Interbeat Interval Research Articles

A Novel Approach in Heart-Rate-Variability Analysis Based on Modified Poincaré Plots

Heart-rate variability (HRV), measured by the fluctuation of beat-to-beat intervals, has been growingly considered the most important hallmark of heart rate (HR) time series. The HRV can be characterized by various statistical measures both in the time and frequency domains, or by nonlinear methods. During the past decades, an overwhelming amount of HRV data has been piled up in the research community, but the individual results are difficult to reconcile due to the different measuring conditions and the usually HR-dependent statistical HRV-parameters applied. Moreover, the precise HR-dependence of HRV parameters is not known. Using data gathered by a wearable sensor of combined heart-rate and actigraphy modalities, here, we introduce a novel descriptor of HRV, based on a modified Poincaré plot of 24-h RR-recordings. We show that there exists a – regressive biexponential – HRV versus HR “master” curve (“M-curve”) that is highly conserved for a healthy individual on short and medium terms (on the hours to months scale, respectively). At the same time, we reveal how this curve is related to age in the case of healthy people, and establish alterations of the M-curves of heart-attack patients. A stochastic neuron model accounting for the observed phenomena is also elaborated, in order to facilitate physiological interpretation of HRV data. Our novel evaluation procedure applied on the time series of interbeat intervals allows the description of the HRV(HR) function with unprecedented precision. To utilize the full strength of the method, we suggest a 24-hour-long registration period under natural, daily-routine circumstances (i.e., no special measuring conditions are required). By establishing a patient’s M-curve, it is possible to monitor the development of his/her status over an extended period of time. On these grounds, the new method is suggested to be used as a competent tool in future HRV analyses for both clinical and training applications, as well as for everyday health promotion.

Time-specific associations of wearable sensor-based cardiovascular and behavioral readouts with disease phenotypes in the outpatient setting of the Chronic Renal Insufficiency Cohort.

Patients with chronic kidney disease are at risk of developing cardiovascular disease. To facilitate out-of-clinic evaluation, we piloted wearable device-based analysis of heart rate variability and behavioral readouts in patients with chronic kidney disease from the Chronic Renal Insufficiency Cohort and controls (n = 49). Time-specific partitioning of heart rate variability readouts confirm higher parasympathetic nervous activity during the night (mean RR at night 14.4 ± 1.9 ms vs. 12.8 ± 2.1 ms during active hours; n = 47, analysis of variance (ANOVA) q = 0.001). The α2 long-term fluctuations in the detrended fluctuation analysis, a parameter predictive of cardiovascular mortality, significantly differentiated between diabetic and nondiabetic patients (prominent at night with 0.58 ± 0.2 vs. 0.45 ± 0.12, respectively, adj. p = 0.004). Both diabetic and nondiabetic chronic kidney disease patients showed loss of rhythmic organization compared to controls, with diabetic chronic kidney disease patients exhibiting deconsolidation of peak phases between their activity and standard deviation of interbeat intervals rhythms (mean phase difference chronic kidney disease 8.3 h, chronic kidney disease/type 2 diabetes mellitus 4 h, controls 6.8 h). This work provides a roadmap toward deriving actionable clinical insights from the data collected by wearable devices outside of highly controlled clinical environments.

Heart rate variability before and after 14 weeks of training in Thoroughbred horses and Standardbred trotters with different training experience.

