In-vivo Calibration of Force-Sensing Catheters
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Solution Overview
Problem
Force-sensing catheters used in cardiac procedures face calibration drift due to environmental changes and aging components, leading to inaccurate force measurements during cardiac arrhythmia treatments, particularly in dynamic and in-vivo conditions.
Innovation Solution
A method and system for dynamic calibration of force-sensing catheters in-vivo, where the processor sets a baseline zero force reading by verifying non-contact with tissue using electrocardiogram, impedance, imaging, or electro-anatomic mapping, and adjusts subsequent readings based on stored zeroing zone locations, ensuring accurate force measurement feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force-sensing catheters are used in cardiac procedures, then contact force measurement capability is improved, but calibration drift occurs due to environmental changes and aging components
Solution Approach 1:
The system performs preliminary calibration actions by establishing a zeroing zone where the catheter is known to be in non-contact with tissue. During the procedure, when the catheter returns to this pre-established zeroing zone, the system automatically recalibrates the force sensor reading to zero, compensating for drift before it affects measurement accuracy.
Solution Approach 2:
The system continuously monitors the catheter's spatial location using magnetic field sensing and compares it against the stored zeroing zone location. When the catheter enters the zeroing zone, the system provides feedback by adjusting the force sensor baseline reading, creating a closed-loop calibration system that maintains accuracy throughout the procedure.
2Measurement precision
If dynamic in-vivo calibration is implemented, then measurement accuracy is maintained, but device complexity increases
Solution Approach 1:
The calibration system serves itself by automatically detecting when the catheter is in the zeroing zone and autonomously recalibrating the force sensor. The system uses its own location sensing capabilities to trigger calibration without external intervention, reducing the need for separate calibration equipment or manual procedures.
Solution Approach 2:
The magnetic field sensing system serves multiple functions: it tracks the catheter's spatial location during the procedure and simultaneously provides the trigger signal for calibration when the catheter enters the zeroing zone. This multi-functionality reduces the need for separate calibration-specific hardware.
3Measurement precision
If continuous monitoring of catheter location is performed, then calibration accuracy is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous calibration processing, the system uses periodic action by only triggering calibration when the catheter enters the pre-defined zeroing zone. The location monitoring continues, but the computationally intensive calibration calculations are performed only at discrete moments when the spatial trigger condition is met.
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 approach ensures accurate and reliable force measurement feedback by compensating for calibration drift, maintaining precise contact verification and force measurement accuracy during cardiac procedures, even in changing conditions.
Implementation Method 1
A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields
Implementation Method 2
a force sensor that provides a signal indicative of the force applied to the distal end of the probe
Data Source
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AI summary
A method for the in vivo re-calibration of a force sensing probe (22) such as an electrophysiology catheter provides for the generation of an auto zero zone. The distal tip (32) of the catheter or other probe is placed in a body cavity (26) within the patient. Verification that there is no tissue contact is made using electrocardiogram (ECG) or impedance data, fluoroscopy or other real-time imaging data and/or an electro-anatomical mapping system. Once verification that there is no tissue contact is made, the system recalibrates the signal emanating from the force sensor setting it to correspond to a force reading of zero grams and this recalibrated baseline reading is used to generate and display force readings based on force sensor data. Location data based on information provided by a location sensor for these auto zero zone locations is stored in system memory. During a procedure the probe may be placed in this auto zero zone for re-calibration or may be automatically recalibrated if it is found to be in an auto zero zone at any time.