Distal End Assembly Torque Monitoring via Position Sensors
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Solution Overview
Problem
Existing catheter systems face challenges in accurately measuring the force applied by electrodes on the tissue during ablation procedures, due to twisting of the distal end assembly relative to the catheter shaft.
Innovation Solution
A method is introduced to determine the torque produced by the distal end assembly by sensing the angular rotation of the distal tip relative to the shaft, using a plurality of position sensors. A calibration procedure establishes a correspondence between angular rotation and torque, allowing for the calculation of force on each electrode during the ablation procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the distal end assembly is made flexible to allow maneuvering into position and conform to tissue shape, then the ease of operation and adaptability are improved, but the assembly may twist relative to the shaft, causing inaccurate force measurement
Solution Approach 1:
A calibration procedure is performed before the ablation procedure to establish a correspondence between angular rotation (torsion) and torque. This preliminary calibration creates a mathematical model that will be used during the actual procedure to accurately calculate force despite assembly twisting.
Solution Approach 2:
Position sensors continuously monitor the angular rotation of the distal end assembly during the procedure. This feedback information about torsion is fed back to the computing device, which uses the pre-established calibration correspondence to calculate the actual torque and force on contacting electrodes, compensating for the twisting effect.
2Measurement precision
If position sensors are attached to the distal end assembly to measure angular rotation, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The position sensors serve multiple functions: they track the three-dimensional position of the distal end assembly and simultaneously measure its angular rotation (torsion) relative to the shaft. This multi-functionality reduces the need for separate sensing systems and justifies the added complexity by providing comprehensive measurement capabilities.
Solution Approach 2:
The position sensors act as intermediaries that indirectly measure the force on electrodes. Rather than directly measuring force (which would require complex force sensors on each electrode), the sensors measure angular rotation, and a computing device uses this information along with a calibration model to calculate the force, simplifying the overall measurement approach.
Data Source
AI summary
Apparatus for measuring a torque, consisting of a probe having a shaft with a shaft distal end. The probe has a distal end assembly, configured to be inserted into an organ of a human subject, and having a distal termination and a proximal termination connected to the shaft distal end. A position sensor assembly is attached to the distal end assembly in proximity to the distal termination, the position sensor assembly being configured to provide signals indicative of a three-dimensional position and orientation of the distal termination with respect to the shaft distal end. A processor is configured to compute a torsion of the distal termination with respect to the proximal termination in response to the signals from the position sensor assembly, and compute the torque on the distal end assembly in response to the torsion and a predetermined correspondence between the torsion and the torque.