RESUMEN
BACKGROUND: Patients undergoing maintenance dialysis have been associated with a high incidence of arrhythmias, which increases with hemodialysis (HD) procedures. In recent years, QT dispersion (QT-d), which is defined as the difference between the maximum and minimum QT intervals (QTmax, QTmin) on an electrocardiogram (ECG), has attracted attention as a useful tool for predicting and evaluating ventricular arrhythmias. AIM: To determine the QT interval and QT-d before and after HD in stable subjects on maintenance dialysis. Further, to analyze the association of changes (Delta) in the QT interval and QT-d with the fluid removal ratio and changes in laboratory data. PATIENTS AND METHODS: We selected 82 patients undergoing maintenance dialysis who were less than 80 years of age. QT intervals before and after HD were obtained, and laboratory data including neurohumoral factors and the RA system were carried out. Of all the patients, 63 underwent a 24-hour holter-monitoring ECG. RESULTS: QTmax was significantly prolonged with QTmin remaining unchanged, and QT-d was significantly increased. DeltaQT-d demonstrated a significant correlation with DeltaQTmax, DeltaQTmin and Deltaaldosterone, but showed no correlation with the fluid removal ratio and changes in laboratory data. Results of the holter ECG revealed that in the grade 0 (Lown's classification) group, no change was obtained in DeltaQTmax, DeltaQTmin and DeltaQT-d, and in groups 1 to 5, significant increases were noted in DeltaQTmax and DeltaQT-d. CONCLUSIONS: The increase in QT-d has a possible link with arrhythmia inducibility during HD, and the results of the holter ECG suggest that an increase in QT-d may predict the frequency of arrhythmias. Change in the RA system appeared to have an impact on QT-d, but there was no impact of this parameter on the fluid removal ratio or changes in the laboratory data.