Heart rate variability: a review

Transcranial direct current stimulation improves heart rate variability: A systematic review and meta-analysis

BACKGROUND

Heart rate variability (HRV) is a useful tool for evaluating cardiovascular autonomic nervous system (ANS) functions. This systematic review and meta-analysis examined the potential effects of transcranial direct current stimulation (tDCS) protocols on HRV parameters.

METHODS

This study acquired 97 comparisons from 24 qualified studies for data synthesis. Using standardized mean difference (SMD), individual and overall effect sizes were estimated to show differences in HRV variables between active tDCS and sham stimulation conditions. More positive effect size values indicated that active tDCS caused greater increases in HRV than sham stimulation. Furthermore, moderator variable analyses were performed to determine whether changes in HRV variables differed depending on (a) task types (physical stress versus psychological stress versus resting condition), (b) targeted brain regions, (c) stimulation polarity, (d) characteristics of participants, and (e) specific HRV variables. Finally, we used meta-regression analyses to determine whether different tDCS parameters (i.e., the number of tDCS sessions, stimulation duration, and density) were associated with changes in HRV patterns.

RESULTS

The random-effects model meta-analysis showed that tDCS protocols significantly improved HRV variables (SMD = 0.400; P < 0.001). Moreover, for increasing HRV during the physical stress task (SMD = 1.352; P = 0.001), anodal stimulation on the M1 was effective, while combined polarity stimulation on the PFC improved HRV during the psychological stress task (SMD = 0.550; P < 0.001) and resting condition (SMD = 0.192; P = 0.012). Additional moderator variables and meta-regression analyses failed to show that tDCS protocols had positive effects in certain conditions, such as different stimulus polarity, characteristics of participants, specific HRV variables, and tDCS parameters.

CONCLUSION

These findings tentatively suggest that using tDCS protocols to stimulate optimal targeted brain areas may be effective in improving HRV patterns potentially related to cardiovascular ANS functions.

Effects of different extreme cold exposure on heart rate variability

Frequent extreme cold events in recent years have brought serious threats to outdoor workers and rescuers. Changes in ambient temperature are associated with altered cardiac autonomic function. The study aims to investigate heart rate variability (HRV) and its relationship to other physiological parameters under extreme cold exposures. Twelve males underwent a 30-min preconditioning phase in a neutral environment followed by a 30-min cold exposure (-5, -10, -15, and -20 °C). Time-domain indexes(meanRR, SDNN, RMSSD, and pNN50), frequency domain indexes [Log(HF), Log(LF), and low frequency/high frequency (LF/HF)], parasympathetic nervous system (PNS), and sympathetic nervous system (SNS) were analysed. Results showed all HRV indexes of four cold exposures were significant. The decrease in temperature was accompanied by progressive PNS activation with SNS retraction. SDNN was the most sensitive HRV index and had good linear relationships with blood pressure, pulse, and hand temperature. The results are significant for formulating safety protection strategies for workers in extremely cold environments.Practitioner Summary: This study investigated heart rate variability (HRV) in 12 males during a 30-min cold exposure (-5, -10, -15, and -20 °C). Results showed all HRV indexes of four cold exposures were significant. The decrease in temperature was accompanied by progressive PNS activation with SNS retraction. SDNN was the most sensitive HRV index and had good linear relationships with blood pressure, pulse, and hand temperature.

Predicting angiographic coronary artery disease using machine learning and high-frequency QRS

AIM

Exercise stress ECG is a common diagnostic test for stable coronary artery disease, but its sensitivity and specificity need to be further improved. In this paper, we construct a machine learning model for the prediction of angiographic coronary artery disease by HFQRS analysis of cycling exercise ECG.

METHODS AND RESULTS

This study prospectively included 140 inpatients and 59 healthy volunteers undergoing cycling exercise ECG. The CHD group (N=104) and non-CHD group (N=95) were determined by coronary angiography gold standard. Automated HF QRS analysis was performed by the blinded method. The coronary group was predominantly male, with a higher prevalence of age, BMI, hypertension, and diabetes than the non-coronary group ( P < 0.001 ), higher lipid levels in the coronary group ( P < 0.005 ), significantly longer QRS duration during exercise testing ( P < 0.005 ), more positive leads ( P < 0.001 ), and a greater proportion of significant changes in HFQRS ( P < 0.001 ). Age, Gender, Hypertension, Diabetes, and HF QRS Conclusions were screened by correlation analysis and multifactorial retrospective analysis to construct the machine learning models of the XGBoost Classifier, Logistic Regression, LightGBM Classifier, RandomForest Classifier, Artificial Neural Network and Support Vector Machine, respectively.

CONCLUSION

Male, elderly, with hypertension, diabetes mellitus, and positive exercise stress test HFQRS conclusions suggested a high risk of CHD. The best performance of the Logistic Regression model was compared, and a column line graph for assessing the risk of CHD was further developed and validated.

Computational modeling for the quantitative assessment of cardiac autonomic response to orthostatic stress

Objective.The autonomic nervous system (ANS) plays a critical role in regulating not only cardiac functions but also various other physiological processes, such as respiratory rate, digestion, and metabolic activities. The ANS is divided into the sympathetic and parasympathetic nervous systems, each of which has distinct but complementary roles in maintaining homeostasis across multiple organ systems in response to internal and external stimuli. Early detection of ANS dysfunctions, such as imbalances between the sympathetic and parasympathetic branches or impairments in the autonomic regulation of bodily functions, is crucial for preventing or slowing the progression of cardiovascular diseases. These dysfunctions can manifest as irregularities in heart rate, blood pressure regulation, and other autonomic responses essential for maintaining cardiovascular health. Traditional methods for analyzing ANS activity, such as heart rate variability (HRV) analysis and muscle sympathetic nerve activity recording, have been in use for several decades. Despite their long history, these techniques face challenges such as poor temporal resolution, invasiveness, and insufficient sensitivity to individual physiological variations, which limit their effectiveness in personalized health assessments.Approach.This study aims to introduce the open-loop Mathematical Model of Autonomic Regulation of the Cardiac System under Supine-to-stand Maneuver (MMARCS) to overcome the limitations of existing ANS analysis methods. The MMARCS model is designed to offer a balance between physiological fidelity and simplicity, focusing on the ANS cardiac control subsystems' input-output curve. The MMARCS model simplifies the complex internal dynamics of ANS cardiac control by emphasizing input-output relationships and utilizing sensitivity analysis and parameter subset selection to increase model specificity and eliminate redundant parameters. This approach aims to enhance the model's capacity for personalized health assessments.Main results.The application of the MMARCS model revealed significant differences in ANS regulation between healthy (14 females and 19 males, age: 42 ± 18) and diabetic subjects (8 females and 6 males, age: 47 ± 14). Parameters indicated heightened sympathetic activity and diminished parasympathetic response in diabetic subjects compared to healthy subjects (p < 0.05). Additionally, the data suggested a more sensitive and potentially more reactive sympathetic response among diabetic subjects (p < 0.05), characterized by increased responsiveness and intensity of the sympathetic nervous system to stimuli, i.e. fluctuations in blood pressure, leading to more pronounced changes in heart rate, these phenomena can be directly reflected by gain parameters and time response parameters of the model.Significance.The MMARCS model represents an innovative computational approach for quantifying ANS functionality. This model guarantees the accuracy of physiological modeling while reducing mathematical complexity, offering an easy-to-implement and widely applicable tool for clinical measurements of cardiovascular health, disease progression monitoring, and home health monitoring through wearable technology.

Deep learning and remote photoplethysmography powered advancements in contactless physiological measurement

In recent decades, there has been ongoing development in the application of computer vision (CV) in the medical field. As conventional contact-based physiological measurement techniques often restrict a patient's mobility in the clinical environment, the ability to achieve continuous, comfortable and convenient monitoring is thus a topic of interest to researchers. One type of CV application is remote imaging photoplethysmography (rPPG), which can predict vital signs using a video or image. While contactless physiological measurement techniques have an excellent application prospect, the lack of uniformity or standardization of contactless vital monitoring methods limits their application in remote healthcare/telehealth settings. Several methods have been developed to improve this limitation and solve the heterogeneity of video signals caused by movement, lighting, and equipment. The fundamental algorithms include traditional algorithms with optimization and developing deep learning (DL) algorithms. This article aims to provide an in-depth review of current Artificial Intelligence (AI) methods using CV and DL in contactless physiological measurement and a comprehensive summary of the latest development of contactless measurement techniques for skin perfusion, respiratory rate, blood oxygen saturation, heart rate, heart rate variability, and blood pressure.

Sensor-Assisted Analysis of Autonomic and Cerebrovascular Dysregulation following Concussion in an Individual with a History of Ten Concussions: A Case Study

INTRODUCTION

Concussion is known to cause transient autonomic and cerebrovascular dysregulation that generally recovers; however, few studies have focused on individuals with an extensive concussion history.

METHOD

The case was a 26-year-old male with a history of 10 concussions, diagnosed for bipolar type II disorder, mild attention-deficit hyperactivity disorder, and a history of migraines/headaches. The case was medicated with Valproic Acid and Escitalopram. Sensor-based baseline data were collected within six months of his injury and on days 1-5, 10, and 14 post-injury. Symptom reporting, heart rate variability (HRV), neurovascular coupling (NVC), and dynamic cerebral autoregulation (dCA) assessments were completed using numerous biomedical devices (i.e., transcranial Doppler ultrasound, 3-lead electrocardiography, finger photoplethysmography).

