User's Manual

126
Handling and Implantation
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Sensing Functions
A measuring function for the P- and R-wave amplitudes is available for
testing the sensing function. This test measures the minimum, mean,
and maximum amplitude values over several cycles. An optional
realtime printout contains an amplitude annotation of the measured
value in each individual cycle.
Additionally, the pacemaker provides an intracardiac electrogram with
marker signals. The triggered pacing mode may also be selected, at
which the pacemaker triggers pacing pulses simultaneously with the
sensing events. This enables easy identification of sensed events in the
ECG.
Particularly with unipolar sensing, the sensing function should be
checked for susceptibility to interference from skeletal muscle
potentials. If “oversensing” occurs, reducing sensitivity (setting a
higher value) and/or programming the pacemaker to bipolar sensing (if
a bipolar lead is in place) should be considered.
Retrograde Conduction
Ventricular events that are not synchronized with the atrium (such as
VES) can be conducted to the atrium through retrograde conduction.
The sensing function in the atrium may result in a pacemaker-
mediated tachycardia (PMT).
To prevent PMT, the pacemaker's atrial refractory period must be
longer than the sum of the AV delay and the retrograde conduction
period.