Parasympathetic Research Articles

Abstract 4136938: Autonomous Personalized Dynamic ECG Analysis Predicts 1-hour Incidence of Sudden Cardiac Arrest

Background: Sudden cardiac arrest (SCA) is a leading cause of death in the USA. Defibrillators prevent SCA by delivering shocks for sustained ventricular tachyarrhythmias (VT). However, current clinical methods for predicting SCA are limited. We have shown that distinct nonlinear fluctuation patterns “hidden” within normal-appearing ECG waveforms have unique prognostic value. Hypothesis: Autonomous personalized dynamic ECG analysis predicts the 1-hour incidence of SCA. Methods: In an established pressure-overload model that exhibits key features of human VT and SCA (e.g., cardiac restitution properties), 30% of 37 freely ambulating animals had spontaneous SCA in 4 weeks. The exposures included a rolling 1-hour window of time, frequency and nonlinear domain measures of heart rate and QT time series during sinus rhythm, and EntropyX QT , a higher-dimensional machine learning-based nonlinear measure of cardiac repolarization dynamics. Results: In multivariate analyses, the major independent predictors of 1-hour incidence of SCA were (1) high EntropyX QT ; (2) high parasympathetic tone, as indexed by the high-frequency component of the heart rate power spectral density; and (3) the degree of coupling between RR and QT intervals. The baseline values of EntropyX QT and parasympathetic tone increased by 3.6-fold and 46.5-fold, respectively, during the hour preceding SCA. The adjusted ROC curve area was > 89%. Conclusion: Continuous autonomous analysis of cardiac repolarization and autonomic dynamics strongly and independently predicts the subacute incidence of SCA. Incorporation of these measures into current strategies of SCA risk stratification has potential to save many lives and warrants further evaluation.

Abstract 4118410: The Effect of Positive Tilt Table Tests on Long QT Syndrome Diagnosis: A Cross-Sectional Perspective

Background: The tilt table test (TTT) serves as a widely adopted diagnostic tool for evaluating syncope of undetermined etiology, with a positive result often indicative of parasympathetic overstimulation. This excessive activation of the parasympathetic system holds the potential to influence QTc measurement not only through rate modulation but also by impacting potassium ionic channels, given that muscarinic activation inwardly rectifies the K+ current. Methods: In this cross-sectional study, 478 patients experiencing syncope of unknown origin underwent evaluation with TTT and 24-hour Holter electrocardiogram monitoring. The Schwartz Score, utilized for diagnosing Long QT syndrome, was computed for all participants. Those with secondary causes of long QT were excluded from the analysis. The association between positive TTT results and Schwartz Score was then examined. Results: A total of 478 patients were enrolled in the study, comprising 208 (43.4%) males and 270 (56.4%) females. The mean age of the patients was 42.43±17.979 years. TTT results were positive in 289 (60.46%) patients and negative in 189 (39.54%) patients. Patients with positive TTT results exhibited a significantly higher mean Schwartz Score compared to those with negative results (2.77±0.08 vs. 1.99±0.12) (P<0.001) (Figure 1). The odds ratio for higher Schwartz scores in the presence of positive TTT results was 4.547. Conclusion: Caution is warranted when diagnosing long QT syndrome as a potential cause of syncope solely based on the Schwartz Score. This study underscores the necessity for potential modifications to the scoring system, acknowledging the impact of tilt table test outcomes on its predictive accuracy. These findings contribute to the ongoing discourse on refining diagnostic approaches for Long QT syndrome in the context of syncope, promoting more accurate and nuanced clinical decision-making.

PECULIARITIES OF ORTHODONTIC TREATMENT FOR PATIENTS WITH GENERALIZED PERIODONTITIS AND PREDOMINANCE OF PARASYMPATHETIC NERVOUS SYSTEM ACTIVITY

