The investigation of the nature of syncope shows that it is caused by failure of compensatory reflex mechanisms of the autonomic nervous system. Therefore, the determination of specific parameters of autonomic nervous system homeostasis and adaptive potential improves the approach to determining the clinical predictors of the syncope and facilitate its early diagnosis. Purpose — to determine the nature and compare of autonomic dysregulation and functional changes of in children with syncope of different genesis, to identify the circumstances for the formation of insufficient autonomic regulation. Materials and methods. The enrolled subjects were 125 children with syncope, aged 8–17 years, and 41 controls. Children were divided into three groups for analysis: 81 — with vasovagal syncope, 25 — with syncope due to orthostatic hypotension, 19 — with cardiogenic syncope. All children underwent a clinical and functional examination of the cardiovascular system to identify features of autonomic homeostasis. Results. Autonomic imbalance with a predominance of sympathetic autonomic regulation was detected in children of all study groups. The results of functional tests and quantitative integrative indicators showed significantly increased autonomic reactivity with depletion of adaptive potential in all study groups (p<0.05). Children with vasovagal syncope had excessive levels more often (p<0.05), and children with syncope due to orthostatic hypotension had insufficient levels of autonomic support (p<0.05). Violations of cardiorespiratory inter systemic connections were found in children with vasovagal and cardiogenic syncope significantly more often, compared to the control group (p <0.05). Correlations were found between the parameters of the initial autonomic balance, autonomic support of the circulatory system, and the manifestations of syncope in children. Conclusions. The correlation between pathological types of autonomic response and the frequency and duration of syncopal episode indicates a pathogenetic relationship between the state of autonomic support and the ability of the circulatory system to respond to triggers. Therefore, indicators of the autonomic homeostasis and adaptive potential can be applied for predicting the occurrence of syncopal episodes and monitoring of effective management of syncope in children. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: children, syncope, autonomic nervous system homeostasis, adaptive potential.
Beta 3 subunit of G-protein and its influence on autonomic nervous system in patients with vasovagal syncope
