Orthostatic Test Research Articles

Heart rate variability at rest and in response to stress: Comparative study between hemodialysis and peritoneal dialysis patients.

Cardiac arrhythmias and sudden death are the leading causes of mortality in end-stage kidney disease (ESKD). Autonomic nervous system (ANS) dysfunction contributes to this arrhythmogenic background. This study compared heart rate variability (HRV) indices between hemodialysis (HD) and peritoneal dialysis (PD) patients, both at rest and in response to mental and physical stimulation maneuvers. Thirty-four HD and 34 PD patients matched for age, sex, and dialysis vintage, and 17 age- and sex-matched controls were studied. ANS function was examined by linear and non-linear HRV indices. Heart rate was recorded continuously (Finometer-PRO) at rest and during ANS maneuvers (orthostatic, mental-arithmetic, sit-to-stand, handgrip exercise tests). At rest, no significant differences between HD and PD were observed in HRV (root mean square of successive differences [RMSSD]: HD = 57.1 ± 81.1 vs PD = 69.6 ± 113.4 ms; P = 0.792), except for detrended fluctuation analysis (DFA-α1) (HD = 0.87 ± 0.40 vs PD = 0.70 ± 0.20; P = 0.047). DFA-α1 was significantly lower in PD than controls (1.00 ± 0.33; P < 0.05). All HRV indices during the mental-arithmetic test (RMSSD: HD = 128.2 ± 346.0 vs PD = 87.5 ± 150.0 ms; P = 0.893) and the physical stress tests were similar between HD and PD. The standard deviation along the line-of-identity (SD2)/the standard deviation perpendicular to the line-of-identity (SD1) ratio during mental-arithmetic was marginally lower in HD and significantly lower in PD than controls (PD = 1.31 ± 0.47 vs controls = 1.79 ± 0.64; P < 0.05). Both dialysis groups presented similar patterns in HRV responses during orthostatic and handgrip exercise tests. After the sit-to-stand, RMSSD, SD1, SD2, and DFA-α2 were higher compared to rest only in HD (RMSSD = 57.1 ± 81.1 vs 126.7 ± 185.7 ms; P = 0.028), suggesting a greater difficulty of HD patients in recovering normal ANS function in response to physical stress. In conclusion, HRV indices at rest and after mental and physical stimulation did not differ between HD and PD; however, the ANS responses following the sit-to-stand test were more impaired in HD. These findings suggest that ANS dysfunction is not largely affected by dialysis modality, but small differences in normal ANS recovery may exist.

Autonomic nervous system and postural control regulation during orthostatic test as putative markers of physical resilience among community-dwelling older adults

IntroductionWe examined whether autonomic nervous system (ANS) and postural control regulation during orthostatic test reflect physical resilience by studying their associations with maximal walking speed and mortality. MethodsThe participants were community-dwelling Finnish men (n = 303) and women (n = 386) aged 75, 80, and 85 years at baseline. Systolic and diastolic blood pressure (BP), heart rate, heart rate variability (HRV), respiratory rate, and postural sway were obtained using a digital sphygmomanometer, a single-channel ECG, and thigh- and chest-worn accelerometers. Linear and Cox regression models were used to estimate the associations of the physiological indices with maximal 10-m walking speed and 5-year mortality separately for sexes. ResultsBetter maintenance of BP under orthostatic stress was associated with faster walking speed in women and lower mortality hazard in men. Greater HRV in terms of low frequency power and lower respiration rate in supine position and smaller orthostatic changes in these were associated with faster walking speed especially in women. Less postural sway after standing up was associated with faster walking speed in women (−0.057, SE 0.022, p = 0.011) and more postural sway with increased mortality hazard in men (HR 1.71, 95 % CI 1.20–2.43) even after controlling for BP responses. ConclusionsIn addition to ANS regulation at rest and under stress, adaptation of postural control system to orthostasis may be used in quantifying older adults' physical resilience. Wearable sensors capturing stimulus-response patterns and natural fluctuations of body functions may provide opportunities to monitor and incorporate different subsystems' resilience also in free-living conditions.

