Electrocardiogram enhancement system and method

Claim 3

The method of claim 1 wherein said expanding of said electrocardiogram signal in the time scale comprises dividing the frequency of each frequency component by a time scale expansion factor.

Claim 4

The method of claim 2 wherein said time scale expansion factor is greater than one.

Claim 5

The method of claim 1 wherein said selectively amplifying said electrocardiogram signal comprises: selecting those frequency components of the electrocardiogram signal within a predetermined frequency range and greater than a minimum amplitude value indicative of notches; and multiplying each of the selected frequency components by an amplification factor.

Claim 6

The method of claim 4 wherein said frequency range is greater than 100 up to and including 1200 Hz.

Claim 7

The method of claim 4 wherein said minimum amplitude value is determined to exclude high frequency signal noise.

Claim 8

The method of claim 6 wherein said minimum amplitude value is greater than 5% of the peak amplitude of notch frequency components.

Claim 9

The method of claim 4 wherein the amplification factor is equal to the ratio of a peak amplitude of non-notch frequency components to a peak amplitude of the notch frequency components multiplied by a gain factor.

Claim 10

The method of claim 8 where the gain factor ranges from a value greater than zero up to one.

Claim 11

The method of claim 1 further comprising: generating a Fourier transform of the electrocardiogram signal to obtain a frequency spectrum comprising the frequency components representing the electrocardiogram signal; and generating an inverse Fourier transform of the frequency spectrum after selectively amplifying and expanding the frequency component of the signal.

Claim 12

The method of claim 1 further comprising the step of accurately recording the expanded signal and displaying the high frequency, low amplitude notches.

Claim 15

The method of claim 12 wherein said time scale expansion factor is greater than one.

Claim 16

The method of claim 12 wherein said amplification factor is a value equal to the ratio of a peak amplitude of non-notch frequency components to a peak amplitude of the notch frequency components multiplied by a gain factor.

Claim 17

The method of claim 14 wherein said gain factor ranges from a value greater than zero up to one.

Claim 18

The method of claim 12 wherein said frequency range is greater than 100 up to and including 1200 Hz.

Claim 19

The method of claim 12 wherein said minimum amplitude value is determined to exclude high frequency signal noise.

Claim 20

The method of claim 17 wherein said minimum amplitude value is greater than 5% of the peak value of the notch frequency components.

Claim 21

The method of claim 12 further comprising the step of accurately recording the enhanced electrocardiogram waveform and displaying the high frequency, low amplitude notches.

Claim 22

Apparatus for enhancing an electrocardiogram signal having high frequency, low amplitude notches that are difficult to visually detect within an electrocardiogram signal waveform and that have frequencies above the signal recording bandwidth of a conventional chart recorder, said signal having a plurality of frequency components, each frequency component having a frequency, phase and amplitude, the frequencies of the frequency components comprising a first inter-component frequency relationship and the phases of the frequency components comprising a first inter-component phase relationship, said apparatus comprising: means for selectively amplifying frequency components representing the notches relative to other frequency components in the electrocardiogram signal; and means for expanding said electrocardiogram signal including the amplified frequency components in time scale by a time scale expansion factor, frequency components representing said expanded signal having a second inter-component frequency relationship and second inter-component phase relationship equivalent to said first inter-component frequency relationship and first inter-component phase relationship, said expanded signal being within the bandwidth of a conventional chart recorder, whereby the expanded signal is accurately recorded, and the high frequency, low amplitude notches are made visible

Claim 23

Apparatus for enhancing an electrocardiogram signal having high frequency, low amplitude notches that are difficult to visually detect within an electrocardiogram signal waveform and that have frequencies above the signal recording bandwidth of a conventional chart recorder, said signal having a plurality of frequency components, each frequency component having a frequency, phase and amplitude, the frequencies of the frequency components comprising a first inter-component frequency relationship and the phases of the frequency components comprising a first inter-component phase relationship, said apparatus comprising: means for selectively amplifying frequency components representing the notches relative to other frequency components in the electrocardiogram signal; and means for expanding said electrocardiogram signal including the amplified frequency components in time scale by a time scale expansion factor, frequency components representing said expanded signal having a second inter-component frequency relationship and second inter-component phase relationship equivalent to said first inter-component frequency relationship and first inter-component phase relationship, said expanded signal being within the bandwidth of a conventional chart recorder, whereby the expanded signal is accurately recorded, and the high frequency, low amplitude notches are made visible

Claim 24

The apparatus of claim 20 wherein the means for expanding said electrocardiogram signal in the time scale comprises a means for dividing the frequency of each frequency component by a time scale expansion factor.

Claim 25

The apparatus of claim 21 wherein said time scale expansion factor is greater than one.

Claim 26

The apparatus of claim 20 wherein the means for selectively amplifying said electrocardiogram signal comprises: means for selecting frequency components within a predetermined frequency range and greater than a minimum amplitude value indicative of notches; and means for amplifying each of the selected frequency components by an amplification factor.

