NorthEast Monitoring, Inc. NEMM019-Rev-O
Page 29 of 35
DR200/HE & DR300 Operator’s Manual
Appendices: Appendix C: Pacemaker Detection
False pacemaker detections are primarily caused by
electrical events. Any external electrical signal that
is coupled to the patient electrodes which looks like
a pacemaker pulse will of necessity be stored by the
recorder. The most common form of electrical sig-
nal that can look like a pacemaker signal is an elec-
trostatic discharge (ESD) or "spark." These happen
very frequently in dry weather but also occur, at a
lower rate, under humid conditions.
Fortunately most ESD spikes as seen at the patient
electrodes are of shorter duration or of lower ampli-
tude than the real pacemaker pulses. While there is
no absolute limit to the size or duration of the ESD
pulses, the recorder ignores all pulses that are less
than 150 micro-seconds long or are less than two
millivolts in size.
As pacemakers are normally programmed to a pulse
width greater than 200 microseconds, this does not
cause a loss of detection. The requirement that the
pacemaker pulse be at least two millivolts in size is
not a common problem.