Method and apparatus for analyzing and interpreting electrocardiograms using spectro-temporal mapping
First Claim
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1. The method of evaluating electrocardiogram (ECG) signals of a patient which comprises:
- digitizing a large number of successive, repetitive ECG waveforms, each waveform representing an amplitude with respect to time from the patient, at sampling points equal to a sampling rate greater than about 500 per second;
averaging the digital sample values at corresponding sample points on the successive ECG waveforms to produce a single digitized signal averaged, high resolution ECG (HRECG) waveform having significantly enhanced signal-to-noise ratio;
producing a set of digital spectrum values representative of an approximate power density spectrum at each of a large number of generally equally spaced sampling time intervals over the HRECG waveform, each spectrum value being a function of the power of the HRECG waveform in a finite time/amplitude window having a time deviation substantially less than the time period of the HRECG waveform which is of interest; and
determining the presence of late potentials from the set of power density spectrums.
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Abstract
Method and apparatus for analyzing ECG signal data for diagnostic purposes by performing an incrementally moving, short window FFT analysis to produce a set of spectral templates representative of the spectral frequency content of the ECG at each window position. The spectral templates may be displayed as a representation of a three dimensional surface or mathematically analyzed. The changes in the shape of the templates or surface with time represent a change in the spectrum, which are shown to be an indication of abnormalities in the heart.
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Citations
19 Claims
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1. The method of evaluating electrocardiogram (ECG) signals of a patient which comprises:
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digitizing a large number of successive, repetitive ECG waveforms, each waveform representing an amplitude with respect to time from the patient, at sampling points equal to a sampling rate greater than about 500 per second; averaging the digital sample values at corresponding sample points on the successive ECG waveforms to produce a single digitized signal averaged, high resolution ECG (HRECG) waveform having significantly enhanced signal-to-noise ratio; producing a set of digital spectrum values representative of an approximate power density spectrum at each of a large number of generally equally spaced sampling time intervals over the HRECG waveform, each spectrum value being a function of the power of the HRECG waveform in a finite time/amplitude window having a time deviation substantially less than the time period of the HRECG waveform which is of interest; and determining the presence of late potentials from the set of power density spectrums. - View Dependent Claims (3, 4)
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2. The method of claim 2 wherein the set of power density spectrum approximations are displayed as a three dimensional visual display in which the spectral values of the power density are represented as an apparent surface, one ordinate of the surface is time, the second ordinate is the frequency of the energy, and the third ordinate is power.
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5. The method for evaluating an electrocardiogram (ECG) which comprises:
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producing a set of digital values representative of a three dimensional surface defined by a three generally orthogonal axis coordinate system in which a first axis represents the time domain of the ECG, a second axis represents the frequency domain of the ECG and the third axis represents an approximation of the magnitude of the spectral frequency of the ECG; and visually displaying the surface such that the three dimensional character of the surface can be observed and from which an evaluation of the ECG data can be made.
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6. The method for producing and evaluating a high resolution electrocardiogram (HRECG) which comprises:
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averaging corresponding digital sample points of successive waveforms of an ECG from a patient to produce digital data representative of a single HRECG waveform having an enhanced signal-to-noise ratio when compared to the original ECG data; producing a set of digital values representative of a three dimensional surface defined by a three orthogonal axis coordinate system in which a first axis represents the time domain of the HRECG, a second axis represents the frequency domain of the HRECG and the third axis represents an approximation of the magnitude of the power of the HRECG; and visually displaying the surface such that the three dimensional character of the surface can be observed and from which an evaluation of the ECG data can be made.
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7. The method for evaluating an electrocardiogram (ECG) of a patient which comprises:
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calculating from the ECG and storing digital data defining a three dimensional surface representative of the spectral frequency of the ECG in which the first axis is the time domain of the ECG, the second axis is the frequency domain, and the third axis is representative of the amplitude or power domain; and evaluating the data representative of the surface to diagnose the condition of the patient'"'"'s heart. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification