7 ECG, Arrhythmia, ST and QT Monitoring
You should choose a lead as primary or secondary lead that has these characteristics:
• the normal QRS complex should be either completely above or below the baseline and it should not
be biphasic. For paced patients, the QRS complexes should be at least twice the height of pace
• the QRS complex should be tall and narrow
• the P-waves and the T-waves should be less than 0.2 mV.
For ease of identification on the screen, the pacer spikes can be configured to have a fixed size. They are
then shown in the background as a dotted lines. The length of the dotted line is fixed to the wave
channel height and is independent of the actual pacer amplitude.
Setting the Paced Status (Pace Pulse Rejection)
In the Setup ECG menu, select Paced to toggle between Yes and No.
You can also change the paced status in the Patient Demographics window.
When Paced is set to Yes:
– Pace Pulse Rejection is switched on. This means that pacemaker pulses are
not counted as extra QRS complexes.
– pace pulse marks are shown on the ECG wave as a small dash (only when
the pacer spikes are not configured to have a fixed size)
– the paced symbol is displayed on the main screen.
When Paced is set to No, pacer spikes are not shown in the ECG wave. Be
aware that switching pace pulse rejection off for paced patients may result in
pace pulses being counted as regular QRS complexes, which could prevent an
asystole event from being detected.
Avoiding Pace Pulse Repolarization Tails
Some unipolar pacemakers display pace pulses with repolarization tails. These tails may be counted as
QRSs in the event of cardiac arrest or other arrhythmias.
If you note a visible repolarization tail, choose a lead that decreases the size of the repolarization tail.
Monitoring Paced Patients