METHOD AND SYSTEM FOR CARDIOVASCULAR SYSTEM DIAGNOSIS

• US 20090076399A1
• Filed: 08/19/2008
• Published: 03/19/2009
• Est. Priority Date: 01/27/2004
• Status: Active Grant

• Current Assignee: Spirocor Ltd.
• Original Assignee: Spirocor Ltd.
• Inventors: Tal, Yoram, Arbel, Ronen, Ortenberg, Michael
• Granted Patent: US 7,771,364 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• 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 of computing a respiratory stress response (RSR) indicator comprising:

obtaining pulse wave signals of a cardiovascular system during a rest state and during a periodic excitation state of said cardiovascular system;

computing a power spectrum representation of at least some of said pulse wave signals;

defining a plurality of regions associated with said power spectrum representation; and

computing at least one respiratory stress response (RSR) indicator by relating a first parameter associated with a first subset of said regions to a second parameter associated with a second subset of said regions.

2. The method of claim 1, wherein relating the first parameter to the second parameter includes dividing the first parameter by the second parameter.

3. The method of claim 1, wherein said first parameter and said second parameter are areas associated with said first and second subsets of regions, respectively.

4. The method of claim 1, wherein said regions are defined according to respective frequency ranges.

5. The method of claim 1, wherein said regions are defined according to respective relative intensities of said power spectrum representation.

6. The method of claim 1,

wherein defining said plurality of regions comprises:

defining a first region of said power spectrum wherein said first region is delimited by a first frequency, a second frequency, and a predefined minimum value of a relative intensity of said power spectrum, and

defining a second region of said power spectrum wherein said second region is delimited by the first frequency, the second frequency, and a predefined maximum value of a relative intensity of said power spectrum; and

wherein computing said RSR indicator comprises dividing an area of said first region by an area of said second region.

7. The method of claim 6,

wherein defining said plurality of regions further comprises defining a third region of said power spectrum, wherein said third region is delimited by said second frequency and by a third frequency, wherein said third frequency is greater than said second frequency;

and

wherein computing said RSR indicator comprises dividing the area of said first region by the area of said third region.

8. The method of claim 7,

wherein defining said plurality of regions further comprises defining a fourth region of said power spectrum wherein said fourth region is delimited by said first frequency and by a fourth frequency, wherein said fourth frequency is smaller than said first frequency;

and

wherein computing said RSR indicator comprises dividing the area of said first region by the area of said fourth region.

9. The method of claim 8, further comprising computing said RSR indicator by dividing an area of said first region by a sum of areas of said third region and said fourth region.

10. The method of claim 8, further comprising computing said RSR indicator by dividing an area of said first region by a sum of areas of said second region, said third region and said fourth region.

11. The method of claim 8, further comprising computing said RSR indicator by dividing a sum of areas of said first region and said second region by a sum of areas of said third region and said fourth region.

12. The method of claim 8,

wherein defining said plurality of regions further comprises defining a fifth region of said power spectrum, wherein said fifth region is delimited by said fourth frequency and by a fifth frequency, wherein said fifth frequency is lower than said fourth frequency;

and

wherein computing said RSR indicator comprises dividing a sum of areas of said first region and said second region by a sum of areas of said third region, said fourth region and said fifth region.

13. The method of claim 12, further comprising computing said RSR indicator by dividing an area of said first region by a sum of areas of said second region, said third region, said fourth region and said fifth region.

14. The method of claim 2, wherein said first parameter is a relative intensity associated with a peak in a first region and wherein said second parameter is a relative intensity associated with a peak in a second region.

15. The method of claim 1, wherein the periodic excitation of the cardiovascular system is achieved by periodically applying pressure to an eyeball of the subject associated with the cardiovascular system.

16. The method of claim 1, wherein the periodic excitation of the cardiovascular system is achieved by periodically contracting extraocular muscles of the subject associated with the cardiovascular system.

17. The method of claim 1, wherein the periodic excitation of the cardiovascular system is achieved by periodically performing a Valsalva manoeuvre.

18. The method of claim 1, wherein the periodic excitation of the cardiovascular system is achieved by periodically performing a Muller manoeuvre.