Changes in heart rate and heart rate variabilty (HRV) were investigated in untrained (UT; starting their first racing season) and detrained (DT; with 1-3 years of race experience) racehorses before and after 14-week conventional training. HRV was measured at rest over 1 h between 9:00 and 10:00 AM on the usual rest day of the horses. The smallest worthwhile change (SWC) rate was calculated for all HRV parameters. UT horses had significantly higher heart rate compared to DT (P<0.001). There were no gender- or training-related differences in heart rate. The root-mean-square of successive differences (rMSSD) in the consecutive inter-beat-intervals obtained after the 14-week training period was lower compared to pre-training rMSSD (P<0.001). The rMSSD was not influenced by breed, age or gender. In DT horses, there was a significant decrease in the high frequency (HF) component of HRV (P≤0.05) as the result of the 14-week training. These results may reflect saturation of high-frequency oscillations of inter-beat intervals rather than the reduction in parasympathetic influence on the heart. The HF did not differ significantly between the two measurements in UT horses; however, 16.6% of the animals showed a decrease in HF below SWC (P≤0.05). This supports the likelihood of parasympathetic saturation. Although no significant decrease in heart rate was found for the post-training, 30.0% of DT and 58.3% of UT horses still showed a decrease in heart rate below the SWC. Also by individual examination, it was also visible that despite significant post-training decrease in rMSSD, 1 (4.6%) DT and 2 (6.7%) UT horses reached SWC increase in rMMSD. In the case of these horses, the possibility of maladaptation should be considered. The present results indicate that similar to as found in human athletes, cardiac ANS status of racehorses also changes during the physiological adaptation to training. To explore more precise links between HRV and training effectiveness in horses, a more frequent recording would be necessary. Detailed analysis of HRV parameters based on SWC will be able to highlight the importance of fitness evaluation at individual level.

Interoceptive attentiveness and autonomic reactivity in pain observation

Aim: This study explores interoceptive attentiveness (IA) influence on autonomic reactivity related to pain and self-regulation during situations evoking physiological mirroring for pain. Methods: 20 participants observed face/hand, painful/non-painful stimuli in an individual versus social condition while the autonomic response was measured [Electrodermal activity, Pulse Volume Amplitude (PVA), and Heart Rate (HR)] was measured. The sample was divided into experimental (EXP) subjects, required to focus on their interoceptive correlates while observing the stimuli, and the control (CNT) group. HR inter-beat interval (IBI), and HR Variability (HRV) were calculated. Results: Results showed high accuracy to painful and non-painful stimuli recognition. Regarding autonomic indices, higher PVA values were detected for hand painful versus non-painful stimuli, whereas for the EXP group a significant activation of IBI was found for face painful vs non-painful stimuli. Conclusion: In the context of observation of pain in others, PVA and IBI could be respectively markers of mirroring mechanisms and autonomic self-regulation mediated by IA.

Investigating the Immediate Influence of Moderate Pedal Exercises during an Assembly Work on Performance and Workload in Healthy Men.

Physical inactivity has increased in prevalence among adults in industrialized and developing countries owing to the fact that the majority of job situations require individuals to remain seated for extended periods of time. This research aims to evaluate the influence of cycling on a stationary bike while executing a keyboard assembly task on the task completion time, error percentage, and physiological and subjective measurements. The physiological measures were electroencephalography (EEG) and electrocardiographic (ECG) signal responses, whereas the subjective measures were subjective workload ratings and subjective body discomforts. Two variables were evaluated, namely assembly methods (with versus without pedal exercises at a moderate intensity) and session testing (pre- versus post-test). Thus, the repeated measures design (i.e., assembly method by session testing of participants) was used. According to the completion time, error %, participant self-reports, and ECG and EEG statistical analysis data, the participants’ performances in the keyboard assembly task did not decrease while they performed pedaling exercises (p > 0.05). Additionally, when participants completed the assembly task while executing the pedaling exercises, the mean inter-beat (RR) intervals significantly reduced (p < 0.05) while the mean heart rate increased (p < 0.05), which mean that pedaling exercises caused physical workloads on the participants. Participant performance was unaffected by performing a workout while performing the assembly activity. Thus, administrations should encourage their employees to engage in short sessions of moderate-intensity exercise similar to the suggested exercise in the study to improve a person’s physical health during work without interfering with the effectiveness of work.

