1. Laboratory for Biosignals, Institute of Biophysics, Faculty of Medicine, University of Belgrade, Višegradska 26-2, 11000 Belgrade, Serbia
2. Pacemaker Center, University Clinical Center of Serbia, University of Belgrade, 11000 Belgrade, Serbia
3. Department of Engineering, University of Palermo, Viale delle Scienze, Building 9, 90128 Palermo, Italy