Methods of evaluation of autonomic nervous system function

Chemotherapy and Radiation-Associated Cardiac Autonomic Dysfunction

PURPOSE OF REVIEW

Cardiovascular autonomic dysfunction (AD) among cancer survivors is increasingly being recognized. However, the mechanisms and incidence are poorly understood. In this review, the clinical features, diagnostic modalities, proposed mechanisms, and currently available treatments of cardiovascular AD in cancer survivors are described.

RECENT FINDINGS

Much of our current understanding of cardiovascular AD is based on disease states such as diabetes, multisystem atrophy, and Parkinson's disease. Several non-invasive tests, measurements, and scoring systems have been developed as surrogates for autonomic function, with some even demonstrating associations with all-cause mortality. The mechanism of cardiovascular AD specifically in the cancer population, however, has not been directly studied. The etiology of cardiovascular AD in cancer survivors is likely multifactorial, and proposed mechanisms include direct nerve damage by chemoradiation, the pro-inflammatory state associated with malignancy, and paraneoplastic syndromes. It may also be that cardiovascular AD is an early marker of global cardiomyopathy rather than its own condition. Current pharmacologic options for cardiovascular AD are extrapolated from how it has been treated in other disease processes, and these agents have not been studied in the cancer population or compared head-to-head. Cardiovascular AD in cancer survivors can cause significant debilitation and may be associated with all-cause mortality. Current diagnostic modalities have several limitations, such as standardization and validity. However, given the nonspecific nature of cardiovascular AD, these tools provide an objective marker for diagnosis and tracking treatment response. While the mechanism of cardiovascular AD in cancer survivors has not been directly studied, it may be useful to evoke mechanisms of cardiovascular AD in other disease states such as diabetes, Parkinson's disease, and multisystem atrophy in addition to identifying unique conditions associated with malignancy like a pro-inflammatory state. Until further studies are performed, management of cardiovascular AD as seen in other disease states may serve as a guide for symptom management in cancer survivors.

Changes in sympathetic nervous system activity after renal denervation: results from the randomised Oslo RDN study

PURPOSE

Sympathetic nervous system (SNS) over-activity is associated with essential hypertension. Renal sympathetic denervation (RDN) possibly lowers office- and ambulatory blood pressure (BP) in patients with treatment-resistant hypertension (TRH). We aimed to assess the effect of RDN compared to drug adjustment on SNS activity among patients with TRH by measuring plasma catecholamines and heart rate variability (HRV) during stress tests.

MATERIALS AND METHODS

Patients with TRH were randomised to RDN (n = 9) or Drug Adjustment (DA) (n = 10). We measured continuous HRV and beat-to-beat-BP using FinaPres® and obtained plasma catecholamines during standardised orthostatic- and cold-pressor stress tests (CPT) before- and six months after randomisation.

RESULTS

CPT revealed no differences between groups at baseline in peak adrenaline concentration (69.3 pg/mL in the DA group vs. 70.0 pg/mL in the RDN group, p = 0.38) or adrenaline reactivity (Δ23.1 pg/mL in the DA group vs. Δ29.3 pg/mL in the RDN group, p = 0.40). After six months, adrenaline concentrations were statistically different between groups after one minute (66.9 pg/mL in the DA group vs. 55.3 pg/mL in the RDN group, p = 0.03), and six minutes (62.4 pg/mL in the DA group vs. 50.1 pg/mL in the RDN group, p = 0.03). There was a tendency of reduction in adrenaline reactivity after six months in the RDN group (Δ26.3 pg/mL at baseline vs. Δ12.8 pg/ml after six months, p = 0.08), while it increased in the DA group (Δ13.6 pg/mL at baseline vs. Δ19.9 pg/mL after six months, p = 0.53). We also found a difference in the Low Frequency band at baseline following the CPT (667µs² in the DA group vs. 1628µs² in the RDN group, p = 0.03) with a clear tendency of reduction in the RDN group to 743µs² after six months (p = 0.07), compared to no change in the DA group (1052µs^2, p = 0.39).

CONCLUSION

Our data suggest that RDN reduces SNS activity after six months. This finding warrants investigation in a larger study. Clinical Trial Number registered at www.clinicaltrials.gov: NCT01673516.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus

BACKGROUND

We are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.

AIM

Assessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).

PATIENTS AND METHODS

We analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.

RESULTS

AD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.

CONCLUSION

Cardiovascular autonomic neuropathy should be taken into account in COVID-19 patients' assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Quantitative examination of early diabetes by light-emitting diodes light-induced pupillary light reflex

This study investigated the abnormal pupillary light reflex in patients with early diabetes mellitus (DM) without retinopathy by using a custom-made noninvasive portable pupilometer. The pupilometer recorded and analyzed the pupillary light reflex. Two light intensities, 0.2 cd and 1.2 cd, and four wavelengths of stimulus light-white (400 nm-800 nm), red (640 ± 5 nm), green (534 ± 5 nm), and blue (470 ± 5 nm)-were used to stimulate the pupil for 10 ms. The pupillary response was recorded for 15 s. A total of 40 healthy people and 40 people with DM without retinopathy participated in the experiment at the National Taiwan University Hospital. The mean and standard deviation of DM duration were 4.5 years and 3.9 years. Of the 16 indices, the duration that pupil restores from its minimum size to half of its resting size (DRP), maximum pupil restoration velocity (MRV), and average restoration velocity (ARV) exhibited the most significant differences between the healthy people and those with DM. Compared with healthy participants, DRP was 16.33% higher, and MRV and ARV were 17.45% and 4.58% lower, respectively, in those with DM. This might be attributable to the sympathetic nervous system (SNS) controlling the dilator muscle during the dark-adapted period and relaxing the pupil; the SNS had few degenerated nerve endings in people with DM. The three aforementioned indices might be used to evaluate the severity of autonomic neuropathy in early DM.

Heart rate response to orthostatic challenge in patients with dementia with Lewy bodies and Alzheimer's disease

BACKGROUND

To elucidate the differences in autonomic dysfunction between dementia with Lewy bodies (DLB) and Alzheimer's disease using a simple and convenient method, we investigated the heart rate response to orthostatic challenge.

METHODS

Ninety-seven people participated in this cross-sectional study, and data from 26 DLB patients, 29 Alzheimer's disease patients, and 25 healthy elderly individuals were analysed. Participants underwent postural changes, including 5 min in a supine position, 1 min in a sitting position, and 3 min in an orthostatic position. Their heart rates were continuously recorded. Two heart rate variables were analysed as main outcomes: (i) the difference between heart rate in the sitting position and the peak heart rate within 15 s of orthostasis, defined as the 'early heart rate increase'; and (ii) the difference between the peak heart rate and the negative peak heart rate after this, defined as 'early heart rate recovery.' An early heart rate increase has been considered to reflect parasympathetic and sympathetic functions. Early heart rate recovery is considered to reflect parasympathetic function. We also investigated the frequency domains of resting heart rate variability.

RESULTS

A significant difference was observed across the three groups in early heart rate increase, and that of the DLB group was lower than that of the healthy control group. Early heart rate recovery also differed significantly across the three groups, and that of the DLB group was less than that of the healthy control group. In addition, the power of the low-frequency component, which represents both sympathetic and parasympathetic activity, was significantly decreased in the DLB group compared to the Alzheimer's disease group.

CONCLUSIONS

Impaired heart rate response to standing was detected in patients with DLB. Electrocardiogram is a convenient, non-invasive method that might be useful as a subsidiary marker for DLB diagnosis and differentiation from Alzheimer's disease.

Sounds of Silence in Times of COVID-19: Distress and Loss of Cardiac Coherence in People With Misophonia Caused by Real, Imagined or Evoked Triggering Sounds

The extreme, unprecedented situations in the current COVID-19 pandemic are risk factors for psychosocial stress for the entire population. However, strict confinement had a particular impact on people suffering from misophonia and their families. Misophonia is a condition in which hearing certain sounds triggers intense anger, disgust and even severe autonomic nervous system responses. This prospective cohort study examined the impact of strict confinement (Spain, March 14-June 21, 2020) on a sample of 24 people (16 women and eight men) who had been diagnosed with moderate to extreme misophonia and were regularly attending a medical psychology center in Barcelona. The 3-month period of confinement caused general emotional maladjustment, distress, and a transitory crisis. Long-term biomonitoring of their heart variability rate (HRV) enabled to identify a significant increase in physiological arousal after the confinement period, which had already been recorded in a loss of cardiac coherence under basal rest/relaxation conditions. Certain auditory stimuli triggered adverse responses, lowered HRV scores, and an increased stress level and heart rate. Loss of cardiac coherence in their responses to these auditory stimuli (triggering mouth, nose and other sounds), as well as to non-triggering mouth, nose and other sounds was increased when compared to two assessments performed during the previous year. Despite the limited sample size, sex differences were observed in the incidence. Loss of cardiac coherence worsened with the severity of the misophonia. Most importantly, imagined or evoked triggering sounds, as well as real ones, were enough to cause the aversive responses, as displayed by the increased loss of cardiac coherence with respect to the at-rest basal level. A semi-structured interview revealed the exceptional nature of the situations, increased hyper-sensorial sensitivity, fear of being infected with or dying from COVID-19, the patients' coping strategies, and the difficulties and constraints they faced. Finally, the article gives recommendations for better management of misophonia. Improved knowledge of this disorder would help address the current lack of health and social care, hopefully preventing this shortfall's impact on social and affective relationships, which are particulary important for well-being now and in the coming periods of physical distancing measures.