Arterial oscillography as an indicator of adaptation of the cardiovascular system during active orthostatic test

The article is devoted to the study of an effective means of early diagnosis of premorbid conditions, control of the effectiveness of treatment results, physical exercises and sports, namely the orthostatic test, as well as registration methods that make it possible to assess the state of the cardiovascular system and the functional reserves of blood circulation regulation mechanisms. The orthostatic test is the simplest and most accessible method, which makes it possible to assess the state of the cardiovascular system and the functional reserves of blood circulation regulation mechanisms. 21 people aged 18-22 years without health complaints were examined. Arterial oscillograms were recorded during blood pressure measurement with an electronic tonometer in the supine position and after standing up. For the morphological analysis of the arterial oscillogram, the Oranta-AO Software Complex (PC) developed by the authors was used. The type of arterial oscillogram, the level of health, and the adaptation capabilities of the subjects were evaluated. Orthoprobe is accompanied by an increase in blood pressure and heart rate, which indicates its stimulating effect on the state of the sympathetic link of the autonomic nervous system. According to the results of the arterial oscillogram in the supine position, only 33% of the examined were excellent and good. After standing up, the quality of the arterial oscillogram improved in 47% of the examinees, which indicates the functional nature of disorders caused by the lability of the autonomic nervous system and the positive effect of the orthoprobe on the pulsatility of blood vessels.&#x0D; Deterioration refers to a decrease in the functional capacity of the cardiovascular system and its regulatory mechanisms. The use of PC Oranta-AO enables the doctor (as well as the patient) in offline or online mode, immediately after measuring blood pressure, to obtain conclusions about the state of the cardiovascular system and its regulatory mechanisms.

Impaired parasympathetic function in long-COVID postural orthostatic tachycardia syndrome – a case-control study

PurposeEighty percent of patients infected by SARS-CoV-2 report persistence of one symptom beyond the 4-week convalescent period. Those with orthostatic tachycardia and orthostatic symptoms mimicking postural tachycardia syndrome, they are defined as Long-COVID POTS [LCP]. This case-control study investigated potential differences in autonomic cardiovascular regulation between LCP patients and healthy controls.MethodsThirteen LCP and 16 healthy controls, all female subjects, were studied without medications. Continuous blood pressure and ECG were recorded during orthostatic stress test, respiratory sinus arrhythmia, and Valsalva maneuver. Time domain and power spectral analysis of heart rate [HR] and systolic blood pressure [SBP] variability were computed characterizing cardiac autonomic control and sympathetic peripheral vasoconstriction.ResultsLCP had higher deltaHR (+ 40 ± 6 vs. + 21 ± 3 bpm, p = 0.004) and deltaSBP (+ 8 ± 4 vs. -1 ± 2 mmHg, p = 0.04) upon standing; 47% had impaired Valsalva maneuver ratio compared with 6.2% in controls (p = 0.01). Spectral analysis revealed that LCP had lower RMSSD (32.1 ± 4.6 vs. 48.9 ± 6.8 ms, p = 0.04) and HFRRI, both in absolute (349 ± 105 vs. 851 ± 253ms2, p = 0.03) and normalized units (32 ± 4 vs. 46 ± 4 n.u., p = 0.02). LFSBP was similar between groups.ConclusionsLCP have reduced cardiovagal modulation, but normal sympathetic cardiac and vasoconstrictive functions. Impaired parasympathetic function may contribute to the pathogenesis of Long-COVID POTS syndrome.

Адаптационные, регуляторные и функциональные возможности студентов с разным биологическим возрастом по шкале «Bio-age»

Biological age (BA) is determined by a set of metabolic, structural, functional, regulatory and adaptive characteristics of the body. Assessment of biological age is the key to studying the influence of time and environmental conditions on changes in the body at all stages of ontogenesis. The purpose of this article was to study the adaptive, regulatory and functional characteristics of students of different biological ages, determined using the Bio-Age scale. Materials and methods. The research involved 521 students aged 18–25 years who were examined at the Health Centre based at Arzamas City Hospital No. 1. These included anthropometry, bioelectrical impedance analysis, cardiointervalography, anklebrachial index test, as well as determination of total cholesterol and glucose levels in the blood. Results. Biological age assessment using the Bio-Age scale showed that only in 1/2 of the students the biological age coincides with the chronological age, while 1/3 of the subjects already have an accelerated rate of ageing. The adaptive capabilities of students whose biological age is less than the chronological age (BA &lt; CA) are better than of those whose biological age exceeds the chronological age (BA &gt; CA). This is confirmed not only by the adaptation degree according to R.M. Baevsky’s method, but also by stress index dynamics and by the parameters of heart rate spectral analysis. In students with BA &lt; CA, the functional state of the body is optimal both at rest and during an orthostatic test: the total power of the cardiointervalogram spectrum decreases due to reduced activity of the parasympathetic division. In students with BA &gt; CA, both in the supine and prone positions, a mismatch in the functioning of different parts of the autonomic nervous system was identified, namely, greater involvement of the central parts of heart rate control, increased sympathetic influences and a weaker activity of the parasympathetic division of the autonomic nervous system.

Influence of end-tidal CO2 on cerebral blood flow during orthostatic stress in controls and adults with myalgic encephalomyelitis/chronic fatigue syndrome.

