Fully automatic and physiologic rate-adaptive pacing

• US 6,408,208 B1
• Filed: 10/28/1999
• Issued: 06/18/2002
• Est. Priority Date: 10/28/1999
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sun, Weimin
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/428,831
• Time in Patent Office: 964 Days
• Field of Search: 607/17, 607/18, 607/19, 607/20, 600/513
• US Class Current: 607/17
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

Methods and apparatus for automatic estimation of output mapping parameters for a control system where those output mapping parameters may be estimated from changes in sensor input data when the control system enters steady-state motion. Methods and apparatus for automatic estimation of minute ventilation at anaerobic threshold and minute ventilation at peak exercise for adjustment of rate-adaptive curves of pacemakers. The methods include detecting steady-state motion of the pacemaker and calculating minute ventilation at anaerobic threshold and minute ventilation at peak exercise from changes in minute ventilation sensor data corresponding to the period of steady-state motion.

Claims

1. A method of adjusting an output mapping of a control output versus a control input for a control system, comprising:

collecting first signal input data from a first sensor indicative of motion of the control system;

collecting second signal input data from a second sensor;

storing the first and second signal input data in a memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the system from the stored first signal input data;

calculating at least one parameter for the output mapping in response to changes in the stored second signal input data during a period of steady-state motion, thereby producing at least one calculated parameter; and

adjusting the output mapping in response to the at least one calculated parameter.

2. The method of claim 1, wherein collecting first signal input data from a first sensor comprises collecting first signal input data from an accelerometer.

3. The method of claim 1, wherein detecting steady-state motion of the system comprises subjecting the stored first signal input data to Fourier analysis to convert the stored first signal input data to its harmonically-related frequency components.

4. The method of claim 3, wherein detecting steady-state motion of the system comprises detecting steady-state motion when the frequency components exhibit an amplitude maxima at a frequency component in the range of about 1 to 4 Hertz.

5. The method of claim 4, wherein a power ratio of frequency components within a range of about 0.5 Hertz from the frequency component corresponding to the amplitude maxima to remaining frequency components is at least 2.

6. A method of adjusting a rate-adaptive curve of a pacemaker, comprising:

collecting first signal input data from a first sensor indicative of motion of the pacemaker;

collecting second signal input data from a minute ventilation sensor;

storing the first and second signal input data in a memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the pacemaker from the stored first signal input data;

calculating at least one parameter for the rate-adaptive curve in response to changes in the stored second signal input data during a period of steady-state motion, thereby producing at least one calculated parameter; and

adjusting the rate-adaptive curve in response to the at least one calculated parameter.

7. The method of claim 6, wherein collecting first signal input data from a first sensor comprises collecting first signal input data from an accelerometer.

8. The method of claim 6, wherein detecting steady-state motion of the pacemaker comprises subjecting the stored first signal input data to Fourier analysis to convert the stored first signal input data to its harmonically-related frequency components.

9. The method of claim 8, wherein detecting steady-state motion of the pacemaker comprises detecting steady-state motion when the frequency components exhibit an amplitude maxima at a frequency component in the range of about 1 to 4 Hertz.

10. The method of claim 9, wherein a power ratio of frequency components within a range of about 0.5 Hertz from the frequency component corresponding to the amplitude maxima to remaining frequency components is at least 2.

11. The method of claim 6, wherein the at least one parameter is selected from the group consisting of minute ventilation at anaerobic threshold and minute ventilation at peak exercise.

12. The method of claim 6, wherein collecting second signal input data comprises collecting a minute ventilation data component, a respiratory rate data component and a tidal volume data component from a minute ventilation sensor.

13. A method of adjusting a rate-adaptive curve of a pacemaker, comprising:

collecting first signal input data from an accelerometer;

collecting second signal input data from a minute ventilation sensor;

storing the first and second signal input data in a memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the pacemaker from the stored first signal input data by subjecting the stored first signal input data to Fourier analysis;

calculating at least one parameter for the rate-adaptive curve selected from the group consisting of minute ventilation at anaerobic threshold and minute ventilation at peak exercise in response to changes in the stored second signal input data during a period of steady-state motion, thereby producing at least one calculated parameter; and

adjusting the rate-adaptive curve in response to the at least one calculated parameter.

14. A method of adjusting a two-slope rate-adaptive curve of a pacemaker, wherein the two-slope rate-adaptive curve is defined by parameters including minute ventilation at anaerobic threshold and minute ventilation at peak exercise, the method comprising:

collecting first signal input data from an accelerometer;

collecting second signal input data from a minute ventilation sensor;

storing the first and second signal input data in a memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the pacemaker from the stored first signal input data by subjecting the stored first signal input data to Fourier analysis;

calculating the minute ventilation at anaerobic threshold and minute ventilation at peak exercise in response to changes in the stored second signal input data during a period of steady-state motion; and

adjusting the rate-adaptive curve in response to the calculated minute ventilation at anaerobic threshold and the calculated minute ventilation at peak exercise.

15. A control system, comprising:

a processor;

a memory coupled to the processor and having output mapping data stored thereon defining an output mapping;

a regulator coupled to the processor;

a first sensor input coupled to the processor and adapted to receive first sensor input data indicative of motion of the control system;

a second sensor input coupled to the processor and adapted to receive second sensor input data;

a control output coupled to the regulator; and

a detection module coupled to the processor and adapted to detect steady-state motion of the control system in response to the first sensor input data;

wherein the processor is adapted to adjust the output mapping data in response to changes in the second sensor input data when the detection module detects steady-state motion of the control system.

