Assessment Of Autonomic Function Research Articles

Association of neuropeptide Y promoter polymorphism (rs16147) with perceived stress and cardiac vagal outflow in humans.

Neuropeptide Y (NPY) is involved in resilience to stress, and higher vagal (parasympathetic) activity has been associated with greater stress resilience. Thus, we examined whether rs16147, a functional promoter polymorphism (C>T) of the NPY gene, could influence vagal tone during chronic high stress levels. NPY genotyping, chronic psychological stress level measurement (using the Perceived Stress Scale [PSS]), cardiac autonomic function assessment (using short-term heart rate variability [HRV]) were performed in 1123 healthy, drug-free Han Chinese participants who were divided into low- and high-PSS groups. In the high-PSS group (n = 522), the root mean square of successive heartbeat interval differences and high frequency power (both HRV indices of parasympathetic activity) were significantly increased in T/T homozygotes compared to C/C homozygotes. However, no significant between-genotype difference was found in any HRV variable in the low-PSS group (n = 601). Our results are the first to demonstrate that functional NPY variation alters chronic stress-related vagal control, suggesting a potential parasympathetic role for NPY gene in stress regulation.

Assessment of vascular autonomic function using peripheral arterial tonometry.

Peripheral autonomic function is impaired in diabetic polyneuropathy. However, it is difficult to evaluate it due to the lack of non-invasive quantitative assessment. We aimed to establish a novel index to evaluate vascular autonomic function using reactive hyperemia peripheral arterial tonometry (RH-PAT), a widely performed endothelial function test. Sixty-five subjects were enrolled, including healthy subjects, cases with sympathetic nerve blockers, and diabetic patients. RH-PAT was performed with 5-min blood flow occlusion in unilateral arm. We calculated the reduction ratio of the post-occlusion pulse amplitude to the baseline in the non-occluded arm (RPN), with 1-min sliding window. In healthy subjects, RPN gradually increased with time-dependent manner. However, this phenomenon was eliminated in cases with sympathetic nerve blockers. Plasma concentration of norepinephrine was measured before and after the blood flow occlusion, which showed a significant increase. We then compared RPNs with the change in heart rate variability (HRV) parameters. RPN calculated at 5min after the reperfusion had the highest correlation with the change in sympathetic HRV parameter, and thus, we named sympathetic hypoemia index (SHI). Finally, we studied the relationship between SHI and diabetes. SHI was significantly lower in diabetic patients than matched controls. SHI, a novel index derived from RH-PAT, represented the peripheral sympathetic activity. SHI may be useful for assessing the vascular autonomic activity in diabetic patients.

Assessment of autonomic function in a cohort of patients with ANCA-associated vasculitis.

To assess symptoms and objective parameters of autonomic dysfunction (AD) in patients with ANCA-associated vasculitides. Symptoms and objective parameters of AD were assessed in patients with ANCA-associated vasculitis and in age-matched healthy controls. Autonomic symptoms were explored by COMPASS31, a validated questionnaire addressing symptoms of six autonomic domains (orthostatic, vasomotor, secretomotor, gastrointestinal, pupillomotor, and bladder dysfunction). Objective autonomic parameters consisted of expiratory/inspiratory (E/I) ratio during the deep breathing test (DBT), blood pressure response to cold pressor test (CPT), and skin conductance changes during mental arithmetic. 27 patients and 27 healthy controls have been enrolled. 27 patients and 27 controls completed COMPASS31. 21 patients and 18 controls underwent objective autonomic testing. Vasculitis patients had significantly higher COMPASS31 total scores than controls (median 10.4 vs 3.0; p=0.005). In the sub-domain analysis, significant differences were seen in the vasomotor and the bladder domain (p=0.004; p<0.001, respectively). No correlation was found between COMPASS31 score and disease duration, number of affected organs, or Birmingham vasculitis activity score (BVAS). There was no significant difference in any of the objective autonomic parameters between patients and controls. In a subgroup analysis, no difference in objective autonomic parameters was found between patients with active disease (n=12) and patients in remission (n=7). Patients with ANCA-associated vasculitides commonly have symptoms of autonomic dysfunction that are independent of disease duration and disease severity. However, at least in this single-centre observation, there was no evidence of impaired autonomic regulation in three autonomic function tests in vasculitis patients.

