Medtronic PROTECTA XT DR D314DRG, Clinician Manual

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Figure 80. Operation of MVP mode and Mode Switch
AAI(R)
DDIR DDD(R)
Normal Sinus, AV Conduction
AV Block AT/AF
Atrial Refractory Period – When MVP is operating in AAIR or AAI mode, the Atrial
Refractory Period is not programmable. Instead, it is automatically adjusted according to
the current heart rate: 600 ms for rates below 75 bpm and 75% of the ventricular interval for
rates at or above 75 bpm.
PVCs and ventricular tachyarrhythmias – When MVP is operating in AAIR or AAI mode,
the device inhibits atrial pacing in response to PVCs, PVC runs, and ventricular
tachyarrhythmia episodes. This behavior is intended to prevent unnecessary atrial pacing
when the ventricular rate is faster than the pacing rate. It also allows tachyarrhythmia
detection features to operate without disruption from blanking periods caused by atrial
pacing.
After cardioversion or defibrillation therapy – After cardioversion or defibrillation
therapy, the device operates in the DDDR or DDD mode for 1 min. If an AV conduction check
was scheduled to occur during this time, the check is postponed until after 1 min has passed.
7.3.3 Programming considerations for MVP mode
V-V interval variations – Depending on the patient’s intrinsic rhythm and conduction, the
MVP mode allows V-V interval variations and occasional pauses of up to twice the lower
rate interval. See Figure 77 and Figure 79.
Medtronic PROTECTA™ XT DR D314DRG
Clinician Manual 227