The use of orthodontic treatment for patients with generalized periodontitis enhances the effectiveness of comprehensive care. However, it is important to consider the reduced capacity for alveolar bone regeneration in these patients. Therefore, as part of the complex treatment of generalized periodontitis, the inclusion of medications to support alveolar bone regeneration is essential. The course of various diseases can be influenced by the state of the patient’s autonomic nervous system. In this study, medications were administered to normalize parasympathetic nervous system activity in patients with generalized periodontitis undergoing orthodontic treatment. The objective of the study was to evaluate the effectiveness of orthodontic treatment in patients with generalized periodontitis, particularly those with a predominance of parasympathetic autonomic nervous system activity. This was assessed by the supplementary use of a combination of drugs designed to stimulate alveolar bone formation and regulate parasympathetic nervous system function. Materials and methods. This study involved 35 young patients (aged 18-35) with generalized periodontitis and a predominance of parasympathetic autonomic nervous system activity, all of whom presented with displacement of the maxillary frontal teeth. These patients underwent orthodontic treatment. To correct the state of the autonomic nervous system over the treatment of generalized periodontitis, patients were prescribed to take a complex of medicines including the preparation “Calcinova” for stimulating osteogenesis. A comprehensive periodontal examination, including the assessment of hygienic indices, was conducted to evaluate periodontal status throughout the treatment. Results. The periodontal examination revealed that almost all patients demonstated an improvement in oral health. Noticeable dynamics in the pathological process were observed as a result of the complex treatment. The analysis of these findings underscores the importance of orthodontic treatment for patients with generalized periodontitis, particularly when combined with methods to correct parasympathetic nervous system activity and promote osteogenesis. This approach was shown to positively affect periodontal tissues and enhance the effectiveness of generalized periodontitis treatment. Conclusions. Correction of parasympathetic autonomic nervous system function enhances the effectiveness of therapy. In this study, a complex of medications was used to improve parasympathetic nervous system activity. The addition of “Calcinova” to stimulate osteogenesis further contributed to achieving more stable treatment outcomes in patients with generalized periodontitis.

Cardiovascular reactivity during conversations about discrimination is buffered by social support among U.S. Latines

Racial discrimination is conceptualized as an acute and chronic stressor. Like other acute stressors, lab-based studies demonstrate acute effects of discrimination-related stressors on stress-related cardiovascular outcomes, including total cardiac output, blood pressure, and indices of sympathetic and parasympathetic nervous system activity. Critically, it is important to understand how individual and social factors buffer the experience of race-related acute stress. The current study extends existing work by measuring cardiovascular indices of stress during conversations about racial/ethnic discrimination and examines the moderating role of social support. Latine/Hispanic participants (N = 97) talked about personal discrimination experiences with either a close other or a research assistant they had never previously met. Participants in both conditions exhibited cardiovascular reactivity indicative of stress during the conversation. Additionally, patterns of reactivity reflected a more adaptive stress response and recovery profile when participants talked about discriminatory experiences with a close other relative to a stranger (less parasympathetic withdrawal during the stressor and more parasympathetic rebound during recovery). These patterns are consistent with a stress buffering account of social support, which suggests social bonds and community-level support are critical to consider in interventions to mitigate the harms of experiencing discrimination and prevent chronic health disparities.

Effectiveness of Facial Massage and Exercise in Alleviating Visual Fatigue: A Systematic Review

Background: With the widespread use of electronic devices, visual fatigue has become a prevalent issue in modern society. Non-pharmacological interventions, such as facial massage and exercise, have been proposed as effective methods for alleviating visual fatigue. However, the specific effects and mechanisms behind these interventions require further exploration. Objectives: This systematic review aims to evaluate the effectiveness of facial massage and exercise in reducing visual fatigue and to explore the underlying mechanisms of these interventions. Methods: A comprehensive search was conducted across multiple databases, including PubMed, Web of Science, Scopus, and the Cochrane Library. Randomized controlled trials and crossover experiments were included for both quantitative and qualitative analyses of relevant studies. Results: The findings suggest that both facial massage and exercise can reduce visual fatigue. Facial massage alleviates eye strain by stimulating the parasympathetic nervous system, reducing stress and anxiety, relaxing muscles, and improving blood circulation. Exercise alleviates visual fatigue through two mechanisms: (1) enhancing overall blood circulation, reducing stress, improving sleep quality, and overall health; (2) directly exercising eye muscles through eye yoga, which helps relieve visual fatigue. Conclusions: Preliminary research indicates that facial massage, full-body exercise, and eye yoga hold potential as non-pharmacological interventions for visual fatigue. Eye yoga has experimental support for its ability to strengthen eye muscles and improve focus. Massage stimulates parasympathetic activity and boosts blood circulation, while full-body exercise enhances systemic circulation to relieve eye fatigue. Future research should focus on investigating the mechanisms of these interventions in more detail and comparing the effects of various types, intensities, and durations to provide more precise clinical recommendations.

