Atrial escaped interval
The interval from a paced or sensed ventricular event to the
next scheduled paced atrial event.
Figure 15: Intervals and timing in DDD mode. Core Pace Module 6. Single and
Dual Pacemaker timing ppt presentation 2003 12
DDD Examples The Four Faces of DDD • Atrial and ventricular pacing
– Atrial pace re-starts the lower rate timer and
triggers an AV delay
• The PAV expires without being inhibited by a ventricular sense, resulting
in a ventricular pace
A P A P V P V P On this slide, we see AV sequential or dual chamber pacing. Both the atrium
and the ventricles are being paced, first the atrium and then the ventricle.
Looking at the 2 complexes shown:
The pacemaker begins by pacing in the atrium. 2 timers are started:
• The lower rate timer
• The AV Interval timer
Intensive Care: Learning Packages Intensive Care Unit
Pacemaker Learning Package LH_ICU2016_Learning_Package_Pacemaker_Learning_Package
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The AV Interval timer expires WITHOUT BEING INHIBITED by a
ventricular sense – so the pacemaker paces in the ventricle.
The lower rate timer continues.
If it expires without being inhibited by an atrial event (as
shown above), the pacemaker paces in the atrium, and the
cycle begins again.
IN SUMMARY Intervals and timing can be a hard concept to understand, but fortunately
the pacemaker calculates all these intervals for us. It is important to know
how pacing works using its sensing, output and timing mechanisms as it helps
For example: looking at the above slide and DDD mode
• Why does the pacemaker’s AV interval timer expire without being inhibited?
Perhaps the patient has a heart block
Perhaps the patient has delayed AV conduction — the
patient’s PR interval is longer than the PAV programmed into
• Why does the pacemaker’s atrial escape interval expire?
The patient’s sinus rate is less than the pacemaker’s
programmed rate (i.e. sinus bradycardia)