Expandable Vascular Sheath Retraction for Safer Device Insertion
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Solution Overview
Problem
Existing vascular introducer sheaths cause vascular damage, increase procedure time, and risk infection due to multiple insertions and failures in expanding and retracting, particularly in complex vascular systems, compromising the safety of procedures like TAVR.
Innovation Solution
A retractable sheath design featuring a rigid collar and a circumferentially retractable sleeve with a continuous elastomeric outer layer and an expandable inner layer, providing balanced properties for navigation, expansion, and retraction, minimizing vascular injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple introducer sheaths are inserted to widen the vascular opening, then the vessel aperture is enlarged to allow device passage, but the procedure time increases and the risk of vascular damage and infection increases
Solution Approach 1:
The introducer sheath incorporates an expandable sleeve that can dynamically change its diameter. The sleeve is inserted in a compressed state through a small puncture, then expanded to a larger diameter to accommodate the medical device, and finally re-compressed for removal. This dynamic size change eliminates the need for multiple sheath insertions, reducing procedure time and vascular exposure time.
Solution Approach 2:
The expandable sleeve is designed with a nested structure where the sleeve can be compressed within itself or within the introducer sheath during insertion, then deployed to its expanded state. This nesting principle allows the large-diameter sheath to pass through a small puncture site by temporarily reducing its cross-sectional area.
2Adaptability or versatility
If multiple introducer sheaths are inserted to widen the vascular opening, then the vessel aperture is enlarged to allow device passage, but the risk of vascular damage increases
Solution Approach 1:
The expandable sleeve allows the sheath to adapt its diameter dynamically. During insertion, the sleeve is in a low-profile compressed state that minimizes trauma to the vessel wall. Once positioned, it expands to the required diameter to accommodate the device, providing protection only when needed. During removal, it re-compresses to minimize damage during extraction.
Solution Approach 2:
The sleeve is constructed from flexible materials that can deform elastically between compressed and expanded states. This flexibility allows the sheath to conform to the vessel wall during insertion and removal, reducing abrasion and mechanical trauma, while providing a protective barrier when expanded.
3Ease of operation
If an expanding sheath is designed with a bonded composite material structure, then the sheath can be inserted in a small diameter and expanded, but the expanding section introduces structural weakening that causes the sheath to collapse or buckle during insertion
Solution Approach 1:
The expandable section is designed to be dynamically strong when needed and flexible when not in use. During insertion in the compressed state, the structure maintains sufficient rigidity through its collapsed geometry. When expanded, the structural elements engage to provide the necessary strength and rigidity to support the medical device, eliminating the buckling problem.
Solution Approach 2:
The sheath employs composite construction combining materials with different mechanical properties. The expandable section uses a lattice or framework structure that provides high strength-to-weight ratio, maintaining structural integrity during insertion while enabling expansion. The bonding interfaces are designed to distribute stresses evenly, preventing failure at the joints between expanded and non-expanded sections.
4Ease of operation
If an expanding sheath is designed to be retracted to reduce diameter, then the sheath can be removed through the puncture site, but the sheath frequently fails to retract fully causing injury to the vessel or opening
Solution Approach 1:
The retractable sleeve incorporates a mechanical or elastic mechanism that ensures complete retraction to the compressed state. This dynamic mechanism actively pulls or pushes the sleeve to its minimum diameter, preventing partial retraction that could cause the leading edge to traumatize the vessel or puncture site during removal.
Solution Approach 2:
The design includes features that cushion or protect the vessel and puncture site during the retraction process. This may involve rounded leading edges, lubricious coatings, or mechanical elements that control the retraction speed and force, preventing sudden movements that could cause injury while ensuring complete retraction.
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 effectively protects the vascular wall, reduces procedure time, and minimizes infection risk by ensuring smooth passage and safe removal of medical devices, enhancing the safety and accessibility of procedures like TAVR.
Implementation Method 1
the stiff polymeric sheet characterised as having outward annular resistance when forcibly coiled
Implementation Method 2
the elongated sleeve comprising two separate layers including a continuous elastomeric outer layer and an expandable inner layer
Data Source
AI summary
The disclosure generally relates to adjustable sheath devices for insertion into the body to provide intravascular access to various medical devices, involving a dynamically expandable sheath capable of expanding within the blood vessel when a medical device is passed through the sheath and retracting back to almost its original size when the medical device is removed from the sheath. Embodiments generally comprise a rigid collar and an elongated sleeve comprising a continuous elastomeric outer layer and an expandable inner layer.