Expandable Sheath with Longitudinal Rods for Vessel Access
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Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems face challenges such as increased procedure time, vessel trauma, and risk of radial or longitudinal tearing during implantation of prosthetic valves, due to their large profile and complex mechanisms, which can also dislodge calcified plaque, leading to clot formation.
Innovation Solution
An expandable introducer sheath with an elastic outer tubular layer and an inner tubular layer having thick and thin wall portions, which temporarily expands to accommodate the implant and then returns to its original diameter, reducing the initial profile size and minimizing trauma, while integrated longitudinal rods facilitate easy expansion and collapse, reducing the push force required for implant advancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional introducer sheath with large profile is used to deliver prosthetic valves, then the delivery system can accommodate the implant, but the sheath causes vessel trauma, increases risk of radial or longitudinal tearing, and may dislodge calcified plaque
Solution Approach 1:
The introducer sheath employs a dynamic structure that transitions between compressed and expanded states. The sheath is compressed during insertion to minimize profile and vessel trauma, then expanded at the delivery site to accommodate the prosthetic valve. This dynamic size change allows the system to resolve the contradiction between small insertion profile and large delivery capacity.
Solution Approach 2:
The sheath is divided into multiple segments or sections that can move relative to each other during expansion. This segmentation allows the sheath to collapse into a compact form for insertion while expanding to provide sufficient lumen diameter for device delivery, thereby reducing vessel trauma during access while maintaining adequate delivery capability.
2Ease of operation
If multiple dilators or sheaths are used to progressively dilate the vessel, then access to the vessel is achieved, but the procedure time increases and the risk of vessel damage increases
Solution Approach 1:
The introducer sheath is pre-configured with expandable structure that allows it to be inserted in a compressed state and then expanded at the target site. This preliminary configuration eliminates the need for multiple progressive dilation steps, as the sheath can directly expand to the required size after single insertion, thereby reducing procedure time and minimizing repeated vessel manipulation.
3Stability of the object's composition
If conventional sheaths with complex mechanisms are used, then the sheath can maintain expanded configuration, but the device complexity increases
Solution Approach 1:
The sheath utilizes material parameter changes, specifically elastic deformation, to achieve and maintain expanded configuration. By selecting appropriate elastic materials and designing the sheath geometry to leverage elastic recovery, the system achieves stable expanded state without requiring complex mechanical locking or ratcheting mechanisms, thus reducing overall device complexity while maintaining configuration stability.
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 minimizes vessel trauma, reduces procedure time, and decreases the risk of vessel tears and plaque dislodgement by allowing temporary expansion and subsequent return to the original diameter, thereby enhancing the safety and efficiency of prosthetic valve implantation.
Implementation Method 1
an elastic outer tubular layer and an inner tubular layer. The outer tubular layer defines an initial elastic lumen extending axially therethrough and having an initial diameter
Implementation Method 2
The sheath may also include selectively placed longitudinal rods that mediate friction between the inner and outer tubular layers to facilitate easy expansion and collapse
Data Source
AI summary
A delivery sheath includes an outer tubular layer and an initially folded inner tubular layer. When an implant passes therethrough, the outer tubular layer expands and the inner tubular layer unfolds into an expanded lumen diameter. The sheath may also include selectively placed longitudinal support rods that mediate friction between the inner and outer tubular layers to facilitate easy expansion, thereby reducing the push force needed to advance the implant through the sheath's lumen.