RESULTS

Total symptom and symptom severity scores were higher for the first-week post-injury, with physical and emotional symptoms being the most impacted. The NVC response showed lowered activation in the first three days post-injury, while autonomic (HRV) and autoregulation (dCA) were impaired across all testing visits occurring in the first 14 days following his concussion.

CONCLUSIONS

Despite symptom resolution, the case demonstrated ongoing autonomic and autoregulatory dysfunction. Larger samples examining individuals with an extensive history of concussion are warranted to understand the chronic physiological changes that occur following cumulative concussions through biosensing devices.

Vagal predominance correlates with mood state changes of winter-over expeditioners during prolonged Antarctic residence

OBJECTIVE

Winter-over expeditioners in Antarctica are challenged by various environmental and psycho-social stress factors, which may induce psychophysiological changes. The autonomic nervous system (ANS) plays a crucial role in the adaptation process under stress. However, the relationship between ANS activity and the mood states of expeditioners remains largely unexplored. This study aims to uncover the pattern of ANS adjustment under extreme Antarctic environments and provide new insights into the correlations between ANS activity and mood state changes, which may provide scientific data for medical interventions.

METHODS

Fourteen expeditioners at Zhongshan Station participated in this study. The study was conducted during four representative periods: pre-Antarctica, Antarctica-1 (pre-winter), Antarctica-2 (winter), and Antarctica-3 (summer). The heart rate variability (HRV) of the expeditioners was continuously measured for 24 hours to evaluate ANS activity. Plasma levels of catecholamines were tested by ELISA. Mood states were assessed by the Profile of Mood States (POMS) scale.

RESULTS

HRV analysis showed a disturbance of ANS during winter and summer periods. For frequency domain parameters, very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) significantly increased during the second half of the mission. Especially, LF/HF ratio decreased during summer, indicating the predominance of vagal tone. Results of the time domain analysis showed increased heart rate variability during the austral winter and summer. Plasma epinephrine (E) significantly increased during residence in Antarctica. Compared with pre-Antarctica, the vigor, depression, and anger scores of the expeditioners decreased significantly during the austral summer. Notably, the depression score showed a moderate positive correlation with LF/HF, while weak negative correlations with other HRV indicators, including TP, VLF, and LF. Anger score showed a moderate positive correlation with LF/HF and weak negative correlations with the average normal-to-normal (NN) interval, and the root mean square of differences between adjacent RR intervals (RMSSD). Plasma E level weakly correlated with the average NN interval.

CONCLUSION

Prolonged residence in Antarctica increased the ANS activities and shifted the cardiac autonomic modulation towards vagal predominance. The alteration of HRV correlated with mood states and plasma epinephrine levels.

A Bayesian non-stationary heteroskedastic time series model for multivariate critical care data

We propose a multivariate GARCH model for non-stationary health time series by modifying the observation-level variance of the standard state space model. The proposed model provides an intuitive and novel way of dealing with heteroskedastic data using the conditional nature of state-space models. We follow the Bayesian paradigm to perform the inference procedure. In particular, we use Markov chain Monte Carlo methods to obtain samples from the resultant posterior distribution. We use the forward filtering backward sampling algorithm to efficiently obtain samples from the posterior distribution of the latent state. The proposed model also handles missing data in a fully Bayesian fashion. We validate our model on synthetic data and analyze a data set obtained from an intensive care unit in a Montreal hospital and the MIMIC dataset. We further show that our proposed models offer better performance, in terms of WAIC than standard state space models. The proposed model provides a new way to model multivariate heteroskedastic non-stationary time series data. Model comparison can then be easily performed using the WAIC.

Effect of Laterality in Microsurgery: Comparative Study of an Expert and a Novice

Background: Hand laterality has an impact on surgical gestures. In this study, we sought to measure the multi-parameter variability of the microsurgical gesture depending on the hand used and the differences between expert microsurgeons and novices. Methods: Ten experienced microsurgeons and twenty medical students with no prior microsurgical experience performed arterial anastomosis on a chicken wing artery using dominant and non-dominant hands. We measured time and force using a homemade force-sensing microsurgical needle holder, heart rate variability with a Polar H10 chest strap, anxiety with the STAI-Y questionnaire and anastomosis quality using the MARS 10 scale. Results: In the microsurgeons' group, duration of anastomosis (p = 0.037), force applied to the needle holder (p = 0.047), anxiety (p = 0.05) and MARS10 (p = 0.291) were better with the dominant hand. For novices, there was no difference between the dominant and non-dominant hand pertaining to force, time and stress level. There were no differences between microsurgeons and novices pertaining to force and anxiety using the non-dominant hand. Conclusions: The study highlighted a marked laterality among microsurgical experts, a finding that may be explained by current learning methods. Surprisingly, no laterality is observed in students, suggesting that for a specific gesture completely different from everyday tasks, laterality is not predefined. Ambidexterity training in the residency curriculum seems relevant and may help microsurgeons improve performance and postoperative outcomes.

Postextrasystolic repolarization changes of ventricular premature beats correlate with structural heart disease and suggest prognostic implications

Ventricular premature beats (VPBs) can potentially lead to life-threatening arrhythmias, especially in patients with structural heart disease (SHD). However, identifying dangerous VPBs has always been a topic and challenge in clinical research. This study aimed to evaluate the relationship of postextrasystolic repolarization changes of VPBs with SHD and its possible additional prognostic value. 125 cases of frequent VPBs with SHD and 156 cases without SHD were included. VPBs were stratified selected from 24 h Holter recording according to the scale of heart rate. Average QTDV (difference value of QT interval between the first beat follow VPB with beats preceding VPB) and max QTDV were significantly longer in SHD group than that in the non-SHD group. For identifying patients with SHD, the best cutoff value were 19 ms for average QTDV (AUC = 0.931) and 29 ms for max QTDV (AUC = 0.910) respectively. For Tu morphology analysis, PT2 (postextrasystolic T wave amplitude change ≥2 mV), reversed T wave, and Pu (postextrasystolic u wave) change were all highly specific, but low sensitive as identification of SHD. Compared with average QTDV < 19 ms patients, average QTDV ≥ 19 ms patients had significantly larger left heart size and wores left cardiac function. The presence of non-persistent ventricular tachycardia runs was higher in average QTDV ≥ 19 ms group and positive Pu change group than that in control groups. The findings indicated that postextrasystolic repolarization changes of VPBs correlated with SHD and suggested potential value in prognosis asssessment.

Effect of Maternal Speech on Neural Development in Premature Infant

INTRODUCTION

Maternal speech has been shown to benefit premature infants by improving feeding outcomes and potentiating the development of the auditory cortex. To our knowledge, limited studies have addressed the benefits of exposure to maternal speech on neural development in premature infants. The objective of this study was to investigate the effect of early controlled exposure to maternal recording a passage of speech on heart rate variability (obtained before, during, and after playback of a test stimulus of a female stranger speaking the same passage) in very low-birth-weight premature infants tracked weekly from 28 to 34 weeks.

METHODS

Prospective, randomized controlled trial, longitudinal, and repeated-measures design were conducted on 49 subjects. Infants heard a recording of their mother's speech twice a day from either 28 to 34 weeks (group 1) or from 32 to 34 weeks (group 2). Spectral analysis was measured weekly for 45 seconds before, during, and after playback of maternal speech. A generalized linear mixed model was conducted to examine the 2-way interaction in the log high-frequency power between groups, genders, sessions, and conditions.

RESULTS

It was found that there were no significant differences between groups before, during, and after playback of the stimulus. A significant difference, however, was noted between conditions (before vs during period).

CONCLUSION

It can be concluded cautiously that playing back of maternal speech recordings to the premature infant has a beneficial impact on neural development after 32 weeks gestational age.

Impaired brain-heart axis in focal epilepsy: Alterations in information flow and implications for seizure dynamics

This study delves into functional brain-heart interplay (BHI) dynamics during interictal periods before and after seizure events in focal epilepsy. Our analysis focuses on elucidating the causal interaction between cortical and autonomic nervous system (ANS) oscillations, employing electroencephalography and heart rate variability series. The dataset for this investigation comprises 47 seizure events from 14 independent subjects, obtained from the publicly available Siena Dataset. Our findings reveal an impaired brain-heart axis especially in the heart-to-brain functional direction. This is particularly evident in bottom-up oscillations originating from sympathovagal activity during the transition between preictal and postictal periods. These results indicate a pivotal role of the ANS in epilepsy dynamics. Notably, the brain-to-heart information flow targeting cardiac oscillations in the low-frequency band does not display significant changes. However, there are noteworthy changes in cortical oscillations, primarily originating in central regions, influencing heartbeat oscillations in the high-frequency band. Our study conceptualizes seizures as a state of hyperexcitability and a network disease affecting both cortical and peripheral neural dynamics. Our results pave the way for a deeper understanding of BHI in epilepsy, which holds promise for the development of advanced diagnostic and therapeutic approaches also based on bodily neural activity for individuals living with epilepsy.