Claim 27

The apparatus of claim 23 wherein said frequency range is greater than 100 up to and including 1200 Hz.

Claim 28

The apparatus of claim 23 wherein said amplitude range excludes high frequency signal noise.

Claim 29

The apparatus of claim 25 wherein said minimum amplitude value is equal to 5% of the peak value of the notch frequency components.

Claim 30

The apparatus of claim 23 wherein said amplification factor is equal to the ratio of a peak amplitude of non-notch frequency components to a peak amplitude of the notch frequency components multiplied by a gain factor.

Claim 31

The apparatus of claim 27 wherein said gain factor ranges from a value greater than zero up to one.

Claim 32

The apparatus of claim 20 further comprising: means for generating a Fourier transform of the electrocardiogram signal to obtain a frequency spectrum comprising the frequency components representing the electrocardiogram signal; and means for generating an inverse Fourier transform of the frequency spectrum after selectively amplifying and expanding in the time scale the frequency components of the signal.

Claim 33

The apparatus of claim 29 wherein the means for generating a Fourier transform, means for selectively amplifying, means for expanding and means for generating an inverse Fourier transform comprises a microprocessor.

Claim 34

The apparatus of claim 20 further comprising a means for counting the high frequency notches and a means for displaying said count of notches.

Claim 35

The apparatus of claim 31 wherein the means for counting the notches comprises: means for detecting the beginning and end of a QRS wave of the electrocardiogram signal waveform; means for calculating the slope of the waveform at a first test point; means for calculating the slope of the waveform at a second subsequent test point, said second test point being a predetermined time period after said first test point; means for comparing the slopes of said first and second test points; means for incrementing a notch counter if the signs of said slopes of said test points are not equal; means for setting said first test point equal to said second test point wherein the means for calculating the slope of the waveform at the second test point, means for comparing the slopes of said first and second test points and means for incrementing said notch counter continue to operate to sequence until the end of the QRS wave is detected.

Claim 36

The apparatus of claim 31 wherein the means for counting the notches comprises: a threshold detector which generates an output pulse upon detection of those notches of a predetermined minimum amplitude; means for inputting selected frequency components indicative of notches to the threshold detector; and a digital counter which counts the output pulses of the threshold detector.

Claim 37

The apparatus of claim 20 further comprising a chart recording device for the display of said expanded signal whereby the electrocardiogram signal is accurately recorded and the high frequency, low amplitude notches are visible in the displayed signal.

Claim 38

The apparatus of claim 20 further comprising means for accurately recording the expanded signal and means for displaying the high frequency, low amplitude notches.

Claim 39

Apparatus for enhancing an electrocardiogram signal in a first frequency range having high frequency, low amplitude notches that are difficult to visually detect and analyze within a electrocardiogram signal waveform and that have frequencies above the signal recording bandwidth of a conventional chart recorder comprising: means for performing a Fourier transform operation upon the electrocardiogram signal whereby a frequency spectrum signal is obtained, said frequency spectrum signal comprising frequency components having an amplitude, frequency, and phase, the frequencies of the frequency components comprising a first inter-component frequency relationship and the phases of the frequency components comprising a first inter-component phase relationship; means for selecting frequency components within a predetermined frequency range and greater than a minimum amplitude value that are indicative of notches; means for amplifying each of the selected frequency components by an amplification factor; means for expanding the frequency spectrum in time scale by dividing each frequency component by a time scale expansion factor, frequency components having a second inter-component frequency relationship and a second inter-component phase relationship equivalent to said first inter-component frequency relationship and first inter-component phase relationship; means for performing an inverse Fourier transform operation upon the expanded frequency spectrum signal to obtain an enhanced electrocardiogram signal, said enhanced electrocardiogram signal having a frequency range within the bandwidth of conventional chart recorders; and chart recording means for display of the expanded signal where in the high frequency, low amplitude notches are visible within the displayed signal.

Claim 40

Apparatus for enhancing an electrocardiogram signal in a first frequency range having high frequency, low amplitude notches that are difficult to visually detect and analyze within a electrocardiogram signal waveform and that have frequencies above the signal recording bandwidth of a conventional chart recorder comprising: means for performing a Fourier transform operation upon the electrocardiogram signal whereby a frequency spectrum signal is obtained, said frequency spectrum signal comprising frequency components having an amplitude, frequency, and phase, the frequencies of the frequency components comprising a first inter-component frequency relationship and the phases of the frequency components comprising a first inter-component phase relationship; means for selecting frequency components within a predetermined frequency range and greater than a minimum amplitude value that are indicative of notches; means for amplifying each of the selected frequency components by an amplification factor; means for expanding the frequency spectrum in time scale by dividing each frequency component by a time scale expansion factor, frequency components having a second inter-component frequency relationship and a second inter-component phase relationship equivalent to said first inter-component frequency relationship and first inter-component phase relationship; means for performing an inverse Fourier transform operation upon the expanded frequency spectrum signal to obtain an enhanced electrocardiogram signal, said enhanced electrocardiogram signal having a frequency range within the bandwidth of conventional chart recorders; and chart recording means for display of the expanded signal where in the high frequency, low amplitude notches are visible within the displayed signal.