OP-090 Assessment of Cardiac Autonomic Functions by Heart Rate Recovery Indices in Patients with Myocardial Bridge

OP-090 Assessment of Cardiac Autonomic Functions by Heart Rate Recovery Indices in Patients with Myocardial Bridge

From the Ewing Classic Battery to the New Methods of Assessment of Autonomic Function: Revisiting Dysautonomia in Multiple Sclerosis Patients (P2.152)

From the Ewing Classic Battery to the New Methods of Assessment of Autonomic Function: Revisiting Dysautonomia in Multiple Sclerosis Patients (P2.152)

Heart rate variability is associated with interstitial glucose fluctuations in type 2 diabetic women treated with insulin.

Heart rate variability (HRV) analysis is a commonly used tool for assessment of autonomic function in diabetic subjects. Nevertheless, the effects of glucose fluctuations on HRV remain to be clarified. In this study we investigated the associations of frequency-domain HRV parameters with current and antecedent interstitial glucose fluctuations in insulin-treated type 2 diabetic women at high cardiovascular risk. Sixty-seven women with type 2 diabetes, from 48 to 78 years of age, including 46 ones with cardiovascular autonomic neuropathy (CAN), underwent simultaneous continuous glucose monitoring (CGM) and Holter recording. Eight glucose variability (GV) indices, including standard deviation, 2-h continuous overlapping net glycemic action (CONGA2), lability index, J-index, mean amplitude of glucose excursions, mean absolute glucose (MAG), low blood glucose index (LBGI) and high blood glucose index (HBGI), were calculated from CGM data. The low frequency (LF) and high frequency (HF) power values were estimated on 5-min intervals at fasting and postprandial daytime periods, at night and during CGM-defined hypoglycemia. The values of LF and HF power declined after meals in diabetic women with normal autonomic function tests. Patients with CAN demonstrated blunted postprandial LF and HF reduction and diminished LF/HF ratio during daytime hypoglycemic events. Daytime LF and HF at fasting state correlated negatively with MAG derived from antecedent nocturnal CGM recordings. Positive correlation was found between fasting LF and nocturnal LBGI. The LF power during daytime hypoglycemia demonstrated negative correlations with nocturnal CONGA2, J-index, HBGI and MAG. The nocturnal HBGI and CONGA2, along with HbA1c and daily insulin dose, were predictors of LF during daytime hypoglycemia in multiple regression analysis. Both postprandial and antecedent nocturnal glucose fluctuations affect daytime frequency-domain HRV parameters in insulin-treated type 2 diabetic women. In patients with increased GV the results of short-term assessment of HRV should be interpreted with caution. Fasting state rather than postprandial one seems to be preferable for HRV estimation.

Tilt table test today - state of the art.

A tilt table test (TTT) is an inexpensive, noninvasive tool for the differential diagnosis of syncope and orthostatic intolerance and has good diagnostic yield. The autonomic system malfunction which underlines the reflex syncope is manifested as either hypotension or bradycardia, while an orthostatic challenge is applied. The timing of the response to the orthostatic challenge, as well as the predominant component of the response help to differentiate between various forms of neurocardiogenic syncope, orthostatic hypotension and non-cardiovascular conditions (e.g., pseudosyncope). Medications, such as isoproterenol and nitrates, may increase TTT sensitivity. Sublingual nitrates are easiest to administer without the need of venous access. TTT can be combined with carotid sinus massage to evaluate carotid sinus hypersensitivity, which may not be present in supine position. TTT is not useful to access the response to treatment. Recently, implantable loop recorders (ILR) have been used to document cardioinhibitory reflex syncope, because pacemakers are beneficial in many of these patients, especially those over 45 years of age. The stepwise use of both TTT and ILR is a promising approach in these patients. Recently, TTT has been used for indications other than syncope, such as assessment of autonomic function in Parkinson's disease and its differentiation from multiple system atrophy.