Association of secondhand smoke exposure with all-cause mortality and cardiovascular death in patients with hypertension: Insights from NHANES

BACKGROUND AND AIM

The impact of environmental chemical exposure on blood pressure (BP) is well-established. However, the relationship between secondhand smoke exposure (SHSE) and mortality in hypertensive patients in the general population remains unclear.

METHODS AND RESULTS

This cohort study included US adults in the National Health and Nutrition Examination Survey from 2007 to 2018. All-cause mortality and cause-specific mortality outcomes were determined by associating them with the National Death Index records. Cox proportional risk models were used to estimate hazard ratios (HRs) for all-cause mortality and cardiovascular disease (CVD) mortality, and 95% confidence intervals (CIs) for SHSE. The cohort included 10,760 adult participants. The mean serum cotinine level was 0.024 ng/mL. During a mean follow-up period of 76.9 months, there were 1729 deaths, including 469 cardiovascular disease deaths recorded. After adjusting for lifestyle factors, BMI, hypertension duration, medication use, and chronic disease presence, the highest SHSE was significantly associated with higher all-cause and CVD mortality.

CONCLUSIONS

This study demonstrates that higher SHSE is significantly associated with higher all-cause mortality and CVD mortality. Further research is necessary to elucidate the underlying mechanisms.

Physiological stress responses in horses participating in novice endurance rides

Horses participating in endurance events encounter enormous physical challenges. Heart rate (HR) and heart rate variability (HRV) have been reported before and after endurance rides, but these have not been determined during the rides. Moreover, the modulation in HRV and haematology in horses with different ride results (completed a course or disqualified due to irregular gait) have not been elucidated. Therefore, this study aimed to investigate changes in HR, HRV, and haematological parameters during novice endurance rides and to compare these parameters between horses that successfully completed the course (SC) or were disqualified for irregular gait (FTQ-GA). Beat-to-beat (RR) intervals of 16 healthy horses (aged 6-14 years) were recorded before and throughout the approximately 40 km endurance event. Blood samples were taken at the pre-ride inspection and after passing each veterinary inspection. HRV and haematology measures were determined from nine SC and seven FTQ-GA horses. Horses with different ride results demonstrated distinctive physiological stress responses. Increases in PCV, RBC, WBC and neutrophils after completing the ride were found only in SC horses, implying that they were ridden with greater effort than FTQ-GA horses. A reduction in HRV during warm-up, followed by a significant reduction during the first and second riding phases, was observed. HRV returned to baseline at the compulsory rest period of both phases. FTQ-GA horses experienced lower RR intervals, RR triangular index, modified deceleration capacity, very-low-frequency band, and parasympathetic nervous system index, coinciding with higher HR and sympathetic nervous system and stress indices than SC horses. These results indicated that endurance horses revealed a shift toward sympathetic activity during the ride. Lower parasympathetic activity in FTQ-GA horses suggests they were under more stress or discomfort than SC horses in novice endurance rides. These results have welfare implications, indicating the need for additional rest breaks in FTQ-GA horses.

Exploring Biopsychosocial Stress Markers in Women With Fibromyalgia

BACKGROUND

Identification of fibromyalgia has been a challenge for healthcare professionals due to the lack of a clinical biomarker. A well-supported integrative hypothesis holds that this condition is a chronic pain problem partly caused by long-term dysregulation of stress response. Therefore, stress assessment from a biopsychosocial perspective may be a useful approach to recognizing fibromyalgia.

PURPOSE

A cross-sectional case-control study was conducted to explore stress markers from a multidimensional perspective, including heart rate variability (as a biomarker of stress) as well as psychological distress and social stress.

METHODS

Forty-seven women with fibromyalgia were recruited from support groups and another 47 were recruited as matched pain-free controls. Comparison and discriminant function analyses were performed.

RESULTS

The data support the goodness of biopsychosocial stress markers in women with fibromyalgia, resulting in the identification of between 70% and 74.5% of fibromyalgia cases (sensitivity) and 85%-87% pain-free controls (specificity), with medium-high levels of fit (λ = 0.58 and λ = 0.59; p < .00). Women with fibromyalgia were characterized by high levels of psychological distress, social stress (disorder levels), and autonomic dysregulation. Although distress and social stress had a greater weight in discriminant functions, dysregulation in terms of low parasympathetic activity and high sympathetic activity at rest was also relevant.

CONCLUSIONS

A biopsychosocial approach to stress with an objective biomarker such as heart rate variability may be a useful tool to identify and manage FM.

Construction of a comprehensive fetal monitoring database for the study of perinatal hypoxic ischemic encephalopathy

This article describes the methods used to build a large-scale database of more than 250,000 electronic fetal monitoring (EFM) records linked to a comprehensive set of clinical information about the infant, the mother, the pregnancy, labor, and outcome. The database can be used to investigate how birth outcome is related to clinical and EFM features. The main steps involved in building the database were: (1) Acquiring the raw EFM recording and clinical records for each birth. (2) Assigning each birth to an objectively defined outcome class that included normal, acidosis, and hypoxic-ischemic encephalopathy. (3) Removing all personal health information from the EFM recordings and clinical records. (4) Preprocessing the deidentified EFM records to eliminate duplicates, reformat the signals, combine signals from different sensors, and bridge gaps to generate signals in a format that can be readily analyzed. (5) Post-processing the repaired EFM recordings to extract key features of the fetal heart rate, uterine activity, and their relations. (6) Populating a database that links the clinical information, EFM records, and EFM features to support easy querying and retrieval. •A multi-step process is required to build a comprehensive database linking electronic temporal fetal monitoring signals to a comprehensive set of clinical information about the infant, the mother, the pregnancy, labor, and outcome.•The current database documents more than 250,000 births including almost 4,000 acidosis and 400 HIE cases. This represents more than 80% of the births that occurred in 15 Northern California Kaiser Permanente Hospitals between 2011-2019. This is a valuable resource for studying the factors predictive of outcome.•The signal processing code and schemas for the database are freely available. The database will not be permitted to leave Kaiser firewalls, but a process is in place to allow interested investigators to access it.

Predicting Fatigue-Associated Aberrant Driving Behaviors Using a Dynamic Weighted Moving Average Model With a Long Short-Term Memory Network Based on Heart Rate Variability

OBJECTIVE

This study proposed a moving average (MA) approach to dynamically process heart rate variability (HRV) and developed aberrant driving behavior (ADB) prediction models by using long short-term memory (LSTM) networks.

BACKGROUND

Fatigue-associated ADBs have traffic safety implications. Numerous models to predict such acts based on physiological responses have been developed but are still in embryonic stages.

METHOD

This study recorded the data of 20 commercial bus drivers during their routine tasks on four consecutive days and subsequently asked them to complete questionnaires, including subjective sleep quality, driver behavior questionnaire and the Karolinska Sleepiness Scale. Driving behaviors and corresponding HRV were determined using a navigational mobile application and a wristwatch. The dynamic-weighted MA (DWMA) and exponential-weighted MA were used to process HRV in 5-min intervals. The data were independently separated for training and testing. Models were trained with 10-fold cross-validation strategy, their accuracies were evaluated, and Shapley additive explanation (SHAP) values were used to determine feature importance.

RESULTS

Significant increases in the standard deviation of NN intervals (SDNN), root mean square of successive heartbeat interval differences (RMSSD), and normalized spectrum of high frequency (nHF) were observed in the pre-event stage. The DWMA-based model exhibited the highest accuracy for both driver types (urban: 84.41%; highway: 80.56%). The SDNN, RMSSD, and nHF demonstrated relatively high SHAP values.

CONCLUSION

HRV metrics can serve as indicators of mental fatigue. DWMA-based LSTM could predict the occurrence of the level of fatigue associated with ADBs.

APPLICATION

The established models can be used in realistic driving scenarios.

Usefulness of the heart rate variability test in predicting intradialytic hypotension in patients undergoing chronic haemodialysis

Background

Intradialytic hypotension (IDH) is the primary complication of haemodialysis (HD); however, its diverse pathophysiology and inconsistent definitions complicate its prediction. Despite attempts using the heart rate variability (HRV) test for IDH prediction, studies on its usefulness for predicting IDH diagnosed per the nadir 90 criterion are lacking. We aimed to evaluate HRV test efficacy and reproducibility in predicting IDH based on the nadir 90 criterion.

Methods

Seventy patients undergoing HD participated in this multicentre prospective observational study. The HRV test was performed during non-HD periods and IDH was monitored during 12 HD sessions. IDH was diagnosed according to the nadir 90 criterion, defined as a decrease in systolic blood pressure of ≤90 mmHg during HD. After monitoring, the HRV test was repeated. An HRV-IDH index was developed using multivariate logistic regression analysis employing HRV test parameters. The predictive power of the HRV-IDH index was analysed using the area under the receiver operating characteristics curve (AUROC). Reproducibility was evaluated using correlation analysis of two HRV tests on the same patient.

Results

There were 37 and 33 patients in the IDH and non-IDH groups, respectively. The HRV-IDH index predicted IDH occurrence with AUROCs of 0.776 and 0.803 for patients who had experienced at least one or repeated IDH episodes, respectively. Spearman's correlation coefficient for HRV-IDH indices was 0.859 for the first and second HRV tests.

Conclusions

The HRV test holds promise for predicting IDH, particularly for patients with recurring IDH diagnosed based on the nadir 90 criterion.

