Heart rate variability characteristics in children with cardiac syncope

Abstract

The imbalance of autonomic nervous system is one of the main pathophysiological mechanism of syncope. At the heart of their development of any genesis is to reduce systemic blood pressure, causing a decrease in total cerebral blood flow current and leads to loss of consciousness. It is proved that the sudden cessation of cerebral blood flow on 6–8 s causes loss of consciousness. The aim of the study – to learn the features of time and frequency domain parameters of heart rate variability in children with cardiac syncope. Materials and Methods. 19 patients with cardiac syncope and 41 healthy children aged 8–17 years were examined. The European Society of Cardiology Guidelines (2018) was used in the diagnosis of cardiac syncope. Time (SDANN, RMSSD, pNN50) and frequency domain (TP, VLF, LF, HF, LF/HF) parameters of heart rate variability were studied using a 3-Channel Digital ECG Holter Recorder SDM3 (Ukraine). Serum 25(OH)D level was determined by colorimetric enzyme-linked immunosorbent assay using the Monobind test system (USA). Results. Heart rate variability parameters SDANN, RMSSD, pNN50 and LF/HF did not differ in patients of the main and control groups (p>0.05). However, there were high values of TP ​​(12751.64±2060.01) ms2, (5482.44±396.87) ms2; p = 0.00005), VLF (6615.17±819.89) ms2; (3906.29±269.09) ms2; p = 0.003), LF (5194.583±797.16) ms2; (2379.22±172.60) ms2; p = 0.0015), and HF (4049.14±774.07) ms2; (2446.54±316.16) ms2; p = 0.028) in patients with cardiac syncope compared with healthy children. A direct correlation between the vitamin 25(OH)D level and pNN50 (r = 0.49; p = 0.04) was found which indicates the possible influence of vitamin D deficiency to the development of dysautonomia in children with syncope. The obtained results can be useful for using of heart rate variability analysis as independent criteria to monitoring of a patient with cardiac syncope and assessment of treatment effectiveness. Conclusions. The functional state of autonomic nervous system in children with cardiac syncope is characterized by a balanced autonomic influence on cardiac activity. At the same time stress of regulatory systems on the background of increased activity of sympathetic and parasympathetic links of regulation, and a high level of central mechanisms activity of heart rate regulation are observed

Keywords

• cardiac syncope
• heart rate variability
• autonomic nervous system
• children