64 Stratos LV/LV-T Technical Manual

In the case of ventricular sensed events outside of the AV delay and the VES discrimination interval after a ventricular extrasystole (VES or PVC), the basic interval starts without simultaneously starting an AV delay. To protect the atrium from retrograde conduction, an extended PMT protection window is started at the same time as the basic interval. If an atrial sensed event does not occur within the basic interval (but outside the refractory period), atrial pacing occurs after the basic interval has elapsed, and the basic interval and AV delay are restarted. Upon an atrial paced event, the AV safety interval starts with a long basic interval. If a ventricular sensed event occurs within the AV delay, ventricular pacing is inhibited.

Table 18 summarizes the intervals initiated by sensing or pacing. The table distinguishes between two kinds of ventricular sensed and ventricular paced events: VP at the end of the AV delay; VP at the end of the safety AV delay, referred to as ventricular safety pace (VSP); VS within the AV delay; and VS outside of the AV delay, referred to as “ventricular extrasystole” (VES).

Table 18: Timing Intervals

 

Timing

 

 

 

 

 

 

 

Event

 

 

 

 

 

 

Interval

 

 

Ap

 

As

 

As

 

 

Vp

 

Vsp

 

VS

 

VES

 

 

 

 

 

 

 

(PMT)

 

 

 

 

 

 

 

 

 

 

Basic interval

 

X

 

X

 

 

 

 

 

 

 

 

 

 

X

 

(DDD)*

 

 

 

 

 

 

 

 

 

 

 

 

 

Basic interval

 

 

 

 

 

 

 

 

X

 

 

 

X

 

X

 

(DDI)†

 

 

 

 

 

 

 

 

 

 

 

 

 

Atrial refractory

 

X

 

X

 

X

 

 

 

 

 

 

 

 

 

 

period‡

 

 

 

 

 

 

 

 

 

 

 

 

 

Upper basic rate

 

 

 

 

 

 

 

 

X

 

X

 

X

 

X

 

Ventricular

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Refractory

 

 

 

 

 

 

 

 

X

 

X

 

X

 

X

 

Period

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*This timing interval is also applicable to the following modes: DDD(R), VDD(R),

AAI(R), DDT, VDT, AAT, DOO(R) and AOO(R)

† In DDI(R), DVI(R), VVI(R), DVT(R), DDI/T(R) and V00(R) lower rate timing starts with Vp, and/or Vs, and/or Vs event outside of the AV delay and the VES

discrimination window (VES).

‡ In DDI(R), DDI/T, VDD(R), and VDT, the atrial refractory period will also be reset upon time-out of the VA-interval whether or not an atrial pulse is emitted.