Resting Heart Rate Variability Is Associated With Subsequent Orthostatic Hypotension: Comparison Between Healthy Older People and Patients With Rapid Eye Movement Sleep Behavior Disorder

Background: Orthostatic hypotension (OH) caused by autonomic dysfunction is a common symptom in older people and patients with idiopathic rapid eye movement sleep behavior disorder (iRBD). The orthostatic challenge test is a standard autonomic function test that measures a decrease of blood pressure during a postural change from supine to standing positions. Although previous studies have reported that changes in heart rate variability (HRV) are associated with autonomic dysfunction, no study has investigated the relationship between HRV before standing and the occurrence of OH in an orthostatic challenge test. This study aims to examine the connection between HRV in the supine position and the occurrence of OH in an orthostatic challenge test. Methods: We measured the electrocardiograms of patients with iRBD and healthy older people during an orthostatic challenge test, in which the supine and standing positions were held for 15 min, respectively. The subjects were divided into three groups: healthy controls (HC), OH-negative iRBD [OH (-) iRBD], and OH-positive iRBD [OH (+) iRBD]. HRV measured in the supine position during the test were calculated by time-domain analysis and Poincaré plots to evaluate the autonomic dysfunction. Results: Forty-two HC, 12 OH (-) iRBD, and nine OH (+) iRBD subjects were included. HRV indices in the OH (-) and the OH (+) iRBD groups were significantly smaller than those in the HC group. The multivariate logistic regression analysis for OH identification for the iRBD groups showed the model whose inputs were the HRV indices, i.e., standard deviation 2 (SD2) and the percentage of adjacent intervals that varied by more than 50 ms (pNN50), had a receiver operating characteristic curve with area under the curve of 0.840, the sensitivity to OH (+) of 1.000, and the specificity to OH (-) of 0.583 (p = 0.023). Conclusions: This study showed the possibility that short-term HRV indices in the supine position would predict subsequent OH in iRBD patients. Our results are of clinical importance in terms of showing the possibility that OH can be predicted using only HRV in the supine position without an orthostatic challenge test, which would improve the efficiency and safety of testing.

Effects of Different Neck Manual Lymphatic Drainage Maneuvers on the Nervous, Cardiovascular, Respiratory and Musculoskeletal Systems in Healthy Students

The aim of this study is to describe the short-term effects of manual lymph drainage (MLD) isolated in supraclavicular area in healthy subjects. A 4-week cross-sectional, double-blinded randomized clinical trial was conducted. Participants: 24 healthy participants between 18 and 30 years old were recruited from Universidad Europea de Madrid from December 2018 to September 2019. A total of four groups were studied: control, placebo, Vodder, and Godoy. The order of the interventions was randomized. Resting Heart Rate and Oxygen Saturation, blood pressure, pressure pain threshold of trapezius muscle, respiratory rate, range of active cervical movements were measured before and after every intervention. All the participants fulfilled four different interventions with a one-week-wash-out period. No statistically significant differences were found between groups in descriptive data; neither in saturation of oxygen, diastolic blood pressure and cervical range of motion. Significant differences were found in favor of Vodder (p = 0.026) in heart rate diminution and in cardiac-rate-reduction. A significant difference in respiratory rate diminution is found in favor of the Godoy group in comparison with the control group (p = 0.020). A significant difference is found in favor of the Godoy group in systolic blood pressure decrease (p = 0.015) even in pressure pain threshold (p < 0.05). MLD decreases systolic blood pressure in healthy participants. However, it does not produce any changes in other physiologic outcomes maintaining physiologic values, which may suggest the safety of the technique in patients suffering from other pathologies.

Error Estimation of Ultra-Short Heart Rate Variability Parameters: Effect of Missing Data Caused by Motion Artifacts

Application of ultra–short Heart Rate Variability (HRV) is desirable in order to increase the applicability of HRV features to wrist-worn wearable devices equipped with heart rate sensors that are nowadays becoming more and more popular in people’s daily life. This study is focused in particular on the the two most used HRV parameters, i.e., the standard deviation of inter-beat intervals (SDNN) and the root Mean Squared error of successive inter-beat intervals differences (rMSSD). The huge problem of extracting these HRV parameters from wrist-worn devices is that their data are affected by the motion artifacts. For this reason, estimating the error caused by this huge quantity of missing values is fundamental to obtain reliable HRV parameters from these devices. To this aim, we simulate missing values induced by motion artifacts (from 0 to 70%) in an ultra-short time window (i.e., from 4 min to 30 s) by the random walk Gilbert burst model in 22 young healthy subjects. In addition, 30 s and 2 min ultra-short time windows are required to estimate rMSSD and SDNN, respectively. Moreover, due to the fact that ultra-short time window does not permit assessing very low frequencies, and the SDNN is highly affected by these frequencies, the bias for estimating SDNN continues to increase as the time window length decreases. On the contrary, a small error is detected in rMSSD up to 30 s due to the fact that it is highly affected by high frequencies which are possible to be evaluated even if the time window length decreases. Finally, the missing values have a small effect on rMSSD and SDNN estimation. As a matter of fact, the HRV parameter errors increase slightly as the percentage of missing values increase.

The sympathetic muscle metaboreflex is not different in the third trimester in normotensive pregnant women

Isometric handgrip (IHG) is used to assess sympathetic nervous system responses to exercise and may be useful at predicting hypertension in both pregnant and nonpregnant populations. We previously observed altered sympathetic nervous system control of blood pressure in late pregnancy. Therefore, we measured muscle sympathetic nerve activity (MSNA) and blood pressure during muscle metaboreflex activation (IHG) in normotensive pregnant women in the third trimester compared with in healthy nonpregnant women. Further, 19 pregnant (32 ± 3 wk gestation) and 14 nonpregnant women were matched for age, non/prepregnant body mass index (BMI), and parity. MSNA (microneurography), heart rate (ECG), and arterial blood pressure (Finometer) were continuously recorded during 10 min of rest, and then during 2 min of IHG at 30% of maximal voluntary contraction, and 2 min of postexercise circulatory occlusion (PECO). Baseline sympathetic nerve activity (SNA) was elevated in pregnant (41 ± 11 bursts/min) compared with nonpregnant women (27 ± 9 bursts/min; P = 0.005); however, the sympathetic baroreflex gain and neurovascular transduction were not different between groups (P = 0.62 and P = 0.32, respectively). During IHG and PECO, there were no significant differences in the pressor responses (ΔMAP) between groups, (P = 0.25, main effect of group) nor was the sympathetic response different between groups (interaction effect: P = 0.16, 0.25, and 0.27 for burst frequency, burst incidence, and total SNA, respectively). These data suggest that pregnant women who have maintained sympathetic baroreflex and neurovascular transduction also have similar sympathetic and pressor responses during exercise.NEW & NOTEWORTHY We compared sympathetic nervous system activation by muscle metaboreflex between pregnant women in the third trimester and nonpregnant women. We show that the sympathetic nerve activity and associated pressor responses to isometric handgrip and post-exercise circulatory occlusion are not different between third-trimester pregnant and nonpregnant women. These data suggest that unlike other reflexes (e.g., cold pressor test or head-up tilt), metaboreflex control is maintained in pregnant women.

Dietary supplementation with L-carnosine improves patient-reported outcomes, autonomic nervous system performance, and brain metabolism in 3 adult patients with multiple sclerosis

This pilot trial reports the effects of L-carnosine administration on autonomic nervous system performance, brain metabolism, and various patient- and clinician-reported outcomes in a case series of patients with multiple sclerosis (MS). We hypothesized that medium-term L-carnosine supplementation would improve selected patient- and clinician-reported outcomes in MS patients, with no negative effects on self-reported side effects. L-carnosine (2 g/day) was administered orally for 8 weeks in 2 women and one man suffering from MS. The intensity of symptoms and signs of MS after L-carnosine administration diminished in 5 out of 7 domains in CASE 1, in 3 out of 7 domains in CASE 2, and one domain in CASE 3; general fatigue was reduced in all 3 cases at the follow-up. This was accompanied by an improved walking distance to exhaustion in all patients, with values improved for 51.1% in CASE 1, 19.5% in CASE 2, and 2.1% in CASE 3 at 8-week follow-up. Tests of autonomic cardiovascular reflexes demonstrate normalized parasympathetic modulation and balanced sympathetic function after L-carnosine intervention in all MS cases. An increase in serum total antioxidant capacity (TAC) was found at 8-week follow-up in all patients (from 4.6 to 49.6%); this was accompanied by lower blood lactate at post-administration in all cases (23.5% on average). Single-voxel 1.5 T MR spectroscopy revealed increased brain choline-contained compounds (18.9% on average), total creatine (21.2%), and myo-inositol levels (12.3%) in girus cinguli at 8-week follow-up in all MS cases. This case study demonstrates that an 8-week intervention with L-carnosine appears to be a safe and beneficial therapeutic strategy with regard to the reduction of presence and severity of symptoms of MS.