A Dynamical Systems View of Psychiatric Disorders-Practical Implications: A Review

Importance

Dynamical systems theory is widely used to explain tipping points, cycles, and chaos in complex systems ranging from the climate to ecosystems. It has been suggested that the same theory may be used to explain the nature and dynamics of psychiatric disorders, which may come and go with symptoms changing over a lifetime. Here we review evidence for the practical applicability of this theory and its quantitative tools in psychiatry.

Observations

Emerging results suggest that time series of mood and behavior may be used to monitor the resilience of patients using the same generic dynamical indicators that are now employed globally to monitor the risks of collapse of complex systems, such as tropical rainforest and tipping elements of the climate system. Other dynamical systems tools used in ecology and climate science open ways to infer personalized webs of causality for patients that may be used to identify targets for intervention. Meanwhile, experiences in ecological restoration help make sense of the occasional long-term success of short interventions.

Conclusions and Relevance

Those observations, while promising, evoke follow-up questions on how best to collect dynamic data, infer informative timescales, construct mechanistic models, and measure the effect of interventions on resilience. Done well, monitoring resilience to inform well-timed interventions may be integrated into approaches that give patients an active role in the lifelong challenge of managing their resilience and knowing when to seek professional help.

Cardiac Autonomic Neuropathy in Graves' Disease: Smoking and Age as Predictive Factors

OBJECTIVES

Hypermetabolic state in Graves' disease (GD) has a great impact on heart homeostasis, acting directly on the heart muscle and modulating the autonomic nervous system. To characterize cardiac autonomic neuropathy (CAN) as a possible complication in patients with GD.

METHODS

We evaluated euthyroid GD patients and a control group of healthy euthyroid people. CAN was assessed using autonomic tests of cardiovascular reflex and heart rate variability: respiratory, Valsalva, orthostatic and orthostatic hypotension tests, high frequency, low frequency, and very low-frequency bands. Transthoracic echocardiography was performed in GD patients.

RESULTS

Sixty GD patients and 50 people in control group were assessed. CAN was diagnosed in 20% of GD and 14% in the control group. Among GD, 13.3% presented incipient, and 6.7% established CAN, while in the control group, it was verified incipient in 8% and established in 6% (P = .7479). All GD patients with CAN presented an alteration in the deep breathing test. Age and smoking were evidenced as factors associated with the presence of CAN, while higher TRAb values at diagnosis decreased the chance of CAN.

CONCLUSIONS

The prevalence of CAN in euthyroid GD patients was 20%. Changes in the cardiac autonomic nervous system were identified, pointing to the importance of evaluating this complication in these patients. Smoking was a predictive factor for CAN, increasing its relationship with conditions that aggravate GD.

Heart rate deceleration and acceleration capacities associated with circadian rhythm of blood pressure in essential hypertension

BACKGROUND

This study aimed to investigate the potential association between the circadian rhythm of blood pressure and deceleration capacity (DC)/acceleration capacity (AC) in patients with essential hypertension.

METHODS

This study included 318 patients with essential hypertension, whether or not they were being treated with anti-hypertensive drugs, who underwent 24-hour ambulatory blood pressure monitoring (ABPM). Patients were categorized into three groups based on the percentage of nocturnal systolic blood pressure (SBP) dipping: the dipper, non-dipper and reverse dipper groups. Baseline demographic characteristics, ambulatory blood pressure monitoring parameters, Holter recordings (including DC and AC), and echocardiographic parameters were collected.

RESULTS

In this study, the lowest DC values were observed in the reverse dipper group, followed by the non-dipper and dipper groups (6.46 ± 2.06 vs. 6.65 ± 1.95 vs. 8.07 ± 1.79 ms, P < .001). Additionally, the AC gradually decreased (-6.32 ± 2.02 vs. -6.55 ± 1.95 vs. -7.80 ± 1.73 ms, P < .001). There was a significant association between DC (r = .307, P < .001), AC (r=-.303, P < .001) and nocturnal SBP decline. Furthermore, DC (β = 0.785, P = .001) was positively associated with nocturnal SBP decline, whereas AC was negatively associated with nocturnal SBP (β = -0.753, P = .002). By multivariate logistic regression analysis, deceleration capacity [OR (95% CI): 0.705 (0.594-0.836), p < .001], and acceleration capacity [OR (95% CI): 1.357 (1.141-1.614), p = .001] were identified as independent risk factors for blood pressure nondipper status. The analysis of ROC curves revealed that the area under the curve for DC/AC in predicting the circadian rhythm of blood pressure was 0.711/0.697, with a sensitivity of 73.4%/65.1% and specificity of 66.7%/71.2%.

CONCLUSIONS

Abnormal DC and AC density were correlated with a blunted decline in nighttime SBP, suggesting a potential association between the circadian rhythm of blood pressure in essential hypertension patients and autonomic nervous dysfunction.

Predicting sports performance of elite female football players through smart wearable measurement platform

Recent development of information technology and wearable devices has led to the analysis of multidimensional sports information and the enhancement of athletes' sports performance convenient and potentially more efficient. In this study, we present a novel data platform tailored for capturing athletes' cognitive, physiological, and body composition data. This platform incorporates diverse visualization modes, enabling athletes and coaches to access data seamlessly. Fourteen elite female football players (average age=20.6±1.3years; 3 forwards, 5 midfielders, 4 defenders, and 2 goalkeepers) were recruited from National Taiwan Normal University, Taiwan, as the primary observational group, and 12 female university students without regular sport/exercise habits (average age=21.6±1.3years) were recruited as control group. Through multidimensional data analysis, we identified significant differences in limb muscle mass and several cognitive function scores (e.g., reaction times of attention and working memory) between elite female football varsity team and general female university students. Furthermore, 1-month heart rate data obtained from wearable devices revealed a significant negative correlation between average heart rate median and cognitive function scores. Overall, this study demonstrates the potential of this platform as an efficient multidimensional data collection and analysis platform. Therefore, valuable insights between cognitive functions, physiological signals and body composition can be obtained via this multidimensional platform for facilitating sports performance.

Heart rate variability as a preictal marker for determining the laterality of seizure onset zone in frontal lobe epilepsy

Determining the laterality of the seizure onset zone is challenging in frontal lobe epilepsy (FLE) due to the rapid propagation of epileptic discharges to the contralateral hemisphere. There is hemispheric lateralization of autonomic control, and heart rate is modulated by interactions between the sympathetic and parasympathetic nervous systems. Based on this notion, the laterality of seizure foci in FLE might be determined using heart rate variability (HRV) parameters. We explored preictal markers for differentiating the laterality of seizure foci in FLE using HRV parameters. Twelve patients with FLE (6 right FLE and 6 left FLE) were included in the analyzes. A total of 551 (460 left FLE and 91 right FLE) 1-min epoch electrocardiography data were used for HRV analysis. We found that most HRV parameters differed between the left and right FLE groups. Among the machine learning algorithms applied in this study, the light gradient boosting machine was the most accurate, with an AUC value of 0.983 and a classification accuracy of 0.961. Our findings suggest that HRV parameter-based laterality determination models can be convenient and effective tools in clinical settings. Considering that heart rate can be easily measured in real time with a wearable device, our proposed method can be applied to a closed-loop device as a real-time monitoring tool for determining the side of stimulation.

The effectiveness of a standardized tobacco cessation program on psychophysiological parameters in patients with addiction undergoing long-term rehabilitation: a quasi-experimental pilot study

BACKGROUND

Although there is a very high comorbidity between tobacco dependence and other addictive disorders, there are only few studies examining the implementation and outcomes of a tobacco cessation program in patients with addictive diseases. Therefore, the aim of this study is to investigate to what extent a standardized tobacco cessation program leads to improvements regarding psychological/physical parameters in patients with addiction undergoing therapy and whether there is a reduction in tobacco consumption.

METHODS

The study took place in a therapeutic community specialized in addiction therapy. A total sample of 56 participants were non-randomly assigned to an intervention group (IG; n = 31) and a treatment as usual group (TAUG; n = 25). The IG participated in a 6-week tobacco cessation program, while the TAUG received no additional treatment. Both groups were assessed for changes in primary outcomes (tobacco dependence, smoked cigarettes per day (CPD), and general substance-related craving) and secondary outcomes (heart rate variability (HRV): root mean square of successive differences, self-efficacy, and comorbid psychiatric symptoms) at two measurement time points (pre- and post-treatment/6 weeks).

RESULTS

We observed significant improvements in self-efficacy (F(1,53) = 5.86; p < .05; ηp2 = .11) and decreased CPD in the IG (β = 1.16, ρ < .05), while no significant changes were observed in the TAUG. No significant interaction effects were observed in psychiatric symptoms, general substance-related craving, and HRV.

CONCLUSIONS

The results highlight the potential benefit of an additional tobacco cessation program as part of a general addiction treatment. Although no improvements in the physiological domain were observed, there were significant improvements regarding self-efficacy and CPD in the IG compared to the TAUG. Randomized controlled trials on larger samples would be an important next step.

TRIAL REGISTRATION

ISRCTN15684371.