MmHRV: Contactless Heart Rate Variability Monitoring Using Millimeter-Wave Radio

Heart rate variability (HRV), which measures the fluctuation of heartbeat intervals, has been considered as an important indicator for general health evaluation. To alleviate the user burden and explore the usability for long-term health monitoring, noncontact methods for HRV monitoring have drawn tremendous attention. In this article, we present mmHRV, the first contact-free multiuser HRV monitoring system using commercial millimeter-wave (mmWave) radio. The design of mmHRV consists of two key components. First, we develop a calibration-free target detector to identify each user’s location. Second, a heartbeat signal extractor is devised, which can optimize the decomposition of the phase of the channel information modulated by the chest movement and, thus, estimate the heartbeat signal. The exact time of heartbeats is estimated by finding the peak location of the heartbeat signal while the interbeat intervals (IBIs) can be further derived for evaluating the HRV metrics of each target. We evaluate the system performance and the impact of different settings, including the distance between human and the device, user orientation, incidental angle, and blockage. Experimental results show that mmHRV can measure the HRV accurately with a median IBI estimation error of 28 ms (with respect to 96.16% accuracy). In addition, the root-mean-square error (RMSE) measured in the nonline-of-sight (NLOS) scenarios is 31.71 ms based on the experiments with 11 participants. The performance of the multiuser scenario is slightly degraded compared with the single-user case; however, the median error of the 3-user case is within 52 ms for all three tested locations.

Ear and Finger PPG Wearables for Night and Day Beat-to-Beat Interval Detection.

In this work, we study the accuracy of ear and finger photoplethysmography (PPG) based inter-beat interval (IBI) detection and estimation compared to the R-to-R interval (RRI) values derived from the electrocardiography (ECG). Seven male subjects with a mean age of 34.29±5.28 years are asked to wear simultaneously the Senbiosys earbud SBE2200 and the Senbiosys ring SBF2200 together with the Shimmer3 ECG development kit. The study includes 43 recordings with a total duration of 72.21 hours divided into 37.10 and 35.11 hours of sleep and wake recordings, respectively. The obtained results show that the earbud PPG enables a higher beat detection rate and a more accurate IBI estimation than the ring. They also show that the performance of the beat detection and estimation is significantly better for the sleep recordings compared to the wake recordings with an increase of ∼ 1.5% in the detection rate and a decrease of ∼ 1 ms and ∼ 4 ms in the mean absolute error (MAE) and the root mean square error (RMSE), respectively. Moreover, we propose a novel fusion scheme that smartly combines the IBI values from both devices and achieves a superior performance with a beat detection rate of 99.22% and an IBI estimation with MAE and RMSE values of 7.42 ms and 13.45 ms, respectively.

Assessment of Sepsis in the ICU by Linear and Complex Characterization of Cardiovascular Dynamics.

Sepsis is one of the pathological conditions with the highest incidence in intensive care units. Sepsis-induced cardiac and autonomic dysfunction are well-known effects, among others, caused by a dysregulated host response to infection. In this context, we investigate the role of complex cardiovascular dynamics quantified through sample entropy indices from the inter-beat interval, systolic and diastolic blood pressure time series as well as the cross-entropy between heartbeat and systolic blood pressure in patients with sepsis in the first hour of intensive care when compared with non-septic subjects. Results show a significant (p<0.05) reduction in the probability of being septic for a unitary increase in entropy for systolic and diastolic time series (odds equal to 0.038 and 0.264, respectively) when adjusting for confounding factors. A significant (p<0.001) odds ratio (0.248) is observed also in cross-entropy, showing a reduced probability of being septic for an increase in heartbeat and systolic pressure asynchrony. The inclusion of our measures of complexity also determines an increase in the predictive ability (+0.03) of a logistic regression model reaching an area under the receiving operating and precision recall curves both equal to 0.95.Clinical relevance The study demonstrates the ability of information theory in catching a reduction of complex cardiovascular dynamics from vital signs commonly recorded in ICU. The considered complexity measures contribute to characterize sepsis development by showing a general loss of the interaction between heartbeat and pressure regulation. The extracted measures also improve the ability to identify sepsis in the first hour of intensive care.

