Methods for quantifying the risk of cardiac death using exercise induced heart rate variability metrics
First Claim
1. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
- providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test;
determining a frequency domain value based on at least one of energy values of frequency bands and spectral s1ope(s) across selected frequency ranges of the heart activity data in the windowed time series; and
assessing the risk of a cardiac event based on the frequency domain value;
wherein providing heart activity data comprises determining an instantaneous heart rate sequence from an ECG waveform obtained during an exercise period of increasing heart rate and a recovery period of decreasing heart rate, providing a uniform sample series of the instantaneous heart rate sequence, and reducing the uniform sample series by filtering and/or detrending via fitting a polynomial function to the heart activity data across a selected time window to obtain a heart rate variability waveform associated with variances in the heart rate between beats in a desired frequency band.
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Accused Products
Abstract
Methods and apparatus for assessing cardiac risks in a specific patient. One embodiment of a method in accordance with the invention comprises providing heart rate activity of a specific patient including a windowed time series relating to heart rate variability during a heart rate test. This method further includes determining a frequency domain value based on energy values of frequency bands of the heart rate variability in the windowed time series, and/or determining an aggregate power for a frequency band of the windowed time series. This method further includes assessing the risk of a cardiac event based on the frequency value and/or the aggregate power.
39 Citations
35 Claims
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1. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on at least one of energy values of frequency bands and spectral s1ope(s) across selected frequency ranges of the heart activity data in the windowed time series; and assessing the risk of a cardiac event based on the frequency domain value; wherein providing heart activity data comprises determining an instantaneous heart rate sequence from an ECG waveform obtained during an exercise period of increasing heart rate and a recovery period of decreasing heart rate, providing a uniform sample series of the instantaneous heart rate sequence, and reducing the uniform sample series by filtering and/or detrending via fitting a polynomial function to the heart activity data across a selected time window to obtain a heart rate variability waveform associated with variances in the heart rate between beats in a desired frequency band. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on at least one of energy values of frequency bands and spectral slope(s) across selected frequency ranges of the heart activity data in the windowed time series; and assessing the risk of a cardiac event based on the frequency domain value; wherein determining a frequency domain value based on at least one of the energy values comprises (a) fitting a line to the spectral power across a selected frequency range, and (b) determining a slope of the line to obtain a spectral slope, wherein the frequency domain value comprises the spectral slope.
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8. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on at least one of energy values of frequency bands and spectral slope(s) across selected frequency ranges of the heart activity data in the windowed time series; and assessing the risk of a cardiac event based on the frequency domain value; wherein assessing the risk of a cardiac event comprises comparing the determined frequency domain value with a reference frequency domain value range associated with a population that has experienced the cardiac event. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for assessing cardiac risks in a specific patent based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test, the windowed time series including ecotopic beats; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the aggregate power; wherein providing heart activity data comprises determining an instantaneous heart rate sequence from an ECG waveform obtained during an exercise period of increasing heart rate and a recovery period of decreasing heart rate, providing a uniform sample series of the instantaneous heart rate sequence, and reducing the uniform sample series via filtering the heart activity data and/or detrending by subtraction of a fit polynomial function of the heart rate variability data to obtain a heart rate variability waveform associated with variances in the heart rate between beats in a desired frequency band; and determining the aggregate power comprise performing (a) a Fourier transform of the windowed time series into a spectrum for frequency domain analysis and/or (b) a root-means-square computation of the filtered or detrended time series. - View Dependent Claims (16, 17)
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18. A method for assessing cardiac risks in a specific patent based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test, the windowed time series including ecotopic beats; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the aggregate power; wherein providing the heart activity data comprises;
identifying a peak exercise phase and a mid-recovery phase of the heart rate test;
determining instantaneous heart rate sequences for the peak exercise phase and the mid-recovery phase by ascertaining R-R intervals of an ECG waveform of the peak exercise phase and the mid-recovery phase;
providing uniform sample series of the instantaneous heart rate sequences by interpolating between adjacent beats at a uniform sample rate;