Exercise-induced changes in plasma S-Klotho levels are associated with the obtained enhancements of heart rate variability in sedentary middle-aged adults: the FIT-AGEING study

The shed form of the Klotho protein (S-Klotho) is considered a biomarker of longevity, but it is still unknown whether the levels are related to heart rate (HR) and heart rate variability (HRV); both of them greatly influenced by the ageing process, physical fitness, exercise, and health status. This study aimed (i) to investigate the association between S-Klotho plasma levels with HR and HRV parameters and (ii) to examine the association of exercise-induced changes in S-Klotho and those obtained in HR and HRV parameters after a 12-week exercise intervention in sedentary middle-aged adults. Sixty-six sedentary middle-aged adults participated in this study (50% women; 45-65 years old). Participants were randomized into 4 groups: (a) a control group (no exercise), (b) a physical activity recommendation from the World Health Organization group, (c) a high-intensity interval training group, and (d) a high-intensity interval training group adding whole-body electromyostimulation. S-Klotho plasma levels, HR, and HRV parameters (SDNN, RMSSD, high frequency, stress score, and sympathetic/parasympathetic ratio) were measured. At baseline, S-Klotho plasma levels were not related to HR and HRV parameters. After the intervention, exercise-induced changes in S-Klotho plasma levels were positively associated with changes in SDNN (β=0.261; R2=0.102; p=0.014) and negatively related to changes in stress score and sympathetic/parasympathetic ratio (all β=-0.257; R2 ranges between 0.092 and 0.131; all p<0.020). Our study suggests that higher S-Klotho plasma levels are related to increased vagal influence and reduced sympathetic tone in the autonomic nervous system in sedentary middle-aged adults after different training programs. ClinicalTrials.gov identifier: CT03334357.

Relationship between Non-Invasive Brain Stimulation and Autonomic Nervous System

Non-invasive brain stimulation (NIBS) approaches have seen a rise in utilization in both clinical and basic neuroscience in recent years. Here, we concentrate on the two methods that have received the greatest research: transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS). Both approaches have yielded pertinent data regarding the cortical excitability in subjects in good health as well as pertinent advancements in the management of various clinical disorders. NIBS is a helpful method for comprehending the cortical control of the ANS. Previous research has shown that there are notable changes in muscular sympathetic nerve activity when the motor cortex is modulated. Furthermore, in NIBS investigations, the ANS has been employed more frequently as an outcome measure to comprehend the overall impacts of these methods, including their safety profile. Though there is ample proof that brain stimulation has autonomic effects on animals, new research on the connection between NIBS and the ANS has produced contradictory findings. In order to better understand NIBS processes and ANS function, it is crucial to take into account the reciprocal relationship that exists between central modulation and ANS function.

Lumbar Paravertebral Muscle Pain Management Using Kinesitherapy and Electrotherapeutic Modalities

BACKGROUND

Low back pain is considered a public health problem internationally. Low back pain is a cause of disability that occurs in adolescents and causes negative effects in adults as well. The work environment and physical and psychosocial factors can influence the occurrence and evolution of low back pain.

METHODS

The purpose of this paper is to highlight the physiological and functional changes in young adults with painful conditions of the lumbar spine, after using exercise therapy. The study was of the longitudinal type and was carried out over a period 6 months in an outpatient setting. The rehabilitation treatment included electrotherapeutic modalities and kinesitherapy.

RESULTS

The results obtained when evaluating each parameter, for all moments, show statistically significant values in both groups. The results obtained regarding the relationship between the therapeutic modalities specific to rehabilitation medicine and low back pain are consistent with those reported in studies.

CONCLUSIONS

Depending on the clinical-functional status of each patient, kinesitherapy can accelerate the heart rate and increase the blood pressure and oxygen saturation of the arterial blood, values that can later return to their initial levels, especially through training.

Cardiac Rhythm Aberrations in Subacute Sclerosing Panencephalitis: Insights From Heart Rate Variability Analysis

PURPOSE

Subacute sclerosing panencephalitis (SSPE) is a fatal neurological disorder resulting from persistent measles virus infection within the brain. Although neurological manifestations have been well-documented, the impact of SSPE on cardiac autonomic function, assessed through heart rate variability (HRV), remains understudied.

METHODS

In this prospective single-center study conducted from January 2022 to March 2023 in Southern India, 30 consecutive SSPE patients and age- and sex-matched controls underwent electrocardiogram recordings for HRV analysis. Various HRV parameters were assessed, including time-domain metrics (SD of normal-to-normal intervals, root mean square of successive differences between normal heartbeats, percentage of successive normal interbeat intervals greater than 50 msec), SD1 and SD2 for Poincaré plot analysis, and frequency-domain metrics (low frequency %, high frequency %, low frequency:high frequency ratio).

RESULTS

In the study, SSPE patients exhibited markedly reduced HRV. Specifically, SD of normal-to-normal intervals (P = 0.003), percentage of successive normal interbeat intervals greater than 50 msec (P = 0.03), and SD2 (P = 0.0016) were significantly lower compared with controls. Frequency-domain analysis did not reveal significant distinctions. Correlation analysis demonstrated a negative relationship between percentage of successive normal interbeat intervals greater than 50 msec and SSPE severity (r = -0.37, P = 0.042). Heart rate variability did not significantly differ between SSPE stages or with clinical variables. The interbeat interval range showed a narrower distribution in SSPE subjects.

CONCLUSIONS

Our study highlights the clinical relevance of HRV analysis in SSPE and autonomic dysfunction throughout the disease course underscoring its importance in SSPE. This investigation provides valuable insights into cardiac autonomic dysfunction probably because of affliction of the central autonomic networks caused by the disease process and may be a contributing factor to mortality in SSPE.

Increased cardiovascular risk in epilepsy

Epilepsy is associated with increased mortality. Cardiovascular disease confers a significant portion of this increased risk. Recently there is increased interest in the burden of cardiovascular mortality in people with epilepsy. This review discusses the most common cardiovascular risk factors and their association with epilepsy including obesity, diabetes mellitus, and hyperlipidemia. Hyperlipidemia related to the use of enzyme inducing anti-seizure medications is also discussed as a topic that is of particular importance to prescribers that have patients with comorbid cardiovascular risk and epilepsy. Heart rate variability (HRV) and its association with SUDEP is discussed as well as a contributor to vascular risk. Finally, the authors discuss a potential role for neurologists who treat epilepsy to engage closer with their patient's cardiovascular risk factors using available tools such as a the ASCVD score calculator to determine the overall risk of mortality, as well as acting upon this information to guide treatment approaches integrating the information provided in this review.

Childhood Maltreatment and Leukocyte Telomere Length: Cardiac Vagal Activity Influences the Relation in Older Adults

OBJECTIVE

Childhood maltreatment is associated with shorter leukocyte telomere length (LTL). However, the influence of cardiac vagal control on this relation is unknown. We examined whether cardiac vagal control at rest and in response to stress moderates or cross-sectionally mediates the relationship between childhood maltreatment and LTL.

METHODS

Participants were 1179 men and women (aged 65 [7.2] years) suffering from coronary artery disease or non-cardiovascular chronic disease. They completed a childhood maltreatment questionnaire and underwent a stress protocol while electrocardiogram was monitored. High-frequency heart rate variability (HF-HRV) measures were obtained at rest, during stress, and after stress in absolute and normalized units (nu). LTL was measured using quantitative polymerase chain reaction. Mediation and moderation analyses were performed.

RESULT

HF-HRV and HF-HRV in normalized units (HFnu) measures did not mediate the childhood maltreatment-LTL relation. However, baseline HFnu ( p = .027) and HFnu reactivity ( p = .051) moderated the relation. Specifically, maltreatment was associated with significantly lower LTL among those with baseline HFnu at ( b = -0.059, p = .003) or below the mean ( b = -0.103, p < .001), but not among those with higher baseline HFnu. It was also associated with significantly lower LTL among participants who showed either blunted ( b = -0.058, p = .004) or increased HFnu ( b = -0.099, p = .001) responses to stress but not in those with large decreases in HFnu.

CONCLUSIONS

Childhood maltreatment was associated with lower LTL in those who showed a distinct cardiac vagal profile at baseline and in response to stress. The mechanisms and implications remain to be determined.

Impaired post-sleep apnea autonomic arousals in patients with drug-resistant epilepsy

OBJECTIVE

Sudden and unexpected deaths in epilepsy (SUDEP) pathophysiology may involve an interaction between respiratory dysfunction and sleep/wake state regulation. We investigated whether patients with epilepsy exhibit impaired sleep apnea-related arousals.

METHODS

Patients with drug-resistant (N = 20) or drug-sensitive (N = 20) epilepsy and obstructive sleep apnea, as well as patients with sleep apnea but without epilepsy (controls, N = 20) were included. We explored (1) the respiratory arousal threshold based on nadir oxygen saturation, apnea-hypopnea index, and fraction of hypopnea among respiratory events; (2) the cardiac autonomic response to apnea/hypopnea quantified as percentages of changes from the baseline in RR intervals (RRI), high (HF) and low (LF) frequency powers, and LF/HF.

RESULTS

The respiratory arousal threshold did not differ between groups. At arousal onset, RRI decreased (-9.42%) and LF power (179%) and LF/HF ratio (190%) increased. This was followed by an increase in HF power (118%), p < 0.05. The RRI decrease was lower in drug-resistant (-7.40%) than in drug-sensitive patients (-9.94%) and controls (-10.91%), p < 0.05. LF and HF power increases were higher in drug-resistant (188%/126%) than in drug-sensitive patients (172%/126%) and controls (177%/115%), p < 0.05.