Directional Couplings Between Electroencephalogram and Interbeat Intervals Signals in Awake State and Different Stages of Sleep.

Purpose of the work is to identify the directional coupling between the structures of the brain and the autonomic control of the heart rate variability, to analyze the changes in these coupling in sleep and in wakefulness. Infra-slow oscillations of the electroencephalograms potential and low-frequency components (0.04-0.15 Hz) of the interbeat intervals signal where analyzed using a sensitive method for identifying the directional coupling. The technique, based on modeling the dynamics of instantaneous phases of oscillations, made it possible to reveal the presence and quantify the directional couplings between the structures of the brain and the autonomic control of the heart rate variability. It was shown that the coupling coefficients in the frequency band of 0.04-0.15 Hz (associated mainly with sympathetic control of blood circulation), on average, decrease with falling asleep. We have also shown the asymmetry of coupling. At the same time, stronger connections were revealed in the direction from the autonomic control of the heart rate variability to the brain structures than in the opposite direction. It has been shown that the strength of such couplings decreases with increasing of sleep depth.

Contributions of Parasympathetic Arousal–Related Activity to Cognitive Performance in Patients With First-Episode Psychosis and Control Subjects

BackgroundCognitive impairment is integral to the pathophysiology of psychosis. Recent findings implicate autonomic arousal–related activity in both momentary fluctuations and individual differences in cognitive performance. Although altered autonomic arousal is common in patients with first-episode psychosis (FEP), its contribution to cognitive performance is unknown. MethodsA total of 24 patients with FEP (46% male, age = 24.31 [SD 4.27] years) and 24 control subjects (42% male, age = 27.06 [3.44] years) performed the Multi-Source Interference Task in-scanner with simultaneous pulse oximetry. First-level models included the cardiac-blood oxygen level–dependent regressor, in addition to task (congruent, interference, and error) and nuisance (motion and CompCor physiology) regressors. The cardiac-blood oxygen level–dependent regressor reflected parasympathetic arousal–related activity and was created by convolving the interbeat interval at each heartbeat with the hemodynamic response function. Group models examined the effect of group or cognitive performance (reaction times × error rate) on arousal-related and task activity, while controlling for sex, age, and framewise displacement. ResultsParasympathetic arousal–related activity was robust in both groups but localized to different regions for patients with FEP and healthy control subjects. Within both groups, arousal-related activity was significantly associated with cognitive performance across occipital and temporal cortical regions. Greater arousal-related activity in the bilateral prefrontal cortex (Brodmann area 9) was related to better performance in healthy control subjects but not patients with FEP. ConclusionsAutonomic arousal circuits contribute to cognitive performance and the pathophysiology of FEP. Arousal-related functional activity is a novel indicator of cognitive ability and should be incorporated into neurobiological models of cognition in psychosis.

Oxytocin increases physiological linkage during group therapy for methamphetamine use disorder: a randomized clinical trial

Patients and psychotherapists often exhibit behavioral, psychological, and physiological similarity. Here, we test whether oxytocin—a neuropeptide that can enhance expressivity and social perception—influences time-lagged “linkage” of autonomic nervous system responses among participants and facilitators during group therapy. Physiological linkage estimates (n = 949) were created from ten cohorts, each with two facilitators (n = 5) and four to six participants (n = 48), over six weekly sessions of group therapy for methamphetamine use disorder. All participants of a cohort received oxytocin or placebo intranasally in a randomized double-blind procedure before each session. Cardiac interbeat intervals (IBI) were measured continuously during sessions to estimate physiological linkage, operationalized as one cohort-mate’s IBI reactivity during one minute predicting another cohort-mate’s IBI reactivity during the following minute. In oxytocin cohorts, participants and facilitators experienced significant physiological linkage to their cohort-mates (i.e., their physiological responses were predicted by the prior responses of their cohort-mates) and significantly more linkage than people in placebo cohorts. Both effects occurred during the first and second sessions but not later sessions. Results suggest that oxytocin may enhance psychosocial processes often associated with linkage—such as social engagement—in groups and highlight oxytocin’s potential to improve group cohesion during group therapy.Clinical Trials Registration: NCT02881177, First published on 26/08/2016.

