BIOTRONIK Evia DR, Technical Manual

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Evia Technical Manual 65
7.5 Timing Features
Features related to pulse generator timing cycles.
7.5.1 Refractory Periods
Immediately upon sensing or pacing, the pulse generator starts a
refractory period in the same channel. During the refractory
period, intracardiac signals are ignored. This prevents the pulse
generator from responding to the depolarization signal or the
repolarization signal (T-wave) that might otherwise result in
inappropriate inhibition or triggering.
If the pulse generator is programmed to dual chamber sensing,
the refractory periods are independently programmable for each
sensing channel. There are two refractory periods in the atrium:
•
Regular atrial refractory period, which is automatically
adjusted by the Auto Aref functionality
•
PVARP is started with each ventricular pace outside of
the AV delay. In DDI mode, PVARP is also started with a
regular ventricular sense
•
PVARP after PVC is started after a premature
ventricular sensed event (PVC)
Far-field protection is activated in the atrium for ventricular
sensed and paced events. The pulse generator's ventricular
refractory period is always initiated by a sensed or paced
ventricular event.
C
AUT IO N
Short Pacing Intervals
– Use of short pacing intervals (high
pacing rates) with long atrial and/or ventricular refractory
periods may result in intermittent asynchronous pacing and,
therefore, may be contraindicated in some patients.
7.5.2 PVARP
The Post Ventricular Atrial Refractory Period (PVARP) is a
function in the pacemaker to help prevent Pacemaker Mediated
Tachycardia (PMT), by preventing false classification of a
retrograde conduction as an atrial event.