Expandable Introducer Sheath for Low-Trauma Valve Delivery
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Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems require multiple dilations, increasing procedure time and risk of vessel damage, and pose challenges in delivering prosthetic devices due to their large profile and potential for plaque dislodgement.
Innovation Solution
An expandable sheath with an inner and outer layer that locally expands to accommodate the prosthetic device, then returns to its original diameter, minimizing vessel trauma and reducing the need for multiple sheath insertions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional introducer sheaths are used, then the delivery system can be introduced into the vasculature, but multiple dilations are required which increase procedure time and risk of vessel damage
Solution Approach 1:
The sheath transitions from a compressed low-profile state for insertion to an expanded high-profile state for device delivery, then back to compressed state for removal. This dynamic size change eliminates the need for multiple dilations while reducing vessel trauma and procedure time.
Solution Approach 2:
The delivery system is nested within the expandable sheath in a collapsed configuration during insertion, then the sheath expands to accommodate the full profile of the delivery system for device deployment, finally collapsing again for removal. This nesting approach allows a single sheath to accommodate large devices without requiring progressive dilation.
2Reliability
If conventional introducer sheaths are used, then the delivery apparatus can be introduced, but the large profile of the delivery system causes longitudinal and radial tearing of the vessel
Solution Approach 1:
The sheath dynamically adjusts its profile size - remaining compressed during vessel traversal to minimize tearing, then expanding only at the delivery site to accommodate the large delivery system. This dynamic adaptation resolves the contradiction between maintaining vessel integrity and enabling device delivery.
Solution Approach 2:
The sheath maintains a small profile along most of its length for safe vessel insertion, but locally expands at the distal end to accommodate the delivery system. This localized expansion allows device delivery capability while minimizing vessel trauma along the insertion path.
3Reliability
If conventional introducer sheaths are used, then the delivery system can be accessed, but the large profile dislodges calcified plaque within the vessels
Solution Approach 1:
The sheath remains in a compressed low-profile state during vessel navigation to avoid dislodging plaque, then expands to a large profile only when needed for device delivery. This temporal separation of profile sizes eliminates plaque dislodgement risk while maintaining delivery system accommodation capability.
Solution Approach 2:
The sheath functionality is segmented into distinct phases: insertion phase with small profile to avoid plaque disruption, and delivery phase with expanded profile to accommodate the delivery system. This segmentation allows the sheath to optimize for different functions at different times.
4Ease of operation
If conventional introducer sheaths with tubular loaders are used, then the delivery apparatus can be introduced through the seals, but the loader extends from the proximal end decreasing the available working length
Solution Approach 1:
The sheath expands to accommodate the delivery apparatus only when needed, rather than requiring a permanently extended loader structure. This dynamic accommodation preserves the full working length of the delivery system while still enabling introduction through the seals.
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 procedure time and minimizes vessel tears and plaque dislodgement by allowing single sheath insertion, while maintaining a smaller profile and ensuring smooth device delivery.
Implementation Method 1
an inner tubular layer with a folded condition. The inner tubular layer includes a thick wall portion integrally connected to a thin wall portion
Implementation Method 2
When an implant passes therethrough, the outer tubular layer stretches and the inner tubular layer unfolds into an expanded lumen diameter
Data Source
Figure 1
Figure 2A~8
Figure 9~10
AI summary
Aspects of an expandable sheath can be used in conjunction with a catheter assembly to introduce a prosthetic device, such as a heart valve, into a patient. Such aspects can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate the delivery apparatus, followed by a return to the original diameter once the prosthetic device passes through. Some aspects can include a sheath with inner and outer layers having at least one folded portion of the inner liner. Some aspects include the inner liner having etched, unetched, and otherwise surface-modified portions. Aspects of the present expandable sheath can avoid the need for multiple insertions for the dilation of the vessel, thus offering advantages over prior art introducer sheaths.