reducing the uniform sample series comprises filtering the uniform sample series through a selected band filter in a forward direction through at least a portion of the exercise period and a reverse direction through at least a portion of the recovery period to provide the heart rate variability waveform for a selected frequency band during the peak exercise phase and the mid-recovery phase, and/or determining an average of slopes of the mid-exercise and start-recovery phases. - View Dependent Claims (19)
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20. A method for assessing cardiac risks in a specific patent based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test, the windowed time series including ecotopic beats; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the aggregate power; wherein determining an aggregate power comprises performing a root-means-squared computation of corresponding filtered time series. - View Dependent Claims (21, 22)
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23. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on energy values of frequency bands of the heart rate variability in the windowed time series; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the frequency value and the aggregate power; wherein providing heart activity data comprises determining an instantaneous heart rate sequence from an ECG waveform obtained during an exercise period of increasing heart rate and a recovery period of decreasing heart rate, providing a uniform sample series of the instantaneous heart rate sequence, and reducing the uniform sample series to obtain a heart rate variability waveform associated with variances in the heart rate between beats in a desired frequency band. - View Dependent Claims (24, 25, 26)
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27. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on energy values of frequency bands of the heart rate variability in the windowed time series; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the frequency value and the aggregate power; wherein the energy values comprise a low frequency average power, a middle frequency average power, and a high frequency average power of the windowed time series, and wherein determining the frequency domain value comprises (a) fitting a line to the low frequency average power, the middle frequency average power, and the high frequency average power, and (b) determining a slope of the line to obtain a spectral slope, wherein the frequency domain value comprises the spectral slope. - View Dependent Claims (28)
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29. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on energy values of frequency bands of the heart rate variability in the windowed time series; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the frequency value and the aggregate power; wherein providing the heart activity data comprises;
identifying a peak exercise phase and a mid-recovery phase of the heart rate test;
determining instantaneous heart rate sequences for the peak exercise phase and the mid-recovery phase by ascertaining R-R intervals of an ECG waveform of the peak exercise phase and the mid-recovery phase;
providing uniform sample series of the instantaneous heart rate sequences by interpolating between adjacent beats at a uniform sample rate; and
reducing the uniform sample series by filtering the uniform sample series through a selected band filter in a forward direction through at least the exercise period and in a reverse direction through at least a portion of the recovery period to provide the heart rate variability waveform for selected frequencies during the peak exercise phase and the mid-recovery phase. - View Dependent Claims (30, 31)
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32. A method for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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providing heart activity data of a specific patient including a windowed time series related to heart rate variability during a heart rate test; determining a frequency domain value based on energy values of frequency bands of the heart rate variability in the windowed time series; determining an aggregate power for a frequency band of the windowed time series; and assessing the risk of a cardiac event based on the frequency value and the aggregate power; wherein determining an aggregate power comprises performing a root-means-squared calculation of a corresponding windowed time series. - View Dependent Claims (33, 34)
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35. An apparatus for assessing cardiac risks in a specific patient based on heart rate variability, comprising:
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at least one sensor configured to obtain cardiac signals from a specific patient; and a computer configured to receive the cardiac signals from the sensor, and the computer including a computer operable medium having instructions that cause the computer to (a) provide heart activity data of the specific patient including a windowed time series related to heart rate variability during a heart rate test, (b) determine a frequency domain value based on at least one of energy values of frequency bands and spectral slope(s) across selected frequency ranges of the heart activity data in the windowed time series, and (c) assess the risk of a cardiac event based on the frequency domain value; wherein the heart activity data comprises an instantaneous heart rate sequence from an ECG waveform obtained during an exercise period of increasing heart rate and a recovery period of decreasing heart rate, and the instructions cause the computer to provide a uniform sample series of the instantaneous heart rate sequence, and reduce the uniform sample series by filtering and/or detrending via fitting a polynomial function to the heart activity data across a selected time window to obtain a heart rate variability waveform associated with variances in the heart rate between beats in a desired frequency band.
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Specification