IMPLANTABLE MEDICAL DEVICE WITH AUTOMATIC TACHYCARDIA DETECTION AND CONTROL IN MRI ENVIRONMENTS

• US 20110137359A1
• Filed: 10/19/2010
• Published: 06/09/2011
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Schuster, Diane, Gilkerson, James O., Stubbs, Scott R., Doshi, Hiten J.
• Granted Patent: US 8,565,874 B2
• Time in Patent Office: Days
• US Class Current: 607/4
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An implantable medical device (IMD) includes a lead having one or more sensing electrodes and one or more therapy delivery electrodes, and a sensor configured to detect the presence of static and time-varying scan fields in a magnetic resonance imaging (MRI) environment. A controller, in electrical communication with the lead and the sensor, is configured to process signals related to tachycardia events sensed via the one or more sensing electrodes and to deliver pacing and shock therapy signals via the one or more therapy delivery electrodes. The controller compares the sensed static and time-varying scan fields to static and time-varying scan field thresholds. The controller controls delivery of anti-tachycardia pacing and shock therapy signals as a function of the detected tachycardia events, the comparison of the sensed static scan field to the static scan field threshold, and the comparison of the time-varying scan fields to the time-varying scan field thresholds.

Claims

1. An implantable medical device (IMD) comprising:

a lead including one or more sensing electrodes and one or more therapy delivery electrodes;

a sensor configured to detect the presence of static and time-varying scan fields in a magnetic resonance imaging (MRI) environment; and

a controller, in electrical communication with the lead and the sensor, configured to process signals related to tachycardia events sensed via the one or more sensing electrodes and to deliver pacing and shock therapy signals via the one or more therapy delivery electrodes, the controller further configured to compare the sensed static and time-varying scan fields to static and time-varying scan field thresholds, wherein the controller controls delivery of anti-tachycardia pacing and shock therapy signals as a function of the detected tachycardia events, the comparison of the sensed static scan field to the static scan field threshold, and the comparison of the time-varying scan fields to the time-varying scan field thresholds.

2. The IMD of claim 1, wherein the controller disqualifies the tachycardia events to inhibit delivery of the anti-tachycardia pacing and shock therapy signals when the static and time-varying scan field thresholds are exceeded.

3. The IMD of claim 1, wherein the controller processes sensed tachycardia events, enables delivery of the anti-tachycardia pacing signals, and inhibits delivery of the shock therapy signals when the static scan field threshold is exceeded and the time-varying scan field thresholds are not exceeded.

4. The IMD of claim 1, wherein the controller processes sensed tachycardia events and enables delivery of the anti-tachycardia pacing and shock therapy signals when the neither of the static and time-varying scan field thresholds is exceeded.

5. The IMD of claim 1, wherein the controller is operable to switch the IMD between a normal mode and an MRI mode, and wherein the sensor is disabled in the normal mode and the sensor is enabled in the MRI mode.

6. The IMD of claim 5, wherein the controller automatically switches the IMD from the MRI mode to the normal mode when the static scan field is less than the static scan field threshold.

7. The IMD of claim 1, wherein the controller further controls delivery of anti-tachycardia pacing and shock therapy signals as a function of programmed therapy settings.

8. A method for operating an implantable medical device (IMD), the method comprising:

sensing static and time-varying scan fields in a magnetic resonance imaging (MRI) environment;

comparing the sensed static and time-varying scan fields to static and time-varying scan field thresholds;

detecting signals related to tachycardia events; and

controlling delivery of anti-tachycardia pacing and shock therapy signals as a function of the detected tachycardia events, the comparison of the sensed state electromagnetic field to the static scan field threshold, and the comparison of the time-varying scan fields to the time-varying scan field thresholds.

9. The method of claim 8, wherein the controlling step comprises:

delivering anti-tachycardia pacing and/or shock therapy signals when a tachycardia event is detected and neither of the static and time-varying scan field thresholds is exceeded.

10. The method of claim 8, wherein the controlling step comprises:

delivering the anti-tachycardia pacing signals and inhibiting delivery of the shock therapy signals when signals related to a tachycardia event is detected and the static scan field threshold is exceeded and the time-varying scan field thresholds are not exceeded.

11. The method of claim 8, wherein the controlling step comprises:

inhibiting delivery of the anti-tachycardia pacing and shock therapy signals and disqualifying detected tachycardia events when the static and time-varying scan field thresholds are exceeded.

12. The method of claim 8, wherein the controlling step further comprises controlling delivery of anti-tachycardia pacing and shock therapy signals as a function of programmed therapy settings.

13. The method of claim 8, wherein, prior to the sensing step, the method further comprises:

switching the IMD from a normal mode to an MRI mode.

14. The method of claim 13, and further comprising:

automatically switching the IMD from the MRI mode to the normal mode when the static scan field is less than the static scan field threshold.

15. A method for operating an implantable medical device (IMD), the method comprising:

sensing static and time-varying scan fields in a magnetic resonance imaging (MRI) environment;

comparing the sensed static and time-varying scan fields to static and time-varying scan field thresholds;

detecting signals related to tachycardia events; and

controlling delivery of anti-tachycardia pacing and shock therapy signals, wherein the controlling step comprises;

delivering anti-tachycardia pacing and/or shock therapy signals when a tachycardia event is detected and neither of the static and time-varying scan field thresholds is exceeded;

delivering the anti-tachycardia pacing signals and inhibiting delivery of the shock therapy signals when signals related to a tachycardia event is detected and the static scan field threshold is exceeded and the time-varying scan field thresholds are not exceeded; and

inhibiting delivery of the anti-tachycardia pacing and shock therapy signals and disqualifying detected tachycardia events when the static and time-varying scan field thresholds are exceeded.

16. The method of claim 15, wherein, prior to the sensing step, the method further comprises:

switching the IMD from a normal mode to an MRI mode.

17. The method of claim 16, and further comprising:

automatically switching the IMD from the MRI mode to the normal mode when the static scan field is less than the static scan field threshold.

18. The method of claim 15, wherein the controlling step further comprises controlling delivery of anti-tachycardia pacing and shock therapy signals as a function of programmed therapy settings.