Automated assessment of non-technical skills by heart-rate data.

Observer-based scoring systems, or automatic methods, based on features or kinematic data analysis, are used to perform surgical skill assessments. These methods have several limitations, observer-based ones are subjective, and the automatic ones mainly focus on technical skills or use data strongly related to technical skills to assess non-technical skills. In this study, we are exploring the use of heart-rate data, a non-technical-related data, to predict values of an observer-based scoring system thanks to random forest regressors. Heart-rate data from 35 junior resident orthopedic surgeons were collected during the evaluation of a meniscectomy performed on a bench-top simulator. Each participant has been evaluated by two assessors using the Arthroscopic Surgical Skill Evaluation Tool (ASSET) score. A preprocessing stage on heart-rate data, composed of threshold filtering and a detrending method, was considered before extracting 41 features. Then a random forest regressor has been optimized thanks to a randomized search cross-validation strategy to predict each score component. The prediction of the partially non-technical-related components presents promising results, with the best result obtained for the safety component with a mean absolute error of 0.24, which represents a mean absolute percentage error of 5.76%. The analysis of feature important allowed us to determine which features are the more related to each ASSET component, and therefore determine the underlying impact of the sympathetic and parasympathetic nervous systems. In this preliminary work, a random forest regressor train on feature extract from heart-rate data could be used for automatic skill assessment and more especially for the partially non-technical-related components. Combined with more traditional data, such as kinematic data, it could help to perform accurate automatic skill assessment.

The relation of cluster headache to alexithymia, depression, and anxiety.

The pathophysiology of cluster headaches (CHs) involves the trigeminovascular system, the parasympathetic nervous system, and the hypothalamus. Because of the affected hypothalamus, there may be limbic system involvement in CH. To investigate the relationship between depression, anxiety, and alexithymia in CH, to demonstrate that the limbic system is affected. A total of 18 patients with CHs who were outside of cluster period and 18 healthy controls were included. Participants were administered the Beck depression inventory (BDI), Beck anxiety inventory (BAI), and Toronto alexithymia scale-20 (TAS-20). Patients with CHs had significantly higher rates of alexithymia (p = 0.003) and depression (p = 0.014) than controls. There was no significant difference in anxiety levels (p = 0.297) between groups. It was shown that, in addition to previously identified psychiatric disorders, alexithymia can accompany CHs in patients.

Theories of Arousal Predict a Link Between Heart Rate Variability and Reactive Aggression: Meta-Analytic Results Disagree.

Polyvagal theory posits that habitually aggressive individuals might have an impaired capacity to calm after arousal, which has led to the investigation of Arousal-based biological indicators - "biomarkers" - of aggression, to identify individuals at high risk. The most popular approach in research examining (specifically reactive) aggression is the use of wearable technologies that can non-invasively measure heart rate variability (HRV), a cardiovascular phenomenon impacted by activation of the parasympathetic ("rest and digest") nervous system. But there is a problem: no one has systematically analyzed the results of these studies to determine if HRV is an effective predictor of reactive aggression. We surveyed an initial 705 articles, producing 48 effect estimates amenable to meta-analysis. Counter to predictions derived from polyvagal theory, the results reveal no correlation between HRV and reactive aggression. We discuss the implications of this novel finding for theory and practice, considering both the complexity of identifying effective biomarkers and the practical limitations driving methodological decisions in aggression research. We conclude that there is no empirical evidence supporting HRV as a valid biomarker of aggression.

Interpersonal Stressors Predicting Inflammation in Adolescents: Moderation by Emotion Regulation and Heart Rate Variability?