Effects of the Spatial Structure Conditions of Urban Underpass Tunnels' Longitudinal Section on Drivers' Physiological and Behavioral Comfort.

To investigate the physiological and behavioral comfort of drivers traversing urban underpass tunnels with various spatial structure conditions, a driving simulator experiment was conducted using 3DMAX and SCANeRTM studio software. Three parameters, including the slope, slope length, and height of a tunnel, were selected as research objects to explore the optimal combination of structural parameters in urban underpass tunnels. The heart rate (HR), interbeat (RR) interval, speed, and lane centerline offset value were collected for 30 drivers. Then, a measurement model of the relationship among HR, RR interval, speed, lane centerline offset value, and structural parameters was established by using partial correlation analyses and the stepwise regression method. On this basis, a structural constraint model based on the drivers’ physiological and behavioral comfort thresholds was also constructed. The results show that the driver’s HR, RR interval, speed, and lane centerline offsets are significantly related to the tunnel height, slope, and slope length. More importantly, this paper not only analyzed the effects of various structural parameters on drivers’ physiology and behavior but also proposed an optimized combination of structural parameters based on drivers’ physiological and behavioral comfort. It can reasonably improve tunnel design in China, ensure tunnel traffic safety, and seek the maximum comfort of the driver in the driving process.

Study of heart-rate variability in a video task using Holo-Hilbert spectral analysis

In this study, we applied the Holo-Hilbert spectral analysis (HHSA) method to analyze HRV in electrocardiography (ECG) signals. The HHSA intends to interpret the measured interbeat-interval (IBI) signal as the multiplication of an oscillatory signal (carrier wave) with a modulatory signal (envelope wave). Instantaneous frequency analysis (IFA) was adopted to calculate the frequency modulation (FM) and amplitude modulation (AM) frequencies at each time point. The probability of FM-AM distribution across the whole measured IBI signal was accumulated and displayed on a Holo-Hilbert spectrum (HHS). Twenty healthy subjects were recruited in our ECG study. Each subject was requested to view two video clips, including one relaxing video clip and one horror video clip. We observed the very high-frequency (VHF) band was modulated by a ∼0.05 Hz AM frequency on the calculated HHS. The value of VHF power was significantly decreased (p < 0.01, Wilcoxon signed rank test) in viewing the horror video clip, compared to the condition in viewing the relaxing video clip. We also found both the power in VHF and high-frequency (HF) bands decreased in viewing the horror video clip. The HHSA provides a new perspective to analyze HRV which might provide insightful information in future studies.

Deriving electrophysiological phenotypes of paroxysmal atrial fibrillation based on the characteristics of heart rate variability

Aim. To analyze heart rate variability of patients with paroxysmal atrial fibrillation and identify electrophysiological phenotypes of the disease by using methods of exploratory analysis of twenty-four-hour electrocardiographic (Holter) recordings.&#x0D; Methods. 64 electrocardiogram recordings of patients with paroxysmal atrial fibrillation were selected from the open Long-Term Atrial Fibrillation Database (repository PhysioNet). 52 indices of heart rhythm variability were calculated for each recording, including new heart rate fragmentation and asymmetry indices proposed in the last 5 years. Data analysis was carried out with machine learning methods: dimensionality reduction with principal component analysis, hierarchical clustering and outlier detection. Feature correlation was checked by the Pearson criterion, the selected patients subgroups were confirmed by using MannWhitney and Student's tests.&#x0D; Results. For the vast majority of patients with paroxysmal atrial fibrillation, heart rate variability can be described by five parameters. Each of these parameters captures a distinct approach in heart rate variability classification: dispersion characteristics of interbeat intervals, frequency characteristics of interbeat intervals, measurements of heart rate fragmentation, indices based on heart rate asymmetry, mean and median of interbeat intervals. Two large phenotypes of the disease were derived based on these parameters: the first phenotype is a vagotonic profile with a significant increase of linear parasympathetic indices and paroxysmal atrial fibrillation lasting longer than 4.5 hours; the second phenotype with increased sympathetic indices, low parasympathetic indices and paroxysms lasting up to 4.5 hours.&#x0D; Conclusion. Our findings indicate the potential of nonlinear analysis in the study of heart rate variability and demonstrate the feasibility of further integration of nonlinear indices for arrhythmia phenotyping.

