Dynamic RF Ablation Power Control to Prevent Tissue Charring
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Solution Overview
Problem
Conventional radiofrequency ablation techniques maintain a fixed maximum allowable temperature, which does not account for the non-linear tissue response to temperature, potentially leading to undesirable effects like charring and steam pops.
Innovation Solution
A probe with a temperature sensor and power supply that adjusts the delivered radiofrequency power in phases, reducing the maximum allowable temperature during a lower power phase and incorporating a transition time period to allow for gradual temperature decrease, while monitoring impedance to prevent unwanted tissue changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed maximum allowable temperature is maintained during RF ablation, then the ablation process is simple to control, but it does not account for non-linear tissue response leading to charring and steam pops
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed temperature limit to a dynamic temperature limit that varies over time. The controller adjusts the maximum allowable temperature based on the ablation phase (higher temperature limits during initial phases, lower temperature limits in later phases), allowing the system to adapt to non-linear tissue response while maintaining safety and preventing charring and steam pops.
2Productivity
If radiofrequency power is delivered at high levels continuously, then ablation efficiency is improved, but the risk of exceeding maximum allowable temperature and causing tissue damage increases
Solution Approach 1:
The patent implements periodic action by dividing the ablation process into multiple phases with different power delivery characteristics. The controller delivers power at different target levels during different time periods (first target power during initial phase, second target power during later phase), creating a periodic pattern that maintains ablation efficiency while reducing cumulative thermal damage risk.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting multiple parameters including power level, temperature limit, and time period throughout the ablation process. The controller modifies the target power, maximum allowable temperature, and duration based on the ablation phase, optimizing the balance between ablation efficiency and tissue safety.
3Reliability
If the maximum allowable temperature is reduced during lower power phase, then tissue damage is prevented, but the ablation process takes longer
Solution Approach 1:
The patent applies segmentation by dividing the ablation process into distinct time periods with different parameters. The controller segments the ablation into a first time period with higher power and temperature limits, and a second time period with lower power and temperature limits, allowing safe temperature reduction while managing overall ablation duration through structured phases.
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 effectively adapts to non-linear tissue behavior, reducing the risk of charring and steam pops by dynamically adjusting power delivery, ensuring more controlled and efficient tissue ablation.
Implementation Method 1
Tissue surrounding the electrode in the target region is destroyed by heating via RF electric current
Implementation Method 2
a probe having a distal end incorporating a temperature sensor and a transducer in contact with tissue in a body of a living subject
Data Source
Figure 1
Figure 2A~2C
Figure 2D
AI summary
Apparatus, consisting of a probe with a temperature sensor and a transducer in contact with a living subject's tissue. A power supply delivers electrical power to the transducer for tissue ablation. A controller receives a signal from the temperature sensor and in response outputs a tissue temperature. During a first time period the power supply delivers no more than a first target power to the transducer, and reduces the power when a first maximum allowable temperature of the tissue is exceeded. During a transition time period the power supply delivers no more than a second target power, while reducing the delivered power when the first maximum allowable temperature of the tissue is exceeded. During a second time period the power supply delivers no more than the second target power, while reducing the delivered power when a second maximum allowable temperature, less than the first maximum allowable temperature, is exceeded.