This study assessed interpersonal stressors (peer adversity and parental rejection) as predictors of adolescents’ circulating inflammatory markers, while examining emotion regulation and parasympathetic nervous system activity (at rest, reactivity, and recovery) as potential protective moderators. Data were collected in a Belgian cohort of adolescents in 2017 (n=185, 51.4% boys, 10-18y) and 2018 (n=98), and included serum inflammatory markers (CRP, TNFα, IFNγ, IL-6, IL-8 and IL-10), peer adversity, parental rejection, emotion regulation and heart rate variability (RMSSD-HRV, at rest and in 2018 also in response to a Trier Social Stress Test). Contrary to the hypothesis, interpersonal stressors were negatively related to TNFα (in 2017 and 2018), IFNγ (in 2017 and longitudinally) and IL-6 (in 2018). In 23% of the tested associations, HRV at rest was a significant moderator: the negative stressor-inflammation associations were present only among adolescents with low HRV resting values. No significant moderation by HRV reactivity or recovery was detected. After correction for multiple testing, all above-mentioned significant findings disappeared. These unexpected findings may suggest that the positive association between stress exposure and circulating markers of inflammation is not yet detectable in adolescence and perhaps becomes evident only later in life.

Дослідження впливу фаз менструального циклу на функціональний стан кваліфікованої ветеранки спорту з дзюдо

Purpose: to investigate the influence of menstrual cycle phases on the functional status of a qualified female veteran judo athlete. Material and methods. The following methods were used in the study: analysis of scientific and methodological information and Internet sources; generalization of advanced practical experience; measurement of sensorimotor reactions and determination of heart rate variability indices; methods of mathematical statistics. A qualified veteran female judo athlete (Master of Sports of Ukraine) in the age category F2 (1983-1979) took part in the study. We performed 84 measurements of heart rate variability (n=42, HRV in the supine position; n=42, heart rate variability during the test task dedicated to measuring the choice reaction). The measurement was performed using two computer programs for mobile devices running iPadOS «Research HRV» and «HRV SR+CR» during morning hours (7-8 hours) and afternoon hours (17-18 hours). Results: analysis of the dynamics of changes in heart rate variability parameters obtained in the supine position indicates an increase in sympathetic activity in the follicular phase of the menstrual cycle. Analysis of comparisons of heart rate variability parameters in different phases of the menstrual cycle indicates that the greatest number of statistically significant (p<0,05) differences is observed in the first half of the day. These changes indicate the dynamics of the decrease in the tone of the sympathetic part of the autonomic nervous system in the follicular phase when performing test tasks provided by the computer program «HRV SR+CR». Analysis of the study results indicates that the indicators of heart rate variability are also influenced by the measurement conditions. The test tasks of the computer program «HRV SR+CR» provide cognitive load and concentration of attention, especially in the second stage, where it is necessary to choose the sought-after figure. During cognitive tasks there is an increase in the activity of the parasympathetic nervous system, which leads to an increase in heart rate variability. High level of heart rate variability is associated with better cognitive functions and adaptive response to stress. Consequently, these differences in heart rate variability obtained using the «Research HRV» and «HRV SR+CR» programs may be the result of interactions between physiological changes during the menstrual cycle as well as the influence of measurement conditions. Understanding the changes in heart rate variability indices during test tasks related to the manifestation of the choice reaction provides information about the influence of cognitive load and attention concentration on the functional state of the female athlete. This will allow to plan the training process of wrestling taking into account the phases of the menstrual cycle and functional capabilities that are inherent in high-skilled female athletes. Conclusions. The parameters of heart rate variability and sensorimotor reaction time provide information about the functional state of martial artists. Understanding of metabolic and hormonal processes in different phases of the menstrual cycle of qualified wrestlers will allow to optimize their training loads and recovery measures.

Heart rate variability as a biomarker for transdiagnostic depressive and anxiety symptom trajectory in adolescents and young adults.

