Stratos LV/LV-T Technical Manual 93

The features of Atrial Overdrive pacing include:

After every atrial sensed event (non-AES), the pacing rate is increased by a programmable rate increase above the last P-P interval (2… (2)…10 ppm). If the intrinsic rate does not continue to rise after the programmable number of cycles (overdrive pacing plateau), the overdrive pacing rate is reduced in steps of 1 ppm. In each instance, the rate drop occurs after the programmed number of cycles has been completed. Values between 1 and 32 cycles can be assigned to the overdrive pacing plateau.

The pacing rate is reduced until an atrial event is again sensed. Afterwards, the overdrive pacing cycle begins again at an increased rate.

Protection Function of the Algorithm

Preventive overdrive pacing (Overdrive Mode) consists of different functions that become effective at high atrial rates:

When the programmed maximum overdrive rate (MOR, standard setting 120 ppm, (90… (5)…160 ppm) is exceeded as with atrial tachycardias, the algorithm is automatically deactivated. If the rate falls below the MOR, the overdrive algorithm is reactivated.

The function is deactivated when the mean of the atrial rate over a period of twelve hours exceeds the average safety rate (“overdrive average rate limit = OAR”). The average safety rate is determined indirectly from the maximum overdrive pacing rate (MOR minus 10ppm). If the average safety rate is exceeded, the pacing rate is incrementally reduced to the basic rate. If the average atrial heart rate falls below the average safety rate, the preventive overdrive pacing is reactivated (activation/deactivation only in a 12 hour rhythm).

If the function is deactivated for a third time because the average safety rate has been exceeded, overdrive pacing remains OFF permanently. The overdrive mode can not be reactivated until after the pacemaker has been programmed.