Patent ID: 7693568

Claim:
A medical device, comprising: a sensor for detecting gradient magnetic fields; and a microprocessor for switching from a first signal processing mode to a second signal processing mode in response to detecting one or more MRI magnetic fields, wherein the microprocessor is configured to, while operating in the second signal processing mode, compare a timing of electrical signals received through at least one lead with the sensed incidences of gradient magnetic fields, maintain a counter to track a number of consecutive electrical signals that coincide with the sensed incidences of gradient magnetic field detection, ignore the electrical signals received through the at least one lead after the counter exceeds a predetermined number, compare the timing of electrical signals received through the at least one lead with an extrapolated series of cardiac events, and process electrical signals that coincide with the sensed incidences of gradient magnetic field detection as if the signal were actual cardiac events for control of therapy delivery when the electrical signals coincide with the extrapolated series of cardiac events and occur prior to the counter exceeding the predetermined number.