الفهرس 
Introduction
End Stage Renal DiseaseOnly 14 pages are availabe for public view
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Abstract
Cardiovascular diseases represent the main causes of death (especially sudden cardiac arrest) in patients affected by renal failure and chronic hemodialysis (Sniderman AD., et al., 2010).
The reasons for great incidences of arrhythmia and death are complex and multifactorial. Dialytic treatment per se can be considered as an arrhythmogenic stimulus; moreover, uremic patients are characterized by a pro-arrhythmic substrate because of the high prevalence of ischaemic heart disease, left ventricular hypertrophy and autonomic neuropathy, myocardial dysfunction, changes in electrolyte concentration like calcium and potassium (Voroneanu L., et al., 2009).
Among the noninvasive techniques which can be useful for predicting the patients at risk for sudden death is the measurement of QT interval changes with 12-lead surface electrocardiogram (Crisu D., 2010).
The QT interval is a measure of the duration of ventriculardepolarization and repolarization. In patients with the long QT syndrome and in a healthy population, prolongation ofthe QT interval predicts cardiovascular death. QT dispersion (Maximum - Minimum QT interval on standard 12-lead electrocardiogram [ECG]) is a marker of variability of ventricular repolarization and is elevated in various “high-risk” groups, such as diabetic patients, patients with cardiac failure,and essential hypertensive patients(Barr CS., et al., 1994).
In the current study, 50 patients were studied, with the mean of age of 44.28 ± 12. 07 (19 – 59). There were 19 (38%) male and 31 (62%) female patientswho attend HD unit in Assiut General Hospital between Jan. 2014 and March 2015. All patients were subjected to careful historytaking and clinical examination. All of them were investigated with laboratory tests (kidney function & serum electrolytes) 30 minutes before and one day after HD. In addition, ECG was done before and after HD.
Accordingto our results of the comparison of different subgroups, it was found that the maximal QT and QTc interval prolongation, QT and QTc interval dispersion after hemodialysis were independent of gender and age of patients (p > 0.05)
Analysis of the risk factors in the study showed that, Diabetes was encountered in 20 % (10 patients) and Hypertension in 84% ( 42 patients) and neither Diabetes nor Hypertension significantly affect the maximal QT and QTc interval prolongation, QT and QTc interval dispersion after hemodialysis (p > 0.05).
In the present study, both QT and QTc intervals and QT and QTc dispersions increased significantly at the end of hemodialysis (P < 0.05).
Laboratory tests including serum electrolytes were performed before and after hemodialysis to the patients of the study. The serum potassium and Magnesium level decreased significantly (P = 0.001), whereas calcium serum level increased significantly (P = 0.001). There were no significant change in the levels of sodium as the mean before hemodialysis (P=0.835).
Our findings demonstrated that the increase of QT interval duration and QTD were not significantly correlated with serum potassium and/or magnesium levels (p > 0.05 for all). However, we found a significant correlation between the changes of Sodium level after dialysis and the post-dialysis QTc interval duration, with Pearson’s correlation coefficients r = 0.286, p = 0.044.
In conclusion, this study showed that QT interval and QT dispersion,markers of risk for arrhythmias and sudden death and they areelevated in hemodialysis patients after dialysis. Themechanisms responsible are unclear but may reflect myocardialischemia in those patients with known ischemic heartdisease,or changes in acid-base status in patients without ischemicheart disease.
Recommendations;
• QT interval and QT dispersion is an easily obtainable, noninvasive, simple, inexpensive, and widely available method of risk stratification in uremic patients receiving chronic hemodialysis.
• QT dispersion reflects the non-homogeneous recovery of ventricular excitability and might predict ventricular arrhythmias.
• There are higher percentages of ESRD patients with dialysis therapy that have prolonged QT dispersion and hence are susceptible to ventricular arrhythmias.
• Due to its high reproducibility and non-invasive methodology, QT dispersion should be a routine test in the care of dialysis patients, especially those with preexisting heart disease.
• The factors contributing to greater QTc dispersion should be avoided, at least for patients with pre-existing cardiac diseases.
• QT dispersion may prove a novel target for intervention studies to reduce sudden death in this high-risk population.
• Additional larger studies are required to assess the importance of QT interval and dispersion on cardiovascular outcome in chronic renal failure.
References