CONCLUSIONS

Cardiac reactivity following sleep apnea is impaired in drug-resistant epilepsy.

SIGNIFICANCE

This autonomic dysfunction might contribute to SUDEP pathophysiology.

An open trial of biofeedback for long COVID

OBJECTIVE

Biofeedback is a therapeutic treatment model that teaches self-regulation of autonomic functions to alleviate stress-related symptoms. "Long COVID" refers to chronic physical and cognitive sequelae post-SARS-CoV-2 infection. This study examined the efficacy of a six-week intervention, consisting of weekly one-hour sessions combining heart rate variability and temperature biofeedback, for alleviating mood symptoms, somatic symptoms and sleep disturbance of patients diagnosed with long COVID.

METHODS

Data were collected from 20 adult participants aged 22-63 (Mage = 44.1, SDage = 12.2) with varying long COVID symptoms. Within this single arm design, 16 of the 20 participants completed all six sessions of biofeedback; 14 completed an assessment at the three-month post-treatment time point.

RESULTS

Participants self-reported significant improvements in somatic, anxiety, and depressive symptoms, sleep quality, quality of life, and number of "bad days" immediately after the intervention and three months later (Cohen's d effect size (ES) = 1.09-0.46). Reduced number of medical doctor visits (ES = 0.85) and prescription drug use over the last month (odds ratio = 0.33), as well as improved emotional wellbeing (ES = 0.97) were observed at the three-month time point only.

CONCLUSION

Results suggest that this short, readily scalable intervention can be potentially efficacious in alleviating symptoms of long COVID. Despite notable improvements, the major limitation of this study is its lack of control group. While a randomized trial merits study, biofeedback appears to be a brief, effective, non-invasive, and low-cost treatment option for patients with chronic somatic symptoms secondary to SARS-CoV-2 infection.

CLINICALTRIALS

govID: NCT05120648.

Early exposure to mercury and cardiovascular function of seven-year old children in Guadeloupe (French West Indies)

BACKGROUND

The cardiotoxicity of prenatal exposure to mercury has been suggested in populations having regular contaminated seafood intake, though replications in the literature are inconsistent.

METHODS

The Timoun Mother-Child Cohort Study was set up in Guadeloupe, an island in the Caribbean Sea where seafood consumption is regular. At seven years of age, 592 children underwent a medical examination, including cardiac function assessment. Blood pressure (BP) was taken using an automated blood pressure monitor, heart rate variability (HRV, 9 parameters) and electrocardiogram (ECG) characteristics (QT, T-wave parameters) were measured using Holter cardiac monitoring during the examination. Total mercury concentrations were measured in cord blood at birth (median = 6.6 μg/L, N = 399) and in the children's blood at age 7 (median = 1.7 μg/L, N = 310). Adjusted linear and non-linear modelling was used to study the association of each cardiac parameter with prenatal and childhood exposures. Sensitivity analyses included co-exposures to lead and cadmium, adjustment for maternal seafood consumption, selenium and polyunsaturated fatty acids (n3-PUFAs), and for sporting activity.

RESULTS

Higher prenatal mercury was associated with higher systolic BP at 7 years of age (βlog2 = 1.02; 95% Confidence Interval (CI) = 0.10, 1.19). In boys, intermediate prenatal exposure was associated with reduced overall HRV and parasympathetic activity, and longer QT was observed with increasing prenatal mercury (βlog2 = 4.02; CI = 0.48, 7.56). In girls, HRV tended to increase linearly with prenatal exposure, and no association was observed with QT-wave related parameters. Mercury exposure at 7 years was associated with decreased BP in girls (βlog2 = -1.13; CI = -2.22, -0.004 for diastolic BP). In boys, the low/high-frequency (LF/HF) ratio increased for intermediate levels of exposure.

CONCLUSION

Our study suggests sex-specific and non-monotonic modifications in some cardiac health parameters following prenatal exposure to mercury in pre-pubertal children from an insular fish-consuming population.

Heart Rate Variability (HRV) serves as an objective correlate of distress and symptom burden in multiple sclerosis

Background

Autonomic nervous system (ANS) dysfunction is frequently seen in people living with multiple sclerosis (MS). Heart rate variability (HRV) is an easy and objective index for evaluating ANS functioning, and it has been previously used to explore the association between ANS and the experience of symptom burden in other chronic diseases. Given ANS functioning can be influenced by physical and psychological factors, this study investigated whether emotional distress and/or the presence of ANS dysfunction is associated with symptom severity in people living with MS.

Methods

Participants with MS and healthy controls (HC) with no history of cardiac conditions were recruited to self-collect HR data sampled from a chest strap HR monitor (PolarH10). Short-term HR signal was collected for five minutes, and time and frequency HRV analyses were performed and compared between groups. HRV values were then compared to self-reported distress (Kessler Psychological Distress Scale) and MS participants' self-reported measures of symptom burden (SymptoMScreen).

Results

A total of n = 23 adults with MS (51 ± 12 years, 65 % female, median Patient Determined Disease Steps [PDDS]: 3.0) and n = 23 HCs (43 ± 18 years, 40 % female) completed the study procedures. All participants were able to complete the chest strap placement and HR data capture independently. Participants with MS, compared to the HC participants, had a significantly lower parasympathetic activation as shown by lower values of the root mean square of successive differences between normal heartbeats (RMSSD: 21.86 ± 9.84 vs. 43.13 ± 20.98 ms, p = 0.002) and of high-frequency (HF) power band (HF-HRV: 32.69 ± 12.01 vs. 42.39 ± 7.96 nu, p = 0.016), indicating an overall lower HRV in the MS group. Among individuals with MS, HF-HRV was significantly correlated with the severity of self-reported MS symptoms (r = -0.548, p = 0.010). Participants with MS also reported higher levels of distress compared to HC participants (18.32 ± 6.05 vs. 15.00 ± 4.61, p = 0.050), and HRV correlated with the severity of distress in MS participants (r = -0.569, p = 0.007). A significant mediation effect was also observed, with emotional distress fully mediating the association between HRV and symptom burden.

Conclusions

These findings suggest the potential for ANS dysfunction, as measured by HRV (i.e., lower value of HF power), to be utilized as an objective marker of symptom burden in people living with MS. Moreover, it is apparent that the relationship between HRV and symptom burden is mediated by emotional distress.

Heart Rate Measurement Using the Built-In Triaxial Accelerometer from a Commercial Digital Writing Device

Currently, wearable technology is an emerging trend that offers remarkable access to our data through smart devices like smartphones, watches, fitness trackers and textiles. As such, wearable devices can enable health monitoring without disrupting our daily routines. In clinical settings, electrocardiograms (ECGs) and photoplethysmographies (PPGs) are used to monitor heart and respiratory behaviors. In more practical settings, accelerometers can be used to estimate the heart rate when they are attached to the chest. They can also help filter out some noise in ECG signals from movement. In this work, we compare the heart rate data extracted from the built-in accelerometer of a commercial smart pen equipped with sensors (STABILO's DigiPen) to standard ECG monitor readouts. We demonstrate that it is possible to accurately predict the heart rate from the smart pencil. The data collection is carried out with eight volunteers writing the alphabet continuously for five minutes. The signal is processed with a Butterworth filter to cut off noise. We achieve a mean-squared error (MSE) better than 6.685 × 10-3 comparing the DigiPen's computed Δt (time between pulses) with the reference ECG data. The peaks' timestamps for both signals all maintain a correlation higher than 0.99. All computed heart rates (HR =60Δt) from the pen accurately correlate with the reference ECG signals.

From lab to life: Evaluating the reliability and validity of psychophysiological data from wearable devices in laboratory and ambulatory settings

Despite the increasing popularity of ambulatory assessment, the reliability and validity of psychophysiological signals from wearable devices is unproven in daily life settings. We evaluated the reliability and validity of physiological signals (electrocardiogram, ECG; photoplethysmography, PPG; electrodermal activity, EDA) collected from two wearable devices (Movisens EcgMove4 and Empatica E4) in the lab (N = 67) and daily life (N = 20) among adults aged 18-64 with Mindware as the laboratory gold standard. Results revealed that both wearable devices' valid data rates in daily life were lower than in the laboratory (Movisens ECG 82.94 vs. 93.10%, Empatica PPG 8.79 vs. 26.14%, and Empatica EDA 41.16 vs. 42.67%, respectively). The poor valid data rates of Empatica PPG signals in the laboratory could be partially attributed to participants' hand movements (r = - .27, p = .03). In laboratory settings, heart rate (HR) derived from both wearable devices exhibited higher concurrent validity than heart rate variability (HRV) metrics (ICCs 0.98-1.00 vs. 0.75-0.97). The number of skin conductance responses (SCRs) derived from Empatica showed higher concurrent validity than skin conductance level (SCL, ICCs 0.38 vs. 0.09). Movisens EcgMove4 provided more reliable and valid HRV measurements than Empatica E4 in both laboratory (split-half reliability: 0.95-0.99 vs. 0.85-0.98; concurrent validity: 0.95-1.00 vs. 0.75-0.98; valid data rate: 93.10 vs. 26.14%) and ambulatory settings (split-half reliability: 0.99-1.00 vs. 0.89-0.98; valid data rate: 82.94 vs. 8.79%). Although the reliability and validity of wearable devices are improving, findings suggest researchers should select devices that yield consistently robust and valid data for their measures of interest.

