User's Manual

43
Timing Functions
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Negative AV Hysteresis
Purpose
In individual cases it can be necessary to promote ventricular pacing
and allow the least possible amount of conductions of the atrial sinus
rhythm. This can be especially necessary for patients with hypertrophic
obstructive cardiomyopathy (HOCM).
Description
With a sensed ventricular event (Vs), the function decreases the AV
delay and thereby promotes ventricular pacing. With a conventional
positive AV hysteresis, in contrast, the AV delay is increased to support
sinus rhythms.
Negative AV hysteresis is optional. It is possible to program the
negative AV hysteresis together with the negative AV repetitive
hysteresis. This ensures that the pacemaker paces with the shorter AV
delay for a programmable number of cycles when a sensed event
occurs.
The following table shows the correlation between the standard values
of the AV delay and the negative AV hysteresis:
AV Delays (Standard) Negative AV Hysteresis
100 100
120 100
130 100
140 100
150 100
160 120
170 120
180 130
190 140
200 150
225 170
250 180
300 200
Table 4: Negative AV Hysteresis