Impact of haemodialysis on QTc dispersion in children

Electrocardiographic measurements in children with pre-dialysis chronic kidney disease and undergoing kidney replacement therapy

Cardiovascular diseases are the main causes of morbidity in children with chronic kidney disease (CKD). Electrocardiography (ECG) can provide important information about cardiac functions and parameters associated with sudden cardiac death. This study aims to evaluate the potentially dangerous changes in CKD and kidney replacement therapies by ECG and to determine the value of ECG in predicting cardiovascular outcome compared with echocardiography. 101 patients with CKD were divided into subgroups according to treatment modalities as pre-dialysis CKD, hemodialysis (HD), peritoneal dialysis (PD) and kidney transplantation (KTx). Differences in anthropometric measurements, laboratory results, blood pressures, ECG monitoring were compared within groups as well as with 40 healthy controls. Available echocardiographic findings were noted. In the patients, HD group had highest frequency of hypertension. ECG revealed prolonged QTc as more frequent (16.8% vs 0%, p = 0.006) and higher QTcD (56.7 ± 6.5 vs 39.9 ± 5.1 ms, p = 0.001) in the patients compared to controls, especially in dialysis patients, whereas lowest values were in KTx subgroup. Left ventricular (LV) hypertrophy (LVH) was more frequent (47.1%) in HD compared to other CKD subgroups in ECG (p = 0.052). Echocardiography also showed LV mass index as highest in HD and lowest in KTx (121.4 ± 55.7 vs 63.7 ± 18.3 g/m2, p = 0.000), with numerically highest LVH in HD (58.3%, p = 0.063).  Conclusion: ECG can be used to detect cardiovascular problems in patients with CKD, especially in HD. As ECG results were in line with echocardiography, patients with ECG abnormalities suggestive of LVH should be referred for echocardiographic assessment. What is Known: • Cardiovascular diseases such as coronary artery disease, congestive heart failure, arrhythmias and sudden cardiac death are major causes of morbidity and mortality in chronic kidney disease. • Electrocardiography has significant advantages in demonstrating cardiac functions in children because it is readily available, non-invasive and often non-experts can interpret the results. What is New: • The heart rate is higher, QTc is longer and QTcD is higher in dialysis patients and the prolonged QTc is more frequent in patients with underlying glomerular diseases. • Left ventricular hypertrophy is more common in HD patients and those with hypertension, hypercalcemia, anemia or glomerular etiology. The cardiovascular risky conditions are less frequent in the patients with kidney transplantation.

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.

Effect of Metabolic Acidosis on QT Intervals in Patients with Chronic Kidney Disease

Background

There is a strong association between chronic kidney disease (CKD) and cardiovascular events. Increased arrhythmia risk in kidney disease is one of the main predominant factors in increased mortality and sudden cardiac death. To estimate this risk, noninvasive measurement of repolarization abnormalities including QT interval and its heart rate-corrected value (QTc) with surface ECG, are commonly used parameters in clinical practice. The aim of this study is to examine the effect of CKD-related problems – mainly acidosis – on QT intervals.

Methods

30 patients with stage 3–5 CKD whose serum bicarbonate concentrations below 20 mmol/L were included in the study. Alkali therapy with oral sodium bicarbonate was used to maintain the serum bicarbonate concentration in the normal range. At the beginning all patients had sinus rhythm on surface ECG records. Kidney function tests including serum urea, serum creatinine, uric acid, blood gas analysis, and electrolytes were analyzed at the beginning and at the end of alkali treatment. All patients underwent 12 lead-ECGs, recorded simultaneously. One cardiologist examined the ECGs manually in terms of QT intervals, corrected for heart rate (QTc), QT dispersion (QTd) and corrected QT dispersion (QTcd).

Results

There were statistically significant differences in QT intervals, QTc, QTd and QTcd before and after sodium bicarbonate treatment. The correlation analyses revealed that there were significant negative correlations in pretreatment ECGs of patients between QTd and QTcd with blood pH level. Multivariate analyses between biochemical parameters and QTd-QTcd intervals have revealed that pH was related to QTd and QTc.

Conclusions

This study demonstrated that QT intervals on surface ECG are decreased after treatment of acidosis in CKD. Further studies are needed to show whether increased QT intervals cause ventricular arrhythmias in CKD.