Heart Rate Variability and Pulse Rate Variability: Do Anatomical Location and Sampling Rate Matter?

Wearable technology and neuroimaging equipment using photoplethysmography (PPG) have become increasingly popularized in recent years. Several investigations deriving pulse rate variability (PRV) from PPG have demonstrated that a slight bias exists compared to concurrent heart rate variability (HRV) estimates. PPG devices commonly sample at ~20-100 Hz, where the minimum sampling frequency to derive valid PRV metrics is unknown. Further, due to different autonomic innervation, it is unknown if PRV metrics are harmonious between the cerebral and peripheral vasculature. Cardiac activity via electrocardiography (ECG) and PPG were obtained concurrently in 54 participants (29 females) in an upright orthostatic position. PPG data were collected at three anatomical locations: left third phalanx, middle cerebral artery, and posterior cerebral artery using a Finapres NOVA device and transcranial Doppler ultrasound. Data were sampled for five minutes at 1000 Hz and downsampled to frequencies ranging from 20 to 500 Hz. HRV (via ECG) and PRV (via PPG) were quantified and compared at 1000 Hz using Bland-Altman plots and coefficient of variation (CoV). A sampling frequency of ~100-200 Hz was required to produce PRV metrics with a bias of less than 2%, while a sampling rate of ~40-50 Hz elicited a bias smaller than 20%. At 1000 Hz, time- and frequency-domain PRV measures were slightly elevated compared to those derived from HRV (mean bias: ~1-8%). In conjunction with previous reports, PRV and HRV were not surrogate biomarkers due to the different nature of the collected waveforms. Nevertheless, PRV estimates displayed greater validity at a lower sampling rate compared to HRV estimates.

Integrated use of biofeedback and neurofeedback techniques in treating pathological conditions and improving performance: a narrative review

In recent years, the scientific community has begun tо explore the efficacy оf an integrated neurofeedback + biofeedback approach іn various conditions, both pathological and non-pathological. Although several studies have contributed valuable insights into its potential benefits, this review aims tо further investigate its effectiveness by synthesizing current findings and identifying areas for future research. Our goal іs tо provide a comprehensive overview that may highlight gaps іn the existing literature and propose directions for subsequent studies. The search for articles was conducted on the digital databases PubMed, Scopus, and Web of Science. Studies to have used the integrated neurofeedback + biofeedback approach published between 2014 and 2023 and reviews to have analyzed the efficacy of neurofeedback and biofeedback, separately, related to the same time interval and topics were selected. The search identified five studies compatible with the objectives of the review, related to several conditions: nicotine addiction, sports performance, Autism Spectrum Disorder (ASD), and Attention Deficit Hyperactivity Disorder (ADHD). The integrated neurofeedback + biofeedback approach has been shown to be effective in improving several aspects of these conditions, such as a reduction in the presence of psychiatric symptoms, anxiety, depression, and withdrawal symptoms and an increase in self-esteem in smokers; improvements in communication, imitation, social/cognitive awareness, and social behavior in ASD subjects; improvements in attention, alertness, and reaction time in sports champions; and improvements in attention and inhibitory control in ADHD subjects. Further research, characterized by greater methodological rigor, is therefore needed to determine the effectiveness of this method and the superiority, if any, of this type of training over the single administration of either. This review іs intended tо serve as a catalyst for future research, signaling promising directions for the advancement оf biofeedback and neurofeedback methodologies.

Mind and body connection in expert meditators: a computational study based on central and peripheral nervous system

A meditative 'technique' is conceived as a continuum of different affective states involving mind and body jointly. Meditative practices can involve cognitive effort (e.g., focused attention and open-minded techniques), as well as automatic and implicit practices (e.g., transcendental techniques). The NGALSO tantric self-healing meditation technique is a brief, comprehensive meditation technique relying on mind and body connection. In this study, we aimed to investigate the state and the trait neurophysiological correlates of NGALSO meditation practice. First, 19 EEG channels and a 3-lead ECG signal were recorded from 10 expert meditators (more than 7 years of daily meditation) and 10 healthy inexpert participants (controls) who underwent the same meditative procedure. The neuropsychological profiles of experts and controls were compared. Results showed that expert meditators had significantly higher power spectra on alpha, theta and beta, and a higher sympathetic tone with lower parasympathetic tone after meditation. Conversely, the control group had significantly less power spectra on alpha, theta and beta, and a higher parasympathetic tone with lower sympathetic tone after meditation. A machine learning approach also allowed us to classify experts vs. controls correctly by using only EEG Theta bands before or after meditation. ECG results allowed us to show a significantly higher effort by expert meditators vs. controls, thus suggesting that a higher effort is required for this meditation, in line with the principle 'no pain, no gain' in body and mind.

Maternal singing sustains preterm hospitalized newborns' autonomic nervous system maturation: an RCT

BACKGROUND

Premature birth is known to affect the newborn's autonomic nervous system (ANS) maturation, with potential short and long-term impact on their neurobehavioral development. The purpose of the study was to investigate the effects of maternal directed singing and speaking on the preterm infants' autonomic nervous system (ANS) maturation as measured by the heart rate variability (HRV) parameters.

METHODS

In this multi-center randomized clinical trial, 30 stable preterm infants (m = 29,6 weeks of gestational age), without any abnormalities were randomized into an intervention (16) or a control group (14). HRV was measured weekly, for a total of 80 recordings during hospitalization, as well as before and after each session of singing or speaking.

RESULTS

The intervention group showed a significant increase of the percentage value of HRV power in the high frequency range when compared to the control group (p = 0.044). More specifically, the maternal singing significantly increased the high frequency power and decreased the low/high frequency power ratio (p = 0.037).

CONCLUSIONS

The preterm infant's vagal activity significantly increased in the intervention group, potentially enhancing their ANS maturation. The effect is specifically evidenced in the singing condition.

IMPACT

Maternal singing affects the autonomic nervous system maturation of preterm hospitalized newborns in the NICU. No previous studies investigated how early vocal parental intervention can affect preterm infants developement, throught their autonomic nervous system maturation. Early Vocal Contact as an early intervention involving parents has a positive impact on preterm infant's development and it can be easily implemented in the care of preterm infants.

TRIAL REGISTRATION

NCT04759573, retrospectively registered, 17 February 2021.

Coactivation of Autonomic and Central Nervous Systems During Processing of Socially Relevant Information in Autism Spectrum Disorder: A Systematic Review

Body-brain interaction provides a novel approach to understand neurodevelopmental conditions such as autism spectrum disorder (ASD). In this systematic review, we analyse the empirical evidence regarding coexisting differences in autonomic (ANS) and central nervous system (CNS) responses to social stimuli between individuals with ASD and typically developing individuals. Moreover, we review evidence of deviations in body-brain interaction during processing of socially relevant information in ASD. We conducted systematic literature searches in PubMed, Medline, PsychInfo, PsychArticles, and Cinahl databases (until 12.1.2022). Studies were included if individuals with ASD were compared with typically developing individuals, study design included processing of social information, and ANS and CNS activity were measured simultaneously. Out of 1892 studies identified based on the titles and abstracts, only six fulfilled the eligibility criteria to be included in synthesis. The quality of these studies was assessed using a quality assessment checklist. The results indicated that individuals with ASD demonstrate atypicalities in ANS and CNS signalling which, however, are context dependent. There were also indications for altered contribution of ANS-CNS interaction in processing of social information in ASD. However, the findings must be considered in the context of several limitations, such as small sample sizes and high variability in (neuro)physiological measures. Indeed, the methodological choices varied considerably, calling for a need for unified guidelines to improve the interpretability of results. We summarize the current experimentally supported understanding of the role of socially relevant body-brain interaction in ASD. Furthermore, we propose developments for future studies to improve incremental knowledge building across studies of ANS-CNS interaction involving individuals with ASD.

The relationship between alpha power and heart rate variability commonly seen in various mental states

The extensive exploration of the correlation between electroencephalogram (EEG) and heart rate variability (HRV) has yielded inconsistent outcomes, largely attributable to variations in the tasks employed in the studies. The direct relationship between EEG and HRV is further complicated by alpha power, which is susceptible to influences such as mental fatigue and sleepiness. This research endeavors to examine the brain-heart interplay typically observed during periods of music listening and rest. In an effort to mitigate the indirect effects of mental states on alpha power, subjective fatigue and sleepiness were measured during rest, while emotional valence and arousal were evaluated during music listening. Partial correlation analyses unveiled positive associations between occipital alpha2 power (10-12 Hz) and nHF, an indicator of parasympathetic activity, under both music and rest conditions. These findings underscore brain-heart interactions that persist even after the effects of other variables have been accounted for.

How to properly evaluate cardiac vagal tone in oncology studies: a state-of-the-art review

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer.

