Patent ID: 7164946

Claim:
An active implantable medical device for cardiac rhythm management comprising: means for detecting spontaneous atrial and ventricular events, means for counting detected spontaneous atrial events; means for stimulating the ventricle and the atrium, means for operating the device in a DDD mode, means for operating the device in the AAI pacing mode with a ventricular detection, and means for commuting the mode between said DDD pacing mode and said AAI pacing mode according to a predetermined criteria, wherein said mode commuting means further comprises means for monitoring the following four conditions: a) a first counted number of consecutive detected sinus atrial events not followed by a detected spontaneous ventricular event that is greater than a first number (N 1 ); b) a second counted number of non-consecutive detected sinus atrial events not followed by a detected spontaneous ventricular event that is greater than a second number (N 2 ), said second counted number being counted during a monitoring window comprising a third number (N 3 ) of consecutive detected sinus atrial events; c) a third counted number of detected atrial events followed by a detected spontaneous ventricular event occurring after a delay, said delay being greater than a first duration, said third counted number being greater than a fourth value (N 4 ); and d) an interval separating two detected ventricular events that is greater than a second duration, and means for detecting an atrial extrasystole wherein a detected atrial extrasystole is not counted as a detected atrial event, wherein said mode commuting means further comprises switching from said AAI pacing mode to said DDD pacing mode in response to any one of said four conditions being met.