Heart rate variability as a potential diagnostic tool to predict compensatory hyperhidrosis after sympathectomy in patients with primary focal hyperhidrosis

Background

Primary focal hyperhidrosis (PFH) is associated with autonomic nervous activity, and studies investigating this association in patients with PFH are very important. Heart rate variability (HRV) is a simple and noninvasive electrocardiographic test showing activity and balance in the autonomic nervous system, which consists of sympathetic and parasympathetic components. The aims of this study are to investigate associations between autonomic nervous activity and hyperhidrosis characteristics using HRV and to investigate the association between HRV findings and compensatory hyperhidrosis (CH) after sympathectomy.

Methods

From March 2017 to March 2020, 105 subjects with PFH who underwent preoperative HRV tests and sympathectomy were analyzed. All subjects underwent bilateral thoracoscopic sympathectomy. T2 sympathectomy was conducted for craniofacial hyperhidrosis, and T3 sympathectomy was conducted for palmar hyperhidrosis. The following HRV parameters chosen to investigate the association between hyperhidrosis and autonomic nervous activity were measured by time and frequency domain spectral analysis: (I) time domain: standard deviation of normal-to-normal interval (SDNN) and square root of mean squared differences of successive normal-to-normal intervals (RMSSD), (II) frequency domain: total power (TP) of power spectral density, very low frequency (VLF), low frequency (LF), and high frequency (HF). HRV parameters were analyzed according to hyperhidrosis type (craniofacial vs. palmar type), sweat reduction, and CH after sympathectomy. In addition, the independent HRV parameters influencing CH after sympathectomy were investigated with multivariate analysis.

Results

Craniofacial hyperhidrosis was significantly more prevalent in the old age group (P<0.001). Sweat reduction after sympathectomy was significantly more prominent in palmar hyperhidrosis (P=0.037), and CH after sympathectomy was more prominent in craniofacial hyperhidrosis (P<0.001). Palmar type patients exhibited significantly larger SDNN, RMSSD, TP, LF, and HF than craniofacial type patients (all P<0.001). There were no significant differences in any HRV parameters according to sweat reduction after sympathectomy. Low-degree CH was associated with significantly larger SDNN, RMSSD, TP, LF, and HF than high-degree CH (P<0.001, P<0.001, P=0.002, P=0.001, and P<0.001, respectively). Multivariate analysis showed that HF and age group were associated with CH after sympathectomy (P=0.007 and P=0.010, respectively).

Conclusions

This study shows that HRV can provide useful insight into the pathophysiology of PFH and enhance preoperative risk stratification of CH. Large-scale, prospective studies are required to determine the predictive value of HRV in patients at risk for subsequent CH after sympathectomy.

Effect of meditation on autonomic function in healthy individuals: A longitudinal study

Context:

Meditation is very useful to relieve stress via hypothalamo-pituitory axis. Meditation is considered to be useful to relieve stress and cardio-respiratory health.

Aims:

To compare the effect of meditation on autonomic function including heart rate variability (HRV) over a period of 3 months of meditation.

Settings and Design:

Longitudinal study conducted at Physiology Department, AIIMS Bhopal.

Methods and Materials:

Thirty healthy volunteers doing meditation were evaluated for autonomic function using autonomic function test battery (Ewing's battery) and HRV using Power lab (Ad instrument) and digital electrocardiograph (MARKS).

Statistical Analysis Used:

Statistical analysis was done using statistical software. Wilcoxon signed rank test was used.

Results:

Significant change was seen in Valsalva ratio and lying to standing 30:15 ratio. There was no significant change in other parameters studied with 3 months of meditation.

Conclusions:

Three months of meditation does not have any significant effect on major parameters of autonomic functions.

Non-invasive Recording of Parasympathetic Nervous System Activity on Auricular Vagal Nerve Branch

The function of the autonomic nervous system (ANS) influences most of the physiological mechanisms. The popular non-invasive method to estimate the activities of the autonomic nervous system (ANS) is the heart rate variability (HRV). However, the HRV cannot provide real-time information of the ANS function. The skin sympathetic nerve activity (SKNA) is a novel method to evaluate sympathetic nerve system (SNS) activity. The SKNA technique has shown promise in clinical applications but is limited to evaluating SNS activities. To date, a direct non-invasive method for measuring the parasympathetic nerve system (PNS) function is urgently needed. According to anatomy, the auricular branch of the vagus nerve (aVN) is near the concha surface. In this study, we hypothesize that we can measure the aVN activity (aVNA) with the same technique developed for SKNA recording. Flexible auricular electrodes were developed for continuous long-term recording of aVN activity. The SKNA and aVNA were simultaneously recorded during the experiment. The cold face test and cold pressor test were performed to physiologically activate ANS. The SKNA and aVNA can be obtained simultaneously, and they are correlated with the heart rate change during the physiological challenge. The aVNA has a high potential to be developed into a novel method to measure the PNS activity.

Heart Rate Variability Predicts Older Adults' Avoidance of Negativity

OBJECTIVES

The ability to produce situation-appropriate cognitive and emotional responses is dependent on autonomic nervous system (ANS) functionality. Heart rate variability (HRV) is an index of ANS functionality, and resting HRV levels have been associated with cognitive control and inhibitory capacity in young adults, particularly when faced with emotional information. As older adults' greater preference for positive and avoidance of negative stimuli (positivity effect) is thought to be dependent on cognitive control, we hypothesized that HRV could predict positivity-effect magnitude in older adults.

METHOD

We measured resting-level HRV and gaze preference for happy and angry (relative to neutral) faces in 63 young and 62 older adults.

RESULTS

Whereas young adults showed no consistent preference for happy or angry faces, older adults showed the expected positivity effect, which predominantly manifested as negativity avoidance rather than positivity preference. Crucially, older but not young adults showed an association between HRV and gaze preference, with higher levels of HRV being specifically associated with stronger negativity avoidance.

DISCUSSION

This is the first study to demonstrate a link between older adults' ANS functionality and their avoidance of negative information. Increasing the efficiency of the cardiovascular system might selectively improve older adults' ability to disregard negative influences.

Feasibility of a new free mobility procedure to evaluate the function of the autonomic nervous system in patients with syncope

To propose a new test to evaluate the autonomic nervous system in patients with syncope: Multimodal Monitoring for Diagnosis of Dysautonomia (MMDD). We included 21 patients with syncope (16 female, 6 male, mean age 43.5 years) and 21 with no-syncope subjects (15 female, 7 male, mean age 45.1 years) to perform a test of nine 2-min stages: four while resting and four during active testing of autonomic response. Transcranial-Doppler, electrocardiogram, and photoplethysmography blood pressure pulse-to-pulse monitoring, allow registering six variables from the Middle Cerebral Artery and four from the Cardiovascular System. We analyze each variable's mean differences in each stage and its change when they pass from one stage to another with the T and Z tests. To understand the significance of the change, we use a logistic regression model for a certain subgroup of variables. Since we have a small dataset, we use the bootstrap technique to infer the general behavior that characterizes a syncope. Our data confirm differences between syncope and non-syncope patients during MMDD stress stages 2, 4, 6 and 8. Bootstrap and multivariate logistic regression allow us to identify which sets of variables in each of these stages of the MMDD are sufficiently sensitive to recognizing syncope. MMDD protocol can recognize a syncope patient with some confidence by detecting subtle changes in the autonomic nervous system. This protocol encourages us to continue to study the effectiveness of MMDD protocol allowing a new approach to future research.

Circadian rhythm dynamics on multiscale entropy identifies autonomic dysfunction associated with risk of ventricular arrhythmias and near syncope in chronic kidney disease

BACKGROUND

A discordant biological clock could potentially induce sudden cardiac death (SCD). We aimed to evaluate the circadian change of heart rate variability (HRV) and its relationship to the risks of ventricular arrhythmia (VA) and near syncope in patients with chronic kidney disease (CKD).

METHODS

In this retrospective study, non-CKD and CKD patients were enrolled and underwent a 24-hour Holter examination for linear and nonlinear HRV analyses. The multiscale entropy (MSE) method was selected for nonlinear HRV analyses. The documented VAs or episodes of near syncope were classified as high-risk SCD group (n=8) and others as low-risk SCD group (n=21).