Assessment of Autonomic Function in Patients with Schizophrenia Using Spectral Analysis and Approximate Entropy Method

Assessment of Autonomic Function in Patients with Schizophrenia Using Spectral Analysis and Approximate Entropy Method

Assessment of autonomic function in children using cell telephone

Assessment of autonomic function in children using cell telephone

Quantitative sensory testing in type 1 diabetic patients with mild to severe diabetic neuropathy

Background: Small nerve fibre damage has been shown to precede large fibre damage and represents the early stage for diabetic neuropathy (DPN). Aims: To assess small nerve fibre deficit in patients with mild to severe DPN using quantitative sensory testing (QST) and to correlate QST findings with other neuropathy assessment measures in patients with DPN. Materials and Methods: Seventy-nine diabetic patients (49 with and 30 without diabetic neuropathy) and 35 healthy volunteers underwent neuropathy assessment. The evaluation comprised neuropathy symptoms profile, modified neuropathy disability score (NDS), quantitative sensory testing (QST) in form of cold and warm thresholds, vibration pressure threshold (VPT), nerve conduction studies (NCS), deep breathing heart rate variability (DB-HRV), and Neuropad staining scores. Patients were also stratified by their NDS scores into mild, moderate and severe DPN. Measures of QST were compared among various grades of DPN severity and correlated with other clinical and neurophysiological tests. Results: Patients with DPN demonstrated higher vibration perception (P<0.001) and warm (P<0.001) thresholds and lower cold threshold (P<0.001) and these QST abnormalities related directly to the grade of DPN severity. Measures of QST also correlated with those of nerve conduction studies (r range 0.54-0.68) and autonomic function assessment(r range 0.33-0.48). Conclusion: Quantitative sensory testing can identify small nerve fibres impairment which could represent the early stage of diabetic neuropathy and hence the optimal period for intervention.

Assessment of Cardiac Autonomic Functions in Medical Students With Type D Personality.

Type D personality experiences joint occurrence of Negative Affectivity and Social Inhibition. It is an emerging risk factor for cardiovascular disease, with prevalence being 18-53% among cardiac patients. Type D personality people have exaggerated cardiovascular activity mediated by increased sympathetic drive and decreased vagal control of the heart which leads to enhanced risk of hypertension and is an independent risk factor for coronary heart disease. To compare the cardiac autonomic function of Type D and non-Type D students. To compare cardiac autonomic functions among male and female students and students with and without family history of hypertension and coronary artery disease among Type D. To find the most affected test among Type D students. Thirty Type D and 30 non- Type D medical students were identified by DS14. The Parasympathetic cardiac autonomic tests done assessed Heart Rate response to valsalva manoeuvre, immediate heart rate response to standing and heart rate variation during deep breathing. Sympathetic tests assessed BP response to standing and Sustained Hand Grip. The heart rate and R-R interval measurement were got from lead II of ECG recordings on Polyrite D. Statistical analysis was done using SPSS software. Unpaired student's t-test was used and p-value <0.05 was considered to be statistically significant. Type D students showed slightly decreased parasympathetic activity and increased sympathetic activity when compared to non-Type D students even though there was no statistically significant difference between them. There is a statistically significant decrease in valsalva ratio among females (p<0.01) when compared to males. There is a statistically significant decrease in 30:15 ratio and BP response to handgrip (p<0.05) among students with family history of hypertension and coronary artery disease when compared with students with no family history of coronary artery disease. Valsalva ratio is the most affected test in Type D students. Cardiac autonomic functions of Type D personality persons without cardiovascular disease is not different from that of non-Type D. Regular follow up studies over years are required to find if Type D personality is associated with cardiovascular risk in healthy individuals.

Advances in high resolution joint time-frequency biosignal analysis and visualization can transform autonomic function assessment

Advances in high resolution joint time-frequency biosignal analysis and visualization can transform autonomic function assessment

Ameliorating effects and autonomic mechanisms of needle-less transcutaneous electrical stimulation at ST36 on stress-induced impairment in gastric slow waves.