Internalizing psychopathology is associated with abnormalities in heart rate variability (HRV). Lower HRV that reflects reduced parasympathetic nervous system activity has been observed in depressive and anxiety disorders. Existing studies predominantly used categorical rather than dimensional approaches, the latter of which better addresses clinical comorbidity and heterogeneity. Moreover, there is little evidence on the role of HRV in longitudinal symptom trajectory in adolescents and young adults. The current study examined the association between HRV and internalizing symptom trajectory using a dimensional approach-the tri-level model of depression and anxiety. Adolescents and young adults (N = 362) were recruited in a 3-year longitudinal study, where they completed electrocardiogram recordings and self-report symptom questionnaires. Multilevel modeling was conducted with high-frequency power bands (HF power) of interbeat intervals at baseline as the predictor, and tri-level symptom factors over 3 years as the outcome. HF power significantly predicted the trajectory of the broad General Distress symptom factor, but not the intermediate Fears or Anhedonia-Apprehension symptom factors. Higher HF power was associated with a decline in General Distress over time. This association was held when neuroticism, other tri-level symptom factors, and demographic variables were covaried. That is, greater parasympathetic nervous system activity at baseline was significantly associated with a greater decline in the broad internalizing symptom factor, but not symptom factors that are more specific to depressive or anxiety disorders. Parasympathetic activity, therefore, may be a transdiagnostic biomarker for internalizing symptoms in adolescents and young adults. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Mechanism of action of Xipayimaizibizi oral liquid on outlet obstruction-induced overactive bladder: An integrated study

ObjectiveTo observe the effect of Xipayimaizibizi oral liquid (XP) in an overactive bladder (OAB) experimental rat model and to explore its pharmacological mechanisms. MethodsNetwork pharmacology was used to explore the potential mechanisms of action of XP. The rats underwent bladder outlet obstruction surgery and were administered the corresponding drug concentrations by gavage for 4 weeks. The study observed the body weight, water intake, bladder and kidney indices (to evaluate their general status), urination behavior pattern (to observe frequency and urgency), and urodynamics (to measure bladder parameters). Hematoxylin and eosin and Masson's trichome staining were used to observe changes in the bladder structure. Enzyme-linked immunosorbent assay was used to measure the levels of nerve growth factor, brain-derived neurotrophic factor, and acetylcholine in the urine. The key targets involved in these mechanisms were validated using reverse transcription-quantitative polymerase chain reaction, immunohistochemistry, and western blot in vivo/vitro experiments. ResultNetwork pharmacological analysis predicted that XP may alleviate OAB by affecting the cholinergic synapse and calcium signaling pathways. XP treatment significantly reduced the bladder index, improved urine behavior and urodynamic parameters, decreased the neurotransmitters in urine, and reduced the thickness of the bladder wall and collagen ratio. These results indicate that XP can alleviate OAB symptoms and improve the bladder structure. In vivo/vitro experiments further demonstrated that XP can inhibit targets, such as muscarinic acetylcholine receptor 2, and participate in cholinergic synapses to further regulate the parasympathetic nervous system. It can also reduce the overexpression of Ca2+ caused by agonists, inhibit targets such as transient receptor potential vanilloid type 1, and participate in calcium signaling pathways to maintain Ca2+ homeostasis. ConclusionThese results suggest that XP inhibited bladder overactivity by maintaining Ca2+ homeostasis and regulating the parasympathetic nervous system.

Heart rate variability in chronic ischemic stroke: analysis during the sleep-wake cycle.

Alterations of the autonomic nervous system (ANS) in the chronic stage of ischemic stroke (IS) are not well understood. Heart rate variability (HRV) provides a noninvasive approach to assess autonomic function. To compare the HRV parameters during the sleep-wake cycle between patients with IS in the chronic stage and healthy subjects. We conducted a retrospective transversal study based on clinical records and 24-hour electrocardiogram (EKG) monitoring registries of 179 patients with a confirmed IS diagnosis and 184 age- and sex-matched healthy subjects. Circadian variation was calculated according to the variation of the total autonomic activity (VTAI) and the parasympathetic activity (VPAI) indexes. Comparisons were performed using nonparametric tests. Multivariable analyses were performed with canonical discriminant analysis (CDA) and a three-way analysis of variance (ANOVA). Statistical significance was established with a confidence level of 95%. During waking hours, the healthy group exhibited higher variability in the time domain and frequency domain parameters: standard deviation of NN intervals (SDNN, p < 0.001) and of the average NN intervals (SDANN, p < 0.001), as well as low-frequency (LF) band (p < 0.001). During sleep, the difference was higher in the high-frequency (HF) band (p < 0.001), and lower in the low-/high-frequency ratio (LF/HF, p < 0.001). Both VPAI and VTAI showed less significant difference in IS patients (p < 0.001). There was diminished heart vagal activity among IS patients, as measured through HRV. During sleep, this is likely caused by an imbalance in the sympathetic and parasympathetic systems shifting through the sleep phases. These imbalances could persist over time in patients with IS, lasting months after the initial injury.

