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6 ECG, Arrhythmia, and ST Monitoring Switching Arrhythmia Analysis On and Off
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Switching Arrhythmia Analysis On and Off
1 In the Setup Arrhythmia menu, select Arrhythmia to toggle between On and Off.
2 Select the Confirm pop-up key which appears at the bottom of the screen.
Be aware that when arrhythmia analysis is switched off,
–the message
Arrythmia OFF appears beside the ECG wave, if configured to do so
– only the HR-related alarms are detected (the asystole alarm, the ventricular fibrillation/ventricular
tachycardia alarm, the extreme tachycardia/extreme bradycardia alarms, the high heart rate/ low
heart rate alarms)
– HR High and HR Low alarms behave like normal yellow alarms, no timeout periods are active.
Choosing an ECG Lead for Arrhythmia Monitoring
It is important to select a suitable lead for arrhythmia monitoring.
Guidelines for non-paced patients are:
– QRS should be tall and narrow (recommended amplitude > 0.5 mV)
– R-Wave should be above or below the baseline (but not bi-phasic)
– T-wave should be smaller than 1/3 R-wave height
– the P-wave should be smaller than 1/5 R-wave height.
For paced patients, in addition to the above, the pace pulse should be:
– not wider than the normal QRS
– the QRS complexes should be at least twice the height of pace pulses
– large enough to be detected, with no re-polarization.
To prevent detection of P-waves or baseline noises as QRS complexes, the minimum detection level for
QRS complexes is set at 0.15 mV, according to AAMI-EC 13 specifications. Adjusting the ECG wave
size on the monitor display (gain adjustment) does not affect the ECG signal which is used for
arrhythmia analysis. If the ECG signal is too small, you may get false alarms for pause or asystole.
Aberrantly-Conducted Beats
As P-waves are not analyzed, it is difficult and sometimes impossible for the monitor to distinguish
between an aberrantly-conducted supraventricular beat and a ventricular beat. If the aberrant beat
resembles a ventricular beat, it is classified as ventricular. You should always select a lead where the
aberrantly-conducted beats have an R-wave that is as narrow as possible to minimize incorrect calls.
Ventricular beats should look different from these ‘normal beats’. Instead of trying to select two leads
with a narrow R-wave, it may be easier to just select one lead and use single lead arrhythmia
monitoring. Extra vigilance is required by the clinician for this type of patient.
Atrial Fibrillation and Flutter
Since P-waves are not analyzed, it is not possible to discriminate atrial rhythms. If there is constant
variance in the R-R interval, the rhythm is classified as Irregular. It is extremely important for accurate
analysis of the rhythm to have p-waves with an amplitude of less than 1/5 the height of the R-wave or
< 0.15 mV. If the p-waves are larger than this, they may be counted as QRS complexes.