16. A control system, comprising:

a processor;

a memory coupled to the processor and having output mapping data stored thereon defining an output mapping;

a regulator coupled to the processor;

a first sensor input coupled to the processor;

a second sensor input coupled to the processor; and

a control output coupled to the regulator;

wherein the memory has instructions stored thereon capable of causing the processor to perform a method, the method comprising

collecting first signal input data from a first sensor at the first sensor input, wherein the first signal input data is indicative of motion of the control system;

collecting second signal input data from a second sensor at the second sensor input;

storing the first and second signal input data in the memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the system from the stored first signal input data;

calculating at least one parameter for the output mapping in response to changes in the stored second signal input data during a period of steady-state motion of the system, thereby producing at least one calculated parameter; and

adjusting the output mapping in response to the at least one calculated parameter.

17. A rate-adaptive pacemaker, comprising:

a processor;

a memory coupled to the processor and having output mapping data stored thereon defining a rate-adaptive curve;

a variable-rate pulse generator coupled to the processor;

a first sensor input coupled to the processor and adapted to receive first sensor input data indicative of motion of the pacemaker;

a second sensor input coupled to the processor and adapted to receive second sensor input data from a minute ventilation sensor;

a pulse output coupled to the variable-rate pulse generator; and

a detection module coupled to the processor and adapted to detect steady-state motion of the pacemaker in response to the first sensor input data;

wherein the processor is adapted to adjust the output mapping data in response to changes in the second sensor input data when the detection module detects steady-state motion of the pacemaker.

18. The rate-adaptive pacemaker of claim 17, further comprising:

an accelerometer coupled to the first sensor input to provide the first sensor input data.

19. The rate-adaptive pacemaker of claim 17, wherein the detection module is adapted to detect steady-state motion of the pacemaker by subjecting the stored first signal input data to Fourier analysis to convert the stored first signal input data to its harmonically-related frequency components.

20. The rate-adaptive pacemaker of claim 19, wherein the detection module is adapted to detect steady-state motion of the pacemaker when the frequency components exhibit an amplitude maxima at a frequency component in the range of about 1 to 4 Hertz.

21. The rate-adaptive pacemaker of claim 20, wherein the detection module is adapted to detect steady-state motion of the pacemaker when a power ratio of frequency components within a range of about 0.5 Hertz from the frequency component corresponding to the amplitude maxima to remaining frequency components is at least 2.

22. A rate-adaptive pacemaker, comprising:

a processor;

a memory coupled to the processor and having output mapping data stored thereon defining a rate-adaptive curve;

a variable-rate pulse generator coupled to the processor;

a first sensor input coupled to the processor;

a second sensor input coupled to the processor; and

a pulse output coupled to the variable-rate pulse generator;

wherein the memory has instructions stored thereon capable of causing the processor to perform a method, the method comprising;

collecting first signal input data from a first sensor indicative of motion of the pacemaker at the first sensor input;

collecting second signal input data from a minute ventilation sensor at the second sensor input;

storing the first and second signal input data in the memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state motion of the pacemaker from the stored first signal input data;

calculating at least one parameter for the rate-adaptive curve in response to changes in the stored second signal input data during a period of steady-state motion, thereby producing at least one calculated parameter; and

adjusting the output mapping data in response to the at least one calculated parameter.

23. The rate-adaptive pacemaker of claim 22, wherein collecting first signal input data from a first sensor comprises collecting first signal input data from an accelerometer.

24. The rate-adaptive pacemaker of claim 22, wherein detecting steady-state motion of the pacemaker comprises subjecting the stored first signal input data to Fourier analysis to convert the stored first signal input data to its harmonically-related frequency components.

25. The rate-adaptive pacemaker of claim 24, wherein detecting steady-state motion of the pacemaker comprises detecting steady-state motion when the frequency components exhibit an amplitude maxima at a frequency component in the range of about 1 to 4 Hertz.

26. The rate-adaptive pacemaker of claim 25, wherein a power ratio of frequency components within a range of about 0.5 Hertz from the frequency component corresponding to the amplitude maxima to remaining frequency components is at least 2.

27. The rate-adaptive pacemaker of claim 22, wherein the at least one parameter is selected from the group consisting of minute ventilation at anaerobic threshold and minute ventilation at peak exercise.

28. The rate-adaptive pacemaker of claim 22, wherein collecting second signal input data comprises collecting a minute ventilation data component, a respiratory rate data component and a tidal volume data component from a minute ventilation sensor.

29. A method of adjusting a rate-adaptive curve of a pacemaker for use with a patient, comprising:

collecting first signal input data from a first sensor indicative of exercise of the patient;

collecting second signal input data from a minute ventilation sensor;

storing the first and second signal input data in a memory, thereby producing stored first signal input data and stored second signal input data;

detecting steady-state exercise of the patient from the stored first signal input data;

calculating at least one parameter for the rate-adaptive curve in response to changes in the stored second signal input data during a period of steady-state exercise, thereby producing at least one calculated parameter; and

adjusting the rate-adaptive curve in response to the at least one calculated parameter.

30. A rate-adaptive pacemaker for use with a patient, comprising:

a processor;

a memory coupled to the processor and having output mapping data stored thereon defining a rate-adaptive curve;

a variable-rate pulse generator coupled to the processor;

a first sensor input coupled to the processor and adapted to receive first sensor input data indicative of exercise of the patient;

a second sensor input coupled to the processor and adapted to receive second sensor input data from a minute ventilation sensor;

a pulse output coupled to the variable-rate pulse generator; and

a detection module coupled to the processor and adapted to detect steady-state exercise of the patient in response to the first sensor input data;

wherein the processor is adapted to adjust the output mapping data in response to changes in the second sensor input data when the detection module detects steady-state exercise of the patient.