Expandable Sheath Tip for Tortuous Intraluminal Navigation
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Solution Overview
Problem
Delivery sheaths with large diameters face difficulties tracking through narrow, tortuous intraluminal passages and curving wire guides, and existing solutions lack a mechanism for the sheath tip to expand and retract effectively for device deployment and retrieval.
Innovation Solution
A medical device featuring a sheath with an expandable tip comprising a plurality of fingers that can be heat-set to a small, tapered position for easy tracking and expanded to a larger diameter for device deployment, and reversibly return to the tapered position for safe retraction, utilizing materials like Nitinol for rigidity and an elastic covering for expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the delivery sheath has a large diameter, then it provides sufficient structural support and strength, but it cannot track well through tortuous curvature and penetrate narrow intraluminal passages
Solution Approach 1:
The distal tip of the delivery sheath is segmented into multiple collapsible fingers that can independently compress radially. This segmentation allows the tip to reduce its diameter for navigation while maintaining structural integrity through the distributed finger structure, resolving the contradiction between strength and tracking ability.
Solution Approach 2:
The distal tip transitions from a static large-diameter structure to a dynamic collapsible structure. The fingers can be compressed radially inward during navigation to improve tracking through tortuous passages, then returned to their original position to provide structural support, dynamically adapting to different operational requirements.
2Ease of operation
If the distal tip is kept small and tapered for tracking, then it can navigate narrow passages and tortuous wire guides, but it cannot provide sufficient opening for device deployment
Solution Approach 1:
The distal tip employs dynamic fingers that can transition between compressed and expanded states. During navigation, the fingers remain compressed to maintain small profile and good tracking. During device deployment, the fingers expand radially to create sufficient opening, thus resolving the contradiction between tracking ability and device deployment capability.
Solution Approach 2:
The diameter parameter of the distal tip is changed dynamically based on operational phase. The fingers compress to reduce diameter for tracking, then expand to increase diameter for device deployment. This parameter change allows the same structure to satisfy both contradictory requirements at different times.
3Productivity
If the distal tip remains expanded for device deployment, then it facilitates easy device passage, but it causes complications during retraction of the delivery sheath
Solution Approach 1:
The distal tip uses dynamically controllable fingers that can expand for device deployment and then return to their original compressed configuration. This dynamic behavior ensures the tip is expanded only when needed for device passage, and returns to small profile for safe retraction, resolving the contradiction between deployment ease and retraction safety.
Solution Approach 2:
The distal tip temporarily adopts an expanded configuration to facilitate device deployment, then recovers its original compressed state. This temporary state change allows the system to benefit from both expanded (for deployment) and compressed (for retraction) configurations at appropriate times, resolving the contradiction.
4Stability of the object's composition
If the sheath tip is made rigid for structural stability, then it maintains shape and position, but it cannot collapse and expand reversibly for navigation and deployment
Solution Approach 1:
The distal tip combines rigid structural elements (fingers) with flexible connecting structures. The fingers themselves maintain rigid shape for stability, while the connections between fingers and the sheath body provide flexibility for compression and expansion. This composite structure resolves the contradiction between shape maintenance and expandability.
Solution Approach 2:
The distal tip is segmented into multiple rigid fingers that can collectively compress and expand. Each finger maintains its rigid shape for stability, while the segmented structure as a whole can change diameter through radial compression of individual fingers, resolving the contradiction between individual component rigidity and overall adaptability.
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 tip allows for smooth navigation through tortuous passages, effective deployment of expandable devices, and safe retraction without complications, enhancing the tracking ability and reducing the risk of device entanglement or obstruction.
Implementation Method 1
The plurality of fingers are heat set in a first position so that the distal ends of the plurality of fingers define a distal opening with a first diameter
Implementation Method 2
the plurality of fingers is reversibly expandable to a second position wherein the distal opening has a larger second diameter
Implementation Method 3
utilizing materials like Nitinol for rigidity and an elastic covering for expansion and contraction
Data Source
AI summary
A medical instrument is provided including, an expandable tip which is embedded within a sheath. The expandable tip comprises a plurality of fingers which extend distally from the embedded portion. The plurality of fingers are heat set in a first position so that the distal ends of the fingers define a distal opening, where the distal opening has a smaller diameter than the embedded portion of the expandable tip. The plurality of fingers is reversibly expandable to a second position, creating a larger distal opening to deploy an expandable accessory.