Implementation of automatic mode switching in Pacesetter's Trilogy DR+ and affinity DR pulse generators

This paper reviews the rationale for and key features of the automatic mode switching algorithms in the Pacesetter Trilogy DR+ and Affinity DR dual chamber rate-modulated pulse generators along with the subtile differences between these two devices. Critical parameters include independently programmable maximum tracking, maximum sensor and atrial tachycardia detection rates and the post-ventricular atrial blanking period. Guidance is provided as to the assessment of the presence or absence of a far-field R- wave, details as to how the filtered atrial rate interval is calculated in the presence of increasing and decreasing atrial rates and the impact of this calculation on entering or exiting mode switching. Guidelines are provided in programming the sensor using the prediction model. Various methods of assessing the behavior of the mode switch algorithm are provided using multiple different event counters including the automatic mode switch histogram, the event histogram, the event record, and the patient triggered event record and/or event snapshot. The use of these event counters to assess the effectiveness of any therapeutic intervention, be it pharmacologic or a changes in the pacing parameters, is discussed.