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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.