Assessment Of Autonomic Nervous System Research Articles

Autonomic nervous system and cardiovascular risk assessment during one year of growth hormone replacement therapy in adults with growth hormone deficiency.

This prospective study aimed to evaluate the impact of growth hormone deficiency (GHD) on cardiac autonomic tone and on cardiovascular risk and the changes after 12 months of GH replacement therapy (GHRT). GHD is associated with increased cardiovascular morbidity and mortality. This has been attributed to increased markers of cardiovascular risk and to abnormalities of both the cardiac and peripheral autonomic nervous systems. The autonomic cardiac nervous system (ACNS) can be indirectly evaluated by analysis of heart rate variability (HRV) in clinostatism and orthostatism. We compared 14 GHD patients at baseline and after 12 months of GHRT and 17 healthy controls. We analyzed a number of cardiovascular risk factors and we used analysis of HRV during the Tilt Test that identified high frequency (HF) and low frequency (LF), representing parasympathetic and sympathetic activity, respectively. Compared with the control group, in either clinostatism or in orthostatism our patients showed a significantly lower value of LF (P=0.047; P=0.004, respectively), whereas HF was significantly reduced in orthostatism (P=0.037), and indicatively in clinostatism (P=0.065). These values remained unchanged after 12 months of GHRT. No statistically significant differences were found between the LF/HF ratio in untreated and treated patients. In GHD patients, there was a significant reduction of cardiovascular risk in 12 months of replacement therapy (P=0.002). Our study highlights the absence of sympathovagal imbalance in GHD patients; GHRT does not change ACNS during the first year of GH treatment but it reduces the absolute cardiovascular risk in these patients.

An Evaluating Method for Autonomic Nerve Activity by Means of Estimating the Consistency of Heart Rate Variability and QT Variability

The imbalance of autonomic nervous system (ANS) has a close relationship to cardiac mortality. The noninvasive assessment of ANS is of great importance and remains challenging. A new method, characterizing the consistency of short-term nonlinear indexes of heart rate variability (HRV) and QT variability (QTV), is proposed and validated. Holter records from two databases in Telemetric and Holter ECG Warehouse were used, 43 records from one database (named ESRD) as typical subjects of ANS dysfunction and 118 records from the other database (named Normal) as normal controls. The consistency of HRV and QTV was characterized by estimating mutual information (MI) of paired short-term recurrence quantification analysis (RQA) indexes in resting state. The influence of physiological differences on MIs of paired RQA indexes in Normal was investigated as well. Results showed that there were significant differences in MI-DET (day: 0.283 ± 0.070 versus 0.133 ± 0.055 and night: 0.258 ± 0.061 versus 0.117 ± 0.055) and MI-LAM (day: 0.439 ± 0.053 versus 0.293± 0.073 and night: 0.361 ± 0.079 versus 0.241 ± 0.087) between Normal and ESRD, much reduced consistency in ESRD. For MI-DET in Normal, sex had no influence, and there was age related alternations by day but not at night. There was no influence of sex and age on MI-LAM in Normal. The sensitivity, specificity, and total accuracy for discriminating Normal and ESRD were 88.37%, 95.76%, and 93.79%, respectively. The proposed measures are shown to have the advantage in reducing the influence of physiological differences and highlighting the pathological influence, providing a promising method to find clinical application for noninvasive assessment of ANS state.

Heart rate variability analysis using robust period detection.

