Figure 1.

Data acquisition protocol. Holter electrocardiogram (ECG) signals of end-stage renal disease patients undergoing hemodialysis (ESRD-HD) patients were acquired throughout 48 h, starting 5 min before the beginning of the HD therapy. Six blood samples were collected at the beginning of the therapy ($h_0$), each hour during the HD ($h_1$, $h_2$, $h_3$), at the end ($h_4$, at minute 215th or 245th, depending on the HD duration) and before the beginning of the next HD session ($h_5$).