Trajectories of Heart Activity Across Infancy to Early Childhood Differentially Predict Autism and Anxiety Symptoms in Fragile X Syndrome.

Background: Fragile X syndrome (FXS) is a monogenic disorder characterized by high rates of autism spectrum disorder (ASD) and anxiety. A longstanding “hyperarousal hypothesis” in FXS has argued that ANS dysfunction underpins many symptoms of FXS. However, the developmental onset and trajectory of ANS dysfunction, as well as the consequences of ANS dysfunction on later psychiatric symptoms, remain poorly understood in FXS. Insight into the emergence, trajectory, and consequences of ANS dysfunction across early development in FXS has critical implications for prevention, intervention, and optimal outcomes in both typical and atypical development. This longitudinal study investigated whether and when males with FXS evidence atypical ANS function from infancy through early childhood, and how trajectories of ANS function across infancy and early childhood predict ASD and anxiety symptom severity later in development.Methods: Participants included 73 males with FXS and 79 age-matched typically developing (TD) males. Baseline heart activity was recorded at multiple assessments between 3 and 83 months of age, resulting in 372 observations. General arousal and parasympathetic activity were indexed via interbeat interval (IBI) and respiratory sinus arrhythmia (RSA), respectively. ASD and anxiety symptoms were assessed at 36 months of age or later in a subgroup of participants (FXS n = 28; TD n = 25).Results: Males with FXS exhibited atypical patterns of developmental change in ANS function across infancy and early childhood. As a result, ANS dysfunction became progressively more discrepant across time, with the FXS group exhibiting significantly shorter IBI and lower RSA by 29 and 24 months of age, respectively. Shorter IBI at 24 months and a flatter IBI slope across development predicted elevated anxiety symptoms, but not ASD symptoms, later in childhood in both FXS and TD males. Reduced RSA at 24 months predicted elevated ASD symptoms, but not anxiety symptoms, in both groups. Developmental change in RSA across early development did not predict later anxiety or ASD symptoms.Conclusion: This is the first longitudinal study to examine the “hyperarousal hypothesis” in infants and young children with FXS. Findings suggest that hyperarousal (i.e., shorter IBI, lower RSA) is evident in males with FXS by 24–29 months of age. Interestingly, unique aspects of early ANS function differentially relate to later ASD and anxiety symptoms. General arousal, indexed by shorter IBI that becomes progressively more discrepant from TD controls, predicts later anxiety symptoms. In contrast, parasympathetic-related factors, indexed by lower levels of RSA, predict ASD symptoms. These findings support the “hyperarousal hypothesis” in FXS, in that ANS dysfunction evident early in development predicts later-emerging symptoms of ASD and anxiety. This study also have important implications for the development of targeted treatments and interventions that could potentially mitigate the long-term effects of hyperarousal in FXS.

