Patent ID: 7587242

Claim:
A pacing operation of a software system implemented in a medical device to program pacing cycles based on a preferred atrial based pacing mode, the system comprising a computer readable medium having instructions that cause the following action in the medical device: implementing an atrial based pacing mode wherein ventricular pacing is not delivered while the medical device operates in the atrial based pacing mode; detecting whether a relatively reliable AV conduction condition is present based on a ratio of atrial events to ventricular events; switching to a dual chamber pacing mode in the event that the ratio of atrial events to ventricular events falls below a pre-defined acceptance ratio; attempting to detect, while operating in the dual chamber pacing mode, whether the relatively reliable AV conduction condition is present based on the ratio of atrial events to ventricular events and if the ratio of atrial events to ventricular events is greater than or equal to the pre-defined acceptance ratio, then mode switching to the atrial based pacing mode and if the ratio of atrial events to ventricular events remains below the pre-defined acceptance ratio, continuing the dual chamber pacing mode; and repeating the attempting step.