Brain perfusion is sensitive to changes in CO2 levels (CO2 reactivity). Previously, we showed a pathological cerebral blood flow (CBF) reduction in the majority of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients during orthostatic stress. Limited data are available on the relation between CO2 and CBF changes in ME/CFS patients. Therefore, we studied this relation between ME/CFS patients and healthy controls (HC) during tilt testing. In this retrospective study, supine and end-tilt CBF, as measured by extracranial Doppler flow, were compared with PET CO2 data in female patients either with a normal heart rate and blood pressure (HR/BP) response or with postural orthostatic tachycardia syndrome (POTS), and in HC. Five hundred thirty-five female ME/CFS patients and 34 HC were included. Both in supine position and at end-tilt, there was a significant relation between CBF and PET CO2 in patients (p< 0.0001), without differences between patients with a normal HR/BP response and with POTS. The relations between the %CBF change and the PET CO2 reduction were both significant in patients and HC (p< 0.0001 and p= 0.0012, respectively). In a multiple regression analysis, the patient/HC status and PET CO2 predicted CBF. The contribution of the PET CO2 to CBF changes was limited, with low adjusted R2 values. In female ME/CFS patients, CO2 reactivity, as measured during orthostatic stress testing, is similar to that of HC and is independent of the type of hemodynamic abnormality. However, the influence of CO2 changes on CBF changes is modest in female ME/CFS patients.

Evaluation of autonomic disorders in miners with vibration disease

Introduction. Autonomic disorders in the form of autonomic neuropathy develop in vibration disease already at the early stages. As the disease progresses, the compensatory mechanisms of autonomic regulation are depleted, which leads to a worse prognosis for life and an increased risk of sudden cardiac death in patients with a severe degree of autonomic neuropathy. &#x0D; The aim of the study was to evaluate the severity of autonomic disorders and the preservation of compensatory reserves of autonomic regulation in patients with vibration disease. &#x0D; Materials and methods. One hundred thirty six miners with a proven diagnosis of vibration disease and 60 apparently healthy men of similar age without complaints and who had never worked under the conditions of exposure to industrial vibration were examined. Heart rate variability was analyzed at rest and during an active orthostatic test.&#x0D; Results. A decrease in the spectral parameters of heart rate variability in the patients with vibration disease was revealed. In a subgroup of the patients with an initially low level of very low frequency oscillations (less than 30 ms2/Hz), a decrease in the non-linear entropy index (less than 180) was determined; when performing an active orthostatic test, the power of very low frequency spectrum oscillations in the patients of this subgroup decreased by more than 50% of the initial values. In all patients with vibration disease under orthostatic load, a decrease in the oscillations of high and low frequencies of the spectrum of heart rate variability was revealed, whereas in the control group, the low frequency oscillation power remained at the initial level.&#x0D; Limitations. The study was limited to the evaluation of spectral and non-linear indices of heart rate variability in 136 miners with vibration disease. &#x0D; Conclusion. The criteria for a severe course of autonomic neuropathy in the patients with vibration disease were identified: an initial decrease in the power of very low frequency oscillations and a non-linear entropy index of heart rate variability, as well as a decrease in the power of very low frequency oscillations by more than 50% during an orthostatic test. According to these criteria, in 40.4% of the miners with vibration disease, pronounced violations of the autonomic support with a lack of compensatory mechanisms of autonomic regulation were found to be detected.

Overweight and dysregulation of the autonomic nervous system in young persons

Background. More than 1 billion people worldwide are obese, and this number is growing. Obesity at an early age is accompanied by impaired carbohydrate tolerance and the development of type 2 diabetes, lipid metabolism pathology, obstructive apnea, hypercoagulability, chronic inflammation and the development of insulin resistance in the future. In modern literature, there is no single point of view regarding the role of the autonomic nervous system in the coordination of hormonal, nervous and metabolic factors in the body.Aim. The article presents the results of studying the functional state of the sympathetic and parasympathetic parts of the autonomic nervous system in overweight persons and presents an assessment of the central hemodynamic parameter depending on the type of autonomic reactivity of the cardiovascular system.Methods. The study involved measuring systolic and diastolic blood pressure, heart rate, and anthropometric measurements for calculating the corresponding indices. An active orthostatic test to determine the functional state of reflex mechanisms for regulating hemodynamics. Statistical methods were used for data analysis.Results. Based on anthropometric indicators and calculated indices, boys and girls with overweight differed from the control group in abdominal and total distribution of fat. However, there were no differences in terms of vegetative tone (sympathicotonic, vagotonic, eutonic). The distribution of eutonic and vagotonic types of the autonomic nervous system and sympathicotonia was similar in both groups. Most overweight individuals had insufficient reactivity of the parasympathetic autonomic nervous system. Paradoxical reactivity in both groups was observed with the same frequency. In the group of people with paradoxical autonomic reactivity among overweight people, a significantly lower increase in heart rate was found than in the control group. In persons with overweight and increased autonomic reactivity, minute blood volume and pulse pressure increased 1.5-fold, there was a tendency to increase stroke volume and inotropic function of the heart. The increase in this characteristic indicated a hyperkinetic type of hemodynamics in overweight persons in the group with normal autonomic reactivity. In groups with paradoxical and increased autonomic reactivity of the cardiovascular system, a normokinetic type of hemodynamics was observed.Conclusions. Signs of altered autonomic reactivity found in most overweight individuals indicate dysfunction of the parasympathetic autonomic nervous system and possible dysfunction of nonspecific regulatory (limbic-reticular) parts of the brain.