ObjectiveHeart rate variability (HRV) analysis, which is an important tool for activity assessment of the cardiac autonomic nervous system, very often includes the estimation of power spectra for series of interbeat intervals (IBI). Ectopic beats and artifacts have a destructive effect on the standard methods (Fourier transform, FFT) for frequency analysis. This study investigates an alternative method for calculation of the periodogram using a robust period detection (RPD).MethodError free IBI series of 5 minutes for 221 subjects during one day were artificially distorted by randomly changing IBI values by ±15-40%. The low to high frequency rate (LF/HF) were calculated from periodograms estimated by the FFT, RPD and Lomb (LSP) methods for both error free and distorted series and for series with removed beats. Log transformed LF/HF values for series with distorted/removed beats were compared to undistorted values by linear regression.ResultsFor series with 10% of distorted IBI values the regression analysis between distorted and undistorted series showed a goodness of fit, coefficient and intercept of 0.98, 0.94 and 0.02, respectively. In comparison, the values of these parameters were (0.34, 0.46, -1.61) and (0.28, 0.42,-1.32) for the FFT and LSP methods, respectively. Similarly, the comparison between series with removed and undistorted beats yielded goodness of fit, coefficient and intercept of (0.98, 0.96, -0.01), (0.93, 0.78, -0.02) and (0.98, 0.95, 0.19) for RPD, FFT and LSP, respectively.ConclusionThe RPD method demonstrated superior performance compared to the FFT and LSP method by estimation of power spectral characteristics for HRV analysis.Electronic supplementary materialThe online version of this article (doi:10.1186/1475-925X-13-138) contains supplementary material, which is available to authorized users.

Cardiac autonomic modulation and sleepiness: Physiological consequences of sleep deprivation due to 40 h of prolonged wakefulness

The autonomic nervous system (ANS) is modulated by sleep and wakefulness. Noninvasive assessment of cardiac ANS with heart rate variability (HRV) analysis is a window for monitoring malfunctioning of cardiovascular autonomic modulation due to sleep deprivation.This study represents the first investigation of dynamic ANS effects and of electrophysiological and subjective sleepiness, in parallel, during 40h of prolonged wakefulness under constant routine (CR) conditions. In eleven young male healthy subjects, ECG, EEG, EOG, and EMG chin recordings were performed during baseline sleep, during 40h of sleep deprivation, and during recovery sleep. After sleep deprivation, slow-wave sleep and sleep efficiency increased, whereas HRV – global variability and HRV sympathovagal balance – was reduced (all p<0.05). Sleep-stage-dependent analysis revealed reductions in the sympathovagal balance only for NREM sleep stages (all p<0.05). Comparison of the daytime pattern of CR day one (CR baseline) with that of CR day two (CR sleep deprivation) disclosed an increase in subjective sleepiness, in the amount of unintended sleep, and in HRV sympathovagal balance, with accompaniment by increased EEG alpha attenuation (all p<0.05). Circadian rhythm analysis revealed the strongest influence on heart rate, with less influence on HRV sympathovagal balance. Hour-by-hour analysis disclosed the difference between CR sleep deprivation and CR baseline for subjective sleepiness at almost every single hour and for unintended sleep particularly in the morning and afternoon (both p<0.05). These findings indicate that 40h of prolonged wakefulness lead in the following night to sleep-stage-dependent reduction in cardiac autonomic modulation. During daytime, an increased occurrence of behavioral and physiological signs of sleepiness was accompanied by diminished cardiac autonomic modulation. The observed changes are an indicator of autonomic stress due to sleep deprivation — which, if chronic, could potentially increase cardiovascular risk.

128. Functional and morphological demonstration of autonomic nervous system involvement in HSAN type II

The assessment of autonomic nervous system (ANS) in hereditary sensory autonomic neuropathy (HSAN) type II is still lacking. To this aim we investigated the ANS involvement in a new family with HSAN II phenotype. Three siblings from non consanguineous healthy parents were clinically and electrophysiologically evaluated. Two of them underwent quantitative sensory testing (QST), cardiovascular and dynamic sweat tests and skin biopsy. Genetic testing for WNK1 and FAM134B mutations is ongoing. Onset occurred in the first decade, with impaired pain sensitivity and progressive distal mutilating ulceration with amputation and joint deformity. Autonomic disturbances included hypohidrosis with heat intolerance, pupillary abnormalities and chronic diarrhoea. Nerve conduction studies showed a severe axonal sensory neuropathy. Sympathetic skin response was absent. QST was altered for both painful and nonpainful sensory modalities. Autonomic functional studies detected the impairment of both sudomotor and cardiovascular systems. Skin biopsy revealed a lack of epidermal and dermal sensory and autonomic nerve fibers with complete denervation of sweat glands and arteriovenous anastomoses. Our findings expand the HSAN II phenotype providing pathological and functional evidence of a widespread ANS impairment. The complete sensory and arteriovenous denervation accounts for the severe sensory loss and distal ulcerations in HSAN type II.

