Apparatus and method for assessing cardiac therapy

• US 7,894,901 B1
• Filed: 08/21/2006
• Issued: 02/22/2011
• Est. Priority Date: 08/21/2006
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Koh, Steve
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): PATEL, NATASHA
• Application Number:
  US11/466,074
• Time in Patent Office: 1,646 Days
• Field of Search: 607/27, 607/19, 600/509, 600/513
• US Class Current: 607/19
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36507 controlled by gradient or slope of the heart potential
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation

Abstract

A patient'"'"'s response to therapy such as CRT is assessed by cross correlation of a patient'"'"'s evoked response and physical activity surrogates. Based on the cross correlation, a determination may be made as to whether or how much the therapy is helping the patient'"'"'s physical activity. For example, the degree of cross correlation index between IEGM parameters and activity threshold parameters may be used to assess whether the patient'"'"'s heart condition improves the patient'"'"'s physical activity. The therapy may then be modified as necessary in the event the patient is not sufficiently responding to the therapy.

Claims

1. A method of assessing effectiveness of cardiac therapy, comprising:

delivering cardiac resynchronization pacing pulses to left and right ventricles of a patient'"'"'s heart to control synchronization of contractions of the left and right ventricles;

collecting an evoked response from an intracardiac electrogram (IEGM) of the left and right ventricles in response to the delivered pacing pulses;

extracting one or more parameters from the collected evoked response;

collecting data associated with activity of the patient; and

cross correlating the one or more parameters extracted from the evoked response and the collected activity data to generate an indication of effectiveness of the cardiac resynchronization pulses delivered to the left and right ventricles.

2. The method of claim 1 wherein the one or more extracted parameters comprises peak-to-peak intracardiac electrogram data.

3. The method of claim 2 comprising averaging a plurality of samples of the peak-to-peak intracardiac electrogram data to provide the evoked response data.

4. The method of claim 1 wherein the one or more extracted parameters comprises paced depolarization integral data.

5. The method of claim 1 wherein the one or more extracted parameters is indicative of a slope of an intracardiac electrogram signal.

6. The method of claim 1 wherein the activity data comprises patient acceleration data.

7. The method of claim 1 wherein the activity data comprises a maximum heart endurance time.

8. The method of claim 1 comprising monitoring patient activity signals to determine an amount of time the patient maintains a level of activity above a threshold level.

9. The method of claim 1 wherein the activity data comprises a time associated with a continuous accelerometer reading of at least approximately 50 mg.

10. The method of claim 1 wherein the activity data comprises a distance associated with a timed activity.

11. The method of claim 1 wherein the activity data is generated in accordance with a subjective patient evaluation.

12. The method of claim 1 wherein the evoked response data and the activity data are collected periodically.

13. The method of claim 1 comprising generating a moving average of a cross correlation result to generate the indication.

14. The method of claim 1 comprising collecting the evoked response data when the patient is inactive.

15. The method of claim 1 comprising collecting the evoked response data when the patient is asleep.

16. The method of claim 1 comprising collecting the evoked response data in accordance with a measured of activity level of the patient.

17. An apparatus adapted to assess effectiveness of cardiac therapy, comprising:

a pulse generator adapted to deliver cardiac resynchronization pacing pulses to left and right ventricles of a patient'"'"'s heart to control synchronization of contractions of the left and right ventricles;

an evoked response circuit adapted to obtain data associated with an evoked response from an intracardiac electrogram of a patient in response to the delivered cardiac resynchronization pacing pulses and to extract one or more parameters from the evoked response data;

an activity level circuit adapted to obtain data associated with activity of the patient; and

a cross correlator adapted to cross correlate the one or more extracted parameters and the activity data to generate an indication of effectiveness of the delivered cardiac resynchronization pacing pulses.

18. The apparatus of claim 17 wherein:

the evoked response circuit and the activity level circuit are adapted to repeatedly collect the evoked response data and the activity data, respectively, over time; and

the cross correlator is adapted to perform the cross correlation at specified times, wherein the cross correlation is performed over the evoked response data and the activity data collected substantially between the specified times.

19. The apparatus of claim 17 wherein at least a portion of the apparatus is implemented within an implantable cardiac device.

20. An implantable system comprising:

means for delivering cardiac resynchronization pacing pulses to left and right ventricles of a patient'"'"'s heart to control synchronization of contractions of the left and right ventricles;

means for collecting data associated with an evoked response of a patient from an intracardiac electrogram in response to the delivered cardiac resynchronization pacing pulses;

means for extracting one or more parameters from the collected evoked response data;

means for collecting data associated with activity of the patient; and

means for cross correlating the one or more parameters and the collected activity data to generate an indication of effectiveness of the delivered cardiac resynchronization pacing pulses.