Actiheart User Manual 5.1.31 (Jun 2022)
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When the 5 minute analysis epoch is selected, the following further information is
also displayed (otherwise these will be greyed out):
•
SDNN:
The standard deviation of the normal to normal intervals.
•
SDANN:
The standard deviation of the 5 minute average NN intervals.
Histogram Plot:
The upper graph of the Overall Results display shows a plot of the frequency of
each IBI encountered over the analysed period. It may illustrate a well defined
peak if a large amount of total time is spent around one heart rate, or a wider
distribution where the data is more variable or encompasses a number of
different activities.
Overall FFT Graph:
The lower graph of the Overall Results tab displays the results of a Fast Fourier
Transform (FFT) of the entire period selected for analysis. The VLF, LF and HF
bands are marked by colour. Data from the FFT can be exported using the Copy
button to the right of the graph.
3.2.3
Analysis
Results
Table
Statistical information about the IBI data is shown in the Analysis Results Table.
The detail that is shown here is dependent on the analysis epoch selected. Note
that the analysis epoch is for
post hoc
analysis purposes only as the data is
recorded on a continuous basis. The following data is shown for each analysis
epoch:
•
Activity:
Activity counts (movement) in the analysis epoch
•
BPM:
The average heart rate in beats per minute for the epoch
•
IBI Ave:
Average Inter-beat Interval (IBI) for the analysis epoch
•
IBI Min:
Minimum IBI in the epoch
•
IBI Max:
Maximum IBI in the epoch
•
SD:
Standard Deviation of the IBI data
•
RMSSD:
The Root Mean Square of the Successive Differences of IBIs
If either a 1 minute or a 5 minute post hoc analysis epoch is selected then the
following further information is also available:
•
LF:
The low frequency component of the IBI, derived using an FFT
•
HF:
The high frequency component of the IBI derived using an FFT
•
LF/HF:
The ratio of the LF component to the HF component of the IBIs
Additionally in the case of the 5 minute epoch the VLF (very low frequency)
component of the IBI is also visible.
In addition to the above there is a column for “Used”, which is the fraction of time
during each epoch during which IBI were available for the calculation. This is
affected by the quality of data, but also by the use of the “Data-selective HRV”
option, which only allows the inclusion of IBI considered “Valid”.