The Value of Tilt Testing and Autonomic Nervous System Assessment

Tilt testing for the investigation of syncope was introduced in 1986. Since then, it has propagated worldwide as a routine test to determine the cause of transient loss of consciousness when that event has not been diagnosed by history, including that of a witness, physical examination, supine and erect blood pressures, and 12-lead electrocardiogram. Tilt testing allows reproduction of syncope with monitoring of physiologic parameters including electrocardiogram, beat-to-beat blood pressure, electroencephalogram, and middle cerebral artery blood-flow velocity. As a result, much has been learned about syncope.

Smartphone-enabled pulse rate variability: An alternative methodology for the collection of heart rate variability in psychophysiological research

Heart rate variability (HRV) is widely used to assess autonomic nervous system (ANS) function. It is traditionally collected from a dedicated laboratory electrocardiograph (ECG). This presents a barrier to collecting the large samples necessary to maintain the statistical power of between-subject psychophysiological comparisons. An alternative to ECG involves an optical pulse sensor or photoplethysmograph run from a smartphone or similar portable device: smartphone pulse rate variability (SPRV). Experiment 1 determined the simultaneous accuracy between ECG and SPRV systems in n=10 participants at rest. Raw SPRV values showed a consistent positive bias, which was successfully attenuated with correction. Experiment 2 tested an additional n=10 participants at rest, during attentional load, and during mild stress (exercise). Accuracy was maintained, but slightly attenuated during exercise. The best correction method maintained an accuracy of +/−2% for low-frequency spectral power, and +/−5% for high-frequency spectral power over all points. Thus, the SPRV system records a pulse-to-pulse approximation of an ECG-derived heart rate series that is sufficiently accurate to perform time- and frequency-domain analysis of its variability, as well as accurately reflecting change in autonomic output provided by typical psychophysiological stimuli. This represents a novel method by which an accurate approximation of HRV may be collected for large-sample or naturalistic cardiac psychophysiological research.

Effect of modified method of autonomic nervous system activity assessment on results of heart rate variability analysis

Background: Quickness and simplicity of examining procedures belong to the key criteria of decision-making process whether the spectral analysis of heart rate variability (SA HRV) would be implemented into the sports training routine as a diagnostic tool. Objective: The main aim of this study was to find out how results of the SA HRV are influenced when reducing duration of the first position of standardized orthoclinostatic maneuver (supine-standing-supine) from 5 minutes to 60 seconds. Methods: The sample consisted of&#x202F;28 healthy persons divided into two groups (G1 - n&#x202F;=&#x202F;14, 7 males and 7 females aged 19 to 23; G2 - n&#x202F;=&#x202F;14, 9 males and 5 females aged 17 to 22). The G1 underwent the autonomic nervous system (ANS) activity assessment firstly by the modified procedure and consecutively by the standard procedure. This order was reversed in the G2. The ANS activity was represented by both, individual HRV parameters and complex indices of the SA HRV. Results: When comparing the standard and modified procedure of the ANS assessment, no significant differences in any of the assessed parameters of the HRV were found. The correlation analysis that the results of the SA HRV indices between both measures of the ANS are highly related was found. This dependence was also present in a majority of the individual HRV parameters. Conclusions: According to the results of this research, the time-modified method of the ANS assessment provides results of the SA HRV which are comparable to the traditionally applied orthoclinostatic maneuver.

Pupillometric Assessment of Autonomic Nervous System in Children with Allergic Rhinitis

Objective: The purpose of this study was to investigate autonomic nervous system dysfunction by measuring pupil sizes in pediatric patients with allergic rhinitis. Subjects and Methods: The study group consisted of 60 children (28 girls and 32 boys) who were age and gender matched with the control group, which also consisted of 60 children (26 girls and 34 boys). The diagnosis of allergic rhinitis was based on the history, physical examination and skin prick test performed by an allergologist. Pupil diameter measurements were performed using the pupillometer incorporated in the NİDEK OPD-Scan. Results: In the allergic rhinitis group, mean photopic and mesopic pupil diameters were 3.52 ± 0.07 and 5.98 ± 0.21, respectively, while in the control group, corresponding measurements were 4.03 ± 0.18 and 6.55 ± 0.16. There was a significant difference for photopic and mesopic pupil diameter between the groups (p < 0.001). Conclusion: This study showed that the pupil size in response to a light stimulus in children with allergic rhinitis was smaller than that of the control group and may indicate parasympathetic hyperactivity and sympathetic hypoactivity.

