Chronotropic status monitor for implantable cardiac device

• US 20050267541A1
• Filed: 05/25/2004
• Published: 12/01/2005
• Est. Priority Date: 05/25/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Hopper, Donald, Scheiner, Avram
• Granted Patent: US 7,142,920 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• 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

Abstract

An implantable cardiac device with an exertion level sensor is programmed to determine a heart rate appropriate for a given measured exertion level in accordance with a physiological model and/or previously collected physiologic data. The device then compares the model'"'"'s heart rate with a measured intrinsic heart rate. Based upon this data, the device is able to recognize changes in the patient'"'"'s heart rate response and predict or recognize a chronotropically incompetent condition.

Claims

1. A cardiac rhythm management device, comprising:

one or more sensing channels for generating intra-cardiac electrogram signals;

a controller for detecting intrinsic cardiac activity and measuring an intrinsic heart rate from the electrogram signals;

an exertion level sensor interfaced to the controller for measuring a physiological parameter related to metabolic demand; and

,

wherein the controller is programmed to compare a measured intrinsic heart rate and a heart rate appropriate for a given measured exertion level as calculated in accordance with a physiological model.

2. The device of claim 1 wherein the controller is programmed to record a patient'"'"'s intrinsic heart rates along with corresponding measured exertion levels over a period of time and compare the measured intrinsic heart rates with heart rates calculated as being appropriate for the measured exertion levels.

3. The device of claim 2 wherein the controller is programmed to record a patient'"'"'s intrinsic heart rates and corresponding measured exertion levels as averages.

4. The device of claim 2 wherein the controller is programmed to calculate a parameter reflecting the variability between the measured intrinsic heart rates and the heart rates calculated as being appropriate for the corresponding measured exertion levels.

5. The device of claim 4 wherein the controller is programmed to set an alarm flag if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

6. The device of claim 4 further comprising:

a telemetry interface for communicating with a remote monitoring device; and

,

wherein the controller is programmed to send an alert message via the telemetry interface if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

7. The device of claim 4 further comprising:

a pacing channel for pacing a cardiac chamber, wherein the controller is programmed to control the delivery of pacing pulses in accordance with a programmed mode; and

,

wherein the controller is programmed to switch to a rate-adaptive pacing mode if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

8. The device of claim 7 wherein the controller is further programmed to calculate a response factor for rate-adaptive pacing based upon previously measured heart rates and exertion levels.

9. The device of claim 1 wherein the exertion level sensor is a minute ventilation sensor.

10. The device of claim 1 wherein the exertion level sensor is an accelerometer.

11. A method for operating a cardiac rhythm management device, comprising:

generating intra-cardiac electrogram signals and;

detecting intrinsic cardiac activity and measuring an intrinsic heart rate from the electrogram signals;

measuring an exertion level of a patient by measuring a physiological parameter related to metabolic demand; and

,

comparing a measured intrinsic heart rate and a heart rate appropriate for a given measured exertion level as calculated in accordance with a physiological model.

12. The method of claim 11 further comprising recording a patient'"'"'s intrinsic heart rates along with corresponding measured exertion levels over a period of time and comparing the measured intrinsic heart rates with heart rates calculated as being appropriate for the measured exertion levels.

13. The method of claim 12 further comprising recording a patient'"'"'s intrinsic heart rates and corresponding measured exertion levels as averages.

14. The method of claim 12 further comprising calculating a parameter reflecting the variability between the measured intrinsic heart rates and the heart rates calculated as being appropriate for the corresponding measured exertion levels.

15. The method of claim 14 further comprising setting an alarm flag if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

16. The method of claim 14 further comprising:

communicating with a remote monitoring device; and

,

sending an alert message via the telemetry interface if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

17. The method of claim 14 further comprising:

pacing a cardiac chamber in accordance with a programmed mode; and

,

switching to a rate-adaptive pacing mode if the variability between measured intrinsic heart rates and calculated heart rates exceeds a predetermined value.

18. The method of claim 17 further comprising calculating a response factor for rate-adaptive pacing based upon previously measured heart rates and exertion levels.

19. The method of claim 11 wherein the exertion level is measured with a minute ventilation sensor.

20. The method of claim 11 wherein the exertion level is measured with an accelerometer.