Electrolyte concentration during haemodialysis and QT interval prolongation in uremic patients

Aims: To assess the effect of different combinations of potassium and calcium concentrations on QT interval in the dialysis bath in uraemic patients. Methods and results: Sixteen haemodialysis (HD) patients underwent a 24 h Holter recording before and during HD sessions with six randomized combinations of electrolytes concentrations of the dialysis bath (K⁺, 2 and 3 mmol/L; Ca²⁺, 1.25, 1.5, and 1.75 mmol/L). The effect of different dialysis baths on QT interval was significant (P < 0.05). The longest mean QTc was observed with the lowest K⁺ (2 mmol/L) and Ca²⁺ concentrations (1.25 mmol/L), whereas the shortest mean QTc was observed with the highest K⁺ (3 mmol/L) and Ca²⁺ concentrations (1.75 mmol/L). QTc was >440 ms in 9 of 16 patients (56%) at the lowest Ca ²⁺ and K⁺ concentrations, and in 3 of 16 patients (18%) at the highest electrolytes level. Changes in QTc during the HD sessions were inversely correlated with that in total Ca and Ca²⁺ plasma concentrations (P < 0.0001). Conclusion: Changes in ventricular repolarization duration associated with HD largely depend on the concentrations of Ca²⁺ and K⁺ in the dialysis bath. These findings may have important implications for the choice of the electrolytes concentration of the dialysis bath during the HD session. © The Author 2008.