Method and system for cardiovascular system diagnosis

• US 20080045844A1
• Filed: 08/21/2007
• Published: 02/21/2008
• Est. Priority Date: 01/27/2004
• Status: Abandoned Application

• Current Assignee: Spirocor Ltd.
• Original Assignee: Spirocor Ltd.
• Inventors: Tal, Yoram, Arbel, Ronen, Ortenberg, Michael
• Application Number:
  US11/892,256
• Publication Number:
  US 20080045844A1
• Time in Patent Office: Days
• US Class Current: 600/484
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The present invention is directed to a method and system for monitoring function and/or diagnosing dysfunction of the cardiovascular system of a human subject. The method comprise measuring pulse wave signals of the subject during rapid excitation of the cardiovascular system, analyzing the measured signals and computing indicators reflecting a response to said excitation. The cardiovascular excitation preferably comprise a controlled breathing protocol characterized by a predefined frequency of breaths (e.g., about 0.1 Hz).

Claims

1. A method for monitoring function and/or diagnosing dysfunction of the cardiovascular system of a subject, comprising

obtaining pulse wave signals of said subject during periodic excitation of said cardiovascular system;

analyzing frequency components of said signals; and

computing based on said frequency components an indicator reflecting a cardiovascular response to said periodic excitation.

2. The method of claim 1, wherein obtaining said pulse wave signals comprises obtaining pulse wave signals of the subject at rest-state and during excitation of the cardiovascular system.

3. The method of claim 1, wherein analyzing said signals comprises comparing the pulse wave signals obtained at the rest-state to the pulse wave signals obtained during the excitation.

4. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of a periodic physical drill.

5. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of a facilitated periodic movement.

6. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of a periodic visual stimulation.

7. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of a periodic auditory stimulation.

8. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of a periodic pressure application.

9. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of periodic heating.

10. The method of claim 1, wherein the periodic excitation of the cardiovascular system is provided by the use of periodic cooling.

11. A method for computing a cardiovascular system indicator of a subject comprising:

obtaining measurements of a sequence of breath signals and a corresponding sequence of pulse wave signals;

computing a period of said breath signals based on time between consecutive breaths taken by said subject;

locating within the period of any of said consecutive breaths a predefined number of consecutive breaths having a variation in conjoint mean period of less than a predefined value;

calculating a frequency of said conjoint mean period; and

computing a respiratory modulation response indicator around said calculated frequency.

12. The method of claim 11, wherein obtaining said measurement of a sequence of pulse wave signals comprises obtaining measurement of pulse wave signals of the subject at rest-state.

13. The method of claim 11, wherein obtaining said measurement of a sequence of pulse wave signals comprises obtaining measurement of pulse wave signals during periodic excitation of the cardiovascular system of the subject.

14. The method of claim 13, further comprising using a periodic physical drill to provide periodic excitation of the cardiovascular system.

15. The method of claim 13, further comprising using a facilitated periodic movement to provide periodic excitation of the cardiovascular system.

16. The method of claim 13, further comprising using a periodic visual stimulation to provide periodic excitation of the cardiovascular system.

17. The method of claim 13, further comprising using a periodic auditory stimulation to provide periodic excitation of the cardiovascular system.

18. The method of claim 13, further comprising using a periodic pressure application to provide periodic excitation of the cardiovascular system.

19. The method of claim 13, further comprising using periodic heating to provide periodic excitation of the cardiovascular system.

20. The method of claim 13, further comprising using periodic cooling to provide periodic excitation of the cardiovascular system.

21. The method of claim 11, wherein computing a respiratory modulation response indicator comprises comparing the pulse wave signals obtained at the rest-state to the pulse wave signals obtained during the periodic excitation.

22. A method for validating proper execution of a breathing protocol by a subject comprising:

obtaining a pulse wave signal of the subject, at least part of said pulse wave signal being acquired during performance of a breathing protocol executed by said subject;

computing a beat rate waveform corresponding to said pulse wave signal;

computing a first power spectrum corresponding to said beat rate waveform; and

determining whether said first power spectrum includes a first power peak, wherein said first power peak is bounded by a predefined first frequency range.

23. The method of claim 22, further comprising:

computing a second power spectrum of said pulse wave signal; and

determining whether said second power spectrum includes a second power peak, wherein said second power peak is bounded by a predefined second frequency range.

24. The method of claim 23, wherein a difference between said first frequency range and said second frequency range, is less than a predefined value.

25. The method of claim 22, wherein locating a power peak comprises locating a power value corresponding to a predefined frequency range, wherein said power value is greater by at least a predefined factor from any other power value corresponding to said frequency range.

26. The method of claim 23 where in said first power peak and said second power peak correspond to a common frequency range.

27. A method for computing a respiratory modulation response (RMR) indicator comprising:

obtaining a pulse wave signal of a subject;

computing a power spectrum corresponding to said pulse wave signal;

locating one or more power peaks in said power spectrum, wherein said power peaks correspond to harmonic frequencies of a predefined frequency;

computing at least one respiratory modulation response (RMR) indicator corresponding to a respective at least one of said power peaks; and

computing a conjoint RMR indicator corresponding to said at least one RMR indicators.

28. The method of claim 27, wherein at least part of said pulse wave signal is acquired during a controlled excitation of a cardiovascular system of said subject.

29. The method of claim 27, wherein computing said conjoint RMR indicator comprises computing a parameter corresponding to said plurality of RMR indicators, wherein said parameter is selected from a list consisting of:

an average, a weighted average, a mean, a midrange, a median and a mode.