Expandable Sheath Radial Separation for Vessel Protection
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Solution Overview
Problem
Percutaneous medical procedures often involve large, bulky medical devices that can cause injury to the vessel wall due to the force exerted during advancement through narrow and tortuous vasculature.
Innovation Solution
An expandable sheath with a compliant membrane and a discontinuous outer member that separates radially outward when subjected to force, allowing the sheath to expand and accommodate larger medical devices while minimizing vessel wall injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid outer covering is used to protect the vessel wall, then the device can maintain structural integrity, but the device cannot accommodate large medical devices without causing vessel wall injury
Solution Approach 1:
The outer covering is designed to transition from a rigid, compressed state during insertion to an expanded state during device delivery. The covering includes radial expansion features that allow it to dynamically adjust its structure, maintaining protection during insertion while accommodating larger devices without causing vessel wall injury.
Solution Approach 2:
The outer covering's physical parameters (diameter, rigidity) are changed through compression during insertion, then expand upon contact with the medical device. This parameter transformation allows the same structure to serve both as a protective sheath and as an accommodator for large devices.
2Length of moving object
If the sheath is compressed to a small profile for insertion, then it can pass through narrow vasculature, but it cannot accommodate large medical devices
Solution Approach 1:
The sheath is designed with dynamic expandability, allowing it to be compressed to a small profile for insertion through narrow vasculature, then expand radially to accommodate large medical devices. The expansion is triggered by contact with the device or internal pressure, enabling the sheath to adapt its size according to operational needs.
Solution Approach 2:
The outer covering is nested within the inner membrane structure, allowing the sheath to be compressed to a compact profile for insertion. Upon expansion, the nested covering unfolds to provide additional radial support and accommodation capacity, effectively nesting the expanded structure within the original compressed form factor.
3Reliability
If the outer covering is continuous to maintain protection, then it provides uniform coverage, but it cannot expand radially to accommodate larger devices
Solution Approach 1:
The outer covering is segmented into multiple radial sections or panels that can independently expand. This segmentation allows the covering to maintain continuous protective coverage while enabling radial expansion to accommodate larger devices, as each segment can move and adjust relative to the others during expansion.
Solution Approach 2:
The continuous outer covering incorporates dynamic expansion features that allow it to transition from a compressed continuous structure to an expanded configuration. The covering maintains its continuity for protection while incorporating radial movement capabilities through expansion features or articulated joints.
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 effectively reduces the risk of vessel injury by allowing the medical device to expand the sheath radially, maintaining a smaller profile during insertion, and accommodating devices up to 18+ French in size without causing significant trauma to the vessel wall.
Implementation Method 1
The outer member may be configured to separate to a second configuration when subjected to a radially outward force from within the membrane
Implementation Method 2
The one or more folds may be configured to unfold to a second configuration when the outer member is in the second configuration
Data Source
AI summary
An expandable sheath may include an inelastic compliant membrane having a lumen therethrough, and a discontinuous outer member bonded to the membrane. The membrane may include one or more folds formed therein. At least a portion of the outer member may extend continuously around a circumference of the membrane in a first configuration. The outer member may be configured to separate to a second configuration when subjected to a radially outward force from within the membrane. The outer member may taper from a first diameter adjacent a proximal hub to a second smaller diameter at a distal end. A method of manufacturing an expandable sheath may include forming one or more folds in a compliant membrane, cutting a plurality of apertures through a wall of an outer covering; and laminating the outer covering onto the membrane, wherein the plurality of apertures is disposed over the one or more folds.