Expandable Sheath for Minimizing Vessel Trauma During Implant Delivery
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Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems pose challenges such as increased procedure time, vessel damage risk, and plaque dislodgement due to their large profile and complex mechanisms, which complicate the delivery and placement of prosthetic valves and other implants.
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 implants and then returns to a smaller profile, reducing the need for multiple sheath sizes and minimizing vessel trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional introducer sheath with large profile is used to deliver prosthetic devices, then the delivery system can accommodate the implant, but the risk of vessel tears and plaque dislodgement increases
Solution Approach 1:
The introducer sheath employs a dynamic structure with expandable sections that can transition between compressed and expanded states. The sheath includes a first section with a first diameter for insertion, and a second section with a second diameter larger than the first, allowing the sheath to expand at the delivery site to accommodate the prosthetic device while maintaining a smaller profile during vessel navigation
Solution Approach 2:
The sheath is divided into multiple sections with different diameters - a first section with smaller diameter for safe vessel traversal and a second section with larger diameter for implant delivery. This segmentation allows the sheath to perform different functions at different locations, reducing overall vessel trauma while maintaining 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
Solution Approach 1:
The sheath is pre-configured with an expandable section that can be rapidly deployed at the delivery site. The expandable portion is prepared in advance within the sheath structure, allowing for quick expansion without requiring multiple sequential dilation steps, thereby reducing procedure time while maintaining ease of vessel access
3Ease of operation
If a conventional loader extends from the proximal end of the introducer sheath, then the delivery apparatus can be inserted, but the available working length of the delivery apparatus decreases
Solution Approach 1:
The delivery apparatus is nested within the expandable sheath structure. The loader and delivery components are contained within the sheath's lumen, allowing the full working length of the delivery apparatus to be utilized without extension beyond the proximal end of the introducer sheath, thereby maximizing the available working length while maintaining ease of insertion
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 lowers the risk of vessel tears and plaque dislodgement by allowing temporary expansion for implant passage without the need for multiple sheath sizes, facilitating safer and more efficient implant delivery.
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. The inner tubular layer has a thick wall portion integrally connected to a thin wall portion
Implementation Method 2
When the implant passes therethrough, the outer tubular layer stretches and the inner tubular layer at least partially unfolds into an expanded lumen diameter to accommodate the diameter of the implant
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.