Pulse Rate Variability as a Surrogate Method for Autonomic Nervous Systemassessment Comparing with Heart Rate Variability

Pulse Rate Variability as a Surrogate Method for Autonomic Nervous Systemassessment Comparing with Heart Rate Variability

The Study of Spectral Analysis of Heart Rate Variability in Different Blood Pressure Types in Euvolemic Peritoneal Dialysis Patients

Background: Heart rate variability (HRV) is an useful noninvasive tool to assess autonomic nervous system (ANS) function and may provide an insight into the understanding of the role of ANS in the pathogenesis of blood pressure (BP) abnormality in euvolemic continuous ambulatory peritoneal dialysis (CAPD) patients. Methods: In this cross-sectional study, 62 CAPD patients with normal hydration values (assessed by a bioimpedance spectroscopy device) were enrolled from our peritoneal dialysis (PD) unit. Patients were divided into three groups according to their BP: normotension (NT), hypertension (HT), and hypotension (HyT). Spectral analysis of HRV was measured by examination of the average heart rate using standard electrocardiogram in 5 min. Results: The HyT group had the lowest serum urea nitrogen among the three groups (all p < 0.05), and a lower serum potassium and albumin as compared with the NT group (p < 0.05). The HyT group also had the highest total power (TP) and highest frequency power (HF) among the three groups (all p < 0.05), and a lower normalized low frequency power (LF), LF/HF ratio, and a higher normalized HF as compared with the HT group (all p < 0.05). Conclusion: Our study suggested that autonomic insufficiency was present in euvolemic PD patients, and hypotensives had a relatively higher parasympathetic activity and blunted sympathetic activity.

P-302 - Pupillometric assessment of autonomic nervous system functions in children with attention deficit hyperactivity disorder

Introduction Attention deficit and hyperactivity disorder (ADHD) is one of the most frequently seen neurobehavioral disorder in school-aged children. Although the main cause of ADHD is unknown, it's thought that numerous biopsychosocial factors have part in etiology of ADHD together. Objectives/aims This study aims to compare autonomic nervous system functions by measuring pupil diameters in 6–11 aged boys diagnosed ADHD with age and sex matched healthy controls. Methods Thirty-two boys with ADHD and 24 healthy controls were participated into this study. We studied with a more homogeneous group by exclusion of any other psychiatric disorders except oppositional defiant disorder (ODD). The participants were evaluated autonomic nervous system functions by measuring pupil diameter changes in photopic and mesopic conditions. Results There were no statistical differences on photopic and mesopic pupil diameters between ADHD and healthy control groups (p>0.05). Moreover, there were no significant differences on same parameters between pure ADHD and ADHD+ODD groups (p>0.05). Conclusions These findings suggest that boys with ADHD don’t show difference in pupil diameters from typically children. This might indicate no difference in autonomic nervous system functions.

The Effect of Aging on Nonlinearity and Stochastic Nature of Heart Rate Variability Signal Computed using Delay Vector Variance Method

Heart rate variability analysis is fast gaining acceptance as a potential non-invasive means of autonomic nervous system assessment in research as well as clinical domains. In this study, a new nonlinear analysis method is used to detect age related changes in the degree of nonlinearity and stochastic nature of heart rate variability signals. The data obtained from an online and widely used public database (i.e., MIT/BIH physionet database), of young and elderly subjects is used in this study. The method used is the delay vector variance (DVV) method, which is a unified method for detecting the presence of determinism and nonlinearity in a time series and is based upon the examination of local predictability of a signal. From the results it is clear that there is no significant change in the minimum target variance values for young and elderly subjects and also the values are very small, which indicates that there is a strong deterministic component over the stochastic one in both the groups. There is a significant decrease in the degree of nonlinearity from younger to elder subjects (p- value, 0.0002). This indicates that there is no change in the stochastic or deterministic nature of the signals but there is a considerable change in the degree of nonlinearity with aging.

