The aim of the study is to assess the correlation of QTc interval and sudden cardiac arrest in hemodialysis patients to the different dialysate calcium concentrations.

Sudden cardiac death (SCD) is the leading cause of death in hemodialysis. On hemodialysis, arrhythmias can occur during and shortly after receiving treatment, independent of traditional cardiovascular risk factors. Calcium, potassium, and magnesium may contribute to the development of arrhythmias during hemodialysis as these cations play a major role in development of the ventricular action potential and propagation of the electrical impulse. The optimal serum calcium range, and type of calcium measurement remains unclear, but KDOQI recommends that the dialysate calcium concentration be decreased as a means to maintain neutral or negative calcium balance and prevent vascular calcification. During hemodialysis, serum-ionized calcium varies directly with the dialysate calcium concentration, so a potential harmful effect of reducing calcium concentrations in the dialysate and serum of hemodialysis patients may lead to an increased risk of cardiac rhythm disturbances and sudden cardiac arrest (SCA). Changes in serum calcium, in turn, strongly affect the length of the QT interval so, such disparity in repolarization can be assessed by measuring the QT dispersion, that is, the variation in QT interval length, on a standard 12-lead electrocardiogram. This procedure has been shown to be a useful and reliable means of identifying patients at risk of ventricular arrhythmias. Accordingly, The present study is designed to evaluate the effect of dialysate calcium concentration on cardiac electrical stability during hemodialysis treatment by measuring the QT interval and QT dispersion before and after hemodialysis sessions, each with a different concentration of dialysate calcium.

Inclusion Criteria:

• patients with End Stage Kidney Disease (ESKD) on regular hemodialysis (HD), for not less than one year with age above 20 years & less than 60.

Exclusion Criteria:

• Patients with multi- systemic diseases as SLE Patient with organ damage as heart failure, ischemic heart disease, decompensated liver disease & CVS Patients with organ transplantation Malignancy Patients above 60 years & below 20 years

patients on regular hemodialysis for not less than one year with age above 20 years & less than 60 . patients will be studied on two sessions of hemodialysis with different dialysate calcium concentrations, one by bicarbonate dialysate with calcium concentration 1.25 mmol/L, and bicarbonate dialysate with calcium concentration 1.5 mmol/L.