QT dispersiyon in heamodialysied patiensts and change in the QT dispersion during haemdialysis

SUMMARY QT DISPERSION IN HEAMODIALYSIED PATIENTS AND CHANGE IN THE QT DISPERSION DURING HEAMODIALYSIS Chronic renal failure patients on maintenance hemodialysis have cardiovasculer problems. Clinical and experimental data have shown that prolongation of QT interval dispersion is associated with sudden cardiac death and ventricular arrhythmias in a variety of cardiac disorders. Because a higher incidence of ventricular arrhythmias is described during and after hemodialysis, the aim of this study has been to evaluate the QTc dispersion before and after uncomplicated hemodialysis session and the effect of electrolyte changes between the predialysis and postdialysis phases on these parameters. Thirty chronic uremics (16 women, 14 men, mean age 44,8) without heart failure, ischemic heart disease or dialysis hypotension were selected. All HD patients were on bicarbonate three times weekly with hemophane capillaries. The QT interval was measured manually in each and maximum QT, minimum QT, maximum corrected QT and minimum corrected QT, QT dispersion calculated. The QT dispersion was determined as the difference between the longer and the shorter QTc interval measured on electrocardiogram. Serum concentrations of potassium, calcium, sodium, chloride, BUN and creatinin were measured at the same time as ECG acquisition. QT dispersion, maximum QT and minimum QT, increased from a mean 62,4 (18,2) to 90,9 (14,3) ms (p=0.000), 400,7 (38,1) to 426 (44,5) ms (p=0.008) and 349,2 (37,9) to 349,7 (35,8) ms (p=0.011). Serum potassium, BUN and creatinin decreased 36from 4,3 (0.7) to 3.0 (0.5) m Eq / L, 67,4 (23,1) to 24,9 (1 1) mg / L and 6,1 (2,4) to 2,6 (1,3) mg / L respectively, while serum calcium increased from 8,6 (1,1) to 10,5 (1,2) m Eq/L. QT dispersion was higher in subjects on hemodialysis than normal values, and was significantly increased by haemodialysis.There was significant negative correlation between the QT dispersion increase and serum electrolyte change (K+ level) (p < 0.05). The association between serum electrolyte change and QT measurements might provide new insights into the evaluation of the serum electrolits involved in inhomogeneous ventricular repolarization. It is concluded that, decreases of potassium is related to an increase in QT dispersion value and hence these variable may be risk factors for ventricular arrhythmias in uremic patients. 37