Arrhythmia detecting apparatus

• US 6,095,984 A
• Filed: 04/06/1998
• Issued: 08/01/2000
• Est. Priority Date: 04/17/1996
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Amano, Kazuhiko, Ishiyama, Hitoshi, Uebaba, Kazuo
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US08/981,349
• Time in Patent Office: 848 Days
• Field of Search: 600/515, 600/513, 600/500, 600/509, 600/481
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7253 characterised by using transforms
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The arrhythmia detecting apparatus of the present invention is provided with a pulse wave detecting means which non-invasively detects the pulse waveform, and an arrhythmia detecting means which detects arrhythmia by monitoring changes in the pulse waveform detected by the pulse wave detecting means. The arrhythmia detection means has a decision element which determines that arrhythmia has occurred when there is an interruption in the continuity of this change. Methods employed for investigating the continuity of change in the pulse waveform include a time domain method employing pulse wave interval values, and a frequency domain method in which frequency analysis (FFT or wavelet transformation) is carried out on the pulse waveform, with continuity studied based on the results of this analysis. As a result of this design, it is possible to detect arrhythmia by means of a simpler structure and easier operations as compared to an electrocardiogram and so on. Further, it is also acceptable to provide a body motion detecting means, and to determine continuity of change for a pulse wave component after the body motion component detected by the aforementioned means has been removed therefrom. In this case, since it is possible to remove the body motion component from the pulse waveform, arrhythmia can be detected even more accurately throughout the course of daily activities.

Claims

1. An arrhythmia detecting apparatus comprising:

a pulse wave detecting means which non-invasively detects the pulse waveform in the body;

a body motion component excluding means which excludes the only influence of the body motion from the pulse waveform detected by said pulse wave detecting means; and

a notifying means which provides notice of information showing the pure pulse waveform obtained after the only influence of the body motion has been excluded by said body motion component excluding means.

2. An arrhythmia detecting apparatus according to claim 1, further comprising:

body motion detecting means which detects motion of the body and outputs a body motion waveform; and

wherein said body motion component excluding means excludes the only influence of the body motion specified by said body motion waveform from the pulse waveform detected by said pulse wave detecting means.

35. An arrhythmia detecting apparatus according to claim 1, wherein said pulse wave detecting means comprises a pressure pulse wave sensor which uses pressure to detect the arterial pulse in the body.

36. An arrhythmia detecting apparatus according to claim 1, wherein said pulse wave detecting means receives reflected light obtained when the detection site on the body is irradiated with light having a wavelength of 300 to 700 nm, and detects the received light signal as a pulse waveform.

37. An arrhythmia detecting apparatus according to claim 1, wherein said pulse wave detecting means receives transmitted light obtained when the detection site on the body is irradiated with light having a wavelength of 600 to 1000 nm, and detects the received light signal as the pulse waveform.

3. An arrhythmia detecting apparatus comprising:

a pulse wave detecting means which non-invasively detects the pulse waveform in the body;

a body motion component excluding means which excludes the body motion component from the pulse waveform detected by said pulse wave detecting means;

an arrhythmia detecting means which detects arrhythmia by monitoring changes in the pure pulse waveform obtained after the body motion component has been excluded by said body motion component excluding means; and

a notifying means which provides notice of the results of detection by said arrhythmia detecting means.

4. An arrhythmia detecting apparatus according to claim 3, further comprising:

body motion detecting means which detects body motion and outputs a body motion waveform;

a reference value deciding means which obtains a representative value for the interval between pulse waves which compose said pulse waveform during the interval for determining a reference value, and sets said representative value as the reference value for the pulse wave interval; and

a comparing means which obtains an interval value with respect to the pulse waveform detected by said pulse wave detecting means, and determines the difference between said interval value and said reference value;

wherein,

said body motion component excluding means supplies the pulse waveform detected by said pulse wave detecting means to said comparing means only in the case where a body motion waveform is not output from said body motion detecting means; and

said notifying means provides notice of the difference obtained by said comparing means.

5. An arrhythmia detecting apparatus according to claim 3, further comprising:

body motion detecting means which detects body motion and outputs a body motion waveform;

a reference value deciding means which obtains a representative value for the interval between pulse waves which compose said pulse waveform during the interval for determining the reference value, and sets said representative value as the reference value for the pulse wave interval;

a comparing means which obtains the interval with respect to the pulse waveform detected by said pulse wave detecting means, and obtains the difference between said interval value and said reference value; and

a deciding means which determines that arrhythmia has occurred when said difference obtained by said comparing means is outside a prespecified range;

wherein,

said body motion component excluding means supplies the pulse waveform detected by said pulse wave detecting means to said comparing means only in the case where a body motion waveform is not output from said body motion detecting means; and

said notifying means provides notice of the result of determination by said deciding means.

