Heart rate variability in children with chronic pyelonephritis and I–III stages of chronic kidney disease

Abstract

Background. Assessment of heart rate variability allows us to get an idea about the functional state of the autonomic nervous system and to identify changes in autonomic homeostasis in children. The purpose was to study the features of vegetative regulation in children with chronic pyelonephritis at the initial stages of chronic kidney disease by analyzing heart rate variability. Materials and methods. There were surveyed 94 children aged 6–17 years without exacerbation of chronic pyelonephritis with CKD stage I–III. There was conducted daily monitoring of ECG, followed by mathematical processing. Results. Analysis of the statistical characteristics of the Z-scores of the time analysis indicators revealed a significant decrease in the standard (root-mean-square) deviations of the RR interval in patients of all groups with a significant decrease in this indicator in children with CKD stage III. A significant decrease in RMSSD values was demonstrated in patients with CKD stage III, and patients with CKD stages I to III demonstrated pNN50 decline. In a spectral analysis, patients showed a significant increase in the total power of the spectrum of heart rate variability of TP and its domains (VLF, LF), sympathetic-parasympathetic ratio of LF to HF and decrease of HF. Conclusions. 76.6 % of children with chronic pyelonephritis and CKD stage I–III presented with the ve­getative imbalance. With the progression of CKD, the autonomic imbalance exacerbated, as evidenced by the presence of correlations between the glomerular filtration rate and findings of time (SDNN, pNN50) and spectral (TP, LF, HF) analysis of heart rate variability. The revealed changes suggest the expected development of cardiovascular disorders even before the appearance of significant changes in the central hemodynamics.