Guidewire Coil Structure for Repeatable Distal-End Reshaping
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Solution Overview
Problem
The distal end portion of guidewires undergoes irreversible deformation and radial displacement due to plastic deformation when repeatedly shaped to accommodate complex blood vessel shapes, making reshaping difficult and creating steps on the outer periphery.
Innovation Solution
A guidewire design with a core shaft, an outer coil body, and a distal end fixed portion, where the outer coil body has a loosely wound portion with specific diameter and pitch ratios, and optionally an inner coil body with opposite winding directions, to prevent irreversible deformation and radial displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distal end portion of the guidewire is repeatedly shaped to accommodate various blood vessel shapes, then the guidewire can adapt to different blood vessel configurations, but the coil body undergoes plastic deformation resulting in permanent deformation or radial displacement of the wire
Solution Approach 1:
The patent changes the geometric parameters of the coil body by introducing a loosely wound portion with specific pitch characteristics. The pitch representative value Pa is defined as the average pitch in the loosely wound portion, and this parameter is optimized to enable repeated shaping without permanent deformation while maintaining adaptability to blood vessel shapes.
Solution Approach 2:
The patent applies local quality by creating a loosely wound portion with distinct characteristics from the rest of the coil body. This localized region has specific pitch and gap properties that allow it to deform reversibly during shaping operations, while the rest of the coil body maintains its structural integrity.
2Strength
If the coil body is densely wound to maintain structural integrity, then the guidewire has sufficient strength, but radial displacement of wires occurs during reshaping creating steps on the outer periphery
Solution Approach 1:
The patent introduces a loosely wound portion with specific pitch characteristics that is distinct from the densely wound portions. This localized region allows for radial movement of wires during reshaping without creating permanent steps on the outer periphery, while the densely wound portions maintain structural integrity.
Solution Approach 2:
The patent creates dynamic behavior in the loosely wound portion, allowing the wire configuration to change reversibly during shaping operations. The specific pitch and gap properties enable the wire to move radially and then return to its original position, preventing permanent surface defects.
3Ease of operation
If the pitch of the coil body is reduced to improve flexibility, then the guidewire can follow complexly curved blood vessels, but plastic deformation occurs more easily during repeated shaping
Solution Approach 1:
The patent creates a localized loosely wound portion with specific pitch characteristics that is distinct from the rest of the coil body. This region has higher flexibility to accommodate complex blood vessel curves, while the rest of the coil body maintains sufficient rigidity to resist plastic deformation during repeated shaping.
Solution Approach 2:
The patent segments the coil body into different regions: a loosely wound portion with specific pitch for flexibility and adaptability, and densely wound portions for structural integrity. This segmentation allows each region to perform its specific function optimally without compromising the overall performance.
Data Source
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AI summary
The object is to provide a guidewire that can prevent irreversible deformation at a distal end portion of a coil body and that can also prevent radial displacement of a wire constituting the coil body. A medical device 1 includes a core shaft 11, an outer coil body 21 formed by winding a wire w1, w1, and a distal end fixed portion 41 at which a distal end of the core shaft 11 and the outer coil body 21 are fixed to each other. The outer coil body 21 includes a loosely wound portion 21A with a gap between the adjacent wires w1 along the longitudinal axis direction of the core shaft 11, and the loosely wound portion 21A of the outer coil body 21 satisfies the following formulas (1) and (2): in the formulas (1) and (2), D represents the effective diameter of the outer coil body 21, d represents the wire diameter of the outer coil body 21, and Pa represents a pitch representative value of the wire w1 of the outer coil body 21. 3.5≤D/d≤6.5 1<Pa≤3