Charcteristics of the Autonomic Nervous System in Patients with Liver Cirrhosis and its Dependence on the Severity of Portal Hypertension due to the Values of the Heart Rate Variability Parameters

Introduction. Liver cirrhosis, accompanied by the disorders of all organs and systems, including the autonomic nervous system disorders, which greatly accelerates the negative prognosis, taking part in the pathogenesis of the leading syndrome – portal hypertension, is a major cause of death of the hepatological patients. According to the principles of clinical and experimental approach, recommended by A. M. Wein, exploring the autonomic nervous system, primarily it is important to assess its functional status according to the results of functional and dynamic studies: tone, autonomic reactivity and vegetative support of the body, the first two of which characterize the homeostatic capabilities of the organism, and the last – adaptive. The most informative non-invasive method to evaluate the autonomic nervous system status is the heart rate variability recording. Despite the high prevalence of the autonomic nervous system dysfunction in patients with liver cirrhosis, the condition of the autonomic nervous system in patients with liver cirrhosis and its dependence on the severity of portal hypertension is insufficiently studied, because clinicians often do not pay attention to it, focusing on the deviations of laboratory parameters and severity of liver disease. Therefore, the aim of our study was to describe the state of the autonomic nervous system in patients with liver cirrhosis and determine its dependence on the severity of portal hypertension according to the study of heart rate variability indices. Materials and research methods. Into the study in randomized manner with the preliminary stratification by the presence of liver cirrhosis were involved 240 patients with varying degrees of portal hypertension severity [65 women (27.1 %) and 175 men (72.9 %); aged 21 to 78 years, average age – (48.4 ± 0.8 years)], who were hospitalized with the aim of the examination and treatment into created on the basis of the Internal Medicine Department N 1 of Lviv National Medical University and Gastroenterological Department of Lviv Regional Clinical Hospital, Lviv Regional Hepatological Center. All the patients underwent a comprehensive clinical-laboratory and instrumental examination of all organs and systems, according to the requirements of modern medicine and also, improved by us, ultrasound doppler-floumetric examination of the abdominal cavity vessels, by our patented method, under which all the patients were stratified into three groups: the first group (PH of the 1st degree) included 122 persons [33 women (27.0 %) and 89 men (73.0 %)] aged 21 to 78 years (average age 46,4 ± 1,0 years), the second (PH of the 2nd degree) – 57 patients [14 women (24.6 %) and 43 men (75.4 %)] aged 27 to 66 years (average age 48.2 ± 1.3 years) and the 3rd group (PH of the 3rd degree) – 61 patients [18 women (29.5 %) and 43 men (70.5 %)] aged 29 to 73 years (average age 50.2 ± 1.3 years). Also were examined 40 healthy individuals [27 women (67.5 %) and 13 men (32.5 %)] aged 19 to 51 years (average age – 22.9 ± 0.9 years), which formed the control group. The study of the autonomic nervous system was also performed by our patented method, which provides a comprehensive evaluation of the indices of non-invasive examination of heart rate variability. According to the results of our study, we can observe the dynamics of heart rate parameter, that, due to the heart rate variability indices in patients with liver cirrhosis before and after the physical activity was significantly (p < 0.05) increasing with the increase of the portal hypertension severity, demonstrating the prevailing of the influence of sympathetic over parasympathetic nervous system with the increase of the disease severity. Indices of the temporal and spectral analysis are significantly reducing with the increase of the pathological process in the liver and indicate the exceptions of the central mechanisms in regulating the autonomic processes with the transition to local – humoral-metabolic level, because despite the compensatory activation of the sympathetic nervous system in patients with liver cirrhosis, its influence remains small, which is associated with the decreased sensitivity of the receptors of the vessels to vasoconstrictors, including to neurotransmitters. When analyzing the influence of various parts of auto­nomic influence it was found, that on the basis of reduced total spectral power was observed the imbalance of the autonomic nervous system with the dominance of the sympathetic nervous system in patients of all three groups, especially pronounced in the probe with physical activity. Conclusions. The state of the autonomic nervous system in patients with liver cirrhosis is characterized by the decrease of the total activity of the autonomic influence on the heart rate by the reducing the sympathetic and parasympathetic influences, as well as humoral component. Study of the heart rate variability, time and spectral analysis parameters using method for the detecting heart rate variability, recording it before and after the physical activity made it possible to verify the presence of autonomic disorders with predominant influences of the sympathetic branch of the autonomic nervous system over the parasympathetic with directly proportional increase of the neurohormonal effects in patients with different severity grades of portal hypertension, diagnosed using advanced by us noninvasive ultrasound doppler-floumetric examination of the abdominal vessels. Increasing of the autonomic dysfunction grade, with the transition of the regulation to local (humoral-metabolic) level, according to the heart rate variability parameters study, directly proportional on the severity of portal hypertension in patients with liver cirrhosis, which confirms the role of the autonomic nervous system in the pathogenesis of portal hypertension occurrence and can serve as a reliable diagnostic criterion of portal hypertension detecting and as one of the “markers” to determine the degree of its severity