Cardiac Autonomic Regulation Research Articles

Influence of experimental heart failure therapy with different generations of β-adrenergic blockers on Cardiac Electrical Activity (ECG) and Autonomic Regulation of Heart Rhythm (ARHR)

Abstract: In the complex treatment of chronic heart failure (CHF) β-adrenoblockers (carvedilol, nebivolol, bisoprolol, metoprolol) are used, which due to their pharmacological properties increase the survival rate of patients, improve cardio- and haemodynamic parameters, metabolism. However, modern realities in medicine require creation of new more effective and safe β-adrenoblockers. In this regard, the potential drug Hypertirl is of interest. The aim was to evaluate the cardioprotective effect of 1-(b-phenylethyl)-4-amino-1,2,4-triazolium bromide (Hypertril) on cardiac electrical activity and autonomic regulation of heart rhythm in a model of CHF in comparison with β-adrenoblockers of different generations (Nebivolol, Carvedilol, Bisoprolol, Metoprolol). Materials and methods: Chronic heart failure was induced by 14-day administration of doxorubicin in a cumulative dose of 15 mg/kg to white mongrel rats weighing 190–220g (total 85). The investigated drugs were administered after doxorubicin course for 30 days: Hypertril at an experimentally substantiated dose of 3.5 mg/kg, Metoprolol succinate 15 mg/kg, Nebivolol 10 mg/kg, Carvedilol 50 mg/kg, Bisoprolol 10 mg/kg. At the end of drug administration under thiopental anaesthesia (40 mg/kg), electrocardiogram (ECG) and autonomic regulation of heart rhythm (ARHR) were analysed using a computer analyser CardioCom-2000plus (KAI-Medica, Ukraine). The results of the study were calculated using a standard statistical package “STATISTICA for Windows 6.0” (StatSoftInc., №AXXR712D833214FAN5), “SPSS 16.0” and “Microsoft Office Excell 2003”. Results and discussion: Hypertril administration resulted in a negative chronotropic effect, normalisation of atrial (P) and ventricular (R) spike amplitude, ST segment inversion below isoline, increased amplitude of ventricular myocardial repolarisation T. Myocardial repolarisation spike were observed, as well as normalised the duration of atrial (P) and ventricular depolarisation phase (QRS complex) to the intact value and restored the duration of electrical diastole (TR interval). Hypertril reduced systolic and diastolic myocardial dysfunction in animals with CHF. Hypertril restored autonomic mechanisms of heart rhythm regulation and balanced activity of sympathetic and parasympathetic parts of autonomic nervous system in the control of cardiac function. Conclusion: The obtained results demonstrated the undoubted advantage of the new original molecule (Hypertril) over basic β-adrenoblockers (Metoprolol, Nebivolol, Carvedilol and Bisoprolol) and experimentally justify further in-depth study to create on its basis a drug for the treatment of CHF.

Short-term effects on heart rate variability of occipito-mastoid suture normalization in healthy subjects.

Occipito-mastoid structure normalization (OMSN) is an osteopathic manipulative treatment aimed at reducing tension around the jugular foramen, where cranial nerves IX, X, and XI exit the skull. The purpose of this study was to observe how heart rate variability (HRV), a marker of autonomic cardiac regulation, was modulated after an OMSN vs. a sham technique (SHAM). Pre- and post-intervention HRV was analyzed in two randomly chosen groups of 15 participants (OMSN vs. SHAM group). HRV was collected in the supine position 5 min before and 5 min after a 10-min application of either OMSN or SHAM. The time and group effect was analyzed using a two-way ANOVA. Independently from group intervention, a significant time effect induced increased HRV. No group effect differences were observed. Multiple comparisons for time and group interaction showed that the root mean square of successive differences (RMSSD), a vagally mediated HRV variable, increased to a greater extent for the OMSN group (p = 0.03) than for the SHAM group. However, both OMSN and SHAM techniques had a significant effect on HRV. Compared to a SHAM technique, OMSN had a significant effect on HRV vagally related metric RMSSD in the short term. We conclude that 10 min of OMSN may be used to induce a short-term influence on parasympathetic autonomic nervous system modulations.

