Catheter Contact Angle Estimation Using Multi-Frequency Impedance
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Solution Overview
Problem
Current methods for evaluating impedance between catheter electrodes are limited, particularly in intrabody applications, as they rely on standard wires connecting electrodes to sources and meters, lacking a publicly available method for precise impedance measurement.
Innovation Solution
A method and apparatus for evaluating electrical impedance between catheter electrodes using alternating currents of different frequencies, with measurements taken at various voltages and currents, allowing for more accurate impedance calculations and contact force and angle estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard wires connecting electrodes to sources and meters are used, then the device complexity is reduced, but the measurement precision of impedance is insufficient
Solution Approach 1:
The patent introduces a new dimension of measurement by using multiple frequencies instead of a single frequency. The system measures impedance at multiple frequencies (e.g., 50 Hz, 400 Hz, 1 kHz, 10 kHz) to capture the frequency-dependent behavior of biological tissues, thereby improving measurement precision without requiring complex additional hardware beyond standard multi-frequency signal generators and measurement devices.
Solution Approach 2:
The patent changes the electrical parameters by applying alternating currents at different frequencies and amplitudes. By varying the frequency parameter and measuring the corresponding impedance responses, the system extracts more information about tissue properties, improving measurement precision while using conventional equipment capable of parameter variation.
2Measurement precision
If multiple measurements at different frequencies and voltages are taken, then the measurement precision improves, but the loss of time increases
Solution Approach 1:
The patent employs periodic action by applying alternating currents at multiple frequencies in a systematic sequence. The system rapidly cycles through different frequency measurements, utilizing the periodic nature of AC signals to collect multiple data points efficiently. This periodic measurement approach allows comprehensive impedance characterization while minimizing total measurement time through optimized measurement sequences.
Solution Approach 2:
The patent maintains continuity of useful action by performing impedance measurements continuously across multiple frequencies without interrupting the catheter procedure. The system seamlessly transitions between frequency measurements, keeping the measurement process ongoing and productive throughout the medical procedure, thereby reducing overall time loss.
3Adaptability or versatility
If impedance measurements are taken in complex intrabody environments, then the adaptability improves, but the measurement precision deteriorates due to environmental interference
Solution Approach 1:
The patent implements feedback by using the measured impedance data to adjust and refine the estimation of contact force and contact angle. The system continuously monitors impedance at multiple frequencies and uses this feedback to improve the accuracy of tissue interaction parameters, compensating for environmental variations and interference in the intrabody setting.
Solution Approach 2:
The patent adapts to complex intrabody environments by changing measurement parameters, specifically using multiple frequencies to probe different tissue properties. Different frequencies penetrate and interact with tissues differently, allowing the system to select optimal frequency ranges that minimize the impact of environmental interference and improve measurement precision in challenging physiological conditions.
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 evaluation of impedance between catheter electrodes, facilitating accurate estimation of contact force and angle, even in complex intrabody environments, improving tissue interaction and catheter positioning during procedures.
Implementation Method 1
evaluating a first interelectrode impedance based on the plurality of voltages; and evaluating a second interelectrode impedance based on the plurality of voltages
Data Source
AI summary
Systems and methods for determining a contact angle of a catheter relative to tissue are provided. In one embodiment, a system includes a catheter with three or more electrodes, and a processor circuit in communication with the catheter. The processor circuit controls the three or more electrodes to emit a plurality of electrical voltages and to measure the plurality of electrical voltages. Based on the measured electrical voltages, the processor circuit calculates a first interelectrode impedance and a second interelectrode impedance. The processor circuit calculates, for each of a plurality of hypothetical i.e. model angles, a first hypothetical i.e. model contact force and a second hypothetical i.e. model contact force based on the first and second interelectrode impedances. The processor circuit determines and outputs the contact angle of the catheter based on a comparison of the first and second model contact forces calculated for each of the plurality of model angles.