RESULTS

In linear analyses, time and frequency domains revealed no significant difference between groups. In nonlinear analyses with MSE, MSE₅, MSE_6-20, and MSE_{slope 5} were significantly lower (p=0.002, p<0.0001, and p=0.013) in the high-risk SCD group, compared to those in the low-risk SCD group, respectively. Comparing between daytime and nighttime within each group, the MSE₅ revealed no difference in the high-risk SCD group (p=0.128), whereas the daytime was significantly higher in the low-risk SCD group (p=0.048). The area under the curve (AUC) analysis revealed MSE_6-20 has the best predictive power associated with VAs and near syncope with a cut-off value of ≤24.64 (p<0.001).

CONCLUSIONS

Nonlinear analysis with MSE demonstrated the loss of circadian change in CKD patients and was associated with a higher risk for VAs and near syncope. The MSE method demonstrated the diurnal change of rhythm dynamics which identifies potential autonomic dysfunction leading to poor prognosis.

Performance evaluation of a portable bioimpedance cardiac output monitor for measuring hemodynamic changes in athletes during a head-up tilt test

The use of impedance cardiography to monitor physiological changes in sports is rarely reported. Using head-up tilt test, we evaluated a portable noninvasive impedance cardiography device (PhysioFlow) by comparing it with a reference Doppler monitor (USCOM). Accuracy in tracking hemodynamic changes deteriorated with higher tilt, implying a gravitational influence on its performance. Stroke volume measurements were overestimated, but the changes were underestimated. Despite its convenient physical features, the suitability of PhysioFlow for sports use is questionable.

Slow 0.1 Hz Breathing and Body Posture Induced Perturbations of RRI and Respiratory Signal Complexity and Cardiorespiratory Coupling

Objective: We explored the physiological background of the non-linear operating mode of cardiorespiratory oscillators as the fundamental question of cardiorespiratory homeodynamics and as a prerequisite for the understanding of neurocardiovascular diseases. We investigated 20 healthy human subjects for changes using electrocardiac RR interval (RRI) and respiratory signal (Resp) Detrended Fluctuation Analysis (DFA, α1RRI, α2RRI, α1Resp, α2Resp), Multiple Scaling Entropy (MSERRI1-4, MSERRI5-10, MSEResp1-4, MSEResp5-10), spectral coherence (CohRRI-Resp), cross DFA (ρ1 and ρ2) and cross MSE (XMSE1-4 and XMSE5-10) indices in four physiological conditions: supine with spontaneous breathing, standing with spontaneous breathing, supine with 0.1 Hz breathing and standing with 0.1 Hz breathing. Main results: Standing is primarily characterized by the change of RRI parameters, insensitivity to change with respiratory parameters, decrease of CohRRI-Resp and insensitivity to change of in ρ1, ρ2, XMSE1-4, and XMSE5-10. Slow breathing in supine position was characterized by the change of the linear and non-linear parameters of both signals, reflecting the dominant vagal RRI modulation and the impact of slow 0.1 Hz breathing on Resp parameters. CohRRI-Resp did not change with respect to supine position, while ρ1 increased. Slow breathing in standing reflected the qualitatively specific state of autonomic regulation with striking impact on both cardiac and respiratory parameters, with specific patterns of cardiorespiratory coupling. Significance: Our results show that cardiac and respiratory short term and long term complexity parameters have different, state dependent patterns. Sympathovagal non-linear interactions are dependent on the pattern of their activation, having different scaling properties when individually activated with respect to the state of their joint activation. All investigated states induced a change of α1 vs. α2 relationship, which can be accurately expressed by the proposed measure-inter-fractal angle θ. Short scale (α1 vs. MSE1-4) and long scale (α2 vs. MSE5-10) complexity measures had reciprocal interrelation in standing with 0.1 Hz breathing, with specific cardiorespiratory coupling pattern (ρ1 vs. XMSE1-4). These results support the hypothesis of hierarchical organization of cardiorespiratory complexity mechanisms and their recruitment in ascendant manner with respect to the increase of behavioral challenge complexity. Specific and comprehensive cardiorespiratory regulation in standing with 0.1 Hz breathing suggests this state as the potentially most beneficial maneuver for cardiorespiratory conditioning.

Efficacy of Acupuncture in the Treatment of Elderly Patients with Hypertension in Home Health Care: A Randomized Controlled Trial

Objective: To evaluate the efficacy of acupuncture in helping antihypertensive drugs lower the hypertension of elderly patients in home health care. Design: Randomized controlled trial. Setting: Subjects were recruited from Branch of Linsen, Chinese Medicine, and Kunming, Taipei City Hospital, Taipei, Taiwan. Subjects: A total of 70 participants with hypertension in home health care were assigned randomly to the acupuncture group (35 participants) or the control group (35 participants). Interventions: The acupuncture group received antihypertensive drugs plus acupuncture twice a week for 12 weeks, and the control group received antihypertensive drugs only. Acupuncture points SP10, SP6, LR3, ST36, and LI4 were used bilaterally. Each acupuncture treatment session lasted 30 min. All the subjects were instructed not to alter their diet, physical activity, or use of drugs. Outcome measurements: Blood pressure (BP), heart rate variability, and the Constitution in Chinese Medicine Questionnaire (CCMQ) were assessed at baseline and at 6 and 12 weeks from the baseline between 9 am and 10 am in all subjects. Results: A total of 31 participants in each group completed the study. Within-group differences were observed in systolic BP (SBP) (p < 0.001), diastolic BP (p < 0.001), standard deviation of normal sinus beat intervals (SDNN) (p = 0.01), low frequency (p = 0.05), high frequency (p = 0.01), total power (TP) (p = 0.01), percentage of successive intervals that differ by more than 50 msec (PNN50) (p = 0.01), qi deficiency (p = 0.003), blood stasis (p = 0.02), and qi depression (p = 0.03) constitution. Significant between-group differences were observed in SBP (p = 0.001), SDNN (p = 0.008), and TP (p = 0.04). Conclusions: This study suggested that in the home health care hypertension population, antihypertensive drugs plus acupuncture may be more beneficial in lowering BP and in regulating autonomic nervous system activity than drugs alone. A longer follow-up and larger sample size should be considered in future studies to reveal the precise effect of acupuncture followed by evidence-based practice.

Maternal Pregnancy Diet Quality Is Directly Associated with Autonomic Nervous System Function in 6-Month-Old Offspring

BACKGROUND

Many pregnant women are consuming diets of poor overall quality. Although many studies have linked poor prenatal diet quality to an increased risk of specific diseases in offspring, it is not known if exposure to poor prenatal diet affects core neurophysiological regulatory systems in offspring known to lie upstream of multiple diseases.

OBJECTIVE

We aimed to examine the association between prenatal diet quality and autonomic nervous system (ANS) function in infants at 6 mo of age.

METHODS

Data from 400 women (aged >18 y, with uncomplicated pregnancies) and their infants participating in the Maternal-Infant Research on Environmental Chemicals-Infant Development cohort were used to investigate links between prenatal diet quality and infant ANS function at 6 mo of age. Prenatal diet quality was assessed using the Healthy Eating Index (2010), calculated from a validated FFQ completed by women during the first trimester. Infant ANS function was measured using 2 assessments of heart rate variability (HRV) including root mean square of successive differences (RMSSD) and SD of N-N intervals (SDNN). Associations were analyzed before and after adjustment for socioeconomic status, maternal depression symptoms, maternal cardiometabolic dysfunction, breastfeeding, and prenatal smoking.

RESULTS

Poorer prenatal diet quality was associated with lower infant HRV assessed using RMSSD (B: 0.07; 95% CI: 0.01, 0.13; R2 = 0.013) and SDNN (B: 0.18; 95% CI: 0.02, 0.35; R2 = 0.011). These associations remained significant after adjustment for confounding variables [RMSSD: B: 0.09; 95% CI: 0.003, 0.18; squared semipartial correlation (sp2) = 0.14 and SDNN B: 0.24; 95% CI: 0.0, 0.49; sp2 = 0.13].

CONCLUSIONS

In a large cohort study, poorer prenatal diet quality was associated with lower offspring HRV, a marker of decreased capacity of the ANS to respond adaptively to challenge. Therefore, poor prenatal diet may play a significant role in the programming of multiple organ systems and could increase general susceptibility to disease in offspring.

