NorthEast Monitoring, Inc. NEMM048-Rev-G
Page 16 of 21
DR400 User Manual
Appendices: Appendix C: Accessories
At recording time, it is desirable to have the
recorder be as sensitive to the pacemaker pulse as
possible so pulses will not be missed. A conflicting
requirement is that there should be as few false
pacemaker detections as possible.
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.
Appendix C: Accessories
Contact your distributor to purchase accessories for
the DR400.
NEMEL002.
1-lead electrode patch
NEMEL003.
3-lead electrode patch
NEMCA161.
16” Reusable patient extension lead
wire (use with NEMEL002 for 3-channel)
NEMCA162.
3-lead adapter cable with lanyard
NEMH238.
Lanyard for 3-lead adapter
NEMH226.
DR400 docking station.
NEMP00511.
USB Power Port Adapter LV Sun
with 3’ power cord.
NEMP00513.
Sena Parani Mfg PN SD1000U:
Bluetooth USB Adapter for Serial Port
Appendix D: Extraction of
ECG data on 3-channel
It is possible to retrieve the raw ECG files from the
Holter files. For all 3-channel data, the process
results in three files, one for each channel. Each file
is then in the form of a binary file consisting of 16-
bit words (little endian) with each word represent-
ing one sample. The sampling is at 180 samples per
second. The data is scaled so that the least signifi-
cant bit has a value of 12.5 uv. If a pacemaker pulse
was detected, the sample at the time of detection
will be replaced by the value 0x8000.
To generate these files, first analyze the data (actu-
ally the flash.dat) from the recorder using any com-
patible version of the LX Analysis program. At the
completion of this there will be a file "datacard.dat"
in the patient directory. The full path is by default:
c:\nm\pat\xx\datacard.dat
where xx is the number of the patient dataset.
This can be seen in the "No. and Directory" col-
umns of the "File->open/new" display.
Then, change the directory to c:\nm\bin and on a
single command line, run the following command
using the following 5 arguments:
unpackdc d1 f1 f2 f3 0
•
where d1 is the path to the source datacard file,
for example,
d1= c:\nm\pat\xx\datacard.dat
•
f1, f2 and f3 are the resultant binary destination
files, for example:
f1 = c:\nm\pat\xx\flashc0.dat
f2 = c:\nm\pat\xx\flashc1.dat
f3 = c:\nm\pat\xx\flashc2.dat
The result will be the three files in the patient direc-
tory xx described previously. The files are
flashc0.dat flashc1.dat and flashc2.dat which are for
channel 1,2 and 3 respectively. If desired, the desti-
nation paths for this command can be any other
path but spaces are not allowed in the path or file
name.