Fig. 3

Calculated Fourier spectral analysis and filtered maximum velocities. The Fourier spectral analysis was performed in order to show the filtering effect on the processed signals (left-hand panel). In the left panel, the analyses are presented for the first 10 harmonics—black line: unfiltered signals, gray line: signal after filtering; circle: fundamental frequency of the heart cycle; the right-hand panel presents filtered maximum velocities for all examined patients. The five rows from top to bottom represent patients from 1 to 5.