DYNAMIC LEAD CONDITION DETECTION FOR AN IMPLANTABLE MEDICAL DEVICE

• US 20090112292A1
• Filed: 10/26/2007
• Published: 04/30/2009
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: Armstrong, Randolph K.
• Granted Patent: US 8,868,203 B2
• Time in Patent Office: Days
• 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

The present invention provides for a method, apparatus, and system for performing a dynamic detection of a lead condition associated with a lead assembly in an implantable medical device for providing 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 for performing a dynamic detection of a lead condition associated with a lead assembly in an implantable medical device for providing a controlled current therapeutic electrical signal to a cranial nerve, said method comprising:

providing a pulsed therapeutic electrical signal to a portion of a patient'"'"'s body;

providing a multiplicity of feedback signals, each said signal in said multiplicity comprising a voltage signal associated with said lead assembly for a pulse in said pulsed therapeutic electrical signal, determining for each said feedback signal whether said voltage signal is below a predetermined threshold to create a multiplicity of voltage signal comparison results;

determining whether or not a lead condition problem exists based upon said multiplicity of voltage signal comparison results.

2. The method of claim 1, wherein said multiplicity of feedback signals comprises a feedback signal for each pulse in said pulsed therapeutic electrical signal.

3. The method of claim 1, wherein determining that a lead condition problem exists comprises determining that at least one of said multiplicity of feedback signals indicates that the impedance associated with said lead assembly is sufficiently high to indicate the presence of a lead break.

4. The method of claim 2, wherein determining that there is a lead condition problem based upon said multiplicity of voltage signal comparison results comprises determining that the impedance associated with said lead assembly for at least one of said multiplicity of feedback signals is sufficiently low to indicate a lead short.

5. The method of claim 4, wherein said providing said feedback signal comprises:

determining a maximum desired lead impedance;

determining a current value associated with said therapeutic electrical signal;

determining a predicted lead voltage based upon said desired lead impedance and said current value associated with said therapeutic electrical signal;

determining an actual lead voltage during at least a portion of a time period in which said controlled current therapeutic electrical signal is applied to said cranial nerve;

comparing said actual lead voltage to said predicted lead voltage; and

providing said feedback signal in response to a determination that said actual lead voltage is outside of a predetermined acceptable range above or below said predicted voltage.

6. The method of claim 1, further comprising storing data relating to said determining that there is a lead condition problem.

7. The method of claim 6, further comprising providing a time stamp when storing data associated with said determination that there is a lead condition problem, based upon a time period of determining that there is said lead condition problem.

8. The method of claim 1, further comprising acquiring at least one of a patient activity data within a time period substantially proximate to the occurrence of determining the existence of a lead condition problem, or acquiring physiological data within a time period substantially proximate to the occurrence of determining the existence of a lead condition problem.

9. The method of claim 8, further comprising performing at least one of correlating at least one activity relating to said patient activity data to said lead condition problem, and correlating at least one physiological activity to said lead condition problem.

10. A method for performing a substantially continuous assessment of a lead condition associated with a lead assembly in an implantable medical device for providing a pulsed therapeutic electrical signal to a cranial nerve, said method comprising:

providing a pulsed therapeutic electrical signal to a portion of a patient'"'"'s body;

providing a multiplicity of feedback signals, each said feedback signal being indicative of a condition of a pulse of said pulsed therapeutic electrical signal, at least one of said multiplicity of said feedback signals being asserted in response to a determination that the voltage of a corresponding pulse from the multiplicity of pulses is below a predetermined threshold; and

determining that an impedance of said lead assembly is sufficiently out of a predetermined range of tolerance to indicate that a lead condition problem exists during at least one time period of at least one of said multiplicity of pulses, in response to said determination that the voltage of said corresponding pulse from the multiplicity of pulses is below a predetermined threshold.

11. The method of claim 10, further comprising storing data associated with each occurrence of said lead condition problem.

