preprocessing and editing
- data review
and visualization - statistics and extended data analysis
Prepare and select a study folder as described in analysis
settings and study folder.
Click on the "open data
file" button and select a raw data file to analyze.
You will be prompted with the import signals dialog to select
proper ECG signal from your datafile. On this dialog first you
specify wether you wish to load all available data in the file
subsection. You can either select to load a certain time range,
a predefined segment. (see analysis
procedure, data import and
timing files). Second, select the proper ECG channel for
and any additional channels for display you need to edit the
marker/trigger information or accelerometer for artefact
identification). Click ok, and wait for EMEGS to load the data.
The first step performed in
ECG analysis is the R-wave detection, which is done with a
criterion and a refractory period.. You are prompted with a
configure the R-wave detection process if necessary. You can
differntiate or invert the signal, adjust size and position of
sample window, change height and with of the rise criterion and
lenght of the refractory period. When you are done, hit to Ok button to have EMEGS
R-waves with the selected settings.
EMEGS will write a message on the low window to indicate how
many R-waves are found.
Then the instantaneous interbeat interval is calculated and
below the ECG raw signal for editing of false positive R-waves
You can edit the IBI signal by adding, removing and dragging R-waves
the ECG trace - the IBI trace is updated accordingly. Also you can
the connect/exclude functions directly on the IBI signal. In the
case EMEGS will try to set R-wave markers automatically according to
Moving the mouse over R-wave markers, the mouse cursor changes to a
left-right arrow, allowing you to drag them left or right.
over an R-wave marker, you can also select Delete from
context menu to remove the R-wave marker. Select Insert from
context menu when not over an existing R-wave marker to insert a new
R-wave marker at the mouse position. To insert an additional R-wave
marker between two beats select Insert at 50%
from the context menu, to insert 2 markers select Insert at 33% and
In order to fill gaps of unrecognized R-waves, it is sometimes
helpful to continue the current IBI from the borders of a gap as an
estimate for the expected R-wave position. You can extrapolate
IBI-values in this way from the left or the right side using the Continue
to the right and the Continue to the left
command from the context menu.
You can undo all editing step using the history docking
widget, by using the undo/redo button
on the editing toolbar or using the keyboard shortcuts Strg+Z and Strg+Y.
2. P-,Q-, S- and T-wave
When done editing the R-waves, proceed by clicking the Resume
analysis button. A dialog will open to allow you to configure the
detection of the remaining ECG-components: P-, Q-, S- and T-wave.
Although these waves are detected by their maximum amplitude, it is
mostly the onset (or the offset) of these waves that is of further
interest. The onset (or offset) is however often difficult to find,
especially in a noisy signal, which is why EMEGS can set the
onset/offset at a fixed distance from the maximum (P- and Q-wave) or
find the baseline-crossing of a tangent at the steepest slope point
(T-wave) as an alternative. Configure the detection to best match
your data, then click OK.
EMEGS will analyze all beats in your data file, calculate
T-wave amplitude, the QT-interval and the PQ-interval and display
them for editing.
When you zoom in close enough, the corresponding line markers are
displayed and can be edited similarly to the R-wave editing in the
first step. Note that editing of the R-waves must be completed first
and cannot be changed while editing the other components.