Patent ID: 7953483

Claim:
An active implantable medical device, able to operate in at least one AAI operating mode with ventricular sensing, comprising: means for sensing ventricular and atrial spontaneous events; means for delivering atrial pacing pulses (A 1 , A 2 , A 3 ); means able to apply, after delivery of an atrial pacing pulse, concurrently with means for sensing ventricular events, a refractory period (PR) and a safety window (FS) of predetermined durations, the predetermined duration of the safety window being longer than the predetermined duration of the refractory period; means for sensing ventricular events occurring out of the safety window (R 0 , R 1 , R 2 , R 3 ) and ventricular events occurring within the safety window after the end of the refractory period (r 1 , r 2 , r 3 ) in response to the atrial pacing pulse (A 1 , A 2 , A 3 ); means for determining the beginning of a spontaneous ventricular cycle in response to sensing of the ventricular events; means for measuring ventricular coupling intervals between successive ventricular events of the sensed ventricular events (R 1 -r 2 , r 2 -R 2 , R 2 -r 3 ,); means for detecting a ventricular tachycardia by analyzing the ventricular coupling intervals; and means for modulating atrial escape interval (AEI) in response to the ventricular coupling intervals to discriminate a stable ventricular tachycardia from an unstable ventricular tachycardia.