qrs_amplitude_sqi: QRS amplitude (QRS-A): defined as the median value of the peak-to-nadir amplitude
difference of the QRS complexes detected. Beat detection was computed with the QRS
detection algorithm proposed by Pan and Tompkins (1985) on the lead whose windowed
kurtosis (median kurtosis value over a sliding window of 2 s, 50% overlap) was the highest,
and the ECG peak-to-nadir amplitude difference did not exceed a threshold of 5 mV. For each
detected beat, the fiducial point was set to the dominant peak of the QRS complex. Refer to DiMarco et al. 2012
in sqi/amplitude_sqi.py
qrs_amplitude_sqi: QRS amplitude (QRS-A): defined as the median value of the peak-to-nadir amplitude difference of the QRS complexes detected. Beat detection was computed with the QRS detection algorithm proposed by Pan and Tompkins (1985) on the lead whose windowed kurtosis (median kurtosis value over a sliding window of 2 s, 50% overlap) was the highest, and the ECG peak-to-nadir amplitude difference did not exceed a threshold of 5 mV. For each detected beat, the fiducial point was set to the dominant peak of the QRS complex. Refer to DiMarco et al. 2012
ac_dc_sqi: to be checked