12. The method of claim 10, wherein determining that said impedance is sufficiently out of said predetermined range of tolerance to indicate said lead condition problem comprises determining that said lead condition problem is at least one of a leak break or a lead short.

13. The method of claim 10, further comprising:

asserting at least one of said multiplicity of said feedback signals in response to a determination that the voltage of a corresponding pulse from the multiplicity of pulses is above a predetermined threshold; and

determining that an impedance of said lead assembly is sufficiently out of a predetermined range of tolerance to indicate a lead short problem during at least one time period of at least one of said multiplicity of pulses, in response to said determination that the voltage of said corresponding pulse from the multiplicity of pulses is above a predetermined threshold.

14. The method of claim 13, wherein said providing a feedback signal comprises:

determining whether a charge device voltage from a charge device used by said implantable medical device to deliver said pulsed therapeutic electrical signal is sufficient to provide a maximum desired impedance associated with a lead electrically coupled to said implantable medical device;

determining a current value associated with said therapeutic electrical signal;

determining a predicted lead voltage based upon said desired lead impedance and said current value associated with said therapeutic electrical signal;

determining an actual lead voltage during at least a portion of a time period in which said pulsed therapeutic electrical signal is applied to said cranial nerve;

comparing said actual lead voltage to said predicted lead voltage;

asserting said feedback signal in response to a determination that said actual lead voltage is outside of a predetermined acceptable range above or below said predicted voltage; and

determining a presence of said lead condition problem in response to an assertion of feedback and in response to said determination that said charge device voltage is sufficient.

15. The method of claim 10, further comprising storing data associated with determining that a lead condition problem exists.

16. The method of claim 10, further comprising acquiring at least one of:

a patient activity data within a time period substantially proximate to determining the existence of a lead condition problem;

a time period data relating to a determination that a lead condition problem exists;

or

a physiological data within a time period substantially proximate to determining the existence of a lead condition problem

17. The method of claim 16, further comprising performing at least one of:

correlating at least one activity relating to said patient activity data to said lead condition problem;

correlating at least one time period data to said lead condition problem;

or

correlating at least one physiological activity to said lead condition problem.

18. An implantable medical device for performing a dynamic detection of a lead condition associated with a lead assembly coupled to the implantable medical device, comprising:

a stimulation unit to provide a pulsed therapeutic electrical stimulation signal to a cranial nerve through a lead operatively coupled to said IMD; and

a controller operatively coupled to said stimulation unit, said controller to determine that a lead condition problem exists in response to at least one determination that at least one of a multiplicity of feedback signals has been asserted, said feedback signals being asserted in response to a determination that a voltage signal corresponding to at least one of a plurality of pulses of the therapeutic electrical signal is outside a predetermined range of tolerance during at least a portion of a time period during which said at least one of said pulses of said therapeutic electrical signal is provided to said cranial nerve, said controller also to record a plurality of instances of determinations that said voltage signal associated with said lead assembly is above said predetermined threshold.

19. The implantable medical device of claim 18, wherein said lead condition problem is a lead break in response to determination that said feedback signal indicates that the actual voltage of said lead assembly is below a predicted voltage of said lead assembly, indicating that the impedance of said lead assembly is above a predetermined threshold.

20. The implantable medical device of claim 18, wherein said lead condition problem is a lead short in response to determination that said feedback signal indicates that the actual voltage of said lead assembly is above a predicted voltage of said lead assembly, indicating that the impedance of said lead assembly is below a predetermined threshold.

21. The implantable medical device of claim 18, further comprising:

an activity sensor unit to sense an activity of a patient during at least a portion of the time period of the assertion of said feedback signal;

a physiological sensing unit to acquire at least one physiological data during at least a portion of the time period of the assertion of said feedback signal; and

a feedback unit to provide said feedback data to said stimulation unit, said stimulation unit to adjust an output signal in response to said feedback signal.

22. The implantable medical device of claim 21, wherein said controller is capable of correlating an occurrence of said lead condition problem to at least one of data relating to said activity of said patient, or data relating to a physiological data of said patient.