Comparison of two methods for removing baseline wander in the ECG

The authors compare the cubic-spline method with multipole null-phase digital filters in their ability to correct for baseline wander on 69 ECG segments with both normal and abnormal rhythms. A single-pole 0.05-Hz filter was included in this study for comparison. A null-phase, 6-pole filter with a cutoff between 0.75 and 1.0 Hz can attenuate low-frequency noise (i.e. correct baseline) as well as the cubic spline. However, such a filter introduces minor changes in the original signal, especially in the presence of a long RR interval. The cubic spline is very dependent on the accurate determination of QRS onset. However, both perform better than the single-pole 0.05-Hz filter, which does very little to attenuate low-frequency noise