Altered Cardiac Autonomic Regulation in Individuals with Myasthenia Gravis-A Systematic Review and Meta-Analysis.

The aim of this systematic review with meta-analysis was to determine differences in cardiovascular autonomic parameters between patients with myasthenia gravis (MG) and healthy controls (HCs). Two reviewers searched four electronic databases, namely PubMed, Web of Science, EMBASE, and SCOPUS, from database inception to 7 July 2023 for studies investigating cardiovascular autonomic parameters in MG vs. HCs. A random-effects meta-analysis was performed to compute Hedges' g ± 95% confidence intervals (CI). Out of a total of 2200 records, 8 observational studies with a sample size of 301 patients with MG and 454 HCs were included in the systematic review. Meta-analysis revealed lower values of expiration/inspiration ratio (g = -0.45, I2 = 74.7), baroreflex sensitivity (g = -0.56, 95%CI -0.80, -0.33; I2 = 0.3), percentage of adjacent NN intervals differing by more than 50 ms (g = -1.2, I2 = 82.8), square root of the mean of squared differences between successive beat intervals (g = -1.94, I2 = 95.1), mean of the standard deviations of all NN intervals (g = -0.83, 95%CI -1.37, -0.28; I2 = 55.5), and high frequency of HRV during tilt (g = -0.75, 95%CI -0.11, -0.39; I2 = 0). MG patients vs. HCs had higher systolic blood pressure (g = 0.39; I2 = 56.1), sympathovagal balance at rest/during tilt (LF/HF-RRIsupine, g = 0.44; I2 = 0; LF/HF-RRItilt, g = 0.86; I2 = 0; LF/HFtilt, g = 0.40; I2 = 0). As a group, MG patients have altered cardiac autonomic function, including decreased parasympathetic function, lower baroreflex sensitivity, and higher sympathovagal balance at rest and during orthostatic challenges.

Aerobic Physical Exercise is Essential for Cardiac Autonomic Regulation in Hypertensive Patients Undergoing Chronic Treatment with Renin-Angiotensin System Inhibitors.

Hypertension treatment with renin-angiotensin system inhibitors (RASi) presents contradictions about the recovery of damage in cardiovascular autonomic modulation characterized by reduced heart rate variability (HRV) and increased blood pressure variability (BPV). Conversely, the association of RASi with physical training can influence achievements in cardiovascular autonomic modulation. To investigate the effects of aerobic physical training on hemodynamics and cardiovascular autonomic modulation in hypertensive volunteers untreated and treated with RASi. A non-randomized controlled trial in which 54 men ( 40-60 years old) with a history of hypertension for >2 years were allocated in accordance with their characteristics into three groups: untreated (Control; n=16), treated with type 1 angiotensin II (AT1) receptor blocker (losartan; n=21), and treated with angiotensin-converting enzyme inhibitor (enalapril; n=17). All participants underwent hemodynamic, metabolic, and cardiovascular autonomic evaluation using baroreflex sensitivity (BRS) and spectral analysis of HRV and BPV, before and after 16 weeks of supervised aerobic physical training. The volunteers treated with RASi had lower BPV and HRV, both in the supine position and in the tilt test, with the losartan group having the lowest values. Aerobic physical training increased HRV and BRS in all groups. However, the association of enalapril with physical training appears to be more prominent. Long-term treatment with enalapril and losartan may harm the autonomic modulation of HRV and BRS. Aerobic physical training is essential to promote positive adjustments in the autonomic modulation of HRV and BRS in hypertensive patients treated with RASi, especially with enalapril.

