The patients had daily Ws and ECGs recorded and printed routinely with the placement of the limb electrodes on the wrists and ankles, however, for the purposes of this study, the ECGs and Ws from hospital admission and at the point of half-PW gain (HF-W), and PW for the patients with AN, the hospital admission and discharge data for the control subjects, the prehemodialysis and posthemodialysis data for the patients undergoing this procedure, and the data from hospital admission and discharge for the patients with CHF were employed. An ECG unit was used that acquires data simultaneously and digitally from all ECG leads, instead of acquiring data from a few leads and calculating the rest of them online. Calibration of the unit was 1.0 mV = 1.0 cm. Measurements of the sum of the highest positive plus the lowest negative deflections of the QRS complex in all ECG leads of all study ECGs were made to the nearest 0.5 mm, employing hard copies and using manual calipers and a magnifying glass. For ECGs with atrial fibrillation, the average of measurements of three consecutive heart beats was used. Since the six limb leads can be calculated from leads 1 and 2, as per Einthoven law (leads 1 + 3 = 2), and the aV leads, as per formulas (lead aVR = 1/2[1 + 2], aVL = 1 — 1/2, [2], lead aVF = 2 — 1/2, [1], and lead aVR + aVL + aVF = 0), the 2QRS2 was employed as a variable, along with the £QRS12 and 2QRS6. It should be emphasized here that the use of SQRS2 as an ECG system is employed with the full realization that for the derivation of the remaining four limb leads, through the abovedescribed formulas, the values of leads 1 and 2 are treated algebraically in serial online measurements from the entire duration of the QRS complex in ECG machines, while in the present work the sum of the peak-to-peak (ie, positive-to-negative) amplitude values of the QRS complex of these two leads is implemented. Moreover, it should be understood that the same measurement approach was used for all three ECG systems. 2QRS12, SQRS6, and SQRS2 were calculated from the day of admission, the HF-W point, and the PW point for each of the 28 patients. Obviously, the HF-W point was determined after the PW was attained, and it represented a W value that was closest to one half of the PW gained. The mean (± SD) PW gain of the 28 patients with AN was 23.9 ± 14.8 lbs, and the mean HF-W gain was 16.9 ± 10.7 lbs. The corresponding ECG for the day when the HF-W was reached was used in the analysis.