Nested Lap Joint Catheter Shaft Torque Transmission
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Solution Overview
Problem
Electrophysiology catheters face challenges in transmitting torque and resisting compression during medical procedures, leading to potential loss of control and impaired tactile feedback due to significant frictional forces and energy storage, which can result in undesired propulsion of the catheter tip.
Innovation Solution
A medical device featuring a nested lap joint and a fused conductive element, where the connection between shafts is strengthened by a method involving a reflow process to embed compression coils or spring packs, enhancing torque transmission and resistance to compression, thereby reducing the risk of joint separation and kinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a catheter shaft transmits torque through frictional forces, then torque transmission capability is improved, but the frictional forces cause the catheter shaft to twist and store energy, leading to sudden release and undesired propulsion of the distal end
Solution Approach 1:
The catheter shaft is divided into multiple discrete segments or sections that can independently manage torque transmission. Each segment can be optimized with specific friction characteristics, allowing torque to be transmitted in a controlled manner without excessive energy storage that would cause sudden releases and undesired propulsion at the distal end.
Solution Approach 2:
Different sections of the catheter shaft are given different local properties regarding friction and torque transmission. The proximal sections may have higher friction characteristics for effective torque input, while distal sections are designed with lower friction to prevent energy accumulation and sudden releases, thereby eliminating undesired propulsion.
2Ease of operation
If the catheter shaft resists compression, then control and positioning accuracy are improved, but excessive compressibility impairs tactile feedback and complicates positioning
Solution Approach 1:
The catheter shaft is designed with varying compressibility characteristics along its length. Critical sections where tactile feedback is needed have optimized stiffness to maintain reliable feedback, while other sections allow appropriate compression to facilitate navigation through vasculature. This localized optimization ensures both control accuracy and reliable tactile feedback.
3Strength
If nested lap joints are used to connect shafts, then mechanical strength and torque transmission are improved, but the complexity of the joint structure increases
Solution Approach 1:
The catheter shafts are connected using nested lap joints where one shaft is inserted into another in a telescopic arrangement. This nesting configuration provides large overlapping contact areas between shafts, significantly enhancing mechanical strength and torque transmission capability while maintaining a relatively compact and integrated joint structure.
Solution Approach 2:
Multiple functional elements are merged into the nested lap joint structure, combining mechanical connection, torque transmission, and structural support functions into a single integrated joint design. This reduces the number of separate components needed and simplifies the overall assembly while maintaining high strength characteristics.
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 solution provides a more reliable and durable medical device with improved mechanical properties, allowing for precise embedding of conductive elements and reduced costs, while minimizing the risk of joint separation and kinking, thus enhancing control and efficiency during procedures.
Implementation Method 1
a method involving a reflow process to embed compression coils or spring packs
Implementation Method 2
Substantial frictional forces sometimes resist transmission of torque across the length of the catheter
Implementation Method 3
embed compression coils or spring packs, enhancing torque transmission and resistance to compression
Data Source
AI summary
A deflectable catheter is disclosed. The deflectable catheter includes a deflectable shaft including a proximal portion and a distal portion, the distal portion of the deflectable shaft including one or more electrodes. The deflectable catheter also includes a pull ring disposed in the distal portion of the deflectable shaft, a first pull wire, and a second pull wire. Both the first pull wire and the second pull wire extend through the proximal portion of the deflectable shaft and a distal end of the first pull wire and a distal end of the second pull wire are coupled to the pull ring. The deflectable catheter also includes a cylindrical braid structure at least partially disposed within the distal portion of the deflectable shaft.