Bi-directional Catheter Steering Mechanism with U-turn Pulleys
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Solution Overview
Problem
Existing bidirectional steerable catheters have limited mechanical efficiency and deflection capability due to the design of their steering mechanisms, which results in increased friction losses and reduced longitudinal movement of puller wires, limiting the degree of catheter tip deflection and user exertion required.
Innovation Solution
A bi-directional catheter design featuring a steering assembly with pulleys that allow puller wires to make a U-turn, minimizing the offset angle and maximizing travel distance, along with a control handle that includes constant force springs and adjustable stops for enhanced deflection control, and a deflection knob for user-friendly operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional bidirectional steering mechanism is used, then the catheter can be deflected in both directions, but the mechanical efficiency is limited and friction losses increase
Solution Approach 1:
A pulley system is introduced as an intermediary mechanical element between the puller wires and the catheter tip. The pulleys redirect the puller wires to optimize the angle of application, minimizing friction losses and improving mechanical efficiency while reducing the exertion required by the user.
Solution Approach 2:
The design optimizes the angle at which puller wires are applied to the catheter tip by using pulleys to redirect the wires. This parameter change in the angle of force application reduces friction losses and improves the overall mechanical efficiency of the steering mechanism.
2Ease of operation
If the puller wires extend at a greater angle from the longitudinal axis, then steering is achieved, but the efficiency of the steering lever decreases and friction losses increase
Solution Approach 1:
Pulleys serve as intermediary elements that redirect the puller wires to achieve the desired steering angle while maintaining optimal efficiency. The pulleys allow the wires to extend at minimized angles from the longitudinal axis, reducing friction losses.
Solution Approach 2:
The pulley system introduces a dimensional change by redirecting the puller wires through a different spatial path. This allows the wires to maintain a minimized angle relative to the longitudinal axis while still achieving the necessary lateral deflection of the catheter tip.
3Length of moving object
If the longitudinal movement of puller wires is limited to the circumference of a rotatable cam, then the device remains compact, but the degree of catheter tip deflection is limited
Solution Approach 1:
The pulley system is nested within the compact control handle structure, allowing for extended deflection throw without proportionally increasing the volume of the control handle. The components are arranged in a space-efficient configuration that maximizes deflection capability within a compact form factor.
Solution Approach 2:
The design extends the deflection capability by utilizing a different spatial arrangement of the puller wires through pulleys, effectively increasing the longitudinal movement distance without requiring a proportional increase in the control handle volume.
4Adaptability or versatility
If additional lumens are added to accommodate electrode lead wires, then the catheter becomes more functional, but the design complexity increases
Solution Approach 1:
The catheter design integrates multiple functions including bidirectional steering and electrode delivery within a unified structure. The puller wire lumens are positioned and configured to also accommodate or work in conjunction with electrode lead wires, reducing the need for separate dedicated lumens and simplifying the overall design.
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 achieves nearly double the throw in catheter tip deflection with reduced user effort, improved mechanical efficiency, and fine-tuned deflection control within a compact control handle, enhancing the usability and effectiveness of the catheter.
Implementation Method 1
The travel path of each the puller wires includes a U-turn or doubling-back around a pulley which minimizes the offset angle between the puller wire and the longitudinal axis of the control handle while maximizing the travel distance of that puller wire
Implementation Method 2
a control handle that includes constant force springs and adjustable stops for enhanced deflection control
Data Source
AI summary
The present invention provides a bi-directional catheter with nearly double the throw in its catheter tip deflection. In particular, the travel path of each the puller wire includes a U-turn or doubling-back around a pulley which minimizes the offset angle between the puller wire and the longitudinal axis of the control handle while maximizing the travel distance of that puller wire for any given distance traveled by the pulley drawing the puller wire. In one embodiment, the catheter has an elongated catheter body, a catheter tip section with first and second diametrically-opposed off-axis lumens, and a control handle which includes a steering assembly having a lever structure carrying a pair of pulleys for simultaneously drawing and releasing corresponding puller wires to deflect the tip section of the catheter.