Heart rate variability is a marker of the risk of maladaptation of students of various educational institutions

A comparative analysis of the level of adaptive capabilities of cadet corps and secondary school students based on the study of heart rate variability. Materials and methods: Cadets (n = 64) and schoolchildren (n = 86) aged 1012 years took part in the study; spectral parameters of the heart rate were evaluated at rest and under conditions of an active orthostatic test. Results: It was found that the severity of the HF component of the heart rate decreases with age in cadets, which indicates a decrease in the effects of the parasympathetic system, (40.2 8.7) % at 10 years and (25.1 3.6) % at 12 years; р = 0.024. At the age of 12, the values of LF (р = 0.034), LF/HF (р = 0.031) and SI (р = 0.041) in cadets are higher than in schoolchildren, and HF (р = 0.022) are lower. During the active orthostatic test, the cadets showed a decrease in K30:15, as well as an increase in LF (р = 0.035), LF/HF (р = 0.041) and TI (р = 0.038), which demonstrates the predominance of the central contour of regulation. Conclusions: 1) spectral analysis of the heart rate indicates a marked increase in the stress of adaptive mechanisms with age in the cadets of the Cossack corps, which reflects increased physical, intellectual and psycho-emotional stress compared with schoolchildren; 2) spectral characteristics of heart rate variability can be used as sensitive markers of stress of physiological systems and a decrease in adaptive reserves.

Exploring the prevalence of undetected bradyarrhythmia in dementia with Lewy bodies

PurposeTo explore the prevalence of undetected bradyarrhythmia in a cohort of people with dementia with Lewy bodies.MethodsThirty participants diagnosed with dementia with Lewy bodies were enrolled from three memory clinics in southern Sweden between May 2021 and November 2022. None had a history of high-grade atrioventricular block or sick sinus syndrome. Each participant underwent orthostatic testing, cardiac [123I]metaiodobenzylguanidine scintigraphy and 24-h ambulatory electrocardiographic monitoring. Concluding bradyarrhythmia diagnosis was obtained until the end of December 2022.ResultsThirteen participants (46.4%) had bradycardia at rest during orthostatic testing and four had an average heart rate < 60 beats per minute during ambulatory electrocardiographic monitoring. Three participants (10.7%) received a diagnosis of sick sinus syndrome, of whom two received pacemaker implants to manage associated symptoms. None received a diagnosis of second- or third-degree atrioventricular block.ConclusionThis report showed a high prevalence of sick sinus syndrome in a clinical cohort of people with dementia with Lewy bodies. Further research on the causes and consequences of sick sinus syndrome in dementia with Lewy bodies is thus warranted.

СРАВНЕНИЕ ПОКАЗАТЕЛЕЙ ФИЗИЧЕСКОГО РАЗВИТИЯ И ФИЗИЧЕСКОЙ ПОДГОТОВЛЕННОСТИ ПЕРВОКУРСНИКОВ С РАЗНЫМ СОСТОЯНИЕМ ЗДОРОВЬЯ, ПЕРЕНЕСШИХ COVID-19