Relations between ac-dc components and optical path length in photoplethysmography

Photoplethysmography is used in various areas such as vital sign measurement, vascular characteristics analysis, and autonomic nervous system assessment. Photoplethysmographic signals are composed of ac and dc, but it is difficult to find research about the interaction of photoplethysmographic components. This study suggested a model equation combining two Lambert-Beer equations at the onset and peak points of photoplethysmography to evaluate ac characteristics, and verified the model equation through simulation and experiment. In the suggested equation, ac was dependent on dc and optical path length. In the simulation, dc was inversely proportionate to ac sensitivity (slope), and ac and optical path length were proportionate. When dc increased from 10% to 90%, stabilized ac decreased from 1 to 0.89 ± 0.21, and when optical path length increased from 10% to 90%, stabilized ac increased from 1 to 1.53 ± 0.40.

Effects of Antidepressive Treatment of Saint John'S Wort Extract Related to Autonomic Nervous Function in Women with Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) patients usually manifest autonomic nerve dysfunctions and abnormal psychological behaviors. This study was to assess autonomic nervous system (ANS) response to different stressor as well as evaluate effects of antidepressive treatment of Saint John's Wort Extract in women with IBS. Thirty women with IBS and 20 healthy women underwent serial ANS function tests. Five-minute-short-time heart rate variability (HRV) spectral analysis were assessed at a stress or resting recording period. Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) were used to measure their anxiety and depression conditions. After 8-weeks' antidepressant treatment, groups of IBS repeated the tests above. Subjects also completed a GI symptom diary once daily during the 2 weeks before therapy and for 2 weeks in the last scheduled therapy session. IBS-group showed a higher score in HAMA and HAMD (p < 0.01) and showed a significant increase in the low frequency band/high frequency band ratio (L/H) during the period in different stimuli (p <0.01), which was significantly different from controls. After 8-weeks' antidepressive treatment, L/H showed a significant decrease (p < 0.05) response to different stressor, which was significantly different from pre-treatment. Gastrointestinal (GI) symptoms of IBS were also relieved significantly. Antidepressive treatment can improve the conditions of psychology and the ANS reactivity to stress in patients with IBS.

Cardiac autonomic dysfunction in patients with systemic lupus, rheumatoid arthritis and sudden death risk

The manifestations of autonomic nervous system (ANS) dysfunction in autoimmune diseases have been the subject of many studies. However, the published results pertaining to such research are controversial. Sudden cardiac death due to fatal arrhythmias is frequent in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). To analyse risk predictors of sudden cardiac death related to the degree of autonomic dysfunction. We performed cardiovascular ANS assessment in 90 patients in this case-controlled study, including 52 (6 male, 46 female) patients with SLE, 38 (6 male, 32 female) with RA and 41 (23 male, 17 female) healthy subjects. The methodology included a comprehensive ECG analysis (with Schiller software AT-10) of QTc interval, late potentials, short-term heart rate variability (HRV) and nonlinear HRV (Poincare plot) analysis; 24-hour Holter ECG monitoring with ECG QTc interval analysis, HRV analysis; 24-hour blood pressure monitoring with systolic and diastolic blood pressure variability; cardiovascular autonomic reflex tests (according to Ewing). Vagal dysfunction was established by performing 3 tests: Valsalva maneuver, deep breathing test and heart rate response to standing test. Dysfunction of the sympathetic nervous system was examined by applying 2 tests: blood pressure response to standing and handgrip test. In all cardiovascular reflex tests, the frequencies of abnormal results were significantly higher among the patients than among the healthy subjects. Severe autonomic dysfunction was more common in RA. QTc interval was more prolonged in patients with SLE. Both diseases were associated with depressed heart rate variability compared to controls, the reduction being greater in RA patients. In the patients with SLE, autonomic dysfunction is predominantly with higher sympathetic activity while in RA vagal predominance is evident. SLE and RA are associated with severe autonomic dysfunction and the presence of significant risk predictors related to the onset of sudden cardiac death.

