Expandable Sheath with Elastic Wall Portions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems pose challenges due to their large profile, which can cause trauma and risk of vessel damage during implantation of prosthetic devices, and they often require complex dilation procedures, increasing procedure time and risk of complications such as clot formation from dislodged plaque.
Innovation Solution
An expandable introducer sheath with alternating stiff and elastic wall portions, reinforced with braided fibers or a stent structure, allows temporary expansion to accommodate the delivery catheter and returns to its original diameter, minimizing vessel trauma and incorporating features like slots or gaps to enhance expandability and distribute strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional introducer sheath with a large profile is used to safely introduce the delivery apparatus, then the sealing and hemostasis function is improved, but the risk of vessel trauma and damage increases
Solution Approach 1:
The introducer sheath transitions from a static fixed-diameter structure to a dynamic structure that can change its diameter. The sheath is designed to be expandable to accommodate the delivery apparatus and then contract to its original smaller diameter, allowing it to adapt its size based on the operational requirements while minimizing vessel trauma.
Solution Approach 2:
The sheath's diameter parameter is changed dynamically during the procedure. It starts at a smaller diameter for vessel insertion, expands to a larger diameter to receive and seal around the delivery apparatus, and then returns to its original smaller diameter after the procedure, optimizing both sealing performance and vessel safety.
2Ease of operation
If conventional dilation procedures with multiple dilators are used to access the vessel, then the vessel access is achieved, but the procedure time increases and the risk of vessel damage increases
Solution Approach 1:
The sheath is pre-configured with expandable structures that allow it to be inserted in a compact state and then expanded to the required diameter within the vessel. This eliminates the need for sequential dilation with multiple dilators, as the sheath itself performs the dilation function through its expandable design.
Solution Approach 2:
The sheath structure is segmented into expandable sections that can be deployed independently to achieve the required diameter. This segmentation allows for controlled expansion without requiring multiple separate dilation instruments, streamlining the access procedure.
3Strength
If the delivery system has a large profile to ensure structural integrity, then the torque and push strength are improved, but the risk of longitudinal and radial tearing of the vessel increases
Solution Approach 1:
The delivery system utilizes the dynamic expandability of the sheath to achieve high structural strength only when needed. The sheath maintains a small profile during vessel navigation to avoid tearing, then expands to provide the necessary torque and push strength for delivering the prosthetic device, and finally contracts to minimize trauma during withdrawal.
4Ease of operation
If a conventional loader extends from the proximal end of the introducer sheath, then the delivery apparatus can be advanced, but the available working length of the delivery apparatus decreases
Solution Approach 1:
The loader is integrated within the introducer sheath structure rather than extending externally. The loader is nested inside the sheath's lumen, allowing it to function for advancing the delivery apparatus while not extending the overall profile of the system, thereby preserving the full working length of the delivery apparatus.
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 reduces vessel trauma, minimizes the risk of complications, and facilitates smoother delivery of prosthetic devices by accommodating the catheter without causing significant vessel damage or dislodging plaque, thus improving the safety and efficiency of the implantation procedure.
Implementation Method 1
The elastic wall portion has an elastic wall radial thickness equal to the stiff wall radial thickness and extends generally parallel to and partially around the elongate axis. The expandable tubular layer is configured to temporarily expand at least at the elastic wall portion to allow passage of the implant through the lumen and then return to approximate the starting profile after passage of the implant through the lumen.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An expandable introducer sheath for passage of implant delivery catheters, such as catheters for delivery of prosthetic heart valves. The expandable sheath balances the amounts, shapes and positions of various stiff and elastic structures in the sheath to selectively program the expandability and buckling stiffness of the sheath. The expandable sheath can include, for example, an expandable tubular layer that includes alternating stiff and elastic wall portions of a single radial thickness. The combination of stiff and elastic wall portions allow for torque and push strength to advance the expandable sheath while at the same time accommodating temporary expansion. The expandable sheath can also be reinforced with a tubular layer of braided fibers or a stent structure for additional strength. Other embodiments include selective use of slots or gaps at the distal end of a stiff wall portion to enhance expandability and distribute strain.