To study the "post-covid syndrome," as a natural consequence of the pathological course of the new coronavirus infection "covid-19," data from a retrospective analysis of the incidence and testing of motor abilities of freshmen in 2022 are presented. The incidence rate of covid-19 among 2022 freshmen was significantly higher than among 2021 freshmen and had two peaks in October 2021 and February 2022. The ratio of girls who had been ill and did not have covid-19 was significantly higher than in the group of boys. Among young men who had recovered from covid-19, 14.86% belonged to a special medical group, while among those who were not sick, only 4.27% belonged to a special medical group. In the group of girls who had had covid-19, 17.45% belonged to the special medical group, and 11.42% among those who were not sick. Among young men who had been ill and did not have covid-19, 68.92 and 68.29% of freshmen, respectively, had a normal level of body mass index (BMI); 13.51 and 14.63% − reduced BMI values, and 16.22 and 13.42% − high BMI values. Among girls, 64.98 and 69.84% of freshmen were characterized by normal BMI values; 21.52 and 19, 34% − reduced values, and 13.08 and 8.86% − high BMI. Comparison of physical fitness indicators of freshmen who had been ill and did not have covid-19 were performed in subgroups with comparable BMI values. In the group of boys and girls with normal body mass index values, there were no significant differences in physical development and physical fitness among students who had been ill and did not have covid-19. In boys and girls with an insufficient body mass index who had recovered from covid-19, the indicators of active orthostatic test were significantly worse than in those who were not sick. In boys with excessive BMI who have had covid-19, the indicators of the hand dynamometry index and resistance to hypoxia were significantly lower than among non-sick fellow students.

#6044 HEART RATE VARIABILITY AT REST AND IN RESPONSE TO PHYSICAL AND MENTAL STRESS: A COMPARATIVE STUDY BETWEEN HEMODIALYSIS AND PERITONEAL DIALYSIS PATIENTS

Abstract Background and Aims Cardiac arrhythmias and sudden death are the leading causes of cardiovascular mortality in end-stage-kidney-disease (ESKD). Autonomic dysfunction contributes to the arrhythmogenic background of ESKD patients. This is the first study to compare linear and non-linear heart-rate-variability (HRV) indices between hemodialysis (HD) and peritoneal (PD) patients, both at rest and in response to mental- and physical-stimulation maneuvers. Method Thirty-four HD and 34 PD patients matched for age, sex, and dialysis-vintage, as well as 17 age- and sex-matched controls were studied. Autonomic function was examined by linear and non-linear-HRV indices. Heart-rate was recorded continuously with Finometer-PRO at rest and during orthostatic, mental-arithmetic, sit-to-stand, and handgrip-exercise tests. Results No significant between-group differences were observed in resting HRV indices (RMSSD: HD:57.1±81.1 vsPD:69.6±113.4ms; p = 0.792) except for DFA-a1 index (HD:0.87±0.40 vs PD:0.70±0.20, p = 0.047). All HRV indices during the mental arithmetic test (RMSSD HD:128.2±346.0 vs PD:87.5±150.0ms; p = 0.893) and the physical stress tests were similar between HD and PD patients. Both dialysis groups presented similar patterns of HRV responses to orthostatic and handgrip exercise tests; however, after the sit-to-stand test RMSSD, SD1,SD2 and DFA-a2 indices were higher compared to rest only in HD patients (RMSSD: 57.1±81.1 vs126.7±185.7ms, p = 0.028), suggesting a greater difficulty of HD patients in recovering normal ANS function following a physical stress-test. Conclusion HRV indices at rest and after mental and physical stimulation did not differ between HD and PD patients, however the ANS response following the sit-to-stand test was more impaired in HD. These findings suggest that ANS dysfunction is not largely affected by dialysis modality but small differences in normal ANS recovery may exist.

The effectiveness of active medical rehabilitation technologies among Paralympians engaged in playing sports

The purpose of the study: to study the effectiveness of active medical rehabilitation technologies among Paralympians engaged in playing sports.Materials and methods: examined 48 male patients aged 25.9 ± 2.1 years with traumatic disease of the lumbar spinal cord. All examined were divided into 2 groups: patients of the main group (19 people) against the background of standard therapy received a course of active medical rehabilitation (AMR), including mechanotherapy and electrical stimulation with biofeedback under the control of electromyography (EMG) of the muscles of the lower extremities and back. Patients in the comparison group (29 people) received standard therapy. After the AMR course, a comprehensive examination was performed, including the data of the questionnaires: the ASIA classification (American Spinal Injury Association), the FIM (Functional Independence Measure) scale of functional independence, the modified functional assessment scale of activity and quality of life VFM (Valutazione Funzionale Mielolesi), State-Trait Anxiety Inventory, the Beck depression scale; electroneurophysiological studies on the Neurosoft Neuro-EMG-Micro device, heart rate variability (HRV) on the Neurosoft Poly-Spectrum computer electrocardiograph, indicators of free movement with concentric and eccentric muscle contractions on EN-TreeM.Results: polysympathetic reflex excitability (PRV) significantly decreased in patients of the main group. There was also an improvement in vegetative reactivity (coefficient 30/15 is 1.45; p &lt;0.001) during the orthostatic test, indicating normalization of parasympathetic regulation and heart rate. The assessment on the ASIA scale revealed an improvement in sensory function by 13.4 % and motor function by 17.4 %. On the VFM scale, an increase in indicators was observed by 14.7 % and on the FIM scale by 11.5 %. When assessing the psycho-emotional sphere on the Spielberger-Khanin scale, a significant decrease in the level of reactive anxiety was noted by 10.9 %, and the level of depression by 30.5 %. A significant increase in muscle strength by 18.1 % (p &lt; 0.001) was also observed during concentric contractions, the average power increased by 83.1 % (p &lt; 0.001), the average amplitude increased by 68.7 % (p &lt; 0.001), the average speed by 27.2 % (p=0.002). When analyzing the indicators after the treatment, significant differences were obtained between the main and the comparison group (p &lt; 0.001).Conclusion: the use of biofeedback technologies under the control of electromyography leads to an increase in the effectiveness of medical rehabilitation and improves the quality of life in Paralympians with traumatic spinal cord disease.

