Abstract: An implantable medical device is provided having a telemetry circuit antenna; a lead having an elongated body for carrying a conductor extending from a proximal connector to a distal electrode; a circuit for measuring voltage induced on the telemetry circuit antenna and generating an antenna voltage signal corresponding to the measured voltage on the antenna; a circuit for measuring voltage induced on the lead conductor and generating a lead voltage signal corresponding to the measured voltage on the lead; and processing circuitry for receiving the antenna voltage signal and the lead voltage signal and for generating an MRI detection signal if the antenna voltage signal and the lead voltage signal meet an MRI detection requirement. The device further includes control circuitry for providing a safeguard response to the MRI detection signal.

Abstract: In general, the invention is directed to techniques for electrically detecting physiological events. The physiological events may include cardiac events such as R waves or p waves. In addition, the physiological events may include respiratory events. In general, the techniques involve converting an analog physiological signal to a digital delta value, correlating the digital delta value with a correlation template, and detecting a physiological event based on an output of the correlation. A digital correlation-based technique, as described herein, is implemented to reliably detecting physiological events, particularly for very small signals captured in the presence of significant background noise.

Abstract: A system and method for acquiring and processing an EGM signal during a pacing event, wherein a unique converter code is generated upon digitizing of the EGM signal and encrypted in the EGM signal to demarcate a transient event. The system further provides dynamic filtering of the EGM signal and subsequent detection of an intrinsic event signal during the pacing event, from which rhythm events may be diagnosed and classified.