[ impact of chronic hemodialysis on QT dispersion, corrected QT dispersion and maximum QT-dispersion]

ABSTRACT

Sudden cardiac death is common in patients on hemodialysis and may occur in the immediate postdialysis period when ventricular premature complexes are common. QT dispersion, reflecting hetovogelity in ventricle repolarization, has been used for predicting patients with risk of malignant arrhythmia and sudden death. The purpose of the study was to assess the effect of hemodialysis on QT dispersion [QTd], corrected QT dispersion [QTcd] and maximum QTc [QTcMax] in chronic hemodialysis patients. In this descriptive-analytic study, data of 48 patients [30 male and 18 female patients with mean age, 43 +/- 16 yr] on chronic hemodialysis were studied. 12 lead ECG were recorded 5-10 minutes before and after hemodialysis in a standard setting and Na +, K+, Ca+ +, Po4 and Mg++ levels were also determined pre and post hemodialysis. During hemodialysis, no drug therapy was used except isotonic and hypertonic NaCl influsions and sodium heparin. The maintenance drug therapy including digitalis, antihypertensive, antianginal, and beta blocking agents was not changed. The data were analyzed using SPSS software. The maximal QTd interval changed significantly from 434 +/- 12.8 ms to 443 +/- 21.33 ms [P<0.001]. The QTd increased significantly from 55.87 +/- 7.5 ms to 61.27 +/- 9.09 ms [P<0.001] and QTcd from 61.18 +/- 7.43ms to 68.79 +/- 10.32ms [P<0.001]. 33.33% of the patients before and 47.90% after hemodialysis had QTcMax more than 440 ms. Hemodialysis increases the QTd, QTcd and QTcMax in patients with end-stage renal failure. Thus it is likely that heterogeneity of regional ventricular repolarization increases during hemodialysis