Ablation Probe Tissue Temperature Estimation
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Solution Overview
Problem
Existing invasive medical devices face challenges in accurately measuring tissue temperature during ablation procedures, especially when temperature sensors are not in contact with the tissue, and the flow of irrigating fluid can cause temperature readings to be lower than the actual tissue-electrode interface temperature.
Innovation Solution
A method and apparatus that estimate tissue temperature at the electrode interface using a processor that receives temperature data from sensors and fluid-flow rate information, adjusting ablating current power and fluid flow based on estimated temperatures, and learning relationships between sensed and measured temperatures through regression analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are placed away from the tissue interface to avoid interference, then device safety is improved, but temperature measurement precision deteriorates
Solution Approach 1:
The patent introduces fluid flow as an intermediary medium that carries thermal information from the tissue-electrode interface to the temperature sensor. The fluid acts as a thermal conveyor, allowing the sensor to be positioned away from the tissue while still measuring the interface temperature indirectly through the fluid's thermal properties
Solution Approach 2:
The patent replaces direct mechanical contact between the temperature sensor and tissue with a fluid-based thermal transmission system. Instead of physically touching the tissue to measure temperature, the sensor measures the fluid's temperature that has been thermally coupled to the tissue interface through controlled fluid flow
2Temperature
If irrigating fluid flow rate is increased to cool the tissue and prevent thrombus, then tissue overheating is prevented, but temperature reading accuracy deteriorates due to cooling effect on sensor
Solution Approach 1:
The patent applies preliminary action by pre-heating the irrigating fluid before it reaches the tissue-electrode interface. This ensures that the fluid does not artificially cool the sensor reading, as the heating occurs before the fluid contacts both the tissue and sensor, allowing accurate temperature measurement while still providing cooling function
Solution Approach 2:
The patent applies different thermal treatments to different parts of the fluid path: the fluid is heated in a preliminary stage before reaching the interface, then allows natural cooling at the interface for accurate measurement, and finally provides therapeutic cooling to the tissue. Each zone has optimized thermal properties for its specific function
3Measurement precision
If multiple temperature sensors are placed at the electrode tip to measure interface temperature, then temperature measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature measurement function from the electrode structure itself and separates it into an independent fluid-based sensing system. The temperature sensor is positioned in the fluid path rather than embedded in the electrode, simplifying the electrode design while maintaining measurement capability through the fluid's thermal coupling
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 allows for accurate estimation of tissue temperature at the electrode interface, enabling precise control of ablation procedures and reducing thrombus formation by optimizing fluid flow and energy delivery.
Implementation Method 1
a temperature sensor at the distal end of the intra-body probe... while fluid is being passed from the distal end of the intra-body probe at a fluid-flow rate, a temperature is being sensed
Implementation Method 2
an ablation electrode... driving an ablating current into tissue of a subject
Data Source
AI summary
A method for use with an intra-body probe, a distal end of which includes an ablation electrode and a temperature sensor, is described. While (i) the ablation electrode is driving an ablating current into tissue of a subject, and (ii) fluid is passed from the distal end of the intra-body probe at a fluid-flow rate, a processor receives a temperature sensed by the temperature sensor. The processor estimates a temperature of the tissue, based at least on the sensed temperature and at least one parameter selected from the group consisting of: the fluid-flow rate, and a parameter of the ablating current. The processor generates an output in response to the estimated temperature. Other embodiments are also described.