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The workflow is shown as below:
Start
ECG waveform sampling
Recognize all R points by slope method
Waveform superposition taking R point as center
Determine the positions of each wave
Calculate the amplitudes of each wave
Get measurement parameter, interpretation item
End
3.1 Find the cardiac impulse location
1) Data preprocessing, obtain the absolute value trend of slope for each lead; then
superimpose each absolute value, obtain the superimposed graph of absolute value of slope.
2) Smoothing filter the superimposed graph on average of width 80ms, obtain the analytical
data source DDD.
3) Find the cardiac impulse location, give an initial threshold for searching, orderly scan the
data in the analytical data source DDD, then compare it with the threshold value:
When the value is greater than the threshold, it may be the beginning of qrs-complex.
If the distance from the previous qrs-complex to the current location is less than 150ms,
then give up the location.
Otherwise, take the 1/4 of threshold value as a reference, find the beginning of
qrs-complex within 100ms before the current location.
When the value is less than the threshold value, it may be the end of qrs-complex. Take
the 1/4 of threshold value as a reference, find the end of qrs-complex.
If the found qrs-complex is wide, this qrs-complex shall be excluded. Otherwise, save
the found qrs-complex.
4) Locate: after found the qrs-complex, search the max value point between the beginning
point and end point in the ecg original data, mark the point as cardiac impulse location.
