Patent ID: 8565874

Claim:
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 is configured to control 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 such that: when the static and time-varying scan field thresholds are exceeded, the controller disqualifies the tachycardia events to inhibit delivery of the anti-tachycardia pacing and shock therapy signals, and when the static scan field threshold is exceeded and the time-varying scan field threshold is not exceeded, the controller processes sensed tachycardia events, delivers the anti-tachycardia pacing signals upon detection of the tachycardia events, and inhibits delivery of the shock therapy signals.