Studies of alignment methods for averaging of high-resolution cardiac signals

Coherent epoch averaging of cardiac signals requires accurate alignment of the QRS complexes. We present four alignment methods and two evaluation approaches. A method using the positive peak value of the filtered signal as the fiducial point performed best with additive white noise and produced similar standard deviations on both the upslope and the downslope of the QRS complex. For template matching techniques, we found that the QRS complexes aligned on the up-slopes of the waveforms, and these methods were relatively immune to power line noise.