The effects of different electrolyte composition in dialysate on QTc interval; a controlled trial

Magnesium Supplementation Shortens Hemodialysis-Associated Prolonged QT

Hemodialysis affects myocardial depolarization and repolarization notably lengthening the QT interval. Prolonged QT, in turn, has been a reliable surrogate for higher risk of potentially lethal ventricular arrhythmias. We present an adolescent girl with end-stage kidney disease who consistently developed prolonged QT following hemodialysis sessions. Interestingly, her QT intervals were inversely correlated with her serum magnesium levels. Magnesium supplementation appeared to help reduce the QT prolongation after hemodialysis. Our case shows the potential utility of magnesium as a cardioprotective agent in hemodialysis patients. We recommend that patients undergoing hemodialysis receive frequent electrocardiograms and electrolytes monitoring for tailored electrolytes management to reduce the risk of developing potentially lethal cardiac arrhythmias.

Fluctuations in plasma potassium in patients on dialysis

Plasma potassium concentration is maintained in a narrow range to avoid deleterious electrophysiologic consequences of both abnormally low and high levels. This is achieved by redundant physiologic mechanisms, with the kidneys playing a central role in maintaining both short-term plasma potassium stability and long-term total body potassium balance. In patients with end-stage renal disease, the lack of kidney function reduces the body’s ability to maintain normal physiologic potassium balance. Routine thrice-weekly dialysis therapy achieves long-term total body potassium mass balance, but the intermittent nature of dialytic therapy can result in wide fluctuations in plasma potassium concentration and consequently contribute to an increased risk of arrhythmogenicity. Various dialytic and nondialytic interventions can reduce the magnitude of these fluctuations, but the impact of such interventions on clinical outcomes remains unclear.

Effect of Hemodialysis on Corrected QT Interval and QTc Dispersion

Hemodialysis patients are at higher risk of cardiovascular disease due to traditional and dialysis-related risk factors. Our aim was to study the effects of hemodialysis on the corrected QT interval (QTc) and QTc dispersion in chronic kidney disease (CKD) without clinically manifest heart disease. Two hundred cases of CKD on chronic intermittent hemodialysis of >3 months' duration were included in the study. Twelve-lead electrocardiography and samples for serum creatinine, potassium, calcium, and magnesium were taken before and after dialysis. The mean age of patients was 52.4 ± 17 years with male-to-female ratio of 3:1. QTc interval and QTc dispersion were prolonged in 47% and 59% before and 50% and 89% of patients after hemodialysis, respectively. The mean values of QTc were 433.4 ± 36.9 ms before and 451.4 ± 39.6 ms after hemodialysis (p = 0.001) and the mean values of QTc dispersion were 60.5 ± 19.3 ms before and 81.5 ± 24.4 ms after hemodialysis (p = 0.001). Similar pattern was observed in all etiological groups of CKD, except for QTc dispersion in malignancy-related CKD (p = 0.216). After hemodialysis, there was a significant fall in the mean values of serum potassium (p = 0.001), rise in serum calcium (p = 0.001), and no change in magnesium (p = 0.424). Patients with post hemodialysis QTc dispersion >74 ms had significantly low mean values of serum potassium and calcium as compared to <74 ms group. Large numbers of hemodialysis patients have a prolonged QTc interval and QTc dispersion with a significant increase in the mean values after hemodialysis. There is a significant fall in serum potassium and rise in serum calcium after dialysis.