User's Manual

37
Timing Functions
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If scan hysteresis is activated, the pacemaker will reduce the pacing
rate temporarily to the hysteresis rate after every 180 consecutive
atrial paced events. The number of scan intervals can be programmed
(See Figure 9).
Figure 9: Scan rate hysteresis
If no intrinsic event is detected during the scan intervals, pacing at the
basic rate is resumed (at the sensor rate in rate-adaptive mode).
Scanning for a spontaneous rhythm is repeated after an additional 180
cycles.
Reaction to Vasovagal Syncopes and Carotid Sinus Syndrome
The scan rate hysteresis can be used in conjunction with the repetitive
rate hysteresis to treat patients with vasovagal syncopes and carotid
sinus syndrome of a primarily cardioinhibitory type. The following
programming is recommended for this purpose.
Basic rate Increased value, for example 90 ppm
Rate hysteresis Such that the hysteresis rate at rest is always lower
than the intrinsic rhythm (e.g., -50)
Scan rate hysteresis Enabled, with the number of cycles set according to
the patient's condition
Repetitive rate
hysteresis
Enabled, with a low number of cycles