Multiphasic pacing in the presence of electromagnetic interference

• US 9,138,584 B2
• Filed: 11/18/2011
• Issued: 09/22/2015
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Stancer, Christopher C., Edmonson, Jonathan D., Ellingson, Michael L.
• Primary Examiner(s): Bertram, Eric D.
• Application Number:
  US13/299,904
• Publication Number:
  US 20120277818A1
• Time in Patent Office: 1,404 Days
• US Class Current: 1/1
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents

Abstract

An implantable medical system may include an implantable medical lead including at least one electrode and an implantable medical device. The implantable medical device comprises an electromagnetic interference (EMI) detection module that monitors for one or more particular characteristics of EMI. A control module is configured to control a therapy module to generate monophasic stimulation pulses while operating the IMD in a first operating mode. In response to detecting the condition indicative of the presence of EMI, the control module switches the IMD from the first operating mode to a second operating mode and generates at least one multiphasic stimulation pulses while operating the IMD in the second operating mode.

Claims

1. A method comprising:

generating monophasic stimulation pulses while operating an implantable medical device (IMD) in a first operating mode;

detecting a condition indicative of the presence of electromagnetic interference (EMI);

switching the IMD from the first operating mode to a second operating mode in response to detecting the condition indicative of the presence of EMI; and

generating at least one multiphasic stimulation pulses while operating the IMD in the second operating mode.

2. The method of claim 1, wherein generating multiphasic stimulation pulses comprises generating biphasic stimulation pulses having a positive phase and a negative phase.

3. The method of claim 1, wherein generating multiphasic stimulation pulses while operating in the second operating mode comprises generating multiphasic stimulation pulses in which each of the phases has substantially the same amplitude as the monophasic stimulation pulses generated while operating in the first operating mode.

4. The method of claim 1, wherein generating multiphasic stimulation pulses while operating in the second operating mode comprises generating multiphasic stimulation pulses in which a first phase of the multiphasic pacing pulse has an amplitude that is substantially the same as an amplitude of the monophasic stimulation pulses generated while operating in the first operating mode and a second phase of the multiphasic pacing pulse has an amplitude that is larger than the amplitude of the first pacing pulse.

5. The method of claim 1, wherein detecting the condition indicative of the presence of EMI comprises detecting the condition indicative of the presence of EMI based on information provided by one or more sensors.

6. The method of claim 5, wherein detecting the condition indicative of the presence of EMI based on information provided by one or more sensors comprises detecting the condition indicative of the presence of EMI when the output provided by the one or more sensors indicates that the strength of a magnetic field exceeds a threshold strength.

7. The method of claim 5, wherein detecting the condition indicative of the presence of EMI comprises detecting the condition indicative of the presence of EMI when the output provided by the one or more sensors indicates that a strength of a magnetic field exceeds approximately 1.0 Tesla.

8. The method of claim 1, wherein detecting the condition indicative of the presence of EMI comprises receiving a command via wireless telemetry that instructs the IMD to switch into the second operating mode.

9. The method of claim 1, further comprising:

sensing cardiac electrical signals while operating IMD in the second operating mode,

wherein generating the multiphasic stimulation pulses comprises generating the multiphasic stimulation pulses as a function of the sensed cardiac electrical signals while operating the IMD in the second operating mode.

10. The method of claim 1, wherein the second operating mode comprises an asynchronous pacing mode.

11. The method of claim 1, further comprising suspending at least one of tachycardia detection, tachycardia therapy, fibrillation detection, fibrillation therapy, impedance measurements, or battery measurements while operating in the second operating mode.

12. The method of claim 1, further comprising:

detecting gradient magnetic fields while operating in the second operating mode; and

delivering pacing therapy as a function of the detected gradient magnetic fields.

13. The method of claim 12, further comprising:

determining whether a detected gradient magnetic field coincides with a timing of a pacing pulse;

delivering a monophasic pacing pulse when the detected gradient magnetic field does not coincide with the timing of the pacing pulse; and

delivering a multiphasic pacing pulse when the detected gradient magnetic field does coincide with the timing of the pacing pulse.

14. A non-transitory computer-readable medium comprising instructions that, when executed, cause an implantable medical device (IMD) to:

generate monophasic stimulation pulses while operating the IMD in a first operating mode;

detect a condition indicative of the presence of electromagnetic interference (EMI);

switch the IMD from the first operating mode to a second operating mode in response to detecting the condition indicative of the presence of EMI; and

generate at least one multiphasic stimulation pulses while operating the IMD in the second operating mode.

15. The non-transitory computer-readable medium of claim 14, wherein the instructions to generate multiphasic stimulation pulses comprises instructions to generate biphasic stimulation pulses having a positive phase and a negative phase.

16. The non-transitory computer-readable medium of claim 14, wherein the instructions to generate multiphasic stimulation pulses while operating in the second operating mode comprise instructions to generate multiphasic stimulation pulses in which each of the phases has substantially the same amplitude as the monophasic stimulation pulses generated while operating in the first operating mode.

17. The non-transitory computer-readable medium of claim 14, wherein the instructions to generate multiphasic stimulation pulses while operating in the second operating mode comprise instructions to generate multiphasic stimulation pulses in which a first phase of the multiphasic pacing pulse has an amplitude that is substantially the same as an amplitude of the monophasic stimulation pulses generated while operating in the first operating mode and a second phase of the multiphasic pacing pulse has an amplitude that is larger than the amplitude of the first pacing pulse.

18. The non-transitory computer-readable medium of claim 14, wherein the instructions to detect the condition indicative of the presence of EMI comprise instructions to detect the condition indicative of the presence of EMI based on one of information provided by one or more sensors and a command via wireless telemetry that instructs the IMD to switch into the second operating mode.

19. The non-transitory computer-readable medium of claim 14, further comprising instructions that, when executed, cause the IMD to suspend at least one of tachycardia detection, tachycardia therapy, fibrillation detection, fibrillation therapy, impedance measurements, or battery measurements while operating in the second operating mode.

20. The computer-readable medium of claim 14, further comprising instructions that, when executed, cause the IMD to:

detect gradient magnetic fields while operating in the second operating mode; and

deliver pacing therapy as a function of the detected gradient magnetic fields.

21. The computer-readable medium of claim 20, further comprising instructions that, when executed, cause the IMD to:

determine whether a detected gradient magnetic field coincides with a timing of a pacing pulse;

deliver a monophasic pacing pulse when the detected gradient magnetic field does not coincide with the timing of the pacing pulse; and

deliver a multiphasic pacing pulse when the detected gradient magnetic field does coincide with the timing of the pacing pulse.