6. An arrhythmia detecting apparatus according to claim 4, wherein said arrhythmia detecting means has a reference value updating means which updates said reference value using said intervals, in the case where the difference obtained by said comparing means for two continuous pulse wave intervals is within a prespecified range.

7. An arrhythmia detecting apparatus according to claim 3, wherein:

said arrhythmia detecting means has a frequency analysis means which carries out frequency analysis on the pulse waveform detected by said pulse wave detecting means;

said body motion component excluding means excludes the body motion component from the frequency analysis results obtained from said frequency analysis means; and

said arrhythmia detecting means detects arrhythmia using said frequency analysis results from which the body motion component has been excluded by said body motion component excluding means.

8. An arrhythmia detecting apparatus according to claim 7, wherein:

said arrhythmia detecting means has a body motion constancy deciding means which determines the presence or absence of constancy in body motion based on the body motion waveform output from said body motion detecting means; and

said arrhythmia detecting means detects arrhythmia based on the results of frequency analysis by said frequency analysis means, only in the case where said body motion constancy deciding means has determined that constancy is present in body motion.

9. An arrhythmia detecting apparatus according to claim 7, wherein:

said arrhythmia detecting means employs a Fourier transform means as said frequency analysis means, said Fourier transform means carrying out Fast Fourier transform to the pulse waveform detected by said pulse wave detecting means.

10. An arrhythmia detecting apparatus according to claim 9, wherein:

said arrhythmia detecting means has a range estimating means which estimates the appropriate range of variation in the beat frequency; and

a determination is made that arrhythmia has occurred in the case where a frequency spectral line projecting into the range of variation estimated by said range estimating means is not present in the frequency analysis results of said Fourier transform means.

11. An arrhythmia detecting apparatus according to claim 9, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said arrhythmia detecting means has said Fourier transform means as a first Fourier transform means, and a second Fourier transform means which carries out Fast Fourier transform to the body motion waveform detected by said body motion detecting means;

said body motion component excluding means subtracts the results of said second Fourier transform from the results of analysis by said first Fourier transform means; and

said arrhythmia detecting means detects arrhythmia using the results of the subtraction operation by said body motion component excluding means.

12. An arrhythmia detecting apparatus according to claim 9, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said arrhythmia detecting means includes said Fourier transform means as a first Fourier transform means, and a second Fourier transform means which carries out Fast Fourier transform to said body motion waveform detected by said body motion detecting means;

said body motion component excluding means obtains the frequency component corresponding to body motion from the results of frequency analysis by said second Fourier transform means, and excludes said frequency component from the frequency analysis results of said first Fourier transform; and

said arrhythmia detecting means detects arrhythmia using the frequency analysis results from which the frequency component corresponding to body motion has been excluded by said body motion component excluding means.

13. An arrhythmia detecting apparatus according to claim 7, wherein:

said arrhythmia detecting means employs a wavelet transforming means for said frequency analysis means, the wavelet transforming means carrying out wavelet transformation to the pulse waveform detected by said pulse wave detecting means, and generating pulse wave analysis data at each frequency region; and

a determination is made that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of said pulse wave analysis data in each frequency region.

14. An arrhythmia detecting apparatus according to claim 13, wherein said arrhythmia detecting means has a frequency correcting means which carries out correction of said pulse wave analysis data based on each of the corresponding frequencies, so that the power density per frequency becomes constant, and generates corrected pulse wave data;

wherein, a determination is made that arrhythmia has occurred when an anomalous portion is detected by analysis of the continuity of said corrected pulse wave data in each frequency region.

15. An arrhythmia detecting apparatus according to claim 13, further comprising body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said arrhythmia detecting means is provided with said wavelet transforming means as said first wavelet transforming means, and a second wavelet transforming means which carries out wavelet transformation to said body motion pulse wave detected by said body motion detecting means, and generates body motion analysis data at each frequency region;

said body motion component excluding means has a mask means which subtracts said body motion analysis data from said pulse wave analysis data and generates pulse wave analysis data from which body motion has been removed; and

said arrhythmia detecting means determines that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of said pulse wave analysis data generated by said mask means in each frequency region.

16. An arrhythmia detecting apparatus according to claim 13, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform; and

wherein said arrhythmia detecting means includes;

said wavelet transforming means as a first wavelet transforming means;

a frequency correcting means which carries out correction of the pulse wave analysis data based on each of the corresponding frequencies, so that the power density per frequency becomes constant;

a second wavelet transforming means which carries out wavelet transformation to the body motion waveform detected by said body motion detecting means, and generates body motion analysis data for each frequency region;

a second frequency correcting means which carries out correction of said body motion analysis data based on each of the corresponding frequencies, so that the power density per frequency becomes constant, and generates corrected body motion data; and

said body motion component excluding means has a mask means which subtracts said corrected body motion data from said corrected pulse wave data, and generates corrected pulse wave data from which body motion has been excluded;

said arrhythmia detecting means determining that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of said corrected pulse wave data generated by said mask means in each frequency region.