Geometry of the Poincaré plot can segregate the two arms of autonomic nervous system - A hypothesis

Autonomic Nervous System (ANS) operates to achieve the optimum physiological functioning and maintains homeostasis in a tonic and continuous manner. Evaluation of ANS profile is crucial in assessing autonomic dysfunction. Conventional ANS evaluation procedures fail to capture minute dynamic alterations of ANS activities. The ANS output pattern is appropriately reflected in the fine alteration of the resting heart rate (HR). HR is a non-stationary variable, results from the dynamic interplay between the multiple physiologic mechanisms. The control of cardiac rate or the chronotropic regulation of heart is considered as a coupled network of oscillators, each representing a specific facet of the cardiovascular reflex. The slower vasomotor oscillation via sympathetic system is combined with rapid respiratory oscillation by parasympathetic system to modulate the intrinsic oscillation pattern of the SA Node. Heart Rate Variability (HRV) is used to understand the autonomic influence on cardiovascular system in health and disease. Fourier decomposition of HRV offers us mainly two different frequency components. High frequency (HF) variation indicates parasympathetic variability due to respiration and Low frequency (LF) mainly implicates tonic sympathetic influence, due to slower vasomotor modulation of heart rate. However, different studies show conflicting results and direct recording of sympathetic nerve activity also failed to correlate with LF power in either healthy subjects or in patients with increased cardiac sympathetic drive. A scatter-plot where each R-R interval is plotted against the preceding R-R interval forms a distributed elliptic point cloud in two dimensional plane. The phase space realization of this plot with dimension two and delay one is referred to as Poincaré plot analysis, an emerging quantitative-visual technique where the shape of the plot is categorized into different functional classes. The plot provides summary as well as detailed beat-to-beat information of the heart. This plot can be extended to three dimensions and with multi-lag, offering more insight and information. A mathematical expression was developed by an interventional study by Toichi et al., using pharmacological blockers during different physiological variables that calculated the lengths of transverse and longitudinal axes of the Poincaré plot to derive two quantitative expressions of sympathetic and vagal influence on HRV: 'cardiac sympathetic index' (CSI)) and 'cardiac vagal index' (CVI). In the present study, we emulate Poincaré plot patterns seen in normal range of sympatho-vagal balances and also in Diabetes Mellitus (DM), known to cause autonomic dysfunction. The emerging pattern of R-R interval time series would provide valuable insight into the altered temporal dynamics and also extract crucial features embedded within. DM is a major public health crisis globally and particularly in Indian population. We hypothesize that, CSI and CVI will effectively segregate the two arms of ANS and can be utilized as an effective evaluation tool to explore the disease status in patients of Diabetes Mellitus. We also propose that, the dynamics of fluctuations in physiological rhythms that exhibit long-term correlation and memory, can also be explored and expressed quantitatively by incorporating various degrees of 'lag' in these recurrence plots.

Heart rate variability indices, biomarkers, and cardiac nerve density: Independent surrogate markers for diagnosis of diabetic cardiac autonomic neuropathy in type 2 diabetes mellitus animal model

OBJECTIVES

Heart rate variability (HRV) has been shown to represents a promising quantitative marker of autonomic activity. Studies have shown that diabetic patients and animal models have derangements in certain biochemical parameters with reduced cardiac nerve density following development of diabetic cardiac autonomic neuropathy (DCAN). This study, therefore, aims to correlate HRV indices, cardiac histology, and cardiac nerve density with selected biochemical markers in the DCAN rat model using high fat diet (HFD) and streptozotocin (STZ) induction.

METHODS

DCAN was induced in Wistar rats using HFD for 8 weeks with 25 mg/kg STZ daily for 5 days. DCAN features were then assessed using Holter electrocardiography (ECG), invasive biomarkers, and cardiac histology.

RESULTS

DCAN group had significantly higher advanced glycated end product levels (P < 0.0001), noradrenaline (P = 0.010), and insulin resistance (P = 0.016) compared with controls. The level of antioxidants, sorbitol dehydrogenase activity (P = 0.009), nerve growth factors (P < 0.0001), and choline acetyl-transferase (P = 0.031) was, however, significantly reduced. Furthermore, HRV indices which were also reduced with DCAN induction correlated significantly with levels of biomarkers and cardiac nerve density.

CONCLUSION

HRV is a cheap and easy tool for assessing DCAN that significantly correlates with markers of autonomic activity. Holter ECG and HRV evaluation should be considered early in patients with diabetes.

Posttraumatic Stress Disorder and Alterations in Resting Heart Rate Variability: A Systematic Review and Meta-Analysis

OBJECTIVE

The functions of both the central and peripheral autonomic nervous system, indexed by heart rate variability (HRV), are affected by psychology and physiology. This review summarizes the results of studies comparing the evaluation of HRV parameters between individuals with posttraumatic stress disorder (PTSD) and healthy controls.

METHODS

Eligible studies (n=499) were identified through literature searches of the EMBASE, Medline, PubMed and Web of Science databases. Nineteen studies met our inclusion criteria. A random effects model was used, and standardized mean differences for highfrequency HRV(HF-HRV), low-frequency HRV(LF-HRV) and the root mean square of successive R-R interval differences (RMSSD) were calculated.

RESULTS

Significant effects were found for HF-HRV [p<0.0001, Z=4.18; Hedges'g=-1.58, 95% confidence interval (CI) (-2.32, -0.84); k=14] and RMSSD [p<0.00001, Z=4.80; Hedges'g=-1.96, 95% CI (-2.76, -1.16); k=9] relative to healthy controls. Considerable heterogeneity was revealed, but the main effects for HF-HRV and RMSSD were robust in subsequent meta-regression and subgroup analyses.

CONCLUSION

Given the relationships among low vagal state, inflammation, and alterations in brain structure and function, including executive function and emotion regulation, reduced HRV may be regarded as an endophenotype in PTSD research.

Impact of body mass index on cardiac adrenergic derangement in heart failure patients: a 123I-mIBG imaging study

PURPOSE

To assess the impact of body mass index (BMI) on cardiac adrenergic derangement, measured by iodine-123 meta-iodobenzylguanidine (¹²³I-mIBG) imaging in heart failure (HF) patients. Overweight and obesity represent relevant health issues, and augmented sympathetic tone has been described in patients with increased BMI. An extensive literature supports that HF-dependent cardiac denervation, measured through mIBG parameters, is an independent predictor of cardiovascular outcomes and mortality. However, the influence of BMI on cardiac mIBG uptake has not been largely investigated.

METHODS

We prospectively enrolled patients with systolic HF, collecting demographic, clinical, echocardiographic data, and mIBG imaging parameters. In order to detect the factors associated with mIBG parameters, a model building strategy, based on the Multivariable Fractional Polynomial algorithm, has been employed.

RESULTS

We studied 249 patients with systolic HF, mean age of 66.4 ± 10.6 years, and mean left ventricular ejection fraction (LVEF) of 30.7% ± 6.4, undergoing cardiac ¹²³I-mIBG imaging to assess HF severity and prognosis. Seventy-eight patients (31.3%) presented a BMI ≥ 30 kg/m² and obese patients showed a significant reduction in early heart to mediastinum (H/M) ratio (1.66 ± 0.19 vs. 1.75 ± 0.26; p = 0.008) and a trend to reduction in washout rate (33.6 ± 18.3 vs. 38.1 ± 20.1; p = 0.092) compared with patients with BMI < 30 kg/m². Multiple regression analysis revealed that BMI, age, and LVEF were significantly correlated with early and late H/M ratios.

CONCLUSIONS

Results of the present study indicate that BMI, together with LVEF and age, is independently correlated with cardiac mIBG uptake in HF patients.

Long-Term Microgravity Exposure Increases ECG Repolarization Instability Manifested by Low-Frequency Oscillations of T-Wave Vector

Ventricular arrhythmias and sudden cardiac death during long-term space missions are a major concern for space agencies. Long-duration spaceflight and its ground-based analog head-down bed rest (HDBR) have been reported to markedly alter autonomic and cardiac functioning, particularly affecting ventricular repolarization of the electrocardiogram (ECG). In this study, novel methods are developed, departing from previously published methodologies, to quantify the index of Periodic Repolarization Dynamics (PRD), an arrhythmic risk marker that characterizes sympathetically-mediated low-frequency oscillations in the T-wave vector. PRD is evaluated in ECGs from 42 volunteers at rest and during an orthostatic tilt table test recorded before and after 60-day –6° HDBR. Our results indicate that tilt test, on top of enhancing sympathetic regulation of heart rate, notably increases PRD, both before and after HDBR, thus supporting previous evidence on PRD being an indicator of sympathetic modulation of ventricular repolarization. Importantly, long-term microgravity exposure is shown to lead to significant increases in PRD, both when evaluated at rest and, even more notably, in response to tilt test. The extent of microgravity-induced changes in PRD has been associated with arrhythmic risk in prior studies. An exercise-based, but not a nutrition-based, countermeasure is able to partially reverse microgravity-induced effects on PRD. In conclusion, long-term exposure to microgravity conditions leads to elevated low-frequency oscillations of ventricular repolarization, which are potentiated following sympathetic stimulation and are related to increased risk for repolarization instabilities and arrhythmias. Tested countermeasures are only partially effective in counteracting microgravity effects.

Cardiac Autonomic Function in the First Hours of Postnatal Life: An Observational Cross-Sectional Study in Term Neonates

The aim of this study was to evaluate heart rate variability (HRV) within the first hours of extrauterine life in term neonates. HRV at 2-h and 14-h postpartum were compared by means of time domains (iRR, SDNN, and rMSSD); frequency domains (TP, LF, HF, and LF/HF ratio); and Poincare's Plot (SD1 and SD2) indices of HRV in 27 healthy, male, term newborns (NBs) born of elective cesarean delivery. Within 14 h after birth, the mean of the iRRs increased (Δ% = 4.4, p < 0.001) as well as parasympathetic indices (rMSSD: Δ% = 32.6; p < 0.03; HF: Δ% = 43.6; p < 0.00; SD1: Δ% = 32.6, p < 0.03). Respiratory rate (RR) decreased (RR: 2 h = 48 (43-55) cycle/min vs. 14 h = 45 (40-48) cycle/min p < 0.01). We concluded that within the first 14 h of birth, cardiac autonomic adjustments are characterized by an increase in parasympathetic activity. Concurrently, there were no significant changes observed in all other HRV indices in healthy, male, term neonates, and born of elective cesarean delivery.