Chronic rose oxide and exercise synergistically modulate cardiovascular and autonomic functions in hypertensive rats.

With the alarming rise in cases of arterial hypertension worldwide, there is an urgent need to develop combined therapies to mitigate this scenario. Rose oxide (RO), a monoterpene with anti-inflammatory and hypotensive properties, emerges as an alternative. The present study is the first to evaluate the effect of RO administered chronically and combined with physical exercise (swimming) since both have been reported to have beneficial impacts on hypertension. Male SHR and Wistar rats (aged 12weeks) received RO for 34 consecutive days (orally; 100mg/kg). The progression of systolic arterial pressure (SAP) was monitored through tail-cuff plethysmography. Twenty-four hours before the end of the treatment, the animals were anesthetized, and the femoral artery and vein were cannulated to record the pulsatile arterial pressure and to administer drugs, respectively. Hemodynamic and autonomic parameters and baroreflex sensitivity and intrinsic heart rate (IHR) were evaluated. Treatment with RO, administered alone or combined with exercise, reduced SAP and mean arterial pressure in SHR. The swimming protocol did not prevent increases in BP, but when combined with RO, it improved autonomic control, assessed through heart rate variability and parasympathetic tone. IHR was attenuated in SHR, and none of the treatments reversed this response. Therefore, combining RO with physical exercise may enhance their antihypertensive effects, improving autonomic function, reducing oxidative stress and inflammation, providing synergistic cardiovascular benefits, improving metabolic health, promoting a comprehensive lifestyle intervention, and potentially allowing for reduced medication dosages. This multifaceted approach could offer a more effective and sustainable strategy for managing hypertension.

Thermal physiological characteristics of the Xizang people in asymmetrical dressing exposures on the plateau

The Xizang people, living in the “Third Pole of the World,” have long-formed asymmetrical dressing habits that pose unique challenges to their physiological mechanisms. This study examined the physiological parameters of the Xizang people under symmetrical and various asymmetrical dressing angles to analyze the influence of these dressing styles on their thermal responses. Partial correlation analysis was used to further clarify the physiological thermal assessment indicator of the Xizang people. The results showed that, compared to symmetrical dressing, the Xizang people exhibited higher blood perfusion index and core temperature under asymmetrical dressing. In cold environments, those with symmetrical dressing had higher mean arterial pressure, heart rate, and relative activity ratio of sympathetic to parasympathetic nervous system, indicating dominant sympathetic nerve activity. At an ambient temperature of 15 °C, the Xizang people demonstrated a mean skin temperature difference of 2.6 °C and a right wrist temperature difference of 4.5 °C between symmetrical and the asymmetrical dressing angle with 50° Skin temperature was identified as the physiological thermal assessment indicator for the Xizang people considering asymmetrical dressing styles. This study provided a physiological foundation for the accurate design of plateau built environments suitable for the Xizang people.

Effect of selective renal denervation guided by renal nerve stimulation on atrial remodeling

