Quantitative analysis of errors due to power-line interference and base-line drift in detection of onsets and offsets in ECG using wavelets

Abstract

Timing characterisation of the ECG using wavelet transforms is a new technique in which multiscale analysis reduces the influence of noise. This technique issued to investigate the effect of noise and to estimate the errors involved in the detection of onsets and offsets of ECG waves. With appropriate choice of scales of analysis, the study shows that the errors involved in the measurement of QRS width in the presence of base-line wander are negligible. The 50 Hz power-line interference introduces a maximum error of 6.25% if it is greater than 50% of the signal amplitude. The P and T complexes are not affected by power-line interference, but the base-line wander introduces a maximum error of 9.6%. In situations with the simultaneous presence of both types of noise, the use of an optimised scale restricts the errors to within clinically acceptable limits.

Ventricular Arrhythmias Detection using Wavelet Decomposition

“…Senhadji et al (1995) compared the ability of three different wavelets transforms (Daubechies, spline and Morlet) to recognise and describe isolated cardiac beats [4]. Sahambi et al (1997(a) and 1997(b)) employed a first order derivative of the Gaussian function as the wavelet for the characterization of ECG waveforms. They then used modulus maxima-based wavelet analysis employing the Dyadic Wavelet Transform to detect and measure various parts of the signal, specifically the location of the onset and offset of the QRS complex and P and T waves [5] .…”

“…Sahambi et al (1997(a) and 1997(b)) employed a first order derivative of the Gaussian function as the wavelet for the characterization of ECG waveforms. They then used modulus maxima-based wavelet analysis employing the Dyadic Wavelet Transform to detect and measure various parts of the signal, specifically the location of the onset and offset of the QRS complex and P and T waves [5] . Sivannarayana and Reddy (1999) have proposed the use of both launch points and wavelet extrema to obtain reliable amplitude and duration parameters from the ECG [6].…”

Power-line interference elimination from ECG in case of non-multiplicity between the sampling rate and the power-line frequency

“…This is due to differences in the electrode impedances and to stray currents through the patient and the cables, resulting in transformation of the common mode voltage into a false differential signal [1,2]. The residual PL interference (PLI) may corrupt the proper function of automatic ECG analysis, which presumes correct delineation of ECG wave boundaries [3].…”

Removal of power-line interference from the ECG: a review of the subtraction procedure

“…Any residual PL interference may interfere with the correct delineation of ECG wave boundaries [7] and corrupt the proper function of automatic ECG analysis. The interference can also disturb the correct measurement of RR intervals, which is the basis for heart rate variability analysis.…”