Catheter Core Wire Segmentation for Entanglement Prevention
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Solution Overview
Problem
Balloon catheters, particularly RX-type, face issues with entanglement between the inner tube and core wire during insertion, leading to degraded guide wire insertability and potential rigidity imbalances that affect followability in curved blood vessels.
Innovation Solution
A catheter design where the inner tube and core wire are secured and separated within the outer tube using a wall portion with specific hole configurations and a tapered core wire, preventing entanglement while maintaining rigidity and followability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the core wire extends on the tip-end side beyond the base end portion of the inner tube, then rigidity and force transmissibility are improved, but the inner tube and core wire become entangled during insertion
Solution Approach 1:
The overlapping range where the inner tube and core wire coexist is divided into a first range (from base end toward tip end) and a second range (from tip end toward base end). The core wire has different outer diameters in these two ranges, with the outer diameter in the first range being larger than in the second range. This segmentation allows the core wire to provide sufficient rigidity in the first range while reducing entanglement risk in the second range through a smaller diameter.
Solution Approach 2:
The core wire is designed with non-uniform outer diameter along its length, specifically with a larger outer diameter in the first overlapping range and a smaller outer diameter in the second overlapping range. This local quality variation optimizes the balance between rigidity (where larger diameter is needed) and ease of insertion (where smaller diameter reduces friction and entanglement).
2Strength
If the core wire has larger outer diameter, then rigidity is improved, but the space for inner tube movement is reduced increasing entanglement risk
Solution Approach 1:
The core wire features a tapered or stepped structure where the outer diameter varies along its length. The first overlapping range has a larger outer diameter to provide rigidity, while the second overlapping range has a smaller outer diameter to reduce space occupation and minimize entanglement risk with the inner tube.
Solution Approach 2:
The core wire's overlapping range is segmented into two distinct regions with different diameters. This segmentation allows each region to serve its specific function: the first range provides structural support while the second range facilitates smooth movement and reduces interference with the inner tube.
Data Source
AI summary
A catheter includes: an outer tube that includes a lumen; an inner tube that is inserted into the lumen and has a base end portion joined to an intermediate position of the outer tube in an axis direction; a core wire that is inserted into the lumen and extends to a tip end of the outer tube beyond the base end portion; and a securing portion that is disposed at an intermediate position of an overlapping range in the axis direction, the inner tube and the core wire overlapping each other in the overlapping range, and secures the inner tube or the core wire to the outer tube.