User's Manual

36
Timing Functions
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Figure 8: Repetitive rate hysteresis
An existing spontaneous rhythm is thus once again able to inhibit the
pacemaker. This prevents any worsening of the hemodynamics, as
might otherwise occur in modes such as VVI pacing. The pacemaker
supports and stabilizes the spontaneous atrial rhythm in DDD or DDDR
modes. This prevents the undesirable suppression of the spontaneous
rhythm through overdrive, especially during periods of rest. Repetitive
rate hysteresis is only activated in the presence of a stable intrinsic
rhythm, that is, when continuous inhibition by the spontaneous rhythm
has occurred during the previous 180 cycles, at the very least.
Scan Rate Hysteresis
The scan rate hysteresis promotes a spontaneous rhythm during longer
phases of pacing.