Cardiac Autonomic Regulation and Metabolic Syndrome: Clinical Use of A Unitary Autonomic Nervous System Index

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality. About 80% of SHS-related deaths are due to cardiovascular causes. Reducing SHS exposure with smoking bans is associated with improved cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a great candidate for combating SHS exposure-induced cardiovascular outcomes. The goals of this study were to determine 1) the time course of environmentally relevant SHS exposure effects on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of a soluble epoxide hydrolase inhibitor (TPPU) can protect against SHS-induced autonomic and cardiovascular dysregulation. Methods: Male C57BL/6J mice (11 wk) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to 12 wks of either filtered air (FA, n=19) or 3 mg/m3 of SHS (6 hr/d, 5 d/wk, n=18), followed by 4 weeks recovery window (SHS substituted with FA). Separate mice were randomly assigned to one of the 3 groups: FA (n=12), FA+TPPU (n=12), and SHS+TPPU (n=22). TPPU (15 mg/l) was given by drinking water during the 12 weeks of exposure period (estimated dose = 3.75 ug/g/day). BP and ECG were recorded continuously for 36 hours every month when mice were not exposed. Data were stratified by 12-hour circadian window: The dark cycle (dark 1) immediately after the 5th day of exposure and the following light and dark (dark 2) cycles. Baroreflex sensitivity (BRS) was determined with the sequence method. Standard time domain heart rate variability (HRV) parameters were obtained from normal-to-normal R-R intervals. Results: SHS-exposed mice had significantly higher physical activity levels (~ 50% higher, p<0.05), an effect that persisted 4 wks after cessation of SHS exposure. SHS exposure significantly decreased 1) short-term HRV (RMSSD) by ~20% as early as after 4 wks of exposure; 2) overall HRV (SDNN) with maximum effect at 12 wks (-15%, p<0.05); 3) pulse pressure (-8%, p<0.05) as early as week 4; and 4) BRS with maximum effect at 12 wks (-11%, p<0.05). All SHS-induced changes in cardiovascular regulation were ameliorated by 4 weeks of recovery. Treatment with TPPU in drinking water eliminated SHS exposure-induced decreases in HRV, PP and BRS. However, SHS-induced increase in activity persisted (30% higher, p<0.05) even with TPPU treatment. Conclusions: These data suggest that 1) Three months of environmentally relevant SHS significantly reduces cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be rescued by removing from SHS exposure; and 3) oral TPPU can prevent SHS-induced cardiovascular dysregulation. R01 ES025229, T32 HL086350, T32 ES007059, R35ES030443 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Electromagnetic Fields - Do They Pose a Cardiovascular Risk?

Mobile wireless communication technologies have now become an everyday part of our lives, 24 hours a day, 7 days a week. Monitoring the autonomous system under exposition to electromagnetic fields may play an important role in broading of our still limited knowledge on their effect on human body. Thus, we studied the interaction of the high frequency electromagnetic field (HF EMF) with living body and its effect on the autonomic control of heart rate using Heart Rate Variability (HRV) linear and nonlinear analyses in healthy volunteers. A group of young healthy probands (n=30, age mean: 24.2 ± 3.5 years) without any symptoms of disease was exposed to EMF with f=2400 MHz (Wi Fi), and f=2600 MHz (4G) for 5 minutes applied on the chest area. The short-term heart rate variability (HRV) metrics were used as an indicator of complex cardiac autonomic control. The evaluated HRV parameters: RR interval (ms), high frequency spectral power (HF-HRV in [ln(ms2)]) as an index of cardiovagal control, and a symbolic dynamic index of 0V %, indicating cardiac sympathetic activity. The cardiac-linked parasympathetic index HF-HRV was significantly reduced (p =0.036) and sympathetically mediated HRV index 0V % was significantly higher (p=0.002) during EMF exposure at 2400 MHz (Wi-Fi), compared to simulated 4G frequency 2600 MHz. No significant differences were found in the RR intervals. Our results revealed a shift in cardiac autonomic regulation towards sympathetic overactivity and parasympathetic underactivity indexed by HRV parameters during EMF exposure in young healthy persons. It seems that HF EMF exposure results in abnormal complex cardiac autonomic regulatory integrity which may be associated with higher risk of later cardiovascular complications already in healthy probands.

