Hydraulic Actuator for Steerable Catheter Deflection
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Solution Overview
Problem
Current manual actuators for deflectable tip catheters require significant force for deflection and lack the ability to maintain the distal tip in a deflected position or dampen its return, resulting in insufficient travel distance and control during medical procedures like catheter ablation.
Innovation Solution
A hydraulically assisted actuator system that translates small mechanical movements into large travel movements of steering cables, increasing tension for greater deflection and damping the return of the distal tip to an equilibrium position, using a master cylinder and slave cylinders to amplify force and control the catheter tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual actuator is used to deflect the distal tip of the catheter, then the catheter can be steered, but significant manual force is required and the actuator cannot maintain the deflected position or dampen the return
Solution Approach 1:
The patent employs a hydraulic actuator system where a master cylinder receives fluid under pressure from a pump, which then actuates slave cylinders connected to the distal tip. This hydraulic mechanism amplifies the applied force, allowing minimal manual input to generate sufficient deflection force while maintaining stable positioning through fluid pressure equilibrium.
Solution Approach 2:
The invention replaces the purely mechanical manual actuator with a hybrid system that incorporates a fluid power transmission mechanism. The mechanical movement of the master cylinder is converted into hydraulic pressure, which then drives the slave cylinders, substituting direct mechanical force transmission with fluid-mediated force amplification and control.
2Device complexity
If a manual actuator is used, then the structure remains simple, but the travel distance of the steering cable is insufficient for adequate deflection control
Solution Approach 1:
The hydraulic system utilizes the incompressibility of fluid to transmit force over extended distances. The master cylinder's small displacement generates pressure that acts on the slave cylinders, which can produce large linear displacements of the steering cable, effectively extending the control travel distance without proportionally increasing the actuator's physical size.
Solution Approach 2:
The invention changes the physical state and transmission medium from direct mechanical linkage to fluid pressure transmission. By altering the transmission parameter from solid-to-solid contact to fluid pressure, the system achieves greater displacement multiplication while maintaining a relatively compact structure.
3Device complexity
If a manual actuator is used, then the system remains simple, but finer control of the distal end is not achieved
Solution Approach 1:
The hydraulic actuator provides precise control through fluid pressure modulation. Small variations in pump pressure or master cylinder displacement result in proportional changes in slave cylinder actuation, enabling fine control of the distal tip position. The fluid's incompressibility ensures that control inputs are transmitted accurately without mechanical play or slack.
Solution Approach 2:
The system incorporates visual feedback mechanisms (such as radiopaque markers visible under fluoroscopy) that allow the operator to observe the distal tip position in real-time and adjust the hydraulic actuation accordingly, achieving precise positioning through operator observation and adjustment.
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 hydraulic actuator system provides finer control and greater deflection of the catheter tip, allowing for precise positioning and reducing the manual force required, while also dampening the return to a straight position, enhancing the precision and efficiency of medical procedures like catheter ablation.
Implementation Method 1
A hydraulic system has a master cylinder, at least one slave cylinder fluidly coupled with the master cylinder, and at least one steering cable operably connected at a first end with the at least one slave cylinder
Implementation Method 2
The hydraulic system further dampens the return of the ablation tip from a deflected to an equilibrium position
Data Source
AI summary
A hydraulically assisted actuator in a handle connects with a catheter having a deflectable distal ablation tip. The hydraulic actuator translates small mechanical movement by a clinician into large travel movements of connected steering cables and increased tension in the ablation tip for greater deflection. The hydraulic system further dampens the return of the ablation tip from a deflected position to an equilibrium position. The hydraulic actuation system is also incorporated into a set of foot pedals.