Method and apparatus for trending a physiological cardiac parameter

• US 8,594,789 B2
• Filed: 12/11/2012
• Issued: 11/26/2013
• Est. Priority Date: 06/25/2003
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Goode, Paul V. Jr.
• Primary Examiner(s): Holmes, Rex R
• Application Number:
  US13/711,057
• Publication Number:
  US 20130102914A1
• Time in Patent Office: 350 Days
• Field of Search: 607/17, 607/27, 607/122, 600/509
• US Class Current: 607/17
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system

Abstract

The present invention relates to an implantable cardioverter-defibrillator or pacemaker whose standard circuitry is used to trend a physiological cardiac parameter using intra-cardiac impedance measurements. The trend information may be used to predict the onset of a sudden cardiac death (SCD) event. By being able to predict the onset of an SCD event, patients and their physicians may be forewarned of a life-threatening event allowing them to respond accordingly. The trend information may also be used to predict the efficacy of cardiac-related medications, monitor progress of congestive heart failure, detect the occurrence of myocardial infarction, or simply track changes in sympathetic tone.

Claims

1. A system for monitoring congestive heart failure, the system comprising:

a measuring device configured to measure, using a lead, cardiac impedance of a patient when the patient is typically sleeping;

a derivation module configured to derive a physiologic parameter from the measured impedance;

a trending module configured to trend the derived parameter over spaced time intervals to create trended parameter data; and

an analyzing module configured to;

analyze the trended parameter data to determine sympathetic activity; and

analyze the sympathetic activity and use the analysis of the sympathetic activity to monitor congestive heart failure status.

2. The system of claim 1, wherein the derived parameter includes at least one of stroke volume, ejection fraction, and pre-ejection period.

3. The system of claim 1, wherein the derived parameter includes stroke volume.

4. The system of claim 1, wherein the derived parameter includes ejection fraction.

5. The system of claim 1, wherein the derived parameter includes pre-ejection period.

6. The system of claim 1, wherein the analyzing module is configured to:

analyze the trended parameter data to determine changes in sympathetic activity;

analyze the changes in sympathetic activity; and

use the analysis of the changes in sympathetic activity to monitor congestive heart failure status.

7. The system of claim 1, comprising a reporting module configured to report the changes in sympathetic activity to an outside source.

8. The system of claim 1, wherein the derivation module and the trending module are packaged with an implantable device.

9. The system of claim 1, wherein the measuring device is coupled to at least two electrodes configured to measure a voltage resulting from a current applied between the at least two electrodes, wherein the voltage is used to determine the cardiac impedance.

10. The system of claim 9, wherein the electrodes are part of at least one unipolar lead and a remote device.

11. The system of claim 9, wherein the electrodes are part of at least one bipolar lead.

12. The system of claim 9, wherein the electrodes are part of at least one unipolar lead and a bipolar lead.

13. The system of claim 9, wherein the electrodes are part of at least one bipolar lead and a remote device.

14. A device for trending sympathetic activity, the device comprising:

an impedance module configured to measure, using a lead, cardiac impedance of a patient when the patient is typically sleeping;

a derivation module configured to derive a physiologic parameter from the impedance measured when the patient is typically sleeping, wherein the derived parameter includes at least one of stroke volume, ejection fraction, and pre-ejection period;

a trending module configured to trend the derived parameter over spaced time intervals to create trended parameter data; and

an analyzing module configured to;

analyze the trended parameter data to determine sympathetic activity; and

analyze the sympathetic activity and use the analysis of the sympathetic activity to monitor congestive heart failure status.

15. The device of claim 14, wherein the analyzing module is configured to:

analyze the trended parameter data to determine changes in sympathetic activity;

analyze the changes in sympathetic activity; and

use the analysis of the changes in sympathetic activity to monitor congestive heart failure status.

16. The device of claim 14, wherein the measuring device is configured to measure the cardiac impedance of the patient at spaced time intervals.

18. The non-transitory device-readable medium of claim 16, wherein the derived parameter includes at least one of stroke volume, ejection fraction, and pre-ejection period.

19. The non-transitory device-readable medium of claim 16, comprising instructions that, when performed by the previously-implanted medical device, cause the device to perform acts comprising:

analyzing the trended parameter data to determine changes in sympathetic activity;

analyzing the changes in sympathetic activity; and

using the analysis of the changes in sympathetic activity to monitor congestive heart failure status.

17. A non-transitory device-readable medium comprising instructions that, when performed by a previously-implanted medical device, cause the device to perform acts comprising:

measuring, using a lead, cardiac impedance of a patient when the patient is typically sleeping;

deriving a physiologic cardiac parameter from the measured impedance;

trending the derived parameter over spaced time intervals to create trended parameter data;

analyzing the trended parameter data to determine sympathetic activity;

analyzing the sympathetic activity; and

using the analysis of the sympathetic activity to monitor congestive heart failure status.