Reframing the individual stress response: Balancing our knowledge of stress to improve responsivity to stressors

Although responses to stressors have both adverse and positive consequences on health, many believe that stress is entirely negative. Research revealed that negative beliefs about stress can hinder well-being and result in the avoidance of stressors. Stress-optimizing interventions that target various stress appraisal processes may be a useful tool to reframe how individuals understand and respond to stressors. The current study extends previous findings on stress reframing and sought to examine the extent to which the presentation of information about stress outcomes may influence the individual to respond to subsequent stressors. Seventy-seven undergraduate students (96% female) were randomized into one of four reframing conditions (balanced stress outcomes, negative stress outcomes, positive stress outcomes, and control) and underwent a psychosocial stressor. Results highlight similarities between balanced and positive framings of stress across measures of heart rate and blood pressure, whereas subjective ratings of stress and electrodermal activity suggest balanced framing may be efficacious in attenuating stress. Findings are discussed in the context of differing stress-optimizing interventions and consider the complexities of the individual stress response.

Cardiac Autonomic Neuropathy in Obesity, the Metabolic Syndrome and Prediabetes: A Narrative Review

Cardiac autonomic neuropathy (CAN) is a major complication of type 1 and type 2 diabetes mellitus (T1DM and T2DM). The increased morbidity, cardiovascular and all-cause mortality associated with CAN is established from numerous epidemiological studies. However, CAN is increasingly recognised in people with prediabetes (pre-DM) and the metabolic syndrome (MetS) with a reported prevalence up to 11% and 24% respectively. CAN is associated with components of MetS including hypertension and obesity, predating hyperglycaemia. The aetiology of CAN is multifactorial and there is a reciprocal relationship with insulin resistance and MetS. Obstructive sleep apnoea (OSA) is also associated with CAN possibly through MetS and an independent mechanism. An estimated global prevalence of the impaired glucose tolerance (IGT) form of pre-DM of 587 million people by 2045 means CAN will become a major clinical problem. CAN is independently associated with silent myocardial ischaemia, major cardiovascular events, myocardial dysfunction and cardiovascular mortality. Screening for CAN in pre-DM using risk scores with analysis of heart rate variability (HRV) or Sudoscan is important to allow earlier treatment at a reversible stage. The link between obesity and CAN highlights the therapeutic potential of lifestyle interventions including diet and physical activity to reverse MetS and prevent CAN. Weight loss achieved using these dietary and exercise lifestyle interventions improves the sympathetic and parasympathetic HRV indices of cardiac autonomic function. Further research is needed to identify high-risk populations of people with pre-DM or obesity that might benefit from targeted pharmacotherapy including metformin, sodium/glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) analogues. Bariatric surgery also improves HRV through weight loss which might also prevent CAN in severe obesity. This article reviews the literature on CAN in obesity, pre-DM and MetS, to help determine a rationale for screening, early intervention treatment and formulate future research questions in this highly prevalent condition.

The Psychophysiological Implications of Soundscape: A Systematic Review of Empirical Literature and a Research Agenda

The soundscape is defined by the International Standard Organization (ISO) 12913-1 as the human’s perception of the acoustic environment, in context, accompanying physiological and psychological responses. Previous research is synthesized with studies designed to investigate soundscape at the ‘unconscious’ level in an effort to more specifically conceptualize biomarkers of the soundscape. This review aims firstly, to investigate the consistency of methodologies applied for the investigation of physiological aspects of soundscape; secondly, to underline the feasibility of physiological markers as biomarkers of soundscape; and finally, to explore the association between the physiological responses and the well-founded psychological components of the soundscape which are continually advancing. For this review, Web of Science, PubMed, Scopus, and PsycINFO were searched for peer-reviewed articles published in English with combinations of the keywords ‘soundscape’, ‘environmental noise/sound’, ‘physiology/physiological’, ‘psychology/psychological’, and ‘perceptual attributes/affective/subjective assessment/appraisals’. Previous research suggests that Electrocardiography (ECG) and Vectorcardiography (VCG) biometrics quantifying Heart Rate (HR), stimulus-locked experimental design, and passive listening with homogeneous populations are predominantly applied to characterize the psychophysiology underlying the soundscape. Pleasantness and arousal are the most frequent psychological descriptors for soundscape subjective appraisals. Likewise, acoustic environments are reported to inconsistently evoke physiological responses with great variability among studies. The link between the perceptual attributes and physiological responses of soundscape vary within and among existing literature. While a few studies detected a link between physiological manifestations of soundscape and the perceptual attributes, the others failed to validate this link. Additionally, the majority of the study findings were limited to one or two physiological responses.

Impact of cryoballoon-guided pulmonary vein isolation on non-invasive autonomic tests in patients with paroxysmal atrial fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) modulates the intrinsic cardiac autonomic nervous system (ANS). We evaluated the impact of PVI on 5 non-invasive autonomic tests.

METHODS

Thirty patients (76% male, mean age 60.37 ± 9.02 years) with paroxysmal atrial fibrillation (AF) underwent cryoballoon-guided PVI. Five autonomic tests were performed 24hrs before and after PVI (N = 30) and repeated after 6months (N = 22). Parasympathetic function was measured by heart rate (HR) variability during deep breathing (E/I ratio, I-E difference), Valsalva maneuver (Valsalva-ratio) and head-up tilt test (30/15 ratio). Sympathetic function was measured by systolic BP response to sustained handgrip and 10' tilting and by diastolic BP response to cold water.

RESULTS

24hrs after PVI, baseline HR increased from 57.93 ± 9.06 bpm to 71.10 ± 12.75 bpm (p < 0.001). At 6 months, baseline HR was lower than immediately post-PVI (62.59 ± 7.89 vs 71.36 ± 13.58 bpm, p = 0.032) but still higher in comparison to pre-PVI (62.59 ± 7.89 vs 57.09 ± 8.80 bpm, p < 0.001). No differences were seen in baseline BP and parasympathetic tests acutely and at 6months. Besides an acute lowering in systolic BP increase during handgrip test, all sympathetic tests remained unchanged.

CONCLUSIONS

An acute HR increase attenuated at 6months and an acute lowered systolic BP response to sustained handgrip were the only changes after cryoballoon-guided PVI. Non-invasive autonomic tests seem therefore not appropriate to evaluate the autonomic modulatory effect of PVI, either due to a too limited sensitivity or a too localized effect of PVI to influence test results.

Effects of manual cranial therapy on heart rate variability in children without associated disorders: Translation to clinical practice

BACKGROUND

and purpose: Heart rate variability (HRV) represents a marker of autonomic activity, self-regulation and psychiatric illness. Few studies of manual therapy have investigated the neurophysiological effects of manual cranial therapy (MC-t). This study assessed the neurophysiological short/medium-term effects of two manual therapy interventions: massage therapy (Mss-t) and MC-t.

MATERIALS AND METHODS

A double-blind clinical trial was conducted with 50 healthy children, randomized into two groups who received a Mss-t intervention or MC-t. The variables analysed included vital signs (temperature, respiratory rate, heart rate, blood pressure) and HRV components, including the root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF) and LF/HF ratio.

RESULTS

Both interventions produced short-term parasympathetic effects, although the effects of MC-t were more persistent.

CONCLUSION

The persistence of the MC-t intervention suggested a prominent vagal control and better self-regulation. Autonomic imbalances in mental pathologies may benefit from the neurophysiological effects of MC-t.