LINEAR AND NON-LINEAR HEART RATE VARIABILITY INDICES AT REST AND IN RESPONSE TO PHYSICAL AND MENTAL STRESS: A COMPARATIVE STUDY BETWEEN HEMODIALYSIS AND PERITONEAL DIALYSIS PATIENT

Objective: Cardiac arrhythmias and sudden death are the leading causes of cardiovascular mortality in end-stage-kidney-disease(ESKD). Autonomic dysfunction contributes to the arrhythmogenic background of ESKD patients. This is the first study to compare linear and non-linear heart-rate-variability(HRV) indices between hemodialysis(HD) and peritoneal(PD) patients, both at rest and in response to mental- and physical-stimulation maneuvers. Design and method: Thirty-four HD and 34 PD patients matched for age, sex, and dialysis-vintage, as well as 17 age- and sex-matched controls were studied. Autonomic function was examined by linear and non-linear-HRV indices. Heart-rate was recorded continuously with Finometer-PRO at rest and during orthostatic, mental-arithmetic, sit-to-stand, and handgrip-exercise tests. Results: No significant between-group differences were observed in resting HRV indices(RMSSD: HD:57.1 ± 81.1 vs PD:69.6 ± 113.4ms; p = 0.792) except for DFA-a1 index(HD:0.87 ± 0.40 vs PD:0.70 ± 0.20, p = 0.047). All HRV indices during the mental arithmetic test (RMSSD HD:128.2 ± 346.0 vs PD:87.5 ± 150.0ms; p = 0.893) and the physical stress tests were similar between HD and PD patients. Both dialysis groups presented similar patterns of HRV responses to orthostatic and handgrip exercise tests; however, after the sit-to-stand test RMSSD, SD1, SD2 and DFA-a2 indices were higher compared to rest only in HD patients(RMSSD: 57.1 ± 81.1 vs 126.7 ± 185.7ms, p = 0.028), suggesting a greater difficulty of HD patients in recovering normal ANS function following a physical stress-test. Conclusions: HRV indices at rest and after mental and physical stimulation did not differ between HD and PD patients, however the ANS response following the sit-to-stand test was more impaired in HD. These findings suggest that ANS dysfunction is not largely affected by dialysis modality but small differences in normal ANS recovery may exist.

HEMODIALYSIS EFFECTS ON AUTONOMIC FUNCTION: RESULTS OF LINEAR AND NON-LINEAR ANALYSIS OF HEART-RATE-VARIABILITY AT REST AND IN RESPONSE TO PHYSICAL AND MENTAL STRESS TESTS

Objective: Cardiac arrhythmias are the most common cause of death in hemodialysis. Autonomic dysfunction plays a central role in this arrhythmogenic background. Previous studies on hemodialysis-related changes in heart-rate-variability(HRV) give contradictory results. This study investigated HRV indices both at rest and in response to physical and mental stimulation maneuvers at multiple time-points around and during the hemodialysis procedure. Design and method: Autonomic function was assessed by linear and non-linear HRV indices at pre-dialysis, during-dialysis(3 equal time-periods), post-dialysis, and on the non-dialysis day in 36 hemodialysis patients. Continuous measurement of beat-by-beat heart-rate was recorded with Finometer-PRO(The Netherlands) at rest and after orthostatic, sit-to-stand, handgrip and mental-arithmetic test. Results: The RMSSD, SD1, and SD2 indices significantly increased during dialysis(early-HD, mid-HD, late-HD periods) compared with the pre-dialysis levels(p&lt;0.05) and returned to baseline post-dialysis(RMSSD: 54.39±83.73 vs 137.98±109.53* vs 119.85±97.34* vs 144.47±88.74* vs 85.82±121.43msec, *p&lt;0.05 vs pre-dialysis and post-dialysis). No differences were detected in the above indices between the pre-dialysis and non-dialysis day. However, post-dialysis, the HRV responses to orthostatic and sit-to-stand tests were more exaggerated than in the pre-dialysis measurements (p&lt;0.05). The HRV responses both at resting and physical tests in the non-dialysis day were similar to the pre-dialysis levels. HRV indices in mental-arithmetic test during hemodialysis were much higher than at the non-dialysis day(RMSSD: 77.05 (180.41) vs 19.75 (105.47)msec; p = 0.031) were detected. Conclusions: Hemodialysis causes marked changes in autonomic function. Resting HRV indices return to baseline post-dialysis, but HRV responses to physical stress remain exaggerated and return to baseline on the non-dialysis day. Detecting patients with significant autonomic dysfunction may help towards reduction of arrhythmia risk through individualized approaches.

