Dynamic lead condition detection for an implantable medical device

• US 8,868,203 B2
• Filed: 10/26/2007
• Issued: 10/21/2014
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: Armstrong, Randolph K.
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): GHAND, JENNIFER LEIGH-STEWAR
• Application Number:
  US11/925,749
• Publication Number:
  US 20090112292A1
• Time in Patent Office: 2,552 Days
• Field of Search: 607/2, 607/63
• US Class Current: 607/63
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/37241 providing test stimulations

Abstract

A method, apparatus, and system for perform dynamic detection of a lead condition associated with a lead assembly in an implantable medical device that provides a controlled current therapeutic electrical signal to a cranial nerve. A pulsed therapeutic electrical signal is provided to a portion of a patient'"'"'s body. A multiplicity of feedback signals is provided. Each the signal in the multiplicity comprises a voltage signal associated with the lead assembly for a pulse in the pulsed therapeutic electrical signal. For each the feedback signal, a determination is made as to whether the voltage signal is below a predetermined threshold to create a multiplicity of voltage signal comparison results. A determination is made as to whether or not a lead condition problem exists based upon the multiplicity of voltage signal comparison results.

Claims

1. A method comprising:

providing a therapeutic electrical signal to a lead assembly of an implantable medical device;

receiving return signals in response to the therapeutic electrical signal, each return signal comprising a voltage signal associated with the lead assembly for a pulse of the therapeutic electrical signal;

determining, based on the return signals, whether a voltage level of a charge device of the implantable medical device is sufficient to generate a controlled-current level of the therapeutic electrical signal;

comparing the return signals to a threshold range;

asserting a feedback signal for each return signal outside the threshold range; and

determining that a lead condition problem exists when the feedback signal is asserted and the voltage level of the charge device is sufficient to generate the controlled-current level of the therapeutic electrical signal.

2. The method of claim 1, wherein the feedback signal includes a voltage low signal when the return signal associated with a particular pulse is below the threshold range and wherein the feedback signal includes a voltage high signal when the return signal for the particular pulse is above the threshold range.

3. The method of claim 1, further comprising determining that the lead condition problem indicates a lead break when the feedback signal indicates an impedance associated with the lead assembly is above a threshold.

4. The method of claim 1, further comprising determining that the lead condition problem indicates a lead short when the feedback signal indicates an impedance associated with the lead assembly is below a threshold.

5. The method of claim 1, wherein the threshold range comprises a first range above a predicted lead voltage and a second range below the predicted lead voltage, wherein the predicted lead voltage is based on a desired lead impedance and the controlled-current level of the therapeutic electrical signal.

6. The method of claim 1, further comprising performing assessments of lead health prior to delivery of subsequent therapeutic electrical signals after determining that the lead condition problem exists.

7. The method of claim 1, further comprising storing data related to the feedback signal, wherein the data includes a time stamp associated with the feedback signal.

8. The method of claim 1, further comprising acquiring patient activity data;

and in response to the feedback signal being asserted at a particular time, storing data related to the feedback signal and the patient activity data associated with the particular time.

9. The method of claim 8, further comprising comparing the patient activity data and the data related to the feedback signal at the particular time with corresponding patient activity data and feedback signal data associated with a second particular time when the feedback signal was asserted;

and identifying one or more activities common to the particular time and the second particular time.

10. A method comprising:

providing a pulsed therapeutic electrical signal to a lead assembly of an implantable medical device;

measuring a voltage across leads of the lead assembly responsive to each pulse of the pulsed therapeutic electrical signal;

determining, based on the voltage across the leads of the lead assembly responsive to a particular pulse, whether a voltage level of a charge device of the implantable medical device is sufficient to generate a controlled-current level of the pulsed therapeutic electrical signal;

asserting a feedback signal when the voltage corresponding to the particular pulse of the pulsed therapeutic electrical signal is outside a threshold range; and

determining that a lead condition problem exists when the feedback signal is asserted and the voltage level of the charge device is sufficient to generate the controlled-current level of the pulsed therapeutic electrical signal.

11. The method of claim 10, further comprising storing data associated with the feedback signal.

12. The method of claim 10, further comprising determining that the lead condition problem indicates a lead short when the feedback signal indicates an impedance above a threshold.

13. The method of claim 10, wherein the threshold range comprises a first range above a predicted lead voltage and a second range below the predicted lead voltage, wherein the predicted lead voltage is based on a desired lead impedance and the controlled-current level of the pulsed therapeutic electrical signal.

14. The method of claim 10, wherein the feedback signal is a voltage low signal when the voltage corresponding to the particular pulse is below the threshold range and wherein the feedback signal is a voltage high signal when the voltage corresponding to the particular pulse is above the threshold range.

15. The method of claim 10, further comprising acquiring physiological data;

and in response to the feedback signal being asserted at a particular time, storing data related to the feedback signal and the physiological data associated with the particular time.

16. The method of claim 15, further comprising comparing the data related to the feedback signal and the physiological data at the particular time with corresponding physiological data and feedback data associated with a second particular time when the feedback signal was asserted;

and identifying one or more physiological conditions common between the particular time and the second particular time.

17. A non-transitory computer-readable medium comprising instructions executable by a processor to:

cause a pulsed therapeutic electrical signal to be applied to a lead assembly of an implantable medical device;

determine, based on a measured voltage across leads of the lead assembly responsive to a particular pulse of the pulsed therapeutic electrical signal, whether a voltage level of a charge device of the implantable medical device is sufficient to generate a controlled-current level of the pulsed therapeutic electrical signal;

assert a feedback signal when the measured voltage corresponding to the particular pulse of the pulsed therapeutic electrical signal is outside a threshold range; and

determine that a lead condition problem exists when the feedback signal is asserted and the voltage level of the charge device is sufficient to generate the controlled-current level of the pulsed therapeutic electrical signal.

18. The non-transitory computer-readable medium of claim 17, wherein the feedback signal is a voltage low signal when the measured voltage corresponding to the particular pulse is below the threshold range and wherein the feedback signal is a voltage high signal when the measured voltage corresponding to the particular pulse is above the threshold range.

19. The non-transitory computer-readable medium of claim 17, wherein the threshold range comprises a first range above a predicted lead voltage and a second range below the predicted lead voltage, wherein the predicted lead voltage is based on a desired lead impedance and the controlled-current level of the pulsed therapeutic electrical signal.

20. The non-transitory computer-readable medium of claim 17, further comprising instructions executable by the processor to determine that the lead condition problem indicates a lead break when the feedback signal indicates an impedance associated with the lead assembly is above a threshold.

21. The non-transitory computer-readable medium of claim 17, further comprising instructions executable by the processor to determine that the lead condition problem indicates a lead short when the feedback signal indicates an impedance associated with lead assembly is below a threshold.