Ablation Electrode Contact Detection Using Time-Varying Temperature Threshold
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Solution Overview
Problem
Current methods for verifying contact between an ablation probe and tissue during minimally-invasive intra-cardiac ablation procedures are not adequately precise, particularly in determining continuous contact and varying power levels, which can lead to inconsistent tissue ablation results.
Innovation Solution
A system comprising a signal generator delivering RF signals with varying power and a processor that sets a time-varying temperature threshold based on the fourth root of the power, using coefficients for contact and non-contact scenarios to determine probe-tissue contact through temperature measurements, allowing for real-time 'contact/no-contact' indications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed temperature threshold is used to determine probe-tissue contact, then the detection method is simple, but the precision deteriorates when power levels vary
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed temperature threshold to a time-varying threshold that adapts to changing RF power levels. The threshold is dynamically adjusted based on the fourth root of the instantaneous power, allowing the contact detection system to maintain precision across varying power conditions while preserving operational simplicity through automated calculation.
Solution Approach 2:
The patent changes the temperature threshold parameter from a constant value to a variable that depends on RF power levels. By establishing a mathematical relationship between power and threshold (threshold proportional to the fourth root of power), the system maintains measurement precision across different power levels without increasing operational complexity.
2Measurement precision
If temperature measurements are continuously monitored with high precision, then contact verification accuracy improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical or multi-sensor contact detection systems with a simplified thermal-based detection method. By using temperature measurements combined with a power-dependent threshold calculation, the system achieves high contact verification accuracy without requiring complex mechanical structures or multiple sensing elements.
Solution Approach 2:
The system uses the existing RF power delivery mechanism and temperature sensing capability to perform contact verification. The processor automatically calculates the time-varying threshold based on the fourth root of the power signal, making the system self-sufficient without requiring additional external calibration or complex auxiliary systems.
3Measurement precision
If the temperature threshold is adjusted to account for varying power levels, then the precision of contact detection improves, but the device complexity increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the RF power level and automatically adjusting the temperature threshold accordingly. The processor uses the measured power signal to calculate the appropriate threshold in real-time, creating a closed-loop system that maintains detection precision without requiring manual intervention or complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent changes the threshold parameter dynamically based on power level variations. By establishing a mathematical relationship where the threshold is proportional to the fourth root of the power, the system achieves precise contact detection across varying power conditions while keeping the adjustment mechanism simple and automated.
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
Enhances the precision of probe-tissue contact verification, ensuring consistent and controlled tissue ablation by accurately differentiating between contact and non-contact conditions, even with changing power levels, thereby improving the efficacy of the ablation procedure.
Implementation Method 1
a signal generator (36) delivering a Radio Frequency (RF) signal having a time-varying power to an intra-body probe, for application to tissue in a vicinity of the probe, in order to ablate the tissue
Implementation Method 2
a temperature sensor (48) measuring a temperature in a vicinity of the probe
Data Source
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AI summary
A method includes delivering a Radio Frequency (RF) signal having a time-varying power from an intra-body probe to tissue in a vicinity of the probe in order to ablate the tissue. A temperature is measured in the vicinity of the probe. A decision is made as to whether the probe is in contact with the tissue, by comparing the measured temperature to a temperature threshold that varies in time depending on the time-varying power of the RF signal.