Contact-free Measurement of Heart Rate Variability via a Microwave Sensor

Measures of heart rate variability (HRV) are widely used to assess autonomic nervous system (ANS) function. HRV can be recorded via electrocardiography (ECG), which is both non-invasive and widely available. However, ECG needs three electrodes touching the body of the subjects, which makes them feel nervous and uncomfortable, thus potentially affecting the recording. Contact-free detection of the heartbeat via a microwave sensor constitutes another means of determining the timing of cardiac cycles by continuous monitoring of mechanical contraction of the heart. This technique can measure the heartbeat without any electrodes touching human body and penetrate the clothes at some distances, which in some instances may prove a practical basis for HRV analysis. Comparison of 5-minute recordings demonstrated that there were no significant differences in the temporal, frequency domains and in non-linear dynamic analysis of HRV measures derived from heartbeat and ECG, which suggested this technique may prove a practical alternative to ECG for HRV analysis.

Centrale de mesure ambulatoire biomédicale sur PSoC

Improvement in quality and efficiency of health and medicine, at home and in hospital, has become of paramount importance. The solution to this problem would require the continuous monitoring of several key patient parameters, including the assessment of autonomic nervous system (ANS) activity using non-invasive sensors, providing information for emotional, sensorial, cognitive and physiological analysis of the patient. Recent advances in embedded systems, microelectronics, sensors and wireless networking enable the design of wearable systems capable of such advanced health monitoring. The subject of this article is an ambulatory system comprising of a small wrist device connected to several sensors for the detection of the autonomic nervous system activity. It affords monitoring of skin resistance, skin temperature and heart activity. It is also capable of recording the data on a removable media or sending it to computer via a wireless communication. The wrist device is based on a programmable system-on-chip (PSoC) from Cypress.

Pupillometric assessment of autonomic nervous system in children with functional enuresis

Functional enuresis is defined as repeated voiding of urine into bed or clothes in children after 5 years of age following the exclusion of major somatic diseases. Autonomic nervous system dysregulation has been proposed as a pathophysiologic mechanism in the etiopathogenesis. The objective of this study was to evaluate autonomic nervous system functions with pupil diameter measurement in enuretic children. The study group consisted of 17 children with functional enuresis (ten boys, seven girls), and the control group consisted of 34 healthy children (20 boys, 14 girls). Pupil diameter measurements were performed under photopic and mesopic lighting conditions by using a pupillometer. Mean photopic pupil diameter was found to be larger in the enuretic children than in the healthy controls (4.47 +/- 0.52 mm vs. 4.03 +/- 0.75 mm; P = 0.03). Autonomic nervous system imbalance of the ocular system is considered to be part of the autonomic nervous system dysregulation in functional enuretic children.

Cardiovascular autonomic dysfunction in systemic lupus, rheumatoid arthritis, primary Sjögren syndrome and other autoimmune diseases

Neurological manifestations are known to occur in patients with autoimmune diseases, often subclinically, but autonomic nervous system (ANS) involvement has rarely been studied, and studies have shown conflicting results. We performed cardiovascular ANS assessment in 125 patients with autoimmune diseases in this case-control study, including 54 patients with systemic lupus erythematosus (SLE), 39 with rheumatoid arthritis (RA), 20 with primary Sjbgren syndrome (pSS), eight patients with polymyalgia rheumatica (PR), four patients with scleroderma (Ssc) and 35 healthy control subjects. The control group was formed to approximately match the mean age of SLE, RA and pSS patients; controls did not differ significantly by gender from the autoimmune pations. All patients with were in stable condition. Autonomic nervous system dysfunction was diagnosed by applying cardiovascular reflex tests according to Ewing, and was considered to exist if at least two tests were positive. Vagal dysfunction was established by applying three tests: Valsalva manoeuvre, deep breathing test, and heart rate response to standing. Sympathetic dysfunction was examined by applying two tests: blood pressure response to standing and handgrip test. In all cardiovascular reflex tests, frequencies of abnormal results were significantly higher among the patients than among the controls (P < 0.05). The difference between the autoimmune patients and the controls was particularly significant in sympathetic and parasympathetic tests, with P < 0.0001. No correlation was found between disease duration, clinical manifestations, cardiovascular risk factors and diseases activity on the one hand, and ANS dysfunction on the other hand. Cardiovascular autonomic dysfunction was revealed in the majority of autoimmune patients.