User's Manual

77
Antitachycardia Functions
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Caution! When programming the DDD(R)+ overdrive mode,
you should check whether a pacemaker-mediated
tachycardia could be triggered on the basis of the
selected pacemaker program, and whether atrial
overdrive pacing might then develop.
If this is the case, we recommend programming
the maximum overdrive rate (MOR) for the atrial
overdrive to a value which is lower than the
expected rate of the pacemaker-mediated
tachycardia.
VES Lock-in Protection
Purpose
Terminating VES lock-in behavior by an atrial stimulus after detecting a
P wave during the refractory period. This function is particularly
suitable for patients with first-degree AV block.
Description
When ventricular extrasystoles (VES) occur, the following implant
behavior can occur:
— When VES occur, the basic interval and atrial refractory period
are restarted. This enables the P waves to fall within the atrial
refractory period.
— As a result, no ventricular pacing pulses are triggered by the P
waves. This implant behavior is termed VES lock-in.
— To terminate this VES behavior, an atrial stimulus is emitted
during the refractory period after the atrial sense event to
resynchronize the implant with the cardiac activity.
The VES lock-in protection function can be optionally activated, and
you have the option to set the number of detection cycles.