Journal Article

Calcium and potassium changes during haemodialysis alter ventricular repolarization duration: <i>in vivo</i> and <i>in silico</i> analysis

Stefano Severi, Eleonora Grandi, Chiara Pes, Fabio Badiali, Fabio Grandi and Antonio Santoro

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 23, issue 4, pages 1378-1386
Published in print April 2008 | ISSN: 0931-0509
Published online November 2007 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfm765
Calcium and potassium changes during haemodialysis alter ventricular repolarization duration: in vivo and in silico analysis

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Background. Alterations of ventricular repolarization duration, as measured by the QT interval, are frequently observed in haemodialysis (HD) patients. The nature and the sign of these changes are not yet fully understood.

Methods. Different dialysate K+ and Ca2+ levels, leading to different end-HD plasma concentrations in the patient, have been tested in the present study in terms of their impact on QTc. A model of the human cardiomyocyte action potential (AP) has been used to assess in silico whether the changes in Ca2+ and K+ were able to justify at the cellular level the observed alterations of QTc.

Results. QTc was prolonged in HDs with low (1.25 mM) versus high (2 mM) Ca2+ (424 ± 33 versus 400 ± 28 ms, P < 0.05) and in HDs with low (2 mM) versus high (3 mM) K+ (420 ± 35 versus 399 ± 36 ms, P < 0.05). These alterations were confirmed at the cellular level by computational analysis showing prolongation of ventricular AP at low K+ and low Ca2+ at the same extent of the measured QTc variations. Numerical simulation predicted a critically long AP (and QT) when considering low K+ and Ca2+ simultaneously, suggesting the concurrent lowering of Ca2+ and K+ as a potential arrhythmogenic factor.

Conclusions. Numerical simulations of the ventricular AP may be useful to quantitatively predict the complex dependence of AP duration on simultaneous changes in Ca2+ and K+. Moreover, Ca2+ content in the dialysate should be designed not to critically lower serum Ca2+, especially in sessions at risk of end-dialysis hypokalaemia.

Keywords: calcium; electrolytes; electrophysiology; haemodialysis; ventricular repolarization

Journal Article.  5203 words.  Illustrated.

Subjects: Nephrology

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