Analyzing electrocardiogram signals with multiscale short-time fourier transforms
First Claim
1. A non-transitory computer-readable memory medium that stores program instructions executable by a computer system to:
- receive a discrete electrocardiogram (ECG) signal, wherein the discrete ECG signal includes one or more waveform features indicative of cardiac condition;
apply a sliding window multiscale frequency transform to the discrete electrocardiogram (ECG) signal, thereby generating a transform array parameterized by a specified plural set of window features;
determine a plurality of peaks in the transform array, including determining coarse values for each of the specified plural set of window features for each peak;
determine, for each peak, at least three windowed functions, wherein each of the windowed functions has window features with values approximately equal to the coarse values corresponding to the specified plural set of window features; and
determine, for each peak, refined values for the plural set of window features based on the discrete ECG signal and the at least three windowed functions;
wherein the refined values for the plural set of window features are indicative of a specified cardiac condition.
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Accused Products
Abstract
A system, method, and memory medium for operating on an electrocardiogram (ECG) signal. A multiscale short-time Fourier transform (STFT) is perform on a set of ECG samples {s(n)} to obtain a transform array. For each sufficiently energetic peak in the transform array, a refined window width value and a refined window displacement value is generated by: computing an inner product between the set of samples and each of a plurality of functions, where the plurality of functions are sufficiently close to a coarse approximation function given by the peak location; and solving a linear system Av=c for the unknown vector v, where the vector c is determined by the inner products, where the matrix A is determined by the center times of the plurality of functions. After appropriate selection, the refined window width and refined window displacement may be used to represent ECG waveform features.
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Citations
27 Claims
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1. A non-transitory computer-readable memory medium that stores program instructions executable by a computer system to:
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receive a discrete electrocardiogram (ECG) signal, wherein the discrete ECG signal includes one or more waveform features indicative of cardiac condition; apply a sliding window multiscale frequency transform to the discrete electrocardiogram (ECG) signal, thereby generating a transform array parameterized by a specified plural set of window features; determine a plurality of peaks in the transform array, including determining coarse values for each of the specified plural set of window features for each peak; determine, for each peak, at least three windowed functions, wherein each of the windowed functions has window features with values approximately equal to the coarse values corresponding to the specified plural set of window features; and determine, for each peak, refined values for the plural set of window features based on the discrete ECG signal and the at least three windowed functions; wherein the refined values for the plural set of window features are indicative of a specified cardiac condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A non-transitory computer-readable memory medium storing program instructions executable by a computer system to:
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receive a discrete electrocardiogram (ECG) signal, wherein the discrete ECG signal includes a waveform feature indicative of cardiac condition; compute a plurality of windowed multiscale frequency transforms based on the discrete ECG signal, wherein each windowed multiscale frequency transform is computed using a respective value of window width; determine an initial set of parameter values that characterize the waveform feature based on the plurality of windowed multiscale frequency transforms;
determine at least three windowed functions, wherein each of the windowed functions has window features with values approximately equal to the initial set of parameter values;compute at least two refined parameter values of the waveform feature based on the at least three windowed functions and the initial set of parameter values; and store the at least two refined parameter values of the waveform feature in a memory. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A computer-implemented method comprising:
utilizing a computer system to perform; receiving a discrete electrocardiogram (ECG) signal, wherein the discrete ECG signal includes a waveform feature indicative of cardiac condition; computing a plurality of windowed multiscale frequency transforms based on the discrete ECG signal, wherein each windowed multiscale frequency transform is computed using a respective value of window width; determining an initial set of parameter values that characterize the waveform feature based on the plurality of windowed multiscale frequency transforms; determining at least three windowed functions, wherein each of the windowed functions has window features with values approximately equal to the initial set of parameter values; computing at least two refined parameter values of the waveform feature based on the at least three windowed functions and the initial set of parameter values; and storing the at least two refined parameter values of the waveform feature in a memory.
Specification