Stress has long been documented to alter gastrointestinal motility. The effects of electroacupuncture (EA) on stress and gastric motility are relatively well known; however, whether EA has an ameliorating effect on stress-induced dysmotility remained unclear. This study aims to investigate the effects and mechanisms of needle-less transcutaneous electroacupuncture (TEA) on stress-induced impairment in gastric slow waves. A watch-size digital stimulator was developed. Ten healthy volunteers were involved in a four-session study (control, cold stress, TEA, and sham TEA). Electrogastrograpy was used to assess gastric slow waves, and electrocardiogram was recorded for the assessment of autonomic functions. The recordings were made in each session with/without stress and with TEA at ST36 or sham points. The results are as follows: (i) Cold stress-induced gastric dysrhythmia and impaired normal slow waves (P < 0.01). TEA showed a preventive effect on cold stress-induced impairment in gastric slow waves. TEA at ST36, but not sham TEA, normalized slow waves (P = 0.03 vs stress; P = 0.44 vs control), attributed to the suppression of gastric dysrhythmia; (ii) Postprandially, there was a decrease in vagal activity in both control (P = 0.004) and stress (P = 0.002) sessions; this decrease was prevented with TEA (P < 0.05). Similarly, there was a postprandial increase in sympathetic activity in both control (P = 0.01) and stress (P = 0.002) sessions, and this increase was suppressed with TEA. Needle-less TEA at ST36 using a watch-size stimulator is able to improve stress-induced impairment in gastric slow waves, possibly mediated via the autonomic mechanism. Home-based needle-less TEA may be a viable therapy for stress-induced impairment in gastric motility functions.

Association of depressive symptoms with circadian blood pressure alterations in Parkinson's disease.

To assess whether among patients with Parkinson's disease (PD) depression, a common non-motor symptom associated with reduced survival, is associated with cardiovascular dysautonomia. We enrolled 125 subjects with PD consecutively admitted to a geriatric day hospital. All participants underwent comprehensive evaluation, fasting blood sampling, and 24-h ambulatory blood pressure monitoring. The percent reduction in nocturnal blood pressure (dipping) was calculated. Depressive symptoms were assessed through the 15-item Geriatric Depression Scale (GDS); a score ≥5 identified moderate to severe symptoms. Among participants (mean age 72.7 ± 7.8 years, 32 % women) 61 subjects (49 %) presented with a GDS score ≥ 5. When compared with other participants, subjects with a GDS score ≥ 5 had reduced adjusted levels of percent systolic (-2.6 ± 2.7 vs. 4.7 ± 2.5; p = 0.003), diastolic (0.6 ± 2.8 vs. 7.4 ± 2.6; p = 0.007), and mean blood pressure dipping (-0.7 ± 2.6 vs. 6.8 ± 2.5; p = 0.002). In separate logistic regression models, depressive symptoms were associated with reduced systolic (OR 0.94; 95 % CI 0.89; 0.98), diastolic (OR 0.94; 95 % CI 0.90; 0.99), and mean blood pressure dipping (OR 0.93; 95 % CI 0.89; 0.98), after adjusting for potential confounders. Depressive symptoms are prevalent, and independently associated with cardiovascular dysautonomia among patients with Parkinson's disease. This might explain the remarkable incidence of sudden death, as well as the association of depressive symptoms with reduced survival reported in these patients. The finding of depressive symptoms in subjects with Parkinson's disease should therefore prompt assessment of cardiovascular autonomic function.

Assessment of autonomic nervous system function in nursing students using an autonomic reflex orthostatic test by heart rate spectral analysis.

Nursing students experience academic demands, such as tests, theoretical and practical coursework, research activities, various aspects of professional practice, and contact with health professionals and patients. Consequently, nursing students face numerous types of stress, and increased stress levels contribute to physical and psychological distress in nursing students. The aim of the present study was to investigate the autonomic nervous system function of nursing students by assessing active standing load using the autonomic reflex orthostatic tolerance test, which enables quantitative analysis of dynamic autonomic nervous system function. The autonomic nervous system activity in the resting state was low in fourth-year students, they had parasympathetic hypotension, and there was a tendency towards higher sympathetic nervous system activity of fourth-year students compared with first-, second- and third-year students. In the standing state, there was a trend towards a higher autonomic nervous system activity response of fourth-year students compared with first-, second- and third-year students. These results suggest that stress may influence autonomic nervous activity in fourth-year nursing students. By correcting stress in fourth-year nursing students, it may be possible to prevent the development of health problems.

