NorthEast Monitoring, Inc. NEMM048-Rev-G
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Chapter 4 -Appendices
Appendix A: Maintenance and Care of the Recorder
Clean the outside of the recorder with a damp soft cloth between uses; use water and a non-abra-
sive liquid soap, as required. DO NOT use any abrasive cleaners, such as acetone, on the outside
of the recorder.
Disinfect as needed, following instructions from your infection control department. Sani-Cloth
germicidal surface wipes are recommended.
Sterilization is not needed.
Do not submerge the recorder in water.
At the end of their useful lives, all NorthEast Monitoring Inc. products should be disposed of
following local ordinances.
Appendix B: Pacemaker Detection
The recorder has a built-in pacemaker detection capability. This was designed to overcome the
problems inherent with the analysis of Holter recordings from patients with pacemakers.
A pacemaker is designed to initiate cardiac conduction by stimulating a spot on the myocardium
with a pulse of 1-4 volts and a duration of typically 250 to 2,000 microseconds. When this pulse
is seen at the surface recording electrodes it is significantly attenuated. For patients with a uni-
polar electrode configuration, the signal at the surface may range from under 50 to over 200
millivolts. When a bipolar lead configuration is used, the signal is typically much lower and is
in the range of 3 to 50 millivolts. Especially with the bipolar leads, the signal size is dependent
on the positions of the pacemaker lead and the surface electrodes.
The amplitude of the signal being referred to here is not the size of the "spike" commonly seen
on an ECG cart or bedside monitor. Since the duration of the pulse is short compared to a QRS
complex, normal ECG recorders will greatly attenuate the signal; in some cases it cannot be
seen at all. Also, some ECG recorders have devices which enhance the pace pulse to insure that
it will be displayed. Only very wide bandwidth recorders as are sometimes used in an electro-
physiology study will show the unmodified full amplitude of the pulse.
The recorder has the wide bandwidth ECG amplifiers necessary to pass the pacemaker pulse.
Since the pulse would still be too short to be recorded in a reliable manner at any practical sam-
pling rate for Holter recording, the pulse is detected by the recorder. The time of the pulse is
then digitally stored along with the Holter ECG data. When the data is analyzed, the pacemaker
pulse is displayed and used for the analysis.