Evoked response and impedance measures for monitoring heart failure and respiration

• US 20060276848A1
• Filed: 06/06/2005
• Published: 12/07/2006
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Min, Xiaoyi, Park, Euljoon, Ohlander, Malin
• Granted Patent: US 7,430,447 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation

Abstract

An exemplary method includes acquiring impedance values over one or more respiratory cycles, determining an impedance span based on the impedance values and, based at least in part on the impedance span, determining cardiac condition or respiratory condition. Another exemplary method includes acquiring IEGMs over one or more respiratory cycles, determining evoked response measure values based on the IEGMs, determining an evoked response span based on the evoked response measure values and, based at least in part on the evoked response span, determining cardiac condition or respiratory condition. Other exemplary methods, devices, systems, etc., are also disclosed.

Claims

1. A method comprising:

acquiring impedance values over one or more respiratory cycles;

determining an impedance span based on the impedance values; and

based at least in part on the impedance span, determining a cardiac condition.

2. The method of claim 1 wherein the impedance span comprises a difference between a minimum impedance value and a maximum impedance value of the acquired impedance values.

3. The method of claim 1 wherein the acquiring comprises acquiring intrathoracic impedance values.

4. The method of claim 1 wherein the acquiring comprises acquiring impedance values using an implantable device.

5. The method of claim 1 wherein patient posture is substantially constant over the one or more respiratory cycles.

6. The method of claim 1 wherein patient activity is substantially constant over the one or more respiratory cycles.

7. The method of claim 1 further comprising adjusting a cardiac therapy based at least in part on the impedance span.

8. The method of claim 1 further comprising determining a respiratory condition based at least in part on the impedance span.

9. The method of claim 1 wherein the determining a cardiac condition determines whether heart failure exists.

10. The method of claim 1 wherein the determining a cardiac condition determines whether heart failure has worsened.

11. The method of claim 1 wherein the determining a cardiac condition determines whether heart failure has improved.

12. The method of claim 1 wherein the determining a cardiac condition comprises comparing the impedance span to a previously determined impedance span.

13. The method of claim 1 wherein the determining a cardiac condition comprises comparing the impedance span to an average of impedance spans.

14. A method comprising:

acquiring IEGMs over one or more respiratory cycles;

determining evoked response measure values based on the IEGMs;

determining an evoked response span based on the evoked response measure values; and

based at least in part on the evoked response span, determining a cardiac condition.

15. The method of claim 14 wherein the evoked response measures comprise post depolarization integrals.

16. The method of claim 14 wherein the evoked response span comprises a difference between a minimum evoked response measure value and a maximum evoked response measure value of the determined evoked response measure values.

17. The method of claim 14 wherein the acquiring comprises acquiring IEGMs using an implantable device.

18. The method of claim 14 wherein patient posture is substantially constant over the one or more respiratory cycles.

19. The method of claim 14 wherein patient activity is substantially constant over the one or more respiratory cycles.

20. The method of claim 14 further comprising adjusting a cardiac therapy based at least in part on the evoked response span.

21. The method of claim 14 wherein the determining a cardiac condition determines a heart failure condition.

22. A system comprising:

means for acquiring physiologic values over one or more cycles;

means for determining a span based on the physiologic values; and

means for determining a cardiac condition based at least in part on the span.

23. An implantable medical system comprising:

at least one sensor operative to acquire impedance values over one or more respiratory cycles; and

circuitry in communication with the at least one sensor and operative to determine an impedance span based on the impedance values, and to determine a cardiac condition based at least in part on the impedance span.