Claim 41

The apparatus of claim 36 wherein the means for performing a Fourier transform, means for selecting frequency components, means for amplifying the selected frequency components, means for expanding the frequency spectrum and means for performing an inverse Fourier transform comprises a microprocessor.

Claim 42

The apparatus of claim 36 wherein said time scale expansion factor is greater than one.

Claim 43

The apparatus of claim 36 wherein said amplification factor is equal to the ratio of a peak amplitude of non-notch frequency components to a peak amplitude of the notch frequency components multiplied by a gain factor.

Claim 44

The apparatus of claim 39 wherein said gain factor ranges from a value greater than zero up to one.

Claim 45

The apparatus of claim 36 wherein said frequency range is greater than 100 up to and including 1200 Hz.

Claim 46

The apparatus of claim 36 wherein said minimum amplitude value excludes high frequency signal noise.

Claim 47

The apparatus of claim 42 wherein said minimum amplitude value is 5% of the peak value of the notch frequency components.

Claim 50

The method for enhancing an electrocardiogram signal of claim 44 wherein said frequencies of the frequency components of the electrocardiogram signal comprise a first inter-component relationship and the phases of the frequency components comprise a first inter-component phase relationship and frequencies of the frequency components of the expanded signal comprise a second inter-component frequency relationship equivalent to said first inter-component frequency relationship and the phases of the frequency components comprise a second inter-component phase relationship equivalent to said first inter-component phase relationship.

Claim 51

The method for enhancing an electrocardiogram signal of claim 44 further comprising: generating a Fourier transform of the electrocardiogram signal to obtain a frequency spectrum comprising the frequency components representing the electrocardiogram signal; and generating an inverse Fourier transform of the frequency spectrum after amplifying and expanding the signal.

Claim 52

The method of claim 44 further comprising displaying the high frequency, low amplitude notches.

Claim 53

Apparatus for enhancing an electrocardiogram signal having high frequency, low amplitude notches that have frequencies above 100 Hz and are above the signal recording bandwidth of a conventional chart recorder and difficult to visually detect within an electrocardiogram signal waveform, said signal being within a first frequency range and having a plurality of frequency components, each frequency component having a frequency, phase and amplitude, said apparatus comprising: means for amplifying the frequency components above 100 Hz relative to other frequency components in the electrocardiogram signal by an amplification factor; and means for expanding said electrocardiogram signal including the amplified frequency components in time scale by a time scale expansion factor to produce an expanded signal, said expanded signal having frequency components in which the frequencies are those of the frequency components of the electrocardiogram signal divided by the time scale expansion factor, said expanded signal having a frequency range within the bandwidth of a conventional chart recorder.

Claim 54

Apparatus for enhancing an electrocardiogram signal having high frequency, low amplitude notches that have frequencies above 100 Hz and are above the signal recording bandwidth of a conventional chart recorder and difficult to visually detect within an electrocardiogram signal waveform, said signal being within a first frequency range and having a plurality of frequency components, each frequency component having a frequency, phase and amplitude, said apparatus comprising: means for amplifying the frequency components above 100 Hz relative to other frequency components in the electrocardiogram signal by an amplification factor; and means for expanding said electrocardiogram signal including the amplified frequency components in time scale by a time scale expansion factor to produce an expanded signal, said expanded signal having frequency components in which the frequencies are those of the frequency components of the electrocardiogram signal divided by the time scale expansion factor, said expanded signal having a frequency range within the bandwidth of a conventional chart recorder.

Claim 55

The apparatus of claim 48 wherein said frequencies of the frequency components of the electrocardiogram signal comprise a first inter-component frequency relationship and the phases of the frequency components comprise a first inter-component phase relationship and frequencies of the frequency components of the expanded signal comprise a second inter-component frequency relationship equivalent to said first inter-component frequency relationship and the phases oaf the frequency components comprise a second inter-component phase relationship equivalent to said first inter-component phase relationship.

Claim 56

The apparatus of claim 48 further comprising: means for generating a Fourier transform of the electrocardiogram signal to obtain a frequency spectrum comprising frequency components representing the electrocardiogram signal; and means for generating an inverse Fourier transform of the frequency spectrum after amplifying and expanding the signal.

Claim 57

The apparatus of claim 48 further comprising a chart recording device for the display of said expanded signal whereby the electrocardiogram signal is accurately recorded and the high frequency, low amplitude notches are visible in the displayed signal.

Claim 58

The apparatus of claim 48 further comprising means for displaying the high frequency, low amplitude notches.