A model-based analysis of autonomic nervous function in response to the Valsalva maneuver

The Valsalva maneuver (VM) is a diagnostic protocol examining sympathetic and parasympathetic activity in patients with autonomic dysfunction (AD) impacting cardiovascular control. Because direct measurement of these signals is costly and invasive, AD is typically assessed indirectly by analyzing heart rate and blood pressure response patterns. This study introduces a mathematical model that can predict sympathetic and parasympathetic dynamics. Our model-based analysis includes two control mechanisms: respiratory sinus arrhythmia (RSA) and the baroreceptor reflex (baroreflex). The RSA submodel integrates an electrocardiogram-derived respiratory signal with intrathoracic pressure, and the baroreflex submodel differentiates aortic and carotid baroreceptor regions. Patient-specific afferent and efferent signals are determined for 34 control subjects and 5 AD patients, estimating parameters fitting the model output to heart rate data. Results show that inclusion of RSA and distinguishing aortic/carotid regions are necessary to model the heart rate response to the VM. Comparing control subjects to patients shows that RSA and baroreflex responses are significantly diminished. This study compares estimated parameter values from the model-based predictions to indices used in clinical practice. Three indices are computed to determine adrenergic function from the slope of the systolic blood pressure in phase II [α (a new index)], the baroreceptor sensitivity (β), and the Valsalva ratio (γ). Results show that these indices can distinguish between normal and abnormal states, but model-based analysis is needed to differentiate pathological signals. In summary, the model simulates various VM responses and, by combining indices and model predictions, we study the pathologies for 5 AD patients.NEW & NOTEWORTHY We introduce a patient-specific model analyzing heart rate and blood pressure during a Valsalva maneuver (VM). The model predicts autonomic function incorporating the baroreflex and respiratory sinus arrhythmia (RSA) control mechanisms. We introduce a novel index (α) characterizing sympathetic activity, which can distinguish control and abnormal patients. However, we assert that modeling and parameter estimation are necessary to explain pathologies. Finally, we show that aortic baroreceptors contribute significantly to the VM and RSA affects early VM.

Impaired hemodynamic response to tilt, handgrip and Valsalva manoeuvre in patients with takotsubo syndrome

PURPOSE

Long-term β-adrenolytics treatment in takotsubo syndrome (TTS) patients is based on the premise, that TTS is strongly associated with sympathetic nervous system overactivity. The aim of the study was to establish hemodynamic response to tilt, handgrip and Valsalva manoeuvre in patients with takotsubo syndrome compared to healthy subjects (CONTROL) and patients after ST Elevation Myocardial Infarction (STEMI).

MATERIAL AND METHOD

Echocardiographic examination was performed at rest, ECG and continuously non-invasively measured arterial blood pressure were used for evaluation of hemodynamic responses to Valsalva manoeuvre, static handgrip (HG) followed by post-exercise ischemia, and tilt. Ten healthy women, 20 with TTS and 20 after STEMI, mean age 64 ± 8.5 years, participated in the study.

RESULTS

Pressor response to Valsalva manoeuvre and tilt in TTS group was diminished in comparison to CONTROL and close to that of STEMI. During HG, increase of SBP was the lowest in TTS group. Data indirectly suggest that it was due to deficient stroke volume in TTS and STEMI patients during these manoeuvres; though echocardiographic findings at rest did not reveal any significant differences between groups.

CONCLUSIONS

Our data show that despite apparent resolution of the immediate effects of TTS, impaired response to cardiovascular challenge, similar to that in STEMI patients, persisted. As the manoeuvres applied mimic daily life situations, causes of impairment should be searched for and potential health risk evaluated.

Changes in heart rate and skin conductance in the 30 min preceding aggressive behavior

Aggressive behavior of inpatients threatens the safety and well-being of both mental health staff members and fellow patients. It was investigated whether heart rate and electrodermal activity can be used to signal imminent aggression. A naturalistic study was conducted in which 100 inpatients wore sensor wristbands during 5 days to monitor their heart rate and electrodermal activity while staff members recorded patients' aggressive incidents on the ward. Of the 100 patients, 36 displayed at least one aggressive incident. Longitudinal multilevel models indicated that heart rate, skin conductance level, and the number of nonspecific skin conductance responses per minute rose significantly in the 20 min preceding aggressive incidents. Although psychopathy was modestly correlated with displaying aggression, it was not a significant predictor of heart rate and skin conductance preceding aggression. The current findings may provide opportunities for the development of individual prediction models to aid acute risk assessment and to predict aggressive incidents in an earlier stage. The current results on the physiological indicators of aggression are promising for reducing aggression and improving both staff as well as patient safety in psychiatric mental health institutions.

Abnormal sympathetic functioning is linked to familial hypertension in nonathletic young males

BACKGROUND

Sympathetic overactivity mediates abnormal cardiovascular outcome that is affected by stress, lack of physical activity (PA), and familial hypertension (HTN). It can be assessed by blood pressure-based sympathetic function tests.

OBJECTIVE

We studied sympathetic function tests in young nonathletic males in relation to measures of obesity, PA, and familial HTN.

METHODOLOGY

We recruited 100 males (mean age: 19 years) and measured body mass index (BMI) and body composition parameters by tetrapolar bioelectrical impedance such as total body fat, visceral fat, subcutaneous fat, and skeletal muscle mass. Using instrument cardiac autonomic neuropathy system of Recorders and Medicare System Company, India, blood pressures (supine, standing, and post hand grip) were recorded and studied quantitatively and qualitatively.

RESULTS

Physically active and inactive individuals (n = 50 each) had comparable age, BMI, measures of obesity, and sympathetic function tests. However, individuals with familial HTN (n = 37) showed significantly higher obesity measures and blood pressures (supine: systolic blood pressure [SBP] - 133 vs. 115 and diastolic blood pressure [DBP] - 79 vs. 76; standing: SBP - 136 vs. 122 and DBP - 80 vs. 76; post hand grip: SBP - 136 vs. 125 and DBP - 86 vs. 81). Qualitatively, postural hypotension was seen in only two individuals, while worst grading was in post hand grip test significantly and more so in physically inactive group (30%, 28%, and 42% vs. 16%, 20%, and 64%) and individuals with positive familial HTN (32%, 38%, and 30% vs. 17%, 13%, and 70%).

CONCLUSION

Familial HTN, but not physical inactivity, affects sympathetic functioning in nonathletic young male medical personnel. It asks for other lifestyle modifications for better cardiovascular health as primary prevention.

Quantitative Assessment of Autonomic Regulation of the Cardiac System

Autonomic neural system (ANS) regulates the circulation to provide optimal perfusion of every organ in accordance with its metabolic needs, and the quantitative assessment of autonomic regulation is crucial for personalized medicine in cardiovascular diseases. In this paper, we propose the Dystatis to quantitatively evaluate autonomic regulation of the human cardiac system, based on homeostatis and probabilistic graphic model, where homeostatis explains ANS regulation while the probability graphic model systematically defines the regulation process for quantitative assessment. The indices and measurement methods for three well-designed scenarios are also illustrated to evaluate the proposed Dystatis: (1) heart rate variability (HRV), blood pressure variability (BPV), and respiration synchronization (Synch) in resting situation; (2) chronotropic competence indices (CCI) in graded exercise testing; and (3) baroreflex sensitivity (BRS), sympathetic nerve activity (SNA), and parasympathetic nerve activity (PNA) in orthostatic testing. The previous clinical results have shown that the proposed method and indices for autonomic cardiac system regulation have great potential in prediction, diagnosis, and rehabilitation of cardiovascular diseases, hypertension, and diabetes.

Complex cardiac vagal regulation to mental and physiological stress in adolescent major depression

BACKGROUND

Cardiovagal control is known to be reduced in major depressive disorder (MDD), however, the neurocardiac reflex control to distinct types of stressors is still unclear. We aimed to study parasympathetically mediated cardiac reflex functioning in response to mental and physiological stressors using heart rate variability (HRV) linear and nonlinear analysis in adolescent MDD.

METHODS

We examined 60 adolescents (40 girls) with MDD (age 14.9 ± 0.3 years) and 60 age and gender-matched controls. ECG was continuously recorded during stress protocol: baseline, Go/NoGo test, recovery, supine position, and orthostasis. Evaluated HRV linear and nonlinear indices: RR interval, pNN50, rMSSD, HF-HRV, Poincaré plot (SD1), symbolic dynamics 2UV%. Cardiovagal reactivity expressed as percentual change (%) was calculated in response to both stressors.

RESULTS

In each phase of stress protocol, the MDD group had significantly reduced HRV parameters compared to controls, except for symbolic dynamics index 2UV% in supine position. The reactivity of HRV indices was significantly greater in response to orthostasis in MDD compared to controls. No significant differences were found in response to Go/NoGo test.

LIMITATIONS

The smoking status and the menstrual cycle phase potentially affecting the HRV parameters were not monitored. Future research is needed to expand a sample size with respect to sex and to study neurocardiac response to other different stressors in MDD.

CONCLUSIONS

This study revealed reduced resting cardiovagal regulation and greater vagal withdrawal indicating abnormal neurocardiac reflex functioning to physiological stressor (orthostasis) in adolescent MDD patients. Nonlinear HRV analysis was sensitive to detect cardiac-linked regulatory differences in adolescent depression.

Polypharmacy and potentially inappropriate medication use in older patients with multiple myeloma, related to fall risk and autonomous neuropathy

Purpose

Multiple myeloma is a chronic, uncurable hematological cancer with the involvement of multiple organ systems. As a disease affecting older patients, the treatment of multiple myeloma should be based on individual patient characteristics. Polypharmacy is an increasing problem in the care of older patients and in patients with multiple myeloma, polypharmacy is almost inevitable. We aimed to evaluate the applicability of polypharmacy definitions and the relation of polypharmacy with disease outcomes in patients with multiple myeloma.