17. An arrhythmia detecting apparatus according to claim 13, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said arrhythmia detecting means includes said wavelet transforming means as a first wavelet transforming means, and a second wavelet transforming means which carries out wavelet transformation of the body motion waveform detected by said body motion detecting means, and generates body motion analysis data in each frequency region;

said body motion component excluding means has a mask means which subtracts said body motion analysis data from said pulse wave analysis data and generates at each frequency region pulse wave data from which body motion has been excluded; and

said arrhythmia detecting means has a frequency correcting means which carries out correction of said pulse wave data based on each of the corresponding frequencies, so that the power density per frequency becomes constant, and generates corrected pulse wave data;

said arrhythmia detecting means making a determination that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of said corrected pulse wave data generated by said mask means at each frequency region.

18. An arrhythmia detecting apparatus according to claim 13, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said body motion component excluding means generates pulse wave data after excluding frequency components corresponding to body motion from among the pulse wave analysis data; and

said arrhythmia detecting means determines that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of the pulse wave data in each frequency region.

19. An arrhythmia detecting apparatus according to claim 13, further comprising:

body motion detecting means which detects the motion of the body and outputs a body motion waveform;

wherein,

said arrhythmia detecting means includes a frequency correcting means which carries out correction of the pulse wave analysis data based on each of the corresponding frequencies, so that the power density per frequency becomes constant, and generates corrected pulse wave data;

said body motion component excluding means generates pulse wave data after excluding frequency components corresponding to body motion from among said corrected pulse wave data; and

said arrhythmia detecting means makes a determination that arrhythmia has occurred when an anomalous portion is detected by analyzing the continuity of the pulse wave data in each frequency region.

20. An arrhythmia detecting apparatus according to claim 13, wherein said arrhythmia detecting means includes:

a pulse wave period detecting means which detects the period of the pulse waveform; and

wherein

said wavelet transforming means carries out wavelet transformation in synchronization with said detected period.

21. An arrhythmia detecting apparatus according to claim 15 wherein:

said arrhythmia detecting means includes a pulse wave period detecting means which detects the period of said pulse waveform; and

said first wavelet transforming means and said second wavelet transforming means carry out wavelet transformation in synchronization with said detected period.

22. An arrhythmia detecting apparatus according to claim 3 further comprising a recording means which records the time at which an arrhythmia event is detected by said arrhythmia detecting means.

23. An arrhythmia detecting apparatus according to claim 22, wherein notice is provided of information which has been related to the arrhythmia event time stored in said recording means.

24. An arrhythmia detecting apparatus according to claim 22, wherein notice is provided after associating information related to an arrhythmia event time stored in said recording means with physiological rhythms in the body, and rendering said information into a graph.

25. An arrhythmia detecting apparatus according to claim 3 further comprising a frequency calculating means which calculates the number of times that a determination of arrhythmia is made by said arrhythmia detecting means during a prespecified period of time, as arrhythmia frequency information.

26. An arrhythmia detecting apparatus according to claim 25, further comprising a second notifying means which provides notice when said arrhythmia frequency information exceeds a specific value determined in advance.

27. An arrhythmia detecting apparatus according to claim 3 further comprising a summing means which sums the number of times that an arrhythmia determination was made by said arrhythmia detecting means, and generates arrhythmia sum information.

28. An arrhythmia detecting apparatus according to claim 27, further comprising a third notifying means which provides notice when said arrhythmia sum information exceeds a specific value determined in advance.

29. An arrhythmia detecting apparatus according to claim 3 further comprising:

a frequency calculating means which calculates the number of times that a determination of arrhythmia is made by said arrhythmia detecting means during a specific period of time, as arrhythmia frequency information; and

a summing means which sums the number of times that an arrhythmia determination was made by said arrhythmia detecting means, and generates arrhythmia sum information.

30. An arrhythmia detecting apparatus according to claim 3 further comprising:

a frequency calculating means which calculates the number of times that a determination of arrhythmia is made by said arrhythmia detecting means during a specific period of time, as arrhythmia frequency information; and

a summing means which sums the number of times that an arrhythmia determination was made by said arrhythmia detecting means, and generates arrhythmia sum information; and

a fourth notifying means which provides notice when both said arrhythmia frequency information and said arrhythmia sum information exceed the respective specific values determined in advance therefor.

31. An arrhythmia detecting apparatus according to claim 25, wherein notice is provided of said arrhythmia frequency information.

32. An arrhythmia detecting apparatus according to claim 27, wherein notice is provided of said sum information.

33. An arrhythmia detecting apparatus according to claim 29, wherein notice is provided of said arrhythmia frequency information and said sum information.

34. An arrhythmia detecting apparatus according to claim 3, wherein arrhythmia detecting processing and various notice processing may be carried out in parallel by the arrhythmia detecting means.