Expandable Sheath with Extruded Segments for Low-Trauma Delivery
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Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems pose risks of vessel damage and plaque dislodgment due to their large profile and complex mechanisms, necessitating improvements for safer and more efficient implantation of prosthetic devices.
Innovation Solution
An expandable sheath with a multisegmented inner tubular layer having different durometers and coefficients of friction, combined with an elastic outer tubular layer, allows for temporary expansion and contraction to accommodate implants, minimizing vessel trauma and reducing the risk of dislodging plaque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional introducer sheath with a tubular loader is used, then the delivery apparatus can be introduced through the sheath, but the available working length of the delivery apparatus is decreased
Solution Approach 1:
The inner tubular layer is divided into multiple segments (first segment, second segment, third segment) with different properties. This segmentation allows each segment to perform specific functions: the first segment provides sealing, the second segment allows expansion, and the third segment provides structural support, thereby eliminating the need for a separate tubular loader while maintaining delivery apparatus functionality.
Solution Approach 2:
The inner tubular layer is designed to perform multiple functions that previously required separate components. It provides sealing against the vessel wall, allows expansion to accommodate the delivery apparatus, and maintains structural integrity during insertion and removal, effectively replacing the tubular loader's functions within the sheath structure itself.
2Reliability
If multiple dilators or sheaths are used to dilate the vessel progressively, then the vessel can be accessed, but the procedure time increases and vessel damage risk increases
Solution Approach 1:
The inner tubular layer is designed to be dynamically expandable from a compressed state to an expanded state. This dynamic transformation allows the sheath to adapt its diameter to accommodate the delivery apparatus without requiring multiple static dilators, thereby reducing procedure time and minimizing repeated vessel manipulation that could cause damage.
Solution Approach 2:
The sheath undergoes a parameter change in its diameter through the expansion and contraction of the inner tubular layer. This parameter change allows the sheath to transition from a compact insertion profile to a larger delivery profile and back, eliminating the need for progressive dilation with multiple devices and reducing cumulative vessel trauma.
3Ease of operation
If the inner tubular layer has uniform durometer and friction properties, then manufacturing is simpler, but it cannot optimize both sealing and low-friction delivery
Solution Approach 1:
Different segments of the inner tubular layer are assigned different local qualities: the first segment has higher durometer for sealing, the second segment has lower durometer for flexibility, and the third segment has specific friction properties for smooth delivery. This local differentiation optimizes performance in each region while the coextrusion process integrates these variations into a single manufactured component.
Solution Approach 2:
The inner tubular layer is constructed as a composite structure with multiple segments made from different materials or material formulations. This composite approach allows each segment to exhibit tailored mechanical properties (durometer, friction) optimized for its specific function, while the coextrusion technology enables manufacturing this complex composite structure in a single integrated process.
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 expandable sheath facilitates safe and efficient delivery of prosthetic devices by minimizing vessel trauma and reducing the risk of clots, while maintaining a balance between expandability and structural integrity.
Implementation Method 1
an elastic outer tubular layer... In the expanded state, the first and second longitudinally extending ends of the inner tubular layer expand apart... The outer elastic tubular layer urges the inner tubular layer back towards the non-expanded state
Data Source
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AI summary
The expandable sheaths disclosed herein include an elastic outer tubular layer and a multisegmented inner tubular layer that includes at least two coextruded segments having different durometers and different coefficients of friction. The inner tubular layer further includes a thick wall portion integrally connected to a thin wall portion. The thin wall portion has a lower durometer than the thick wall portion. The thick wall portion has a first and second longitudinally extending end, and the thin wall portion extends between the first and second longitudinally extending ends. The elastic outer tubular layer and the inner tubular layer are radially movable between a non-expanded state, where the elastic outer tubular layer urges the first longitudinally extending end under the second longitudinally extending end, and an expanded state, where the first and second longitudinally extending ends of the inner tubular layer expand apart with the thin wall portion extending therebetween.