Effect of hemodialysis on the signal-averaged electrocardiogram

The presence of late potentials (LPs) on signal-averaged electrocardiograph y (SAECG) is predictive of ventricular tachycardia. The effect of hemodialy sis (HD) on SAECG has not been well studied. SAECG was evaluated in 28 pati ents with chronic renal failure immediately before and after HD. In each SA ECG, QRS duration, low-amplitude signal duration (LASd), and root-mean-squa re voltage of the terminal 40 milliseconds of the QRS (RMS40) were measured . To evaluate the effect of fluid removal on SAECG, the last 12 patients we re studied during two different HD sessions, one with and one without fluid removal. Two-dimensional echocardiography was performed before and after H D on these 12 patients. At baseline, four patients met the criteria for LPs on SAECG, Only one patient met the criteria for LPs on SAECG after HD. Aft er HD, the mean LASd decreased (28.3 +/- 12.9 to 24.9 +/- 10.1 milliseconds ; P = 0.041) and RMS40 increased (63.0 +/- 56.9 to 79.0 +/- 59.2 mu V; P = 0.006). Among the 12 patients who underwent HD with and without fluid remov al, left ventricular end-diastolic dimension decreased with (5.4 +/- 0.6 to 5.1 +/- 0.6 cm; P = 0.024) but not without fluid removal (5.2 +/- 0.3 to 5 .1 +/- 0.4 cm; P = not significant [NS]). RMS40 improved with (43.8 +/- 23. 1 to 53.2 +/- 22.6 mu V; P = 0.03) but not without fluid removal (51.0 +/- 26.5 to 51.5 +/- 24.2 mu V; P = NS) A significant negative correlation was found between change in body weight and change in RMS40 parameter (r = 0.45 6; P = 0.0381), SAECG parameters are abnormal in a significant proportion o f patients with chronic renal failure and improve with HD despite electroly te and other proarrhythmic changes. Decreased left ventricular dimension be cause of fluid removal during HD is one possible explanation for this impro vement. (C) 1999 by the National Kidney Foundation, Inc.