HIGH SALT DIET ALTERS CEREBROVASCULAR RESISTANCE IN RESPONSE TO ORTHOSTATIC TEST IN HEALTHY YOUNG INDIVIDUALS

Objective: High salt (HS) diet has been shown to impairs vascular reactivity in animal models, by increasing vasoconstriction to different stimuli. Response to orthostasis occurs via activation of baroreceptor reflex leading to increase in total peripheral resistance that prevents significant fall of arterial blood pressure (ABP) while standing up, aiming to preserve cerebral perfusion pressure. We recently showed that HS diet physiologically suppresses sympathetic arm of autonomic control in healthy humans (Stupin et al. Nutrients 2021; 13:1731. https://doi.org/10.3390/nu13051731). Present study aimed to assess the effect of HS diet on cerebral vasoreactivity in response to orthostatic load. Design and method: Twenty-seven young healthy participants (F:21, M:6, age range 19–24) consumed 7-day low-salt (LS) diet (&lt;2.3 g NaCl /day) and afterwards 7-day HS diet (&gt;11.2 g NaCl/day). In response to orthostatic test cerebral and systemic hemodynamic parameters, arterial blood pressure, heart rate variability and heart rate, and were recorded simultaneously with transcranial Doppler ultrasound and The Task Force® Monitor. Results: Subjects maintained normotension during HS diet. Diastolic blood pressure, as well as mean cerebral blood flow (CBF) and the velocity time integral decreased, while cerebral pulsatility index increased after standing up following both dietary protocols. However, while no change was observed in total peripheral resistance, cerebrovascular resistance significantly increased in response to orthostasis only after HS diet. Baroreflex sensitivity (BRS), sympathetic neural control, serum plasma renin activity and aldosterone, and urine noradrenaline and vanillylmandelic acid concentration was significantly decreased in HS diet. Conclusions: Results demonstrated that following 7-day HS diet, enhanced cerebral autoregulation preserves CBF and is manifested as increased cerebral vascular resistance, in conditions with blunted BRS and sympathetic activity. The study has been published in Eur J Appl Physiol. 2023 Jan 4. doi: 10.1007/s00421-022-05124-w. Online ahead of print.

Evaluating heart rate variability with 10 second multichannel electrocardiograms in a large population-based sample.

Heart rate variability (HRV), defined as the variability of consecutive heart beats, is an important biomarker for dysregulations of the autonomic nervous system (ANS) and is associated with the development, course, and outcome of a variety of mental and physical health problems. While guidelines recommend using 5 min electrocardiograms (ECG), recent studies showed that 10 s might be sufficient for deriving vagal-mediated HRV. However, the validity and applicability of this approach for risk prediction in epidemiological studies is currently unclear to be used. This study evaluates vagal-mediated HRV with ultra-short HRV (usHRV) based on 10 s multichannel ECG recordings of N = 4,245 and N = 2,392 participants of the Study of Health in Pomerania (SHIP) from two waves of the SHIP-TREND cohort, additionally divided into a healthy and health-impaired subgroup. Association of usHRV with HRV derived from long-term ECG recordings (polysomnography: 5 min before falling asleep [N = 1,041]; orthostatic testing: 5 min of rest before probing an orthostatic reaction [N = 1,676]) and their validity with respect to demographic variables and depressive symptoms were investigated. High correlations (r = .52-.75) were revealed between usHRV and HRV. While controlling for covariates, usHRV was the strongest predictor for HRV. Furthermore, the associations of usHRV and HRV with age, sex, obesity, and depressive symptoms were similar. This study provides evidence that usHRV derived from 10 s ECG might function as a proxy of vagal-mediated HRV with similar characteristics. This allows the investigation of ANS dysregulation with ECGs that are routinely performed in epidemiological studies to identify protective and risk factors for various mental and physical health problems.

