GE MAC 1600, Operator'S Manual

Page: 63 / 162

Recording a Resting ECG
2028451-182B MAC™ 1600 5-13
Recording ECGs of Pacemaker Patients
Because of slow paper speed, pacer pulses cannot be displayed directly on
the ECG recording. For example, with 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.
If Pace Enhance is enabled, the recorder reduces the pulse amplitude
and expands its width to make pacer pulses easier to identify. The
system records the pulse with the correct polarity, a width of 5 ms, and
equal 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
following figure of an ECG recording with pacer pulses shows the
amplitude of the reverse current.
047A
WARNING
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.
Recording ECGs during Defibrillation
This equipment is protected against the effects of cardiac defibrillator
discharge to allow the ECG trace to return after defibrillation, as
required by test standards.
The patient signal input is defibrillation-proof; it is not necessary to
remove the ECG electrodes before defibrillating the patient.
However, when using stainless steel or silver electrodes, the defibrillator
discharge current may cause the electrodes to retain a residual charge,
causing an electrode polarization or DC offset voltage. This will block
ECG signal acquisition for several minutes. If polarizing electrodes are
used, GE recommends that the leadwires be disconnected from the
patient before delivering the shock.
To prevent polarization, GE recommends the use of non-polarizing
disposable electrodes with defibrillation recover ratings as specified in
AAMI EC12 3.2.2.4 (MMS PN 9623-105 Silver MacTrodes, MMS spec