Non-Invasive Assessment of Cardiac Autonomic Functions in Healthy Young Adults in Ile-Ife, South-Western Nigeria

Background: This study assessed the responses of Blood Pressure (BP) and Heart Rate (HR) to change of posture, Sustained Handgrip (SH),deep breathing(DB) and Valsalva manoeuvre (VM) in order to determining the normal limits and pattern of Autonomic Cardiovascular Indices (ACI) among healthy young adults. Methods: Two hundred and four volunteer (98 men and 106 women) aged 18- 40 years (mean, 22.45 ± 4.86 years) participated in the study. After excluding systemic diseases by clinical evaluation, each participant performed five non-invasive cardiac autonomic function tests in series. Differences in supine and erect systolic BPs were assessed by sphygmomanometry, diastolic BP responses to SH were determined by dynamometry while HR variability in response to VM, DB and postural change were assessed by continuous electrocardiogram. Normal limits of ACI were determined at 5th and 95th percentiles. Results: The mean (normal limits) for SBP response to change of posture (mmHg); DBP response to sustained handgrip (mmHg); Valsalva ratio; heart rate response to deep breathing (beats per minute); PTI; tachycardia ratio; bradycardia ratio and RHR(beats per minute) respectively were: -4.26 ± 9.17(-19.00-11.00); 20.14 ± 17.35(0.00-54.00); 1.55 ± 0.40(1.10-2.40); 31.82 ± 10.81(13.0048.75); 1.41 ± 0.31(1.08-1.84); 0.80 ± 0.12(0.58-1.00); 1.21 ± 0.20(0.95-1.60) and 70.61 ± 12.23(53.00-93.00). During Valsalva maneouvre, Post-Strain Pause (PSP) which ranged from 1.2812.76s was observed in 14(6.86%) of the participants. PSP occurred more frequently in women (9.43%) than men (4.08%). No significant gender difference in the duration of post-strain pause (t=-1.628, p=0.105). In majority of the participants (67.6%), an elevation of SBP occurred within 2minutes of rising from supine to erect position. Immediate Post-Standing Pause (IPSP) occurred among 139 (68.14%) participants. Conclusion: Non-invasive assessment of cardiac autonomic function is feasible in Nigeria. Increase rather than decrease in systolic blood pressure response occurred more frequently upon a change from supine to erect posture. IPSP was a unique pattern of cardiac autonomic functions in study population.

Inhibitory Effects and Sympathetic Mechanisms of Distension in the Distal Organs on Small Bowel Motility and Slow Waves in Canine.

Rectal distension (RD) is known to induce intestinal dysmotility. Few studies were performed to compare effects of RD, colon distension (CD) and duodenal distension (DD) on small bowel motility. This study aimed to investigate effects and underlying mechanisms of distensions in these regions on intestinal motility and slow waves. Eight dogs chronically implanted with a duodenal fistula, a proximal colon fistula, and intestinal serosal electrodes were studied in six sessions: control, RD, CD, DD, RD+guanethidine, and CD+guanethidine. Postprandial intestinal contractions and slow waves were recorded for the assessment of intestinal motility. The electrocardiogram was recorded for the assessment of autonomic functions. (1) Isobaric RD and CD suppressed intestinal contractions (contractile index: 6.0±0.4 with RD vs. 9.9±0.9 at baseline, P=0.001, 5.3±0.2 with CD vs. 7.7±0.8 at baseline, P=0.008). Guanethidine at 3mg/kg iv was able to partially block the effects. (2) RD and CD reduced the percentage of normal intestinal slow waves from 92.1±2.8 to 64.2±3.4% (P<0.001) and from 90±2.7 to 69.2±3.7% (P=0.01), respectively. Guanethidine could eliminate these inhibitory effects. (3) DD did not induce any changes in small intestinal contractions and slow waves (P>0.05). (4) The spectral analysis of the heart rate variability showed that both RD and CD increased sympathetic activity (LF) and reduced vagal activity (HF) (P<0.05). Isobaric RD and CD could inhibit postprandial intestinal motility and impair intestinal slow waves, which were mediated via the sympathetic pathway. However, DD at a site proximal to the measurement site did not seem to impair small intestinal contractions or slow waves.

The function of the autonomic nervous system during spaceflight.

