Catheter Distal Coil Structure to Prevent Twist and Kinking
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Solution Overview
Problem
Conventional catheters experience twisting of the curving axis, kinking, and decreased pushability due to the deformation of the coil connected to the leaf spring, which affects the ability to achieve a desired curved shape and deliver the distal part to the desired location.
Innovation Solution
A catheter design with a shaft, wire, leaf spring, and coil configuration where the leaf spring is fixed to the coil and shaft, and a cover tube covers the wire and leaf spring, preventing twisting and kinking by limiting the length of the coil fixation and ensuring smooth curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coil is compressed by pulling the wire, then the catheter can be curved, but the coil deforms to spread in the radial direction causing the connection between the coil and the leaf spring to rotate and twist the curving axis
Solution Approach 1:
The patent introduces a cover tube as an intermediary component that encloses the coil and leaf spring connection. This cover tube prevents the coil from spreading radially during wire pulling, thereby stopping the rotation of the connection between the coil and leaf spring that would otherwise twist the curving axis. The cover tube acts as a protective mediator that maintains structural stability while allowing curving operation.
2Stability of the object's composition
If the connection part is fixed to the catheter tube to prevent twisting, then the curving axis stability is improved, but the fixed part becomes hard causing a stiffness step with sudden change in hardness
Solution Approach 1:
The patent segments the catheter shaft into distinct functional zones: a proximal section with the coil and cover tube for stability, and a distal section with the leaf spring for flexible curving. By separating these functions spatially, the design avoids creating a hard fixed part that would cause stiffness steps, while still maintaining curving axis stability through the cover tube enclosure.
3Stability of the object's composition
If the fixed part is made longer to prevent twisting, then the curving axis stability is improved, but the conductive wire is fixed and hinders the catheter from bending
Solution Approach 1:
The cover tube serves as an intermediary structure that provides stability to the coil and leaf spring connection without directly fixing the conductive wire. This allows the conductive wire to remain free-moving within the cover tube lumen, preventing it from hindering catheter bending while still maintaining curving axis stability through the cover tube's enclosing structure.
4Stability of the object's composition
If the coil is provided with a fixed part to prevent rotation, then the connection stability is improved, but the length of the fixed part affects the overall catheter flexibility
Solution Approach 1:
The patent applies local quality by providing the cover tube enclosure only in the specific region where the coil and leaf spring connect, rather than fixing the entire coil length. This localized approach provides connection stability precisely where needed while preserving flexibility in the distal section, optimizing both connection stability and overall catheter flexibility.
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 design prevents twisting of the curving axis, reduces kinking, and maintains pushability, allowing the catheter to achieve a desired curved shape and deliver the distal part to the desired location without damage to the lumen wall.
Implementation Method 1
a leaf spring having a distal end and a proximal end and extending in the longitudinal direction in the lumen of the shaft
Implementation Method 2
when a coil is provided that is connected to the proximal end part of the leaf spring, the coil is compressed by pulling of the wire
Data Source
AI summary
The objective is to provide a catheter that can realize a desired curve shape by preventing the curving axis of the catheter distal part from twisting, and preventing the catheter from kinking and decreased pushability. Disclosed is a catheter (1) having a shaft (2); at least one wire (30); a coil (60); a leaf spring (40) having a first connection part (41) where its proximal part is fixed to a distal end part of the coil (60); and a cover tube (50), wherein the coil (60) has a fixed part (61) where it is fixed to the shaft (2) at a position proximal to the proximal end of the cover tube (50); and the length from the distal end of the fixed part (61) to the proximal end of the cover tube (60) in the longitudinal direction is a length of 20 windings of the coil (60) or shorter.