Catheter Active Return-to-Straight Mechanism
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Solution Overview
Problem
Steerable medical devices, such as electrophysiology catheters, often face challenges in maintaining the ability to return a deflectable portion to a substantially straight configuration throughout a medical procedure, especially as the device becomes less responsive due to factors like fluid absorption or pull wire stretching.
Innovation Solution
The implementation of an active return-to-straight mechanism comprising a primary or gross return actuator and a secondary or fine return actuator, which automatically triggers the fine return actuator when the primary actuator is returned to its neutral position, ensuring the catheter shaft can be reliably returned to a substantially straight configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single return actuator is used to return the catheter to straight configuration, then the device complexity is reduced, but the reliability deteriorates as the catheter becomes less responsive during the procedure
Solution Approach 1:
The return actuator is divided into two independent actuators: a primary return actuator that provides the main return force, and a secondary return actuator that provides additional return force. This segmentation allows each actuator to be simpler in design while collectively providing reliable return-to-straight functionality throughout the procedure even as the catheter becomes less responsive
Solution Approach 2:
The system changes the parameter of return force by employing two actuators with different force characteristics. The primary actuator provides initial return force while the secondary actuator supplements this force as needed, adapting to the changing responsiveness of the catheter during the procedure
2Adaptability or versatility
If the catheter shaft is made more flexible to maintain deflectability throughout the procedure, then the adaptability is improved, but the ability to return to straight configuration deteriorates
Solution Approach 1:
The dual return actuator system provides a counteracting force that compensates for the reduced elastic memory effect in the flexible catheter shaft. As the shaft becomes more flexible and less able to return to straight on its own, the actuators provide the necessary counter force to ensure reliable return-to-straight configuration
3Device complexity
If passive return-to-straight mechanism is used, then the device complexity is reduced, but the productivity deteriorates due to repeated manual manipulation needed as responsiveness degrades
Solution Approach 1:
The dual return actuator system provides active self-service functionality, automatically returning the catheter to straight configuration without requiring repeated manual manipulation by the operator. This active return mechanism maintains procedural efficiency even as the catheter responsiveness degrades during the procedure
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 ensures that the deflectable section of the catheter can be consistently returned to a straight configuration throughout a procedure, even as the device's responsiveness degrades, enhancing procedural efficiency and effectiveness.
Implementation Method 1
a first tension member extending from the shaft proximal end to the shaft deflectable distal portion
Implementation Method 2
a second tension member extending from the shaft proximal end to the shaft deflectable distal portion
Data Source
AI summary
Actuators for steerable medical devices are disclosed that not only deflect or steer a portion of a medical device (e.g., a distal portion of a catheter shaft), but also include mechanisms for actively returning the deflected portion of the medical device to an initial configuration (e.g., straight or substantially straight). These active return-to-straight mechanisms may return a catheter shaft from a deflected configuration to a substantially straight configuration throughout a medical procedure, may employ one or more tension members extending along the catheter shaft, and may comprise a gross return actuator and a fine return actuator. For example, the gross return actuator may be configured to partially reverse the deflection of the distal portion of the catheter; and the fine return actuator may be configured to continue reversing the deflection. The gross return actuator may automatically trigger or actuate (mechanically or electromechanically) the fine return actuator.