Method and device for motion and noise immunity in hemodynamic measurement

• US 7,364,550 B1
• Filed: 06/17/2004
• Issued: 04/29/2008
• Est. Priority Date: 06/17/2004
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Turcott, Robert G.
• Primary Examiner(s): Layno; Carl
• Assistant Examiner(s): Heller; Tammie K.
• Application Number:
  US10/872,165
• Time in Patent Office: 1,412 Days
• Field of Search: 600/526, 607/23
• US Class Current: 600/526
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A method and device, such as an implantable cardiac device, for motion and noise immunity in hemodynamic measurement is presented. The method includes obtaining a template waveform representing hemodynamic performance of a heart during a first hemodynamic state and obtaining an autocharacterization measure from an autocharacterization (e.g., autocorrelation) of the template waveform. The method further includes obtaining a test waveform during a second hemodynamic state, performing a cross-characterization (e.g., cross-correlation) of the template waveform and test waveform to identify a cross-characterization measure, and comparing the autocharacterization measure with the cross-characterization measure as a measurement of hemodynamic status of the second hemodynamic state. The device includes hardware and/or software for performing the described method.

Claims

1. A method of measuring hemodynamic performance of a patient'"'"'s heart, comprising:

obtaining a template waveform representing hemodynamic performance of the heart during a first hemodynamic state;

obtaining an autocharacterization of the template waveform;

identifying a measure from the autocharacterization;

obtaining a test waveform during a second hemodynamic state;

performing a cross-characterization of the template waveform and the test waveform to obtain a cross-characterization function;

identifying a measure from the cross-characterization function; and

measuring a hemodynamic status of the second hemodynamic state by comparing the autocharacterization measure with the cross-characterization measure.

2. The method of claim 1, wherein the performing step comprises performing a cross-correlation of the template waveform and the test waveform to obtain a cross-correlation function.

3. The method of claim 2, wherein the identifying the cross-characterization measure step comprises identifying a maximum value of the cross-correlation function.

4. The method of claim 3, wherein the obtaining an autocharacterization step comprises obtaining an autocorrelation of the template waveform.

5. The method of claim 4, wherein the identifying the autocharacterization measure step comprises identifying a maximum value from the autocorrelation.

6. The method of claim 5, wherein the measuring step comprises comparing a difference between the maximum autocorrelation value and the maximum cross-correlation function value against a predetermined threshold.

7. The method of claim 6, wherein the difference comparing step comprises determining if the maximum cross-correlation function value is less than the maximum autocorrelation value by a predetermined status low threshold, thereby determining if the hemodynamic status of the second hemodynamic state is low.

8. The method of claim 6, wherein the difference comparing step comprises determining if the maximum cross-correlation function value is greater than the maximum autocorrelation value by a predetermined status high threshold, thereby determining if the hemodynamic status of the second hemodynamic state is high.

9. The method of claim 1, wherein the obtaining a template waveform step comprises obtaining a template waveform representing hemodynamic performance of the heart during normal sinus heart rhythm.

10. The method of claim 9, wherein the obtaining a test waveform step comprises obtaining a test waveform during a tachycardia rhythm.

11. The method of claim 1, wherein the obtaining a template waveform step comprises obtaining a template waveform representing hemodynamic performance of the heart during heart pacing with a baseline atrioventricular (AV) delay.

12. The method of claim 11, wherein the obtaining a test waveform step comprises obtaining a test waveform during a test atrioventricular (AV) delay.

13. A device for measuring hemodynamic performance of a patient'"'"'s heart, comprising:

means for obtaining a template waveform representing hemodynamic performance of the heart during a first hemodynamic state;

means for obtaining an autocharacterization of the template waveform;

means for identifying a measure from the autocharacterization;

means for obtaining a test waveform during a second hemodynamic state;

means for performing a cross-characterization of the template waveform and the test waveform to obtain a cross-characterization function;

means for identifying a measure from the cross-characterization function; and

means for measuring a hemodynamic status of the second hemodynamic state by comparing the autocharacterization measure with the cross-characterization measure.

14. The device of claim 13, wherein:

the cross-characterization is a cross-correlation; and

the cross-characterization function is a cross-correlation function.

15. The device of claim 14, wherein the cross-characterization measure is a maximum value of the cross-correlation function.

16. The device of claim 15, wherein the autocharacterization is an autocorrelation.

17. The device of claim 16, wherein the autocharacterization measure is a maximum value of the autocorrelation.

18. The device of claim 17, wherein the means for measuring comprises means for comparing a difference between the maximum autocorrelation value and the maximum cross-correlation function value against a predetermined threshold.

19. The device of claim 18, wherein the difference comparing means comprises means for determining if the maximum cross-correlation function value is less than the maximum autocorrelation value by a predetermined status low threshold, wherein the determining means determines if the hemodynamic status of the second hemodynamic state is low.

20. The device of claim 18, wherein the difference comparing means comprises means for determining if the maximum cross-correlation function value is greater than the maximum autocorrelation value by a predetermined status high threshold, wherein the determining means determines if the hemodynamic status of the second hemodynamic state is high.