Despite decades of study, a clear understanding of autonomic nervous system activity in space remains elusive. Differential interpretation of fundamental data has driven divergent theories of sympathetic activation and vasorelaxation. This paper will review the available in-flight autonomic and hemodynamic data in an effort to resolve these discrepancies. The NASA NEUROLAB mission, the most comprehensive assessment of autonomic function in microgravity to date, will be highlighted. The mechanisms responsible for altered autonomic activity during spaceflight, which include the effects of hypovolemia, cardiovascular deconditioning, and altered central processing, will be presented. The NEUROLAB experiments demonstrated increased sympathetic activity and impairment of vagal baroreflex function during short-duration spaceflight. Subsequent non-invasive studies of autonomic function during spaceflight have largely reinforced these findings, and provide strong evidence that sympathetic activity is increased in space relative to the supine position on Earth. Others have suggested that microgravity induces a state of relative vasorelaxation and increased vagal activity when compared to upright posture on Earth. These ostensibly disparate theories are not mutually exclusive, but rather directly reflect different pre-flight postural controls. When these results are taken together, they demonstrate that the effectual autonomic challenge of spaceflight is small, and represents an orthostatic stress less than that of upright posture on Earth. In-flight countermeasures, including aerobic and resistance exercise, as well short-arm centrifugation, have been successfully deployed to counteract these mechanisms. Despite subtle changes in autonomic activity during spaceflight, underlying neurohumoral mechanisms of the autonomic nervous system remain intact and cardiovascular function remains stable during long-duration flight.

Heart rate variability and the risk of Parkinson disease: The Atherosclerosis Risk in Communities study.

Autonomic dysfunction frequently occurs in the context of Parkinson disease (PD) and may precede onset of motor symptoms. Limited data exist on the prospective association of heart rate variability (HRV), a marker of autonomic function, with PD risk. We included 12,162 participants of the Atherosclerosis Risk in Communities study, a community-based cohort, without a diagnosis of PD at baseline (1987-1989) and with available HRV data (mean age = 54 years, 57% women). A 2-minute electrocardiogram was used to measure HRV. Incident PD was identified through 2008 from multiple sources, and adjudicated. Multivariable Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of PD by quartiles of HRV measurements. During a mean follow-up of 18 years, we identified 78 incident PD cases. Lower values of the root mean square of successive differences in normal-to-normal R-R intervals (rMSSD) and standard deviation of normal-to-normal R-R intervals (SDNN), markers of parasympathetic activity and total variability, respectively, were associated with higher PD risk during follow-up. In multivariate models, the HR (95% CI) of PD in the bottom quartiles of rMSSD and SDNN compared to the top quartiles were 2.1 (1.0-4.3) and 2.9 (1.4-6.1), respectively. Other measures of cardiac autonomic function, including mean R-R interval and frequency-domain measurements, were not associated with PD risk. In this prospective cohort, decreased HRV was associated with an increased risk of PD. Assessment of cardiac autonomic function may help identify individuals at risk for PD.

Study of autonomic functions in young adults of hypertensive and normotensive parents

Background: Hypertension is a major public health problem worldwide, including India. Nowadays, prehypertension is common in young adults. It has genetic basis and runs in families. Parental history of hypertension increases the risk of developing hypertension, especially if both parents are hypertensive. Cause & effect relation of hypertension & autonomic dysfunction is not clear. Therefore, this study was planned to see autonomic function alterations in young adults of hypertensive parents, if any.Methodology: In this study autonomic activity was assessed in students with both parents hypertensive (n= 30), one parent hypertensive (n= 30) and both parents normotensive (n= 30).Resting heart rate and BP was measured for parasympathetic function assessment and rise in diastolic BP with hand grip dynamometer was used for sympathetic function assessment.Results: The study showed no significant difference in resting pulse rate of all the groups. BP was slightly higher in groups with hypertensive parents as compared to a group of normotensive parents, but the difference was statistically insignificant. Statistically significant rise in diastolic BP with handgrip dynamometer was observed in subjects with hypertensive parents.Conclusion: This rise in diastolic BP indicates increased sympathetic activity. Our results showed higher sympathetic activity in those with hypertensive parents. It also confirmed the genetic basis of sympathetic (vasomotor) tone. Young adults having hypertensive parents are at a greater risk of hypertension at an early age. Regular assessment of blood pressure and autonomic function with lifestyle modifications should be recommended to delay onset of hypertension in them.