Estimating Tissue Temperature During Ablation
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Solution Overview
Problem
Existing medical ablation technologies face challenges in accurately measuring tissue temperature at the electrode-tissue interface due to non-contact temperature sensors and the cooling effect of irrigating fluid, which can lead to underestimation of the actual temperature.
Innovation Solution
A processor-based system that estimates tissue temperature by using a coefficient to adjust the sensed temperature based on the ablating current amplitude and fluid flow rate, learned through regression analysis from test ablations, allowing for accurate temperature estimation at the tissue-electrode interface without direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-contact temperature sensors are used to measure tissue temperature, then the risk of overheating is reduced, but the measurement precision deteriorates due to cooling effect of irrigating fluid
Solution Approach 1:
The patent introduces a computational model as an intermediary between the temperature sensor and the actual tissue temperature. The model uses the sensed temperature, fluid flow rate, and ablation power parameters to calculate and estimate the true tissue temperature at the electrode-tissue interface, effectively bridging the gap caused by the cooling effect of irrigating fluid
Solution Approach 2:
The system implements feedback by continuously monitoring the temperature sensed by the sensor, comparing it with the estimated temperature derived from the computational model, and using this information to provide accurate temperature feedback to the physician for controlling the ablation process
2Reliability
If temperature sensors are placed at the distal end of the probe, then the temperature monitoring is enabled, but the measurement accuracy deteriorates due to the cooling effect of irrigating fluid flowing through the electrode
Solution Approach 1:
The patent changes the parameters used for temperature estimation by incorporating fluid flow rate and ablation power into the computational model. Instead of relying solely on the raw temperature sensor reading, the system adjusts the temperature estimate based on these additional parameters to compensate for the cooling effect
Solution Approach 2:
The patent replaces direct mechanical contact measurement with a computational estimation approach. Rather than attempting to place sensors in direct contact with tissue (which would be affected by cooling fluid), the system uses mathematical modeling to substitute and estimate the true tissue temperature
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
Enables precise temperature monitoring during ablation procedures, reducing the risk of overheating and improving the accuracy of temperature feedback to the physician, even when sensors are not in direct contact with the tissue and accounting for the cooling effect of irrigating fluid.
Implementation Method 1
a temperature sensor at a distal end of an intrabody probe
Implementation Method 2
an ablating current driven, by an ablation electrode at the distal end of the intrabody probe, into the tissue
Data Source
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AI summary
Described embodiments include an apparatus that includes an electrical interface and a processor. The processor is configured to receive, via the electrical interface, a temperature sensed by a temperature sensor at a distal end of an intrabody probe, to estimate a temperature of tissue of a subject, based on the sensed temperature and a parameter of an ablating current driven, by an ablation electrode at the distal end of the intrabody probe, into the tissue, and to generate an output in response to the estimated temperature. Other embodiments are also described.