32.1 ASSESSING PARENTING STYLES AND THEIR CONNECTION TO CHILD WELL-BEING AND PSYCHOPATHOLOGY

The assessment of parenting is decades old, reflecting the field’s recognition—in both research and clinical practice—of the incredible influence caregivers have on their children. This presentation will provide an overview of parenting styles and behaviors, the various ways they have been assessed, and their associations with youth psychopathology and well-being. Using a narrative review approach, the talk will highlight several well-studied parenting constructs (eg, warmth, behavioral control, hostility/psychological control, emotion socialization parenting behaviors), a selection of measurement modalities (ie, self-report, parent-child observation, physiological), and representatives of each modality (eg, Coping with Children’s Negative Emotions Scales, the Relationship Affect Coding System, interbeat intervals). Finally, emphasis will be placed on the relations between parenting behaviors and youth psychopathology (eg, internalizing and externalizing symptoms) and well-being (eg, social competence, academic achievement, prosocial behavior, effective emotion regulation). In addition to learning about historical and current approaches to parenting assessment in the context of youth psychopathology and wellness, participants will be introduced to novel approaches, including wearables, used to measure associations between parenting behaviors and parent-child co-regulation. Relevant racial and cultural considerations in the relations between parenting style/behaviors and youth outcomes will also be reviewed. The assessment of parenting is an art and science that continues to evolve and advance empirically based interventions for improving parent-child relationships and treating youth psychopathology.

Movement filtered heart rate variability (HRV) data from a chest-worn sensor

Abstract Recording of heart rate variability (HRV) is a noninvasive and continuous measurement method that allows investigating the autonomic nervous system (ANS) and its reaction to environmental influences. For a precise measurement of HRV data, a carefully chosen study design and environment is required to minimize secondary influences. One major influence to be avoided is movement. However, in the daily routine and for some scientific questions, movement can often not be avoided. If so, a manual or automated method to differentiate between artifacts caused by body movement and the actual psychophysiological effect is needed to ensure the data quality. In this approach, a chest-worn sensor was developed, that measures the heart rate using a single lead ECG and filters the measured change of the HRV caused by movement. Data from an integrated accelerometer is used to detect upper body movements that affect the resting heart rate. The movementcorresponding time stamps are then used to filter the Interbeat Intervals (IBI) accordingly. Functionality and effectiveness of the sensor system have been tested against state-of-the art sports- or clinical devices in varying scenarios. As our test series showed, motion filtering has a decisive effect when motion occurs, two-thirds of all cases showed a significant effect of motion filtering, with small to medium effect sizes for the parameters SD2, SD2/SD1, and SDNN. Thereby, automatic filtering of motion artifacts can help to significantly reduce the need for costly post-processing of distorted data sets. The results show a better data quality of HRV measurement, a method that is commonly used for the investigation of physiological processes in the field of chronic pain, psychology, psychiatry, or sports medicine.

35.1 Links Between Maternal Gestational Depression, Corticosteroids, and Fetal Heart Rate Variability: Predicting Early Markers of Infant Inhibition and Regulation

Maternal depression during gestation adversely affects fetal nervous system development and may lead to childhood behavioral problems. Mechanisms of adverse effects are less understood, although cortisol secretion is a potential mediator. Limited research has evaluated links between maternal depression, corticosteroids, and early markers of nervous system development, such as fetal heart rate variability (FHRV), cerebral inhibition, or temperament characteristics. Thus, the objectives were to: 1) evaluate associations between maternal depression, corticosteroids, and FHRV; and 2) test whether FHRV predicts markers of infant inhibition and regulatory capacity. Maternal depression and hair concentrations of cortisol and cortisone were measured during gestation. Heart rate was recorded in 23 fetuses by transabdominal Doppler. The SD of interbeat intervals over 20 minutes was computed to assess FHRV. Higher FHRV values reflect greater physiological regulation. Maternal depression, corticosteroid, and FHRV measurement occurred between 28 and 33 weeks gestation. Subsequent markers of infant nervous system development and temperament were assessed. Newborn development of cerebral inhibition was evaluated at 44 weeks gestation through an auditory sensory gating paradigm. Parents rated their infant’s temperamental regulatory capacity when infants were 3 months of age. Maternal depression was associated with lower FHRV, especially for male fetuses (β = –0.633; p = 0.045). Maternal depression was associated with lower cortisol to total corticosteroids ratios (β = –0.519; p = 0.033). Higher cortisol ratios were associated with increased FHRV (β = 0.485; p = 0.019). Higher FHRV was associated with decreased newborn sensory gating deficits (β = –0.992; p = 0.035), indicating better development of cerebral inhibition. Higher FHRV was also related to increased infant regulatory capacity (r = 0.454; p = 0.029). Maternal depression is associated via corticosteroids with decreased FHRV. Decreased FHRV predicted worse infant inhibition and infant regulatory capacity. Conclusions are limited due to the small sample size. Interventions addressing gestational depression may mitigate biologically mediated adverse effects on infants and thus need further study.

