IMPLANTABLE MEDICAL DEVICE WITH AUTOMATIC SENSING THRESHOLD ADJUSTMENT IN NOISY ENVIRONMENT

• US 20120277606A1
• Filed: 04/28/2011
• Published: 11/01/2012
• Est. Priority Date: 04/28/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Ellingson, Michael L., Parish, Patrick L., Yoon, Hyun J.
• Granted Patent: US 10,010,716 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents

Abstract

An implantable medical system includes an implantable medical lead including at least one electrode and an implantable medical device (IMD) coupled to the implantable medical lead. The IMD includes a sensing module that obtains electrical signals on the implantable medical lead. The electrical signals on the implantable medical lead include cardiac signals as well as noise-induced signals. The IMD also includes a noise detection module that obtains noise signals independently of the electrical signals on the implantable medical lead. A control module of the IMD adjusts a sensing threshold of the sensing module in response to detecting the noise signals via the noise detection module. In instances in which the amplitude of the noise-induced signal on the lead is too large, the IMD may transition to a noise operating mode specifically designed to accommodate noisy environments.

Claims

1. An implantable medical system comprising:

an implantable medical lead including at least one electrode;

an implantable medical device coupled to the implantable medical lead, the implantable medical device comprising;

a sensing module that obtains electrical signals on the implantable medical lead, wherein the electrical signals include cardiac signals and noise-induced signals;

a noise detection module that obtains noise signals independently of the noise-induced signals on the implantable medical lead; and

a control module that adjusts a sensing threshold of the sensing module in response to detecting the noise signals via the noise detection module.

2. The system of claim 1, wherein the control module adjusts the sensing threshold in response to detecting a first one of the noise signals on the noise detection module.

3. The system of claim 2, wherein the control module further adjusts the sensing threshold as a function of an amplitude of one or more noise-induced signals obtained via the sensing module.

4. The system of claim 3, wherein the control module further adjusts the sensing threshold based on the amplitude of each noise-induced electrical signal subsequent to the first noise signal and obtained via the sensing module.

5. The system of claim 1, wherein the control module compares the amplitude of the noise-induced electrical signals obtained via the sensing module to a threshold amplitude and transitions to a noise operating mode when the amplitude of at least one of the noise-induced electrical signals exceeds the threshold amplitude.

6. The system of claim 5, wherein the threshold amplitude is one of a percentage of the amplitude of a previously sensed electrical signal on the implantable medical lead or an average amplitude of a plurality of previously sensed electrical signals on the implantable medical lead.

7. The system of claim 5, wherein the noise operating mode is an asynchronous pacing mode.

8. The system of claim 5, wherein the noise operating mode is a non-pacing mode.

9. The system of claim 1, wherein the control module determines that no noise signals have been detected via the noise detection module for a predetermined period of time and resets the sensing threshold to a value corresponding to the value used prior to detecting the noise signals.

10. The system of claim 1, further comprising a magnetic field detector that provides an output that is a function of a strength of a magnetic field to which the implantable medical device is exposed, wherein the control module adjusts the sensing threshold of the sensing module when the output of the magnetic field detector exceeds a threshold and the noise detection module detects at least one noise signal.

11. The system of claim 9, wherein the magnetic field detector comprises one of a Hall effect sensor and reed switch.

12. A method comprising:

sensing electrical signals on an implantable medical lead, wherein the electrical signals include cardiac signals and noise-induced signals;

sensing noise signals independently of the noise-induced signals on the implantable medical lead;

adjusting a sensing threshold used to sense the electrical signals of the implantable medical lead in response to sensing the noise signals independently of the noise-induced signals on the implantable medical lead.

13. The method of claim 12, wherein adjusting the sensing threshold comprises adjusting the sensing threshold in response to sensing a first one of the noise signals independently of the noise-induced signals on the implantable medical lead.

14. The method of claim 13, further comprising further adjusting the sensing threshold as a function of an amplitude of one or more of the noise-induced signals sensed on the implantable medical lead.

15. The method of claim 14, wherein further adjusting the sensing threshold comprises further adjusting the sensing threshold based on the amplitude of each noise-induced electrical signal on the implantable medical lead subsequent to the first noise signal.

16. The method of claim 12, further comprising:

comparing an amplitude of the noise-induced electrical signals on the implantable medical lead to a threshold amplitude; and

transitioning to a noise operating mode when the amplitude of at least one of the noise-induced electrical signals exceeds the threshold amplitude.

17. The method of claim 12, further comprising:

determining that no noise signals have been detected independently of the noise-induced signals on the implantable medical lead for a predetermined period of time; and

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resetting the sensing threshold to a value corresponding to the value used prior to detecting the noise signals.

18. The method of claim 12, further comprising:

detecting a magnetic field to which the implantable medical device is exposed;

wherein adjusting the sensing threshold comprises adjusting the sensing threshold when the magnetic field exceeds a threshold strength and the noise detection module detects at least one noise signal independently of the noise-induced signals on the implantable medical lead.

19. A computer-readable medium comprising instructions that, when executed, cause an implantable medical device to:

sense electrical signals on an implantable medical lead, wherein the electrical signals include cardiac signals and noise-induced signals;

sense noise signals independently of the noise-induced signals on the implantable medical lead;

adjust a sensing threshold used to sense the electrical signals of the implantable medical lead in response to sensing the noise signals independently of the noise-induced signals on the implantable medical lead.

20. The computer-readable medium of claim 19, wherein the instructions to adjust the sensing threshold comprise instructions that cause the implantable medical device to adjust the sensing threshold in response to sensing a first one of the noise signals independently of the noise-induced signals on the implantable medical lead.

21. The computer-readable medium of claim 19, further comprising instructions that, when executed, cause an implantable medical device to:

compare an amplitude of the noise-induced electrical signals on the implantable medical lead to a threshold amplitude; and

transition to a noise operating mode when the amplitude of at least one of the noise-induced electrical signals exceeds the threshold amplitude.

22. The computer-readable medium of claim 19, further comprising instructions that, when executed, cause an implantable medical device to:

determine that no noise signals have been detected independently of the noise-induced signals on the implantable medical lead for a predetermined period of time; and

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reset the sensing threshold to a value corresponding to the value used prior to detecting the noise signals.

23. The computer-readable medium of claim 19, further comprising instructions that, when executed, cause an implantable medical device to:

detect a magnetic field to which the implantable medical device is exposed;

wherein the instructions to adjust the sensing threshold comprises instructions to adjust the sensing threshold when the magnetic field exceeds a threshold strength and the noise detection module detects at least one noise signal independently of the noise-induced signals on the implantable medical lead.