Changes of the QT interval dispersion in the electrocardiogram and associated factors during single hemodialysis session

Objective To determine whether changes occur in the QT interval dispersion (QTd) in maintenance hemodialysis patients (MHD) and to assess the effect of hemodialysis on QTd. Methods Serial 12-lead electrocardiogram (ECG) recordings were carried out in 49 MHD patients starting just before a routine dialysis session and ending after dialysis immediately. Plasma electrolyte concentrations, bicarbonate, plasma creatinine, blood pressure, ultrafiltration volume and body weight were assessed before and after each hemodialysis session. Results In MHD patients, QTd was higher than that in control. After the hemodialysis session, we found a significant increase (P0.001) in QTd and a significant increase in plasma bicarbonate concentration (P0.001). A correlation was observed between the increase of QTd and the increase of plasma bicarbonate, ultrafiltration volume respectively (r=0.53,P0.001;r=0.56,P0.001, respectively). In hypertension subgroup and left ventricular hypertrophy subgroup, QTd was higher than that in patients without hypertension and left ventricular hypertrophy (P0.05;P0.01, respectively). Conclusions QTd is significantly increased in MHD patients compared with that in control subjects. Hemodialysis can increase the QTd in patients with terminal-stage renal failure and these changes may be attributed to ultrafiltration and increase of plasma bicarbonate during hemodialysis session.