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78  Stratos LV/LV-T Technical Manual   
2.3.8  Ventricular Refractory Period 
In all modes in which a ventricular depolarization can be sensed, 
the Stratos CRT-Ps begin a ventricular refractory period after 
each ventricular event, using a standard value of 250 ms 
(programmable as 150…(35)…500 ms). 
2.3.9 AV Delay 
2.3.9.1  Dynamic AV Delay 
Programmable values 
Lower AV limit: 
Nominal value: 60 ppm, (30…(10)…180 ppm) 
Upper AV limit: 
Nominal value: 130 ppm, (30…(10)…180 ppm) 
AV Interval Length for Low Rate: 
Standard value: 150 ms (programmable 15… (5) …300 ms) 
The AV delay defines the interval between an atrial paced or 
sensed event and the ventricular pacing pulse. The AV delay 
can be dynamically programmed in DDD(R), DDT(R)A and 
VDD(R) modes. In all other mode the AV delay is a fixed value.  
If the CRT-P is programmed to a dual chamber sensing mode, 
an intrinsic ventricular event falling within the AV delay will inhibit 
the ventricular pacing pulse.  If not contraindicated, a longer AV 
delay can be selected to increase the probability of ventricular 
output pulse inhibition.  Short AV delays are available for testing 
purposes or if ventricular pre-excitation is desired (i.e., 
hemodynamic considerations).  When the dynamic AV delays 
are programmed, the dynamics are calculated from the 
difference between two atrial sense events (As or Ap). 
Dynamic AV Delay provides independent selection of AV Delays 
from five rate ranges at pre-set AV Delay values.  In addition, the 
AV Delay after atrial pace events can be differentiated from the 
AV interval after atrial sense events for dual chamber pacing 
modes.