Methods

Eighty patients older than 65 years and diagnosed with multiple myeloma were retrospectively enrolled. Patient files, prescriptions, evaluations for polypharmacy were determined according to Beers and START/STOPP criteria. Outcomes were recorded from files in terms of fractures, autonomous neuropathy, and renal functions.

Results

Polypharmacy with ≥4 drugs was observed in 65 patients while polypharmacy with ≥5 drugs was observed in 51 patients. Autonomous neuropathy, polypharmacy with more than four or five medications, and use of multiple medications in the same category were related with poor ECOG performance status in women, while prolonged use of benzodiazepines and central nervous system (CNS) affecting drugs and inappropriate polypharmacy were more frequent in men with poor ECOG performance status. The majority of patients aged 75–84 years were observed to use inappropriate polypharmacy. Autonomous neuropathy and fall risk were observed to be significantly related with inappropriate polypharmacy.

Conclusions

Drugs affecting balance and perception should be reconsidered in patients with multiple myeloma.

Assessment of Baroreflex Sensitivity Using Time-Frequency Analysis during Postural Change and Hypercapnia

Baroreflex is a mechanism of short-term neural control responsible for maintaining stable levels of arterial blood pressure (ABP) in an ABP-heart rate negative feedback loop. Its function is assessed by baroreflex sensitivity (BRS)—a parameter which quantifies the relationship between changes in ABP and corresponding changes in heart rate (HR). The effect of postural change as well as the effect of changes in blood O₂ and CO₂ have been the focus of multiple previous studies on BRS. However, little is known about the influence of the combination of these two factors on dynamic baroreflex response. Furthermore, classical methods used for BRS assessment are based on the assumption of stationarity that may lead to unreliable results in the case of mostly nonstationary cardiovascular signals. Therefore, we aimed to investigate BRS during repeated transitions between squatting and standing in normal end-tidal CO₂ (EtCO₂) conditions (normocapnia) and conditions of progressively increasing EtCO₂ with a decreasing level of O₂ (hypercapnia with hypoxia) using joint time and frequency domain (TF) approach to BRS estimation that overcomes the limitation of classical methods. Noninvasive continuous measurements of ABP and EtCO₂ were conducted in a group of 40 healthy young volunteers. The time course of BRS was estimated from TF representations of pulse interval variability and systolic pressure variability, their coherence, and phase spectra. The relationship between time-variant BRS and indices of ABP and HR was analyzed during postural change in normocapnia and hypercapnia with hypoxia. In normocapnia, observed trends in all measures were in accordance with previous studies, supporting the validity of presented TF method. Similar but slightly attenuated response to postural change was observed in hypercapnia with hypoxia. Our results show the merits of the nonstationary methods as a tool to study the cardiovascular system during short-term hemodynamic changes.

Autonomic Disturbances in Acute Cerebrovascular Disease

Autonomic disturbances often occur in patients with acute cerebrovascular disease due to damage of the central autonomic network. We summarize the structures of the central autonomic network and the clinical tests used to evaluate the functions of the autonomic nervous system. We review the clinical and experimental findings as well as management strategies of post-stroke autonomic disturbances including electrocardiographic changes, cardiac arrhythmias, myocardial damage, thermoregulatory dysfunction, gastrointestinal dysfunction, urinary incontinence, sexual disorders, and hyperglycemia. The occurrence of autonomic disturbances has been associated with poor outcomes in stroke patients. Autonomic nervous system modulation appears to be an emerging therapeutic strategy for stroke management in addition to treatments for sensorimotor dysfunction.

Effect of gender-related depression on heart rate variability during an autonomic nervous test

Patients with depression have lower heart rate variability (HRV) compared with controls. However, studies have indicated HRV difference between male and female controls. The gender effect might be interactive with the depression effect on the HRV, resulting in a low accuracy of recognising the patients with depression from the controls. Our study explores the effect of gender-related depression on HRV. Four ANS tests including resting, deep breathing, Valsalva, and orthostatic test are employed as stimuli. HRV were collected from 182 subjects comprising 91 depressive patients (33 females/58 males) and 91 controls (33 females/58 males) in the four tests. Time and frequency domains and nonlinear parameters are employed to quantify HRV. Two-way ANOVA is applied to evaluate the effect of gender-related depression. Most HRV parameters of the patients significantly differ from those of the controls, but some parameters indicate different depression effect between the males and females in the deep breathing and Valsalva test. Some HRV parameters illustrate significant difference between the male and female controls. Therefore, the effect of depression on HRV of each gender should be investigated.

Autonomic activity and its relationship with the endogenous cardiotonic steroid marinobufagenin: the African-PREDICT study

Aim: Marinobufagenin (MBG), a cardiotonic steroid and a natriuretic hormone, is elevated in response to high salt diet consumption. In animal models salt intake stimulates adrenocortical MBG secretion via increased angiotensin II, sympathetic activity and aldosterone. No evidence in humans exists to suggest the involvement of the angiotensinergic-sympatho-excitatory pathway in MBG production. We investigated whether MBG is related to indices of autonomic activity in men and women. Methods: This cross-sectional study included 680 black and white, men and women from the African-PREDICT study (aged 20-30 years). Continuous 24 hr ECG recordings were used to obtain low and high frequency (LF, HF) heart rate variability (HRV). We measured 24 hr urinary MBG excretion and serum aldosterone. Results: We found a positive association of MBG excretion with estimated salt intake (P < 0.001) and aldosterone (P < 0.001) in women and men. In women only, a positive relationship was evident between MBG excretion and LF HRV in multivariate adjusted regression analyses (Adj. R ²= 0.33; β = 0.11; P = 0.030). In men, MBG excretion associated positively with HF HRV in similar regression analyses (R ² = 0.36; β = 0.12; P = 0.034). Sex-specific results were corroborated only in blacks, namely, a positive association of MBG excretion with LF HRV in black women (R ² = 0.38; β = 0.13; P = 0.036), and negative association with HF HRV in black men (R ² = 0.40; β = 0.18; P = 0.045). No relationships were evident in white women (P = 0.58) or men (P = 0.27). Conclusion: Our findings in this human cohort support suggested mechanisms whereby MBG is elevated as a result of increased salt intake, including autonomic activity, previously demonstrated in Dahl salt-sensitive hypertension.

A quantitative model of relation between respiratory-related blood pressure fluctuations and the respiratory sinus arrhythmia

In order to propose an interpretation of recent experimental findings concerning short-term variability of arterial blood pressure (ABP), heart rate variability (HRV), and their dependence on body posture, we develop a qualitative dynamical model of the short-term cardiovascular variability at respiratory frequency (HF). It shows the respiratory-related blood pressure fluctuations in relation to the respiratory sinus arrhythmia (RSA). Results of the model-based analysis show that the observed phenomena may be interpreted as buffering of the respiratory-related ABP fluctuations by heart rate (HR) fluctuations, i.e., the respiratory sinus arrhythmia. A paradoxical enhancement (PE) of the fluctuations of the ABP in supine position, that was found in experiment, is explained on the ground of the model, as an ineffectiveness of control caused by the prolonged phase shift between the the peak of modulation of the pulmonary flow and the onset of stimulation of the heart. Such phasic changes were indeed observed in some other experimental conditions. Up to now, no other theoretical or physiological explanation of the PE effect exists, whereas further experiments were not performed due to technical problems. Better understanding of the short-term dynamics of blood pressure may improve medical diagnosis in cardiology and diseases which alter the functional state of the autonomous nervous system.

Graphical Abstract

Utility of lacrimal caruncle infrared thermography when monitoring alterations in autonomic activity in healthy humans

PURPOSE

Physiological markers that estimate sympathetic activation may be used to infer pain and stress in humans. To date, effective reproducible methods are invasive and pose an undesired risk to participants. Previous work in animal models has used infrared thermography to measure the temperature of the lacrimal caruncle region and may be a promising method for measuring stress and pain non-invasively. The current study aimed to determine whether this method is useful in humans.

METHODS

Sixteen young healthy participants (age: 18-35) were recruited and underwent sympathetic activation using a cold pressor test (CPT) and a muscle chemoreflex (MCR), and completed a control trial. Throughout all trials, infrared thermographic imaging of the lacrimal caruncle, heart rate, heart rate variability, mean arterial blood pressure and pulse transit time were measured.

RESULTS

Heart rate (MCR: 4 ± 3 bpm, CPT: 17 ± 4 bpm p < 0.01) and mean arterial pressure increased (MCR: 6 ± 2, CPT: 5 ± 2 mmHg, p < 0.01) and pulse transit time decreased (p = 0.03) with both sympathetic activation interventions. However, lacrimal caruncle temperature did not vary under any condition remaining at 35.2 ± 0.2 °C which was similar to baseline.

CONCLUSIONS

Our findings suggest infrared thermographic monitoring of eye temperature in humans does not reliably relate to sympathetic activation. This could be due to hemodynamic responses at the lacrimal caruncle that may be more complex than previously proposed with sympathetic activation. Alternatively, pulse transit time seems like a promising non-invasive measure of changes in sympathetic activation in humans.