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Publication Number
US-11576714-B2
Publication Date
2023-02-14
Expiration Date
Abstract
According to some embodiments, a medical instrument comprises an elongate body having a proximal end and a distal end and a pair of electrodes or electrode portions (for example, a split-tip electrode assembly). Systems and methods are described herein that perform contact sensing and/or ablation confirmation based on electrical measurements obtained while energy of different frequencies are applied to the pair of electrodes or electrode portions. The contact sensing systems and methods may calibrate network parameter measurements to compensate for a hardware unit in a network parameter measurement circuit or to account for differences in cables, instrumentation or hardware used.
Core Innovation
The disclosed invention relates to a medical system for determining whether a medical instrument is in contact with tissue based, at least in part, on impedance measurements. The system delivers signals having different frequencies to a pair of electrodes of the medical instrument and generates a contact-indicative output to indicate contact based on the impedance measurements obtained at the electrodes.
The system applies a transform to a resulting waveform that formulates across the pair of electrodes to obtain impedance measurements at a first frequency and a second frequency. It determines a ratio between the magnitude of the impedance at the second frequency and the first frequency, and it generates an output indicative of contact based on the ratio.
The description further addresses impedance-related processing used for contact indication and ablation confirmation, including determining tissue type from impedance magnitude, impedance ratio/slope between frequencies, and impedance phase across frequencies. It also describes circuitry and signal processing concepts to avoid interference with electrogram (EGM) functionality and includes calibration/de-embedding concepts using network-parameter measurement such as S-parameters and transmission matrices so computed contact functions better reflect impedance at the electrode pair.
Claims Coverage
The document includes two independent claims directed to a system and a method for determining whether a medical instrument is in contact with tissue based on impedance measurements. Across the independent claims, there are two core inventive themes: multi-frequency impedance measurement on an electrode pair using a transform, and generating a contact output based on a ratio of impedance magnitudes.
Multi-frequency signals to electrode pair and transform-based impedance extraction
A signal source delivers signals having different frequencies to a pair of electrodes, and a processing device applies a transform to a resulting waveform that formulates across the pair of electrodes to obtain impedance measurements at a first frequency and a second frequency.
Contact output based on impedance magnitude ratio
The processing device determines a ratio between the magnitude of the impedance at the second frequency and the first frequency and generates an output indicative of contact based on the ratio.
Signal application, transform, and ratio-based contact output as a method
The method applies signals having a first frequency and a second frequency to a pair of electrodes, applies a transform to a resulting waveform to obtain impedance measurements at the first frequency and the second frequency, determines a ratio between the magnitude of the impedance at the second frequency and the first frequency, and generates an output indicative of contact based on the ratio.
In both the system and method, contact determination is centered on obtaining impedance measurements at two different frequencies by transforming a resulting waveform that formulates across a pair of electrodes, and generating an output indicative of contact based on a ratio of impedance magnitudes (second-frequency magnitude over first-frequency magnitude).
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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