Patent ID: 7082328

Claim:
A method of operating a pacing system to respond to a presence of electromagnetic interference tending to corrupt the features of an electrogram, comprising: accumulating data from sense events and delivered pacing pulses over a predetermined time interval, deriving a mean heart rate from the accumulated data, and deriving a pacing dependency percentage representing the ratio of delivered pacing pulses to the sum of delivered pacing pulses and sensed events over the predetermined time interval; declaring an interference state if electromagnetic interference tending to corrupt the features of the electrogram is detected; determining whether the patient is pacemaker dependent or pacemaker independent from the pacing dependency percentage; during the declared interference state: setting a pacing mode of the pacing system to an inhibited pacing mode if the patient is determined to be pacemaker independent, whereby pacing pulses are not delivered to the heart chamber; setting the pacing mode to a fixed rate pacing mode if the patient is determined to be pacemaker dependent, whereby a pacing escape interval is not restarted by a sense event and pacing pulses are delivered to the heart chamber at a fixed rate; and adjusting the pacing escape interval to provide an interference state pacing rate exceeding the mean heart rate by a predetermined increment; and operating the pacing system in the interference state pacing mode at the interference state pacing rate, whereby the patient's heart is paced while minimizing occurrences of parasystole.