Projective filtering of time-aligned ECG beats.

A method of electrocardiographic (ECG) signal processing developed by introduction of time synchronization into the method of nonlinear state-space projections is presented. It can be regarded as an extension of time averaging but contrary to usual averaging it preserves variability of ECG beats morphology. For this purpose, after the respective beats time alignment, the synchronized intervals of the signal undergo processing according to the rules of principal component analysis (PCA). PCA allows for determination of orthogonal basis functions which can be employed for approximation of the respective intervals. The operation is aimed to retain the deviations from the mean which result from the desired component changes and to reject the deviations caused by noise. The method's capabilities are investigated and some of its applications are presented.