Association of Corrected QT and QT Dispersion with Echocardiographic and Laboratory Findings in Uremic Patients under Chronic Hemodialysis

Introduction:

Cardiovascular disease is the most common cause of mortality in dialysis patients. Chronic renal failure and hemodialysis (HD) patients may have longer corrected QT (QTc) interval compared with the normal population. Long QTc interval may be a predictor of ventricular arrhythmia and cardiovascular mortality in these patients and hence the aim of this study was the evaluation of the relationship between QTc interval and some echocardiographic findings and laboratory exam results in HD patients.

Materials and Methods:

In a cross-sectional study, 60 HD patients with age >18 years and the dialysis duration >3 months were enrolled. Blood samples were taken, and electrocardiography and echocardiography were done before the dialysis session in the patients.

Results:

Mean age of the patients was 56.15 ± 14.6 years. QTc interval of the patients was 0.441 ± 0.056 s and QT dispersion (QTd) was 64.17 ± 25.93 ms. There was no statistically significant relationship between QTc interval and QTd with duration of dialysis, body mass index, age, and gender (P > 0.05). There was also no significant relationship between QTc interval and QTd with mitral regurgitation, tricuspid regurgitation and aortic insufficiency (P > 0.05). In addition, QTc interval and QTd of the patients had not any correlation with serum parathormon and serum Ca, K, HCO₃ (P > 0.05).

Conclusion:

Based on our results, in HD patients, QTc interval and QTd were not correlated with echocardiographic findings or laboratory exam results. Therefore, it can be concluded that QTc interval prolongation probably has not any correlation with cardiac mortality of the HD patients.

The Acute Cardiac Effects of Dialysis

It is well recognized that the procedure of hemodialysis is associated with significant changes in blood pressure and systemic hemodynamics; 20-30% of treatments are complicated by intradialytic hypotension (IDH). There are now an increasing number of studies using electrocardiographic, isotopic and echocardiographic techniques that show that subclinical myocardial ischemia occurs during dialysis. This concept is supported by some studies showing that dialysis can induce acute rises in troponins and creatinine kinase MB, although this has not been found by all authors. Some of this controversy may at least in part be due to the collection of blood samples immediately postdialysis, which is likely to be too early to reliably detect dialysis-induced elevations of cardiac enzymes. Cardiovascular death is the biggest single cause of mortality in dialysis patients and of this sudden death comprises the largest proportion. As such, there is a large body of evidence examining whether dialysis is pro-arrhythmogenic. It is clear that dialysis can increase QTc interval and QT dispersion and is capable of inducing arrhythmias on Holter monitoring, likely due to the interaction of multiple factors, some of which prime for the development of arrhythmias (particularly the presence of preexisting cardiac disease), and some of which act as triggers. However, the link between these electrocardiographic alterations and sudden death is relatively poorly studied. This review summarizes the available literature regarding the acute cardiac effects of dialysis in relation to the above, and discusses how these acute changes may contribute to the genesis of uremic cardiomyopathy and longer term cardiac outcomes.

Azithromycin as a cause of QT-interval prolongation and torsade de pointes in the absence of other known precipitating factors

During treatment with azithromycin, a 55 year-old woman developed a newly prolonged QT interval and torsade de pointes in the absence of known risk factors. Female gender and acute renal failure may be considerations in patients treated with azithromycin.

QT interval dispersion in dialysis patients

The leading cause of mortality in dialysis patients is cardiovascular complications, including ventricular arrhythmias and sudden cardiac death. A reliable non-invasive predictive test of sudden death is therefore important. The interlead variation in duration of the QT interval on the surface electrocardiogram corrected with heart rate (QTc dispersion) might serve as a surrogate for ventricular arrhythmia. Prolonged QTc dispersion is commonly encountered in dialysis patients and possesses an increased risk of all mortality, including cardiovascular mortality. QT dispersion might be affected by shifts of the intracellular electrolytes during dialysis and increasing deposition of iron in cardiac muscles in these patients who have underlying heart diseases. Although no well-designed study has been done, the factors contributing to prolongation of QTc dispersion should be avoided. We summarize the results of the currently available clinical studies that examined QTc dispersion in dialysis patients.