Retractable Catheter Pull Wire Embedding
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Solution Overview
Problem
Conventional implant catheter delivery systems face challenges with increased friction forces due to longer implants, requiring higher retracting forces that can lead to deflection or breakage of the inner shaft and increased device thickness, limiting treatment options and potentially causing injury in narrow bodily lumens.
Innovation Solution
A retractable catheter with an elongate tubular sheath and a pull element featuring a stepped or tapered end portion embedded within flexible material, which enhances friction and force transmission without additional components, reducing the overall diameter and component count, and improving bond strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional outer rings and inner rings are used to connect the pull wire to the outer sheath, then the connection strength is improved, but the device diameter increases and the outer sheath surface is distorted
Solution Approach 1:
The invention extracts and eliminates the outer ring and inner ring components from the connection assembly. Instead of using these separate fastening components, the pull wire is directly embedded into the outer sheath material, removing the source of diameter increase and surface distortion while maintaining connection functionality through friction and mechanical interlocking.
Solution Approach 2:
The invention merges the pull wire and outer sheath into a single integrated structure. The pull wire is embedded within the outer sheath material, combining two previously separate components (wire and sheath) into one unified assembly, thereby eliminating the need for additional fastening rings and reducing overall device complexity.
2Strength
If the inner shaft thickness is increased to withstand compressive forces from higher retracting forces, then the structural strength is improved, but the device diameter increases reducing treatment options in narrow vasculature
Solution Approach 1:
The invention changes the friction parameter at the interface between the pull wire and outer sheath by embedding the wire within the sheath material. This increases the contact area and friction force, allowing the system to transmit higher retracting forces without requiring increased shaft thickness, thereby maintaining a smaller device diameter suitable for narrow vasculature.
3Ease of manufacture
If the outer sheath diameter is increased to accommodate the inner shaft, stent, and fastening rings, then the assembly capability is improved, but the risk of injury during advancement increases and treatment opportunities are reduced
Solution Approach 1:
The invention removes the outer ring and inner ring components that necessitated increased outer sheath diameter. By eliminating these fastening components and using direct embedding of the pull wire, the outer sheath can maintain a smaller diameter that reduces injury risk during vascular advancement while still providing sufficient space for the inner shaft and stent assembly.
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
This design effectively overcomes large friction forces, reduces the need for additional components, and maintains a smaller profile, facilitating easier assembly and safer use in narrow anatomical spaces.
Implementation Method 1
the stepped and/or tapered portion increases the friction and the force transmission between the end portion and the outer sheath
Data Source
Figure 1~5b
Figure 4a~4h
AI summary
There is disclosed herein a retractable catheter preferably for use in an implant delivery system, the catheter comprising: an elongate tubular sheath (16) made of a relatively flexible material; and a pull element (18) for transmitting a pull force to the sheath (16) to retract it longitudinally, characterized in that: the pull element (18) comprises an end portion (18'') disposed in the relatively flexible material, wherein at least the thickness of the end portion (18'') is substantially less than its length. Also disclosed is a method of manufacturing a retractable catheter.