Expandable Introducer Sheath Structure for Low-Trauma Device Access
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Solution Overview
Problem
Existing introducer sheaths for medical devices, particularly intracardiac blood pumps, are not radially expandable, leading to issues such as excessive vessel opening, tearing, and vascular complications, and require multiple sheaths for insertion and repositioning, increasing procedural complexity and risk of bleeding.
Innovation Solution
An expandable introducer sheath with a frame and coating configuration that allows for radial expansion and contraction, minimizing vessel trauma and reducing the need for multiple sheaths, while maintaining access and reducing clot formation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a non-expandable introducer sheath is used, then the sheath can be manufactured and operated simply, but the inner diameter must be large enough to accommodate the largest device portion, creating excessive vessel opening and requiring multiple sheaths for different device sizes
Solution Approach 1:
The introducer sheath incorporates an expandable frame structure that can dynamically change its radial dimension. The frame expands from a compressed delivery configuration to an expanded deployed configuration, allowing the same sheath to accommodate devices of varying sizes. This dynamic transformation eliminates the need for multiple fixed-size sheaths while maintaining structural integrity during the procedure.
Solution Approach 2:
The sheath utilizes controllable parameter changes in its frame structure, specifically the radial dimension. By controlling the expansion state of the frame, the sheath can adapt its inner diameter to match the size requirements of different medical devices. This parameter change is achieved through mechanical expansion mechanisms that respond to deployment forces or pressure differential.
2Ease of operation
If a peel away introducer sheath is used, then the sheath can be removed after device insertion, but the sheath may tear too easily or require excessive force, leading to bleeding or vascular complications
Solution Approach 1:
The expandable frame provides dynamic structural support during both insertion and removal phases. During removal, the frame can be compressed to reduce radial dimension, allowing controlled withdrawal without requiring excessive peeling force. This dynamic compression capability prevents premature tearing while eliminating the need for aggressive peeling actions that could cause vascular complications.
Solution Approach 2:
The expandable frame structure provides beforehand cushioning by maintaining radial expansion during device passage through the sheath. This pre-maintained structural support protects the sheath walls from stress concentration and prevents premature tearing before the actual removal action is intended. The frame acts as a protective cushion that distributes mechanical stresses uniformly.
3Adaptability or versatility
If a completely flexible expandable sheath is used, then the sheath can expand radially to allow device passage, but the sheath may kink or buckel during insertion or withdrawal due to lack of rigidity
Solution Approach 1:
The sheath frame is segmented into multiple structural elements or struts that can independently flex and expand. This segmentation allows the frame to achieve radial expansion capability while maintaining longitudinal rigidity. Each segment can bend slightly to accommodate curvature, but the overall framed structure prevents kinking and buckling during insertion and withdrawal operations.
Solution Approach 2:
The sheath employs composite construction combining flexible expandable elements with rigid support components. The frame may incorporate materials with different mechanical properties, such as shape memory alloys or composite structures, that provide both radial flexibility for expansion and longitudinal rigidity to prevent kinking. This composite approach enables simultaneous achievement of expandability and structural strength.
Data Source
AI summary
An introducer sheath for the insertion of a medical device into a blood vessel having an expandable sheath. The sheath has a length, a thickness, and proximal and distal ends. The expandable sheath has a frame extending longitudinally between the proximal end and the distal end, and having an exterior surface and an interior surface that forms an interior lumen along the length of the frame. The frame is configured to achieve an expanded state and a contracted state, the expanded state forming an expanded cross-section in the lumen for passing a medical device therethrough. The frame has a smooth coating about the exterior surface and protrusions extending into the lumen along the interior surface. The introducer sheath can be introduced into a patient in the contracted state, with the distal end of the introducer sheath prevented from moving in the proximal direction by an abutment against a dilator end surface.