Patent ID: 7058448

Claim:
A dual chamber pacing system comprising: a pulse generator and electrode arrangement adapted to interact with a subject to deliver pacing pulses to the subject; a control unit connected to the pulse generator for normally operating the pulse generator in an atrial synchronized pacing mode; said control unit being supplied with signals detected from the subject via the electrode arrangement and detecting, from said signals, if and when atrial tachyarrhythmia occurs; a mode switch connected to the control unit for, in response to detection of atrial tachyarrhythmia, switching the pacing mode to a non-atrial synchronized ventricle stimulating mode and to switch the pacing mode back to the atrial synchronized mode after, or at a predetermined time following, detection of cessation of the atrial tachyarrhythmia; and a mode switch supervising unit including a counter for accumulating an accumulated number of mode switches from a starting time, and a comparator to which said accumulated number is supplied, said comparator comparing said accumulated number to a predetermined mode switch number threshold, and said mode switch supervising unit controlling said mode switch to lock said pacing mode to said non-atrial synchronized ventricular stimulating mode for a predetermined time period if said mode switch number exceeds said mode switch number threshold.