INDICATORS OF VEGETATIVE DYSFUNCTION IN ATHLETES WITH SIGNS OF OVERTRAINING

The article examines indicators of autonomic dysfunction and features of autonomic regulation of heart rhythm in athletes. The study was conducted on the basis of the sports medicine center of Sumy State University. Two groups of athletes took part in the study. The first group of athletes included those who had signs of a non-functional state and autonomic dysfunction (in the survey according to Wayne, or it was diagnosed with an unsatisfactory ortho/clinostatic reaction) - 27 people. The second group consisted of 40 people without signs of functional overstrain (overtraining). In the course of the study, highly qualified track and field athletes were examined using the method of heart rate variability (HRV), orthostatic and clinostatic tests, and Wayne's questionnaire. The main temporal, spectral and indicators of heart rate variability were studied, and the predominant type of autonomic regulation of heart activity was established. The study of indicators of vegetative regulation of the heart showed a statistical difference between indicators of heart rate variability in athletes. Thus, the study of the features of heart rate variability makes it possible to assess the state of the mechanisms of regulation of physiological functions in the human body, as well as the general activity of regulatory mechanisms, neurohumoral regulation of the heart, the relationship between sympathetic and parasympathetic links of the autonomic nervous system. It is also quite important that the obtained data on the athlete's functional state can be used in the future to evaluate the athlete's training process and ways to optimize it.

Features of autonomic regulation of heart rate in patients with takotsubo syndrome

BACKGROUND: The pathophysiological mechanisms underlying takotsubo syndrome are still being actively investigated, but it is generally accepted that sympathetic nervous system hyperactivity is of key importance. The method for assessing heart rate variability allows to study the vegetative status of a patient, however, there are few scientific works on this topic at present, and the results obtained are ambiguous.&#x0D; AIM: To study heart rate variability in patients with takotsubo syndrome in acute and late periods of the disease at rest, when performing vegetative tests (the deep-breath test, active orthostatic test), as well as before and after mental stress tests and to compare the data obtained with the results of the examination of the control group.&#x0D; MATERIALS AND METHODS: The study included patients with takotsubo syndrome (n = 48), including 43 (89.6%) women; the average age of the patients was 63.3 13.5 years, and healthy volunteers of the same sex and age (control group, n = 40). All the subjects with takotsubo syndrome in the acute (first 714 days from the onset of the disease) and in the long-term periods of the disease (after 1 year and 2 years) and the ones in the control group underwent cardiorhythmography at rest to assess the heart rate variability after mental stress tests and against the background of vegetative tests.&#x0D; RESULTS: According to the cardiorhythmography at rest, in 47 (97.9%) patients with takotsubo syndrome, the influence of sympathetic nervous system on the heart rate prevailed, which persisted in the long-term period of the disease. The vegetative tests revealed a paradoxical reaction of the sympathetic nervous system and reduced activity of the parasympathetic nervous system in the acute and late periods of takotsubo syndrome, compared with the control group. In the acute and long-term periods in the patients with takotsubo syndrome after mental stress tests, in comparison with control group, there was no increase in parasympathetic nervous system activity.&#x0D; CONCLUSIONS: According to the study findings, the patients with takotsubo syndrome revealed autonomic dysfunction in the form of an excessive increase in the activity of the sympathetic nervous system both before the onset of the disease, and in the acute and long-term periods as well as a decrease in vagal tone, which was reflected in the suppressed response of the parasympathetic nervous system to the deep-breath test and mental stress tests.

Heart Rate Variability and Somatization in Adolescents With Irritable Bowel Syndrome

Changes in autonomic regulation and psychological distress play an important role in the pathobiology of irritable bowel syndrome (IBS). The aim of the current study is to evaluate the autonomic function and to link it to the levels of somatization in adolescents with IBS. We enrolled 30 adolescents with various types of IBS and 35 healthy controls. Time and frequency domain indexes of heart rate variability (HRV) were measured in supine (baseline) and standing (orthostasis) positions using short-term electrocardiographic recordings. The somatic symptoms index was assessed with the modified Screening for Somatoform Symptoms questionnaire. Adolescents with IBS showed no differences of HRV parameters in the supine position compared to healthy control. In orthostasis, a decrease in the standard deviation of normal RR intervals as well as main spectral index total power (TP) were observed. The reduction of TP was attributed to the reduced activities of the high- and low frequency components. Increased somatic symptoms index in IBS patients negatively correlated with TP in orthostasis (r = -0.485, P = 0.007). A subgroup analysis revealed that adolescents with IBS with TP values either < 2500 msec2 or > 5500 msec2 in the supine position demonstrated significantly reduced activity of the low frequency component. Adolescents with IBS showed signs of autonomic dysfunction only during the orthostatic test, which were associated with increased somatization scores. Further research is needed to establish the links between emotional wellbeing and autonomic function in this population.