This article discusses new methods for ECG filtering and a novel approach to post-filter reconstruction. Oversampling (5 KHz sampling rate) allowed to obtained good results is used. Simple π-shaped (time-domain) FIR filters were employed. A novel method for post-filter signal reconstruction was developed. Samples of real and artificial ECG signals enhanced with artificial noise (white and/or network noise, 10% in amplitude) were tested. For each filtering, there followed a matching reconstruction, and the outcome was compared to the original signal. The results achieved are: (a) the errors were less than 0.6%; (b) the peak-nature of the ECG signals - the reconstructed peaks were very close to the original ones; (c) the amplitude - after reconstruction the outcoming amplitudes were very close to the originals.