radially expanded in stages to prevent axial elongation and twisting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single tubular sheath is used to deliver the stent, then the device structure is simple, but the stent deforms (stretches or twists) during expansion due to friction between the sheath and stent
Solution Approach 1:
The single tubular sheath is divided into multiple segments (first tubular sheath, second tubular sheath, third tubular sheath) that can be retracted independently. Each sheath segment corresponds to different longitudinal portions of the stent, allowing controlled sequential expansion of the stent from distal to proximal end without causing deformation or twisting.
Solution Approach 2:
The stent is pre-compressed to a low profile configuration and loaded into the nested sheath structure before delivery. The sheaths are positioned and secured in advance to ensure proper alignment and prevent premature expansion during navigation to the treatment site.
2Ease of operation
If the sheath is retracted to allow stent expansion, then the stent can be deployed, but friction causes the sheath to grip the stent leading to deformation
Solution Approach 1:
The sheath is segmented into multiple independently retractable tubular sections. During deployment, each section is retracted sequentially rather than all at once, reducing friction-induced gripping forces on any single portion of the stent and preventing deformation while maintaining control over the expansion process.
Solution Approach 2:
The sheath structure transitions from a static single-piece design to a dynamic multi-section system where each section can move independently. This dynamic configuration allows the sheath to adapt to the expansion process, reducing mechanical constraints and friction that would otherwise cause stent deformation.
3Reliability
If the stent expands while in contact with the vessel wall, then it provides immediate support, but deformation is transferred to the vessel wall
Solution Approach 1:
The stent is pre-positioned and aligned within the vessel using the delivery system before expansion begins. The sheaths are retracted in a controlled sequence that ensures the stent expands uniformly from distal to proximal end, preventing deformation and avoiding transfer of mechanical distortion to the vessel wall while maintaining reliable support.
Data Source
AI summary
A deployment system and method for an expandable stent are described. The deployment system includes an expandable stent in an unexpanded state and a first tubular sheath having one or more first flaps extending from a distal end thereof. The one or more first flaps overlie one or more first longitudinal portions of the stent. A second tubular sheath may overlie the first tubular sheath. The deployment method includes advancing a deployment system including an expandable stent in an unexpanded state to a treatment site in a body vessel. At the treatment site, one or more second longitudinal portions of the stent are radially expanded to partially deploy the stent, and then one or more first longitudinal portions of the stent are radially expanded to fully deploy the stent. Each of the first and second longitudinal portions preferably extends from a proximal end to a distal end of the stent.