Self-Expanding Implant Delivery System with Confining Sleeve
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Solution Overview
Problem
Self-expanding implants, such as stents, face challenges during storage due to radially outward pressure from the confined stent, leading to potential deformation and increased diameter of the sheath, which can result in fouling or inability to deliver the implant to smaller diameter locations within the body, especially when stored for extended periods.
Innovation Solution
A delivery system with a confining sleeve made of heat-shrinkable material that reduces hoop stress on the sheath during storage, combined with a pull element for easy removal and pressure relief zones to prevent adherence between sheath layers, allowing for minimal wall thickness and efficient deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sheath wall thickness is reduced to enable delivery to smaller diameter locations, then the passing diameter of the distal end is reduced, but the sheath becomes more susceptible to deformation from radially outward pressure during storage
Solution Approach 1:
The patent applies nesting by placing a confining element (inner structure) inside the sheath to provide internal support. The confining element is nested within the sheath during storage to prevent deformation, and can be removed or collapsed before delivery to allow the sheath to maintain its reduced passing diameter profile.
Solution Approach 2:
The confining element is installed in advance during manufacturing to protect the sheath during storage and handling. This preliminary protective action prevents deformation before the sheath is put into service, addressing the stability issue without requiring thicker walls.
2Adaptability or versatility
If the sheath is made more flexible to navigate tortuous delivery paths, then ease of delivery is improved, but resistance to radially outward pressure during storage is reduced
Solution Approach 1:
The confining element is nested within the sheath to provide internal structural support that reinforces the flexible sheath material against radial pressure during storage, while allowing the sheath to maintain its flexibility for navigation during delivery.
Solution Approach 2:
The delivery system combines the flexible polymeric sheath material with the confining element structure to create a composite system that exhibits both flexibility for navigation and strength for pressure resistance during storage.
3Duration of action of stationary object
If the storage period is extended, then availability for use is improved, but sheath deformation and stent expansion increase
Solution Approach 1:
The confining element is installed in advance to prevent deformation during the entire storage period. This preliminary protective measure maintains dimensional stability throughout extended storage, ensuring the sheath and stent remain ready for delivery without degradation.
Solution Approach 2:
The confining element provides more than sufficient support to counteract radial pressure during storage, creating a margin of safety that ensures stability even during extended storage periods beyond the minimum required.
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 minimizes sheath deformation and allows for a smaller passing diameter of the distal end of the catheter system, enabling delivery of implants to smaller locations without fouling, while ensuring the stent is released accurately and without distortion.
Implementation Method 1
A delivery system with a confining sleeve made of heat-shrinkable material that reduces hoop stress on the sheath during storage
Data Source
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AI summary
The present disclosure provides a delivery system for a self-expanding implant (31) which includes a sheath (41, 42) which surrounds and constrains the implant prior to delivery and a confining element (80) which surrounds the sheath during storage. The confining element preferably includes elongate members (81) running axially along the sheath, which compress the sheath and the stent to reduce hoop stress in the system without promoting undesired adhesion between layers of the sheath.