Patent ID: 7844332

Claim:
A method comprising: detecting a first fast atrial pace with an implantable medical device (IMD), wherein the fast atrial pace concludes a timing interval that is shorter than or equal to a first threshold value; detecting a first condition, wherein the first condition comprises a sensed intrinsic first fast ventricular contraction that occurs within a specified first period of a most recently detected first fast atrial pace, wherein the fast ventricular contraction concludes a timing interval that is shorter than or equal to a second threshold value; and attempting, with the IMD, to decrease an atrioventricular (AV) delay at least in part in response to detecting the first condition, wherein attempting to decrease an AV delay includes: establishing a safe sensing ventricular sense or pace to atrial pace interval (VAp), wherein the safe sensing VAp timing interval is equal to a lowest-rate tachyarrhythmia rate interval threshold plus a first incremental value; setting a VAp escape timing interval equal to the safe sensing VAp timing interval, wherein said setting comprises decreasing an escape AV delay interval when detecting a VAp that is less than the safe sensing VAp interval; and calculating a ventricular sense or pace to ventricular pace interval (VVp), wherein if said calculated ventricular sense or pace to ventricular pace interval less the lowest-rate tachyarrhythmia rate interval threshold is less than a specified fixed minimum paced AV delay interval, then delaying generation of the ventricular pace pulse until after the minimum paced AV delay interval elapses following the safe sensing VAp timing interval.