GE MAC 1200, Operator'S Manual

Page: 123 / 200

Revision C MAC 1200/1200 ST 9-3
2012250-021
Pacemaker Patients / Recording During Defibrillation: Recording ECGs of Pacemaker Patients
Recording ECGs of Pacemaker Patients
Due to the slow paper speed, it is not possible to display pacer pulses
directly on the ECG recording. At a paper speed of 50 mm/s and a pulse
duration of only 0.5 ms, the width of the recorded pacer pulse would be
only 0.025 mm.
For this reason, the recorder reduces the pulse amplitude and expands
the pulse width, so that the pacer pulse is easier to identify. The MAC
1200/1200 ST records the pulse with the correct polarity, with a width of
5 ms and with the same amplitude in all leads (depending on the polarity
of the pacer pulse in leads I and II, the pacer pulse in lead III may be
suppressed) The amplitude of the reverse current in the figure below
shows an ECG recording with pacer pulses.
ECG Recording with Pacer Pulses
:$51,1*
INCORRECT HR, NO HR ALARM — If several adverse
conditions exist at once, the possibility that the pacer pulses
are interpreted (and counted) as QRS complexes should be
considered. At the same time, however, QRS complexes
might be suppressed in certain situations. Therefore,
pacemaker patients should always be watched closely.
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