Impact of Antidepressant Treatment on Heart Rate Variability in Patients with Depression - A Cross Sectional Study

Heart rate variability (HRV) is a non-invasive index of cardiac autonomic regulation. HRV is reduced in depression, which indicates decreased Autonomic Nervous System flexibility. It is associated with an increase in the frequency of cardiac co-morbidities. Depression medications usually take six months for complete remission, but no data on patients on antidepressants for more than six months. Therefore, it becomes necessary to determine if anti-depressants have a better impact on HRV. The current study focused on analyzing the correction of HRV parameters after six months of antidepressant therapy. A cross-sectional study was conducted from February to September 2021 at the AFT lab inpatients. They were recruited from the Psychiatry department, Victoria Hospital, Bangalore Medical College and Research Institute, Bengaluru, Karnataka, India. The sample size was calculated to be 40 (20 Patients and 20 Healthy controls). AFT was done on all participants using Power Lab equipment and analyzed using Lab Chart 8 software. Heart rate variability parameters (AFT results) were analyzed using statistical software. The results with a p-value of >0.05% were considered statistically significant and taken up for the study. 55% of the patients with depression in our study were in the age group of 18-25 years, and the mean Ham-D (Hamilton Depression Rating Scale) score was found to be 9.8. There is a reduction in autonomic function flexibility among patients who are on antidepressants when compared to healthy controls, even after six months of treatment. No conclusion could arrive on the class of antidepressant which was more beneficial owing to its effect on autonomic functions. Hence, randomized controlled studies comparing various classes of antidepressants to assess efficacy in reducing autonomic complications of depression should be taken up

Nocturnal Heart Rate Variability Might Help in Predicting Severe Obstructive Sleep-Disordered Breathing.

Obstructive sleep apnea (OSA) can have long-term cardiovascular and metabolic effects. The identification of OSA-related impairments would provide diagnostic and prognostic value. Heart rate variability (HRV) as a measure of cardiac autonomic regulation is a promising candidate marker of OSA and OSA-related conditions. We took advantage of the Physionet Apnea-ECG database for two purposes. First, we performed time- and frequency-domain analysis of nocturnal HRV on each recording of this database to evaluate the cardiac autonomic regulation in patients with nighttime sleep breathing disorders. Second, we conducted a logistic regression analysis (backward stepwise) to identify the HRV indices able to predict the apnea-hypopnea index (AHI) categories (i.e., "Severe OSA", AHI ≥ 30; "Moderate-Mild OSA", 5 ≥ AHI < 30; and "Normal", AHI < 5). Compared to the "Normal", the "Severe OSA" group showed lower high-frequency power in normalized units (HFnu) and higher low-frequency power in normalized units (LFnu). The standard deviation of normal R-R intervals (SDNN) and the root mean square of successive R-R interval differences (RMSSD) were independently associated with sleep-disordered breathing. Our findings suggest altered cardiac autonomic regulation with a reduced parasympathetic component in OSA patients and suggest a role of nighttime HRV in the characterization and identification of sleep breathing disorders.

Cardiovascular and autonomic consequences of sleep fragmentation

Introduction: Sleep disruption is commonly found in normal individuals and those with sleep disorders. Risk factors for sleep fragmentation involve a combination of lifestyle, environmental, psychosocial factors and/or medical conditions. The main objective of this study was to analyse the impact of acute, induced sleep fragmentation upon autonomic cardiovascular regulation, measured by a non-invasive haemodynamic measurement technique. Material and methods: The authors analysed beat-to-beat measurements of haemodynamic and autonomic parameters at 5-time points during sleep fragmentation: 9:00 a.m. (baseline), 9:00 p.m., 00:30 a.m., 4:00 a.m., and 7:30 a.m. Differences in the mean values for chronotropic parameters, cardiac contractility, parameters related to blood pressure regulation and workload of the left ventricle, and autonomic parameters were examined in seventeen healthy male volunteers. Direct results obtained from every time point were analysed using analysis of variance with repeated measures or the Friedman rank