Abstract Background The renal nerves play a crucial role in regulating blood pressure (BP), and the parasympathetic nervous has been confirmed as one of the components of the renal nerves, with close connections to the central solitary nucleus. Renal nerve stimulation (RNS) can activate not only the sympathetic nerves, leading to an elevation in BP, but also the parasympathetic nerves, resulting in a reduction in BP. Multiple clinical studies have demonstrated that compared to pulmonary vein isolation (PVI), renal denervation (RDN) combined with PVI significantly increased the likelihood of freedom from atrial fibrillation, but its mechanism remains unclear. Purpose Exploring the effects of renal sympathetic denervation and renal parasympathetic denervation on atrial neural remodeling and structural remodeling from a histological perspective of atrial myocardium. Methods 24 adult healthy Kunming dogs were randomly divided into three groups: (1) RNS-guided reduced BP response sites ablation (RRA group, n=8), (2) RNS-guided elevated BP response sites ablation (ERA group, n=8), and (3) RNS only, no ablation (RSC group, n=8). Left atrial samples were obtained after a 4-week follow-up period. Results Compared to the RSC group, the ERA group showed a significant decrease in tyrosine hydroxylase (TH), while the RRA group showed a significant decrease in choline acetyltransferase (CHAT) and muscarinic acetylcholine receptor 2 (CM2) (Fig. 1A-1C). Histological results indicated that compared to the RSC group, the ERA group exhibited orderly arrangement of myocardial cells, with a significant reduction in the degree of mitochondrial swelling and a decrease in average myocardial cell area. In contrast, the RRA group showed disordered arrangement of myocardial cells, with some myofibril dissolution, noticeable swelling of cell nuclei and mitochondria, and an increase in average myocardial cell area (Fig. 1D). Further evaluation of left atrial fibrosis degree revealed that compared to the RSC group, the ERA group showed a significant decrease in Collagen I, with a reduction in interstitial fibrosis degree, while the RRA group showed a significant increase in Collagen I expression, with an increase in myocardial interstitial fibrosis degree (Fig.2). Conclusion Renal sympathetic denervation can reduce atrial sympathetic nerve, improve atrial macrostructure, ultrastructure, and fibrosis levels, which may be one of the reasons why RDN combined with PVI is more effective in maintaining sinus rhythm compared to PVI. Renal parasympathetic denervation can decrease atrial parasympathetic nerve, leading to deterioration of atrial tissue structure and exacerbation of fibrosis. This emphasizes the importance of electrical stimulation guidance during the RDN procedure to avoid "side effects" caused by renal parasympathetic nerves ablation.Figure 1Figure 2

A Study on the Physiological Diversity of Hand Bathing under Different Conditions

Achieving the best outcomes and ensuring patients are as comfortable as possible are crucial goals for healthcare professionals. Hospital stress has been linked to worsening patient outcomes and so it is important to implement methods for keeping patients calm. Targeting the autonomic nervous system through hand bathing could provide answers. Associate Professor Hajime Nakano and his collaborators at the Faculty of Nursing, Josai International University, Japan, used precise tools to measure the heart rates of patients bathing their hands in waterbaths maintained at carefully controlled temperatures. The researchers used a probe to non-invasively measure brain activation and found that hand bathing decreased sympathetic nervous system activity, increased parasympathetic nervous system activity and produced feelings of relaxation. Nakano and the team conducted another study in which they activated the sympathetic nervous system in volunteers with mental arithmetic and found that hand bathing significantly suppressed the activation. This led them to posit that thermal stimulation has the potential to impact the stress responses in patients and their motivation in a bidirectional manner, which indicated significant possibilities for clinical applications. The researchers are keen to explore how altering the temperature of the hand bath can positively impact patients and an optimum temperature be selected. The team wants to ensure that interventions are tailored to the unique needs of patients and, as such, observed responses under different conditions and collected vast data that has enabled them to consider a research design that accommodated individual differences.

No improvement in atrial arrhythmia rates in patients on baroreflex activation therapy

Abstract Background Atrial arrhythmias encompass a wide range of abnormal cardiac rhythms including atrial fibrillation, atrial flutter, and atrial tachycardia. Patients with heart failure with reduced ejection fraction (HFrEF) have increased risk of atrial arrhythmias, ultimately leading to increased morbidity. Baroreflex Activation Therapy (BAT) employs an implantable device to increase parasympathetic nervous system activity by stimulating the carotid baroreceptors thereby reducing afterload and heart failure symptoms. In our prior study, BAT therapy has been shown to reduce hospitalization rates in patients with HFrEF. However, the effects of BAT on atrial arrhythmia has never been studied. Objective In this study, we analyzed the effects of BAT on atrial arrhythmia rates in patients with HFrEF. Methods Patients with HFrEF with BAT therapy for at least 12-months at a hospital were retrospectively studied. Inclusion criteria includes implantable cardioverter-defibrillator (ICD) placement of at least 12-months pre- and post-BAT therapy. Additionally, patients diagnosed with atrial arrhythmias prior to the study timeline were excluded. Atrial arrhythmia rates 6 and 12-months pre-BAT therapy and 6 and 12-months post-BAT therapy were compared. Atrial arrhythmia episodes were recorded through ICD interrogation every 1-3 months in the clinic. Of the 31 identified patients on BAT therapy, 11 patients fit the inclusion criteria. For the 11 patients in the study, 3 identified as female and 8 identified as male, 6 identified as white, 4 identified as Hispanic, and 1 identified as African-American with a mean age of 59.8 ± 17.4 years. The average left ventricular ejection fraction pre-BAT therapy was 23.8 ± 10.8%. Results The mean average atrial arrhythmia rates for 6-month pre-BAT therapy and 6-month post-BAT therapy were 0.12/month ± 0.40 and 1.32/month ± 2.76 respectively (p=0.18), suggesting no differences in atrial arrhythmia rates at 6-months with BAT therapy. The mean average atrial arrhythmia rates for 12-month pre-BAT therapy and 12-month post-BAT therapy were 0.11/month ± 0.35 and 2.40/month ± 5.84 respectively (p=0.22), suggesting no differences in atrial arrhythmia rates at 12-months with BAT therapy. Conclusion Although BAT therapy has been shown to decrease hospitalization rates, BAT therapy is not associated with decreased atrial arrhythmia rates at 6 months and 12 months.