Bursted auricular vagus nerve stimulation alters heart rate variability in healthy subjects

Objective. Recent research suggests that percutaneous auricular vagus nerve stimulation (pVNS) beneficially modulates the autonomic nervous system (ANS). Bursted pVNS seems to be efficient for nerve excitation. Bursted pVNS effects on cardiac autonomic modulation are not disclosed yet. Approach. For the first time, the present study evaluates the effect of pVNS on cardiac autonomic modulation in healthy subjects (n = 9) using two distinct bursted stimulation patterns (biphasic and triphasic stimulation) and heart rate variability analysis (HRV). Stimulation was delivered via four needle electrodes in vagally innervated regions of the right auricle. Each of the two bursted stimulation patterns was applied twice in randomized order over four consecutive stimulation sessions per subject. Main results. Bursted pVNS did not change heart rate, blood pressure, and inflammatory parameters in study subjects. pVNS significantly increased the standard deviation of heart inter-beat intervals, from 46.39 ± 10.4 ms to 63.46 ± 22.47 ms (p < 0.05), and the total power of HRV, from 1475.7 ± 616.13 ms2 to 3190.5 ± 2037.0 ms2 (p < 0.05). The high frequency (HF) power, the low frequency (LF) power, and the LF/HF ratio did not change during bursted pVNS. Both stimulation patterns did not show any significant differences in cardiac autonomic modulation. Stimulation intensity to reach a tingling sensation was significantly lower in triphasic compared to biphasic stimulation (p < 0.05). Bursted stimulation was well tolerated. Significance. Bursted pVNS seems to affect cardiac autonomic modulation in healthy subjects, with no difference between biphasic and triphasic stimulation, the latter requiring lower stimulation intensities. These findings foster implementation of more efficient pVNS stimulation.

Is the Association Between Education and Sympathovagal Balance Mediated by Chronic Stressors?

BackgroundThis study investigated whether raised chronic stress in low education groups contributes to education differences in cardiovascular disease by altering sympathovagal balance.MethodsThis study included cross-sectional data of 10,202 participants from the multi-ethnic, population-based HELIUS-study. Sympathovagal balance was measured by baroreflex sensitivity (BRS), the standard deviation of the inter-beat interval (SDNN) and the root mean square of successive differences between normal heartbeats (RMSSD). The associations between chronic stressors (work, home, psychiatric, financial, negative life events, lack of job control and perceived discrimination) in a variety of domains and BRS, SDNN and RMSSD were assessed using linear regression, adjusted for age, ethnicity, waist-to-hip ratio and pack-years smoked. Mediation analysis was used to assess the contribution of chronic stress to the association between education and sympathovagal balance.ResultsModest but significant associations were observed between financial stress and BRS and SDNN in women, but not in RMSSD nor for any outcome measure in men. Women with the highest category of financial stress had 0.55% lower BRS (ms/mmHg; β = -0.055; CI = -0.098, -0.011) and 0.61% lower SDNN (ms; β = -0.061; CI = -0.099, -0.024) than those in the lowest category. Financial stress in women contributed 7.1% to the association between education and BRS, and 13.8% to the association between education and SDNN.ConclusionNo evidence was found for the hypothesized pathway in which sympathovagal balance is altered by chronic stress, except for a small contribution of financial stress in women.