Method and device for motion and noise immunity in hemodynamic measurement

• US 8,540,643 B1
• Filed: 02/29/2008
• Issued: 09/24/2013
• Est. Priority Date: 06/17/2004
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Turcott, Robert
• Primary Examiner(s): Heller, Tammie K
• Application Number:
  US12/040,091
• Time in Patent Office: 2,034 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 selecting an appropriate anti-arrhythmia therapy for a patient according to a hemodynamic status of the patient, comprising:

monitoring electrical activity of the patient'"'"'s heart to detect an arrhythmia;

monitoring hemodynamic performance of the heart, said monitoring comprising;

measuring a parameter indicative of hemodynamic performance during a first state to establish a template waveform,

obtaining an autocharacterization measure for the template waveform by cross-characterizing the template waveform with itself,

measuring the parameter indicative of hemodynamic performance during a second state to establish a test waveform,

performing a cross-characterization between the template waveform and the test waveform to identify a cross-characterization measure,

comparing the cross-characterization measure with the autocharacterization measure to obtain a comparison result, and

obtaining an indication of hemodynamic status based on the comparison result; and

selecting, based on said indication of hemodynamic status, the appropriate anti-arrhythmia therapy to treat the arrhythmia.

2. The method of claim 1, wherein the obtaining an autocharacterization measure step comprises obtaining a maximum autocorrelation value for the template waveform.

3. The method of claim 2, wherein the performing step comprises performing a cross-correlation between the template waveform and the test waveform to identify a maximum cross-correlation value for the test waveform, wherein the maximum cross-correlation value comprises the cross-characterization measure.

4. The method of claim 3, wherein the comparing step comprises comparing the maximum cross-correlation value for the test waveform with the maximum autocorrelation value to obtain an indication of hemodynamic status.

5. The method of claim 4, wherein the comparing step comprises comparing a difference between the maximum autocorrelation value and the maximum cross-correlation value for the test waveform against a predetermined threshold.

6. The method of claim 5, wherein the difference comparing step comprises determining if the maximum cross-correlation value for the test waveform is less than the maximum autocorrelation value by a predetermined status low threshold, thereby determining if the hemodynamic status of the second state is low.

7. The method of claim 5, wherein the difference comparing step comprises determining if the maximum cross-correlation value for the test waveform is greater than the maximum autocorrelation value by a predetermined status high threshold, thereby determining if the hemodynamic status of the second state is high.

8. The method of claim 1, wherein the first measuring step comprises measuring a parameter indicative of hemodynamic performance during a normal sinus heart rhythm to establish a template waveform.

9. The method of claim 8, wherein the second measuring step comprises measuring the parameter indicative of hemodynamic performance during a tachycardia rhythm to establish a test waveform.

10. The method of claim 1, wherein the first measuring step comprises measuring a parameter indicative of hemodynamic performance during heart pacing with a baseline atrioventricular (AV) delay.

11. The method of claim 10, wherein the second measuring step comprises measuring the parameter indicative of hemodynamic performance during a test atrioventricular (AV) delay.

12. The method of claim 1, wherein the obtaining an autocharacterization measure step comprises cross-correlating the template waveform with itself to identify a maximum cross-correlation value for the template waveform, wherein the maximum cross-correlation value comprises the autocharacterization measure.

13. An implantable cardiac device comprising:

means for monitoring electrical activity of a patient'"'"'s heart to detect an arrhythmia; and

a micro-controller configured to monitor hemodynamic performance of the heart, wherein the micro-controller is configured to;

obtain a parameter indicative of hemodynamic performance during a first state to establish a template waveform,

obtain an autocharacterization measure for the template waveform by cross-characterizing the template waveform with itself,

measure the parameter indicative of hemodynamic performance during a second state to establish a test waveform,

perform a cross-characterization between the template waveform and the test waveform to identify a cross-characterization measure,

compare the cross-characterization measure with the autocharacterization measure to obtain a comparison result, and

obtain an indication of hemodynamic status based on the comparison result; and

wherein the micro-controller is also configured to select, based on said indication of hemodynamic status, an appropriate anti-arrhythmia therapy to treat the arrhythmia.

14. The implantable cardiac device of claim 13, further comprising:

means for delivering the appropriate anti-arrhythmia therapy to the heart.

15. The implantable cardiac device of claim 13, wherein the cross-characterization is a cross-correlation.

16. The implantable cardiac device of claim 15, wherein the cross-characterization measure is a maximum test value of the cross-correlation.

17. The implantable cardiac device of claim 16, wherein the autocharacterization measure is a maximum value of an autocorrelation of the template waveform.

18. The implantable cardiac device of claim 17, wherein to compare the cross-characterization measure with the autocharacterization measure, the micro-controller is configured to compare a difference between the maximum autocorrelation value and maximum test value against a predetermined threshold.

19. The implantable cardiac device of claim 18, wherein to compare a difference between the maximum autocorrelation value and maximum value against the predetermined threshold the micro-controller is configured to determine if the maximum test value is less than the maximum autocorrelation value by a predetermined status low threshold and determine if the hemodynamic status of the second state is low.

20. The implantable cardiac device of claim 18, wherein to compare a difference between the maximum autocorrelation value and maximum value against the predetermined threshold the micro-controller is configured to determine if the maximum test value is greater than the maximum autocorrelation value by a predetermined status high threshold and determine if the hemodynamic status of the second state is high.

21. The implantable cardiac device of claim 13, wherein to obtain an autocharacterization measure, the micro-controller is configured to cross-correlate the template waveform with itself and obtain a maximum cross-correlation value for the template waveform, wherein the maximum cross-correlation value comprises the autocharacterization measure.