Can HRV Biofeedback Training Improve the Mental Resilience of Icelandic Police Officers?

High heart rate variability (HRV) is increasingly recognized as an indicator of a healthy regulatory system, reflecting the dynamic balance between sympathetic (SNS) and parasympathetic (PSNS) nervous system activity. According to the neurovisceral integration model, this balance is managed by the central autonomic network (CAN), comprised of specific brain regions involved in emotional, attentional, and autonomic regulation. HRV thus reflects the performance of the cognitive, affective, and autonomic regulation system. Numerous studies support the relationship between HRV and the CAN, including research on HRV biofeedback training (HRVBF). Studies on the effectiveness of HRVBF for professions such as police officers have shown improvements in self-regulation, decision-making, and performance. However, few studies have specifically explored HRVBF's influence on HRV metrics in police officers, highlighting a need for further research. This study addresses this gap by randomly assigning 27 Icelandic police officers to intervention or wait-list control groups. The intervention group underwent a five-week HRVBF program, including group and individual training sessions. Results showed significant increases in HRV metrics for the intervention group, indicating improved autonomic function and stress resilience. Mental resilience increased significantly as measured by subjective measures of attentional control, mindful awareness, and reduced fatigue. These findings support the efficacy of HRVBF in enhancing HRV and mental resilience for police officers, suggesting its applicability and potential for integration into existing training programs.

The Effects of a Single Vagus Nerve’s Neurodynamics on Heart Rate Variability in Chronic Stress: A Randomized Controlled Trial

Background: The modulation of the autonomic nervous system’s activity, particularly increasing its parasympathetic tone, is of significant interest in clinical physiotherapy due to its potential benefits for stress-related conditions and recovery processes. This study evaluated the effectiveness of the addition of neurodynamics in enhancing parasympathetic activation in subjects with chronic stress. Methods: A clinical trial randomly assigned participants to a group with neurodynamics (6 bpm breathing protocol + manual therapy + neurodynamic technique) or a group without neurodynamics (6 bpm breathing protocol + manual therapy only). Metrics of heart rate variability (HRV), including the Mean Heart Rate (Mean HR), standard deviation of intervals between consecutive heartbeats (SDNN), Heart Rate Difference (Diff. HR), Root Mean Square of Successive Differences (RMSSD), number of intervals differing by more than 50 ms (NN50), percentage of consecutive NN intervals that differed by more than 50 ms (pNN50), and the high-frequency component measured in standardized units (HF), were assessed before, during, and after the intervention. Results: During the intervention, the group with neurodynamics showed significant changes in all variables except in the pNN50 and HF while the group without neurodynamics only showed improvements in the Mean HR, SDNN, and RMSSD. In the post-intervention phase, the group with neurodynamics maintained an increase in HRV while the group without neurodynamics experienced a decrease, suggesting an increase in sympathetic activity. Conclusions: Vagal nerve neurodynamics appear to represent an effective method for enhancing parasympathetic activation in patients with chronic stress. The results highlight the importance of a more comprehensive analysis of HRV variables in order to obtain a correct picture of the impact of interventions on the complex and multifaceted functioning of the autonomic nervous system.