Changes in the corrected QT interval and corrected QT dispersion during haemodialysis

Abstract

The link between increased QT dispersion and cardiac death in subjects with diabetes and arterial disease is well recognised. Corrected QT dispersion was studied in subjects with end stage renal failure on haemodialysis. Thirty one stable, chronic subjects on haemodialysis had 12-lead electrocardiograms (ECGs) taken before and after a single haemodialysis session. The QT interval was measured manually in each and the corrected QT and corrected QT dispersion calculated. Serum concentrations of potassium, calcium, and magnesium were measured at the same time as ECG acquisition. Corrected QT dispersion increased from a mean (SEM) 90.6 (5.8) to 117.7 (10.2) ms (p=0.002). Serum potassium and magnesium decreased from 5.0 (0.14) to 3.5 (0.09) mmol/l and 0.95 (0.04) to 0.89 (0.09) mmol/l respectively, while serum calcium increased from 2.56 (0.04) to 2.77 (0.04) mmol/l. Intradialytic weight fell by a mean of 2.1 kg. There was no significant correlation between the change in QTc dispersion and the changes in measured serum anions or the subjects' weight during dialysis. Corrected QT dispersion was higher in subjects on haemodialysis than previously suggested normal values, and was significantly increased by haemodialysis. This reflects increased inhomogeneous ventricular repolarisation, which may lead to an increased risk of arrhythmias and sudden death. Studies looking at QT dispersion in subjects on dialysis should standardise the timing of ECG recordings taken with respect to dialysis.C ardiovascular disease is a major cause of mortality and morbidity among subjects on haemodialysis. Cardiovascular death is responsible for up to 50% of deaths among subjects on dialysis. 1 Cardiac arrhythmias are frequent among the haemodialysis population, particularly during and immediately after a dialysis session. 2-5 These arrhythmias may be caused by the rapid changes in intracellular and extracellular electrolytes during the dialysis session, in hearts that are susceptible due to both myocardial ischaemia and intramyocardiocytic fibrosis. 6 7 A reliable way of predicting subjects at risk of ventricular arrhythmias would be an extremely useful tool for the dialysis physician.Recently, dispersion of the QT interval has emerged as an important predictor of ventricular arrhythmias. The QT dispersion is simply the difference between the shortest and longest QT interval on a standard surface 12-lead electrocardiograph. 8 This is a non-invasive measurement of myocardial repolarisation inhomogeneity and hence predisposition to re-entry arrhythmias. 9 A QT dispersion above 80 ms reflects a loss of synchronisation in the repolarisation process. 10 In clinical studies, a wide QT dispersion has been shown to be a risk factor for cardiac arrhythmia after myocardial infarction, 11 congestive cardiac failure, 12 peripheral vascular disease, 13 and drug induced arrhythmiogenicity. 14 It has also been shown that a wide QT dispersion can narrow when congestive cardiac failure is treated with enalapril 15 and after successful thrombolysis for acut...

Effect of Haemodialysis on Regional and Transmural Inhomogeneities of the Ventricular Repolarisation Phase

“…Changes of serum calcium affect the electrical conduction times of the myocardium, increase the re-entry or triggered activity [3]and may lead to the increase in the dispersion of the action potential. In our trial, the predialysis calcium level was the independent factor that inversely affected the durations of predialysis dispersion parameters and the dialysis induced prolongation of QT-c-D and Tpe-c-D. Our study confirms most of the previous observations that low calcium concentration prolongs QT dispersion parameters in HD patients [12, 13, 16, 18], though Yildiz et al [15]and Howse [27]in their studies have not found such a relation. The lack of relations between potassium or calcium levels in the studies of other authors may result from the fact that other important factors have influenced dispersion parameters, such as diabetes, congestive heart disease and ischaemic heart disease.…”

Cystatin C estimated renal dysfunction predicts T wave axis deviation in US adults: results from NHANES III

“…Heart disease free individuals with CKD are thus at an increased risk for ventricular arrhythmias. These findings are concordant with the conclusions revealed by other studies suggesting that renal disease renders the heart more vulnerable to electrical disturbances [30][31][32][33][34].…”

Effects of Hemodialysis on Methadone Pharmacokinetics and QTc

“…12 Another study found no correlation between QT dispersion and reduction in serum potassium and magnesium during hemodialysis. 13 The other biochemistry findings in our study were as expected in end-stage renal failure.…”