Retractable Catheter Pull Element Direct Reinforcing Structure Connection
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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 poor connection between the pull wire and sheath, and result in a thicker diameter that limits treatment options and increases the risk of injury.
Innovation Solution
A retractable catheter with an elongate tubular sheath made of flexible material incorporating a reinforcing structure of inextensible material, where the pull element is directly connected to an exposed portion of the reinforcing structure, allowing for efficient force transmission without increasing the sheath diameter, using methods like laser welding for secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the implant length is increased, then the treatment capability is improved, but the friction force between the implant and outer sheath increases, requiring higher retracting forces
Solution Approach 1:
The pull element is extracted from the conventional connection system (separate rings and wire) and directly integrated with the reinforcing structure of the outer sheath. This direct connection eliminates intermediate components and creates a more efficient force transmission path, allowing higher retracting forces to be applied without increasing the overall device diameter.
Solution Approach 2:
The outer sheath is constructed as a composite structure combining flexible material with an embedded reinforcing structure (such as braided wire or mesh). This composite construction provides the sheath with both flexibility for navigation and high tensile strength for withstanding retracting forces, enabling the application of up to 110N of force without sheath failure.
2Force
If the retracting force is increased to handle longer implants, then the friction is overcome, but the inner shaft may deflect or move under compression
Solution Approach 1:
The pull element is extracted from the conventional connection system (separate rings and wire) and directly integrated with the reinforcing structure of the outer sheath. This direct connection eliminates intermediate components and creates a more efficient force transmission path, allowing higher retracting forces to be applied without increasing the overall device diameter.
Solution Approach 2:
The reinforcing structure within the outer sheath is designed with a braided or mesh configuration that distributes compressive forces along the length of the sheath. This curved, interlaced structure provides radial support that prevents the inner shaft from deflecting or moving under compression while allowing the sheath to withstand high retracting forces.
3Reliability
If conventional connection methods (outer and inner rings) are used, then the pull wire is fastened to the sheath, but the device diameter increases and treatment opportunities are reduced
Solution Approach 1:
The pull element is extracted from the conventional connection system (separate rings and wire) and directly integrated with the reinforcing structure of the outer sheath. This direct connection eliminates intermediate components and creates a more efficient force transmission path, allowing higher retracting forces to be applied without increasing the overall device diameter.
Solution Approach 2:
The connection system is merged by integrating the pull element directly with the reinforcing structure of the outer sheath. This eliminates the need for separate outer and inner rings, combining multiple functions into a single integrated structure that maintains connection reliability while reducing the overall device diameter profile.
4Strength
If the outer sheath diameter is increased to accommodate thicker inner shaft, then the compressive strength is improved, but the risk of injury during advancement increases
Solution Approach 1:
The outer sheath is constructed as a composite structure combining flexible material with an embedded reinforcing structure (such as braided wire or mesh). This composite construction provides the sheath with both flexibility for navigation and high tensile strength for withstanding retracting forces, enabling the application of up to 110N of force without sheath failure.
Solution Approach 2:
The reinforcing structure within the outer sheath is designed with a braided or mesh configuration that distributes compressive forces along the length of the sheath. This curved, interlaced structure provides radial support that prevents the inner shaft from deflecting or moving under compression while allowing the sheath to withstand high retracting forces.
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 solution enables the application of higher tensile forces up to 110N, reduces the risk of damage, and allows for the deployment of longer implants in narrow body passages with reduced friction, maintaining a low profile and minimizing the risk of injury.
Implementation Method 1
using methods like laser welding for secure connection
Data Source
Figure 1~5b
Figure 4a~4h
AI summary
There is disclosed herein a retractable catheter preferably for use in an implant delivery catheter system, the catheter comprising: an elongate tubular sheath (16) which is at least in a distal portion made of a relatively flexible material; a reinforcing structure (20) which is made of a relatively inextensible material and which is incorporated, along at least a portion of the length of the sheath (16), in the relatively flexible material of the sheath; and a pull element (18) for transmitting a pull force longitudinally to the sheath (16) and the reinforcing structure (20), characterized in that: the pull element (18) is connected directly to a portion of the reinforcing structure (20) exposed from the relatively flexible material, to transmit the pull force directly to the reinforcing structure (20). Also disclosed herein is an implant delivery system which comprises such a retractable catheter, and methods for its manufacture.