User's Manual

ST/AR Arrhythmia Monitoring
6-28 ECG and Arrhythmia Monitoring
For additional information on the ST/AR Algorithm, refer to the Arrhythmia
Monitoring ST/AR Algorithm Application Note.
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 Alarm
The MX40 performs atrial fibrillation analysis using information about the
RR irregularity, PR interval variability, and P-wave variability.
In order to generate an Afib alarm the following criteria must be detected
for 1 minute:
 normal beat RR intervals must be irregular
 PR interval deviation must be large
 P-wave region must not match well
Atrial fibrillation analysis is only available for adult patients and atrial
fibrillation detection cannot be performed on PVCs or Paced beats.
An *End AFIB alarm will occur when no atrial fibrillation waveform is
detected for a configured delay time.
Since most atrial flutters have regular RR intervals, they cannot be detected
by the atrial fibrillation algorithm.
An *AFIB alarm can be falsely detected in the presence of:
 sinus arrhythmia
 muscle noise, or
 electrode motion artifact