Expandable Sheath With Segmented Fins for Symmetric Vessel Expansion
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Solution Overview
Problem
Conventional expandable introducer sheaths used in endovascular delivery systems cause asymmetric expansion, leading to vessel trauma and increased risk of damage during the implantation of prosthetic valves and other devices, due to passive and asymmetric stress distribution.
Innovation Solution
A radially expandable introducer sheath with circumferentially distributed sheath fins that move between unexpanded and expanded states, allowing for symmetric expansion and minimizing vessel trauma by evenly distributing radial pressure, and featuring a hub with a central lumen for secure attachment and hemostasis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional expandable introducer sheaths are used, then the sheath can accommodate delivery devices, but asymmetric expansion occurs causing vessel trauma
Solution Approach 1:
The sheath is divided into multiple discrete struts (typically 3-6 struts spaced circumferentially) that can expand independently. Each strut acts as a separate structural element that distributes expansion forces uniformly around the vessel, preventing the asymmetric expansion and concentrated stress that occurs with conventional single-piece sheaths.
Solution Approach 2:
The sheath transitions from a compressed low-profile state during insertion to an expanded high-strength state during device delivery. This dynamic transformation allows the sheath to minimize trauma during insertion while providing structural support during the procedure, with the expansion controlled by a deployment mechanism that ensures symmetric outward movement of all struts.
2Ease of operation
If multiple dilators or sheaths are used to dilate the vessel, then access is achieved, but procedure time increases and vessel damage risk increases
Solution Approach 1:
The sheath is pre-configured with expandable struts that are ready to deploy immediately upon insertion. The struts are positioned and oriented during manufacturing to ensure symmetric expansion, eliminating the need for sequential dilator exchanges. The sheath can be inserted in its compressed state and then expanded in-situ to the required diameter, reducing the number of procedural steps.
Solution Approach 2:
The expandable sheath design provides multiple functions in a single device: it serves as the introducer sheath, the dilator, and the delivery system support structure. The same struts that provide structural support during device delivery also function as the expansion mechanism, eliminating the need for separate dilators of varying sizes.
3Reliability
If conventional sheaths are used, then vessel access is obtained, but the risk of vessel tears increases
Solution Approach 1:
The sheath structure is segmented into multiple struts that distribute mechanical loads and stresses uniformly around the vessel circumference. This segmentation prevents stress concentration at any single point, reducing the risk of vessel tears while maintaining reliable vessel access and sealing.
Solution Approach 2:
The struts are strategically positioned and dimensioned to provide enhanced structural support at critical locations where vessel tears are most likely to occur, while maintaining flexibility in other areas. The local structural properties of each strut can be optimized for its specific functional requirements.
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 sheath minimizes vessel trauma and reduces the risk of tears and procedural time by enabling symmetric expansion, accommodating devices of varying sizes without the need for multiple sheath sizes, thus enhancing the safety and efficiency of transcatheter procedures.
Implementation Method 1
the sheath is movable between an unexpanded state and an expanded state... enabling symmetric expansion... evenly distributing radial pressure
Data Source
AI summary
Aspects of a sheath are disclosed herein including a radially expandable outer cylinder and including a plurality of sheath fins distributed circumferentially about the inner surface of the central lumen of the sheath. Each of the fins extends along a length of the inner surface of the sheath and when the sheath not expanded, the form a continuous inner surface of the sheath lumen. Each of the sheath fins includes a longitudinally-extending leading edge and a longitudinally-extending trailing edge where the leading edge of each of the sheath fins abuts a trailing edge of an adjacent one of the sheath fins when the sheath is in the unexpanded state, and in an initial unexpanded state adjacent sheath fins are coupled together along their leading edge and trailing edges.