The present invention is directed to the problem of preventing episodes of
"AV Desynchronization Arrhythmia" (AVDA), a dual-chamber pacing behavior
that is initiated by a PVC or other ventricular event that is not closely
preceded by an atrial depolarization event. If the initiating PVC creates
retrograde conduction resulting in an atrial refractory-sensed event, and
should the succeeding AP fail to capture due to pacing within the atrial
refractory period (ARP) a repetitive AVDA sequence
(AP.sub.ineffectual-VP-AR.sub.refractory) can persist for an extended
period of time and symptoms of pacemaker syndrome can occur. After AVDA
detection, the following may occur: delivered atrial pacing (AP) energy
may be (dynamically) increased, a atrial pacing (AP) delay interval may
be implemented, a mode-switch may be executed, a patient notification
process may begin, a histogram may be recorded or processed, and/or a
combination thereof may be used in response the detected AVDA sequence.