Medtronic PROTECTA XT DR D314DRG, Руководство для клиницистов

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9.6.2.4 Synchronizing atrial cardioversion
After charging is complete, the device starts a synchronization interval on the next sensed
or paced ventricular event. The synchronization interval is equal to the Lower Rate pacing
interval. The device uses the synchronization interval to identify the R-wave to deliver the
shock. The atrial cardioversion therapy is delivered on the second ventricular event that is
outside the ventricular refractory period. The length of the ventricular refractory period is set
by the shared programmable parameter called the Minimum R-R Interval. During
synchronization, a ventricular event inside the ventricular refractory period restarts the
synchronization interval. The timing of a typical synchronization for atrial cardioversion is
shown in Figure 211.
The device attempts to synchronize atrial cardioversion with sensed ventricular events. In
the absence of sensed ventricular activity, the device delivers the atrial shock when the
synchronization interval expires. This allows treatment of atrial tachyarrhythmias in patients
with complete heart block.
Figure 211. Atrial cardioversion synchronization
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EGM2: Vtip to Vring
Marker Channel
Ventricular timing
during
synchronization
Refractory
1 The device does not deliver CV therapy on any of these ventricular events because each one
is inside the ventricular refractory period.
2 The device delivers the CV therapy on the second ventricular event that is outside the ventricular
refractory period.
3 Programmed pacing resumes after the next ventricular event.
The atrial cardioversion therapy aborts if 12 refractory sensed ventricular events occur.
Aborting the therapy in this situation prevents delivery during the vulnerable period
preceding a ventricular depolarization. An atrial cardioversion therapy delivered during this
vulnerable period might induce a ventricular tachyarrhythmia.
Medtronic PROTECTA™ XT DR D314DRG
410 Clinician Manual