Bayesian at heart: Towards autonomic outflow estimation via generative state-space modelling of heart rate dynamics

Recent research is revealing how cognitive processes are supported by a complex interplay between the brain and the rest of the body, which can be investigated by the analysis of physiological features such as breathing rhythms, heart rate, and skin conductance. Heart rate dynamics are of particular interest as they provide a way to track the sympathetic and parasympathetic outflow from the autonomic nervous system, which is known to play a key role in modulating attention, memory, decision-making, and emotional processing. However, extracting useful information from heartbeats about the autonomic outflow is still challenging due to the noisy estimates that result from standard signal-processing methods. To advance this state of affairs, we propose a novel approach in how to conceptualise and model heart rate: instead of being a mere summary of the observed inter-beat intervals, we introduce a modelling framework that views heart rate as a hidden stochastic process that drives the observed heartbeats. Moreover, by leveraging the rich literature of state-space modelling and Bayesian inference, our proposed framework delivers a description of heart rate dynamics that is not a point estimate but a posterior distribution of a generative model. We illustrate the capabilities of our method by showing that it recapitulates linear properties of conventional heart rate estimators, while exhibiting a better discriminative power for metrics of dynamical complexity compared across different physiological states.

Photoplethysmogram beat detection using Symmetric Projection Attractor Reconstruction

Many methods have been proposed to detect beats in photoplethysmogram (PPG) signals. We present a novel method which uses the Symmetric Projection Attractor Reconstruction (SPAR) method to generate an attractor in a two dimensional phase space from the PPG signal. We can then define a line through the origin of this phase space to be a Poincaré section, as is commonly used in dynamical systems. Beats are detected when the attractor trajectory crosses the Poincaré section. By considering baseline drift, we define an optimal Poincaré section to use. The performance of this method was assessed using the WESAD dataset, achieving median F 1 scores of 74.3% in the Baseline phase, 63.0% during Stress, 93.6% during Amusement, and 97.7% during Meditation. Performance was better than an earlier version of the method, and comparable to one of the best algorithms identified in a recent benchmarking study of 15 beat detection algorithms. In addition, our method performed better than two others in the accuracy of the inter-beat intervals for two resting subjects.

Individual-Specific Animated Profiles of Mental Health

How important is the timing of the pretreatment evaluation? If we consider mental health to be a relatively fixed condition, the specific timing (e.g., day, hour) of the evaluation is immaterial and often determined on the basis of technical considerations. Indeed, the fundamental assumption underlying the vast majority of psychotherapy research and practice is that mental health is a state that can be captured in a one-dimensional snapshot. If this fundamental assumption, underlying 80 years of empirical research and practice, is incorrect, it may help explain why for decades psychotherapy failed to rise above the 50% efficacy rate in the treatment of mental-health disorders, especially depression, a heterogeneous disorder and the leading cause of disability worldwide. Based on recent studies suggesting within-individual dynamics, this article proposes that mental health and its underlying therapeutic mechanisms have underlying intrinsic dynamics that manifest across dimensions. Computational psychotherapy is needed to develop individual-specific pretreatment animated profiles of mental health. Such individual-specific animated profiles are expected to improve the ability to select the optimal treatment for each patient, devise adequate treatment plans, and adjust them on the basis of ongoing evaluations of mental-health dynamics, creating a new understanding of therapeutic change as a transition toward a more adaptive animated profile.

Is fat-to-lean mass ratio a better predictor of heart variability than body mass index?

BACKGROUND

Body mass index (BMI) may not accurately predict cardiometabolic risk due to confounders like age, gender, relatively high lean mass, and the "thin-fat phenotype" prevalent in south Asian populations. Fat-to-lean mass ratio (FTLM), which assesses the balance between fat and lean body mass, may provide a more complete assessment of cardiometabolic health.

MATERIALS AND METHODS

This cross-sectional analytical study investigated the relationship between FTLM ratio, BMI, and heart rate variability (HRV) in apparently healthy male adults. 88 participants recruited through convenience sampling underwent anthropometric assessments, bioimpedance body composition analysis, and HRV testing. Pearson's or Spearman's correlation and linear regression analyses were performed where appropriate to assess the relationship between FTLM ratio, BMI, and HRV.

RESULTS

Both BMI and FTLM showed significant positive correlation with normalized LF power and LF-HF ratio and a negative correlation with normalized HF power, RMSSD, and pNN50. However, FTLM ratio showed a stronger association with HRV parameters than BMI and could explain a greater percentage of the variability in LF-HF ratio (32% compared to 18.4%, P < 0.001).

CONCLUSION

Assessment of both fat and lean mass, expressed as a ratio, is a better index of quantifying adiposity and predicting the influence of altered body composition on cardiometabolic health.

GABA Supplementation, Increased Heart-Rate Variability, Emotional Response, Sleep Efficiency and Reduced Depression in Sedentary Overweight Women Undergoing Physical Exercise: Placebo-Controlled, Randomized Clinical Trial

Gamma-aminobutyric acid (GABA) serves as a pivotal neurotransmitter implicated in the pathogenesis of stress, anxiety, sleep-related disorders, and heart rate (HR) reactions. Heart-rate variability (HRV), modulated by the sympathetic and parasympathetic branches of the autonomic nervous system (ANS), offers insights into cardiac autonomic control and cardiovascular well-being. The present study aimed to explore the impact of GABA supplementation on emotional metrics, sleep quality, and HRV in sedentary women with overweight or obesity partaking in physical exercise. A randomized, double-blind, placebo-controlled clinical trial was undertaken involving 30 sedentary women with overweight or obesity. Volunteers were assigned randomly to two groups: the intervention group receiving GABA (200 mg) once daily for a total of 90 supplementation doses, and the placebo group. Both groups engaged in physical exercise, while the supplementation regimen spanned 90 days. Assessments were conducted at three intervals: baseline (T0), midway through the study (T45), and study culmination (T90). Following 90 days of GABA supplementation, the intervention group demonstrated enhancements in habitual sleep efficiency, as indicated by reductions in Pittsburgh Sleep Quality Index (PSQI) scores. Moreover, an improved emotional response was observed, characterized by diminished negative affect. GABA supplementation yielded ameliorations in depression scores as per the Depression, Anxiety, and Stress Scale (DASS-21). Notably, an augmented HRV was noted, attributed to heightened parasympathetic autonomic nervous system predominance. GABA supplementation elicited noteworthy enhancements in heart rate variability, emotional response, depression mitigation, and sleep efficiency following a 90-day supplementation.

Urban environment influences on stress, autonomic reactivity and circadian rhythm: protocol for an ambulatory study of mental health and sleep

Introduction

Converging evidence suggests that urban living is associated with an increased likelihood of developing mental health and sleep problems. Although these aspects have been investigated in separate streams of research, stress, autonomic reactivity and circadian misalignment can be hypothesized to play a prominent role in the causal pathways underlining the complex relationship between the urban environment and these two health dimensions. This study aims at quantifying the momentary impact of environmental stressors on increased autonomic reactivity and circadian rhythm, and thereby on mood and anxiety symptoms and sleep quality in the context of everyday urban living.

Method

The present article reports the protocol for a feasibility study that aims at assessing the daily environmental and mobility exposures of 40 participants from the urban area of Jerusalem over 7 days. Every participant will carry a set of wearable sensors while being tracked through space and time with GPS receivers. Skin conductance and heart rate variability will be tracked to monitor participants' stress responses and autonomic reactivity, whereas electroencephalographic signal will be used for sleep quality tracking. Light exposure, actigraphy and skin temperature will be used for ambulatory circadian monitoring. Geographically explicit ecological momentary assessment (GEMA) will be used to assess participants' perception of the environment, mood and anxiety symptoms, sleep quality and vitality. For each outcome variable (sleep quality and mental health), hierarchical mixed models including random effects at the individual level will be used. In a separate analysis, to control for potential unobserved individual-level confounders, a fixed effect at the individual level will be specified for case-crossover analyses (comparing each participant to oneself).

Conclusion

Recent developments in wearable sensing methods, as employed in our study or with even more advanced methods reviewed in the Discussion, make it possible to gather information on the functioning of neuro-endocrine and circadian systems in a real-world context as a way to investigate the complex interactions between environmental exposures, behavior and health. Our work aims to provide evidence on the health effects of urban stressors and circadian disruptors to inspire potential interventions, municipal policies and urban planning schemes aimed at addressing those factors.

Is Acute Lower Back Pain Associated with Heart Rate Variability Changes? A Protocol for Systematic Reviews

Acute lower back pain (ALBP) is an extremely common musculoskeletal problem. ALBP consists of a sudden onset of short-duration pain in the lower back. However, repeated attacks can make the pain chronic. It can be measured through a self-report scale as well as through physical and physiological evaluations. Heart Rate Variability (HRV) has been used to evaluate the body's response to pain. However, to the best of our knowledge, no clear consensus has been reached regarding the relationship between both variables and on an optimal protocol for ALBP evaluation based on HRV. The objective of this review is to analyze the relationship and effectiveness of HRV as an instrument for measuring ALBP. Furthermore, we consider the influence of different types of interventions in this relationship. The protocol of this review was previously recorded in the International Prospective Register of Systematic Reviews (number CRD42023437160). The PRISMA guidelines for systematic reviews and PubMed, WOS and Scopus databases are employed. Studies with samples of adults with ALBP are included. This study sets out a systematic review protocol to help identify the relationship between HRV and ALBP. Understanding this relationship could help in designing early detection or action protocols that alleviate ALBP.