VCG loop alignment, morphologic beat-to-beat variability and the presence of noise

The performance of least squares VCG loop alignment by rotation, scaling and time synchronization is investigated in the presence of noise. The loop alignment is studied using simulated signals obtained from an action potential model which introduces a certain amount of morphologic beat-to-beat variability. The effects of noise due to respiration and muscular activity are studied in terms of morphologic variability and parameter estimate accuracy.