Multi-Frequency Reactance for Cryo Ablation Lesion Assessment
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Solution Overview
Problem
Current methods for assessing lesion quality and depth in cryogenically or RF-treated tissues, such as impedance tomography, lack direct feedback and real-time assessment, providing binary data that does not effectively evaluate transmurality or continuity of lesions.
Innovation Solution
A medical system that measures reactance of treated tissue at multiple frequencies using a medical device with electrodes, compares the measured reactance to predetermined thresholds, and modifies treatment based on the assessment to determine lesion quality and continuity, displaying results for real-time feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance measurements are used to identify treated tissue, then tissue necrosis can be detected, but real-time assessment of lesion depth and quality is not provided
Solution Approach 1:
The patent segments the impedance measurement into two distinct components: resistance and reactance. By analyzing these separate components, the system can provide more detailed information about lesion characteristics. Specifically, reactance measurements are used to assess transmurality and lesion depth, while resistance indicates tissue necrosis, thereby resolving the information loss about lesion quality and depth.
Solution Approach 2:
The patent introduces a new measurement dimension by separating impedance into resistance and reactance components and measuring reactance at multiple frequencies. This dimensional expansion allows the system to extract additional information about lesion depth, transmurality, and tissue properties that cannot be obtained from single-frequency impedance measurements alone.
2Measurement precision
If single frequency impedance measurement is used, then the measurement process is simple, but lesion quality and transmurality cannot be accurately assessed
Solution Approach 1:
The patent segments the frequency spectrum into multiple measurement frequencies and separates the impedance analysis into resistance and reactance components. By measuring reactance at multiple frequencies and analyzing their differences, the system can accurately assess lesion quality, transmurality, and depth while maintaining a manageable system complexity through systematic data processing.
Solution Approach 2:
The patent changes the measurement parameter from single-frequency impedance to multi-frequency reactance. By measuring reactance at multiple frequencies and analyzing the frequency-dependent changes, the system can extract detailed information about lesion characteristics, tissue composition, and transmurality, thereby improving measurement precision for lesion quality assessment.
3Productivity
If impedance tomography is used to map treated areas, then tissue necrosis locations can be identified, but continuous feedback for treatment optimization is not available
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring reactance changes during cryogenic ablation treatment. The system compares measured reactance values against predetermined thresholds and provides real-time feedback about lesion development, transmurality achievement, and treatment effectiveness, enabling dynamic optimization of treatment parameters and duration.
Solution Approach 2:
The patent replaces the mechanical/visual assessment of lesion quality with electrical reactance measurements. By using multi-frequency reactance analysis to detect tissue property changes, the system provides objective, quantitative, real-time feedback about lesion development and transmurality, eliminating the need for subjective visual or mechanical assessment methods.
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 accurate and real-time assessment of lesion quality and depth, allowing for modification of treatment to achieve desired transmurality and continuity, improving the efficacy of cryogenic and RF ablation procedures.
Implementation Method 1
measuring the reactance of the ablated tissue region... inducing a current between the at least two electrodes at a plurality of frequencies; measuring the reactance of the thermally treated tissue region at each of the plurality of frequencies
Implementation Method 2
circulating coolant towards a thermally conductive region of the medical device... thermally treating the tissue region... cryogenically cooling the tissue region
Data Source
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AI summary
A method of assessing lesion quality of an ablated tissue region comprising ablating at least a portion of the tissue region. The reactance of the ablated tissue region is measured at a plurality of frequencies. The lesion quality of the ablated tissue region is determined based on the measured reactance. For example, an untreated tissue reactance value and a predetermined thermally treated tissue region reactance threshold may be determined. The measured reactance at each of the plurality of frequencies is compared to the threshold to determine the lesion quality of the thermally treated tissue region. The thermal treatment of the tissue may be modified based on the lesion quality determination.