Instruction manual

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5 Analysis 52
known as a Power Number. In addition to specifying the range of frequencies transformed, the
frequency resolution can be selected. The higher the frequency resolution, the more data points
required to compute the FFT. Therefore, at slow sampling rates, higher frequency resolutions
may require the processing of more data points from longer recording periods.
Cardiac The Cardiac functions are specifically used for the analysis of electrocardiograms (ECG).
Four of the Cardiac functions calculate Leads: III, aVL, aVF and aVR from the recordings of
Lead I and Lead II.
You can specify which channel corresponds to Lead I
and Lead II in the Cardiac Setup dialog. DataTrax2
can be programmed to do these calculations because
all the points of view in a 6-lead ECG are in the same
plane (frontal) of the body and each lead can be
considered as a vector. So if any two of the limb leads
are recorded, the other four leads can be calculated
from them.
The Cardiac submenu also includes other functions. The Cardiac
Angle function calculates the vector of the cardiac depolarization
that passes through the interventricular septum. Three Power
functions, which are special cases of the general power function
described earlier, are also available. These three power functions
are useful for heart rate variability (HRV) analysis. Low Frequency
(LF) Power (0.04-0.15 Hz), High Frequency (HF) Power (0.18-0.4
Hz) and Total Power are each calculated from the transformation of
a tachogram of an ECG on one of the raw data channels. The HRV
Ratio which is (Low Frequency (LF) Power)/High Frequency (HF)
Power is also available.
Activating Cardiac
Functions
To apply the Cardiac function to a channel, click on the Add Function button in the Channel
bar. Select Cardiac from the Function menu, then select the appropriate submenu. Select the
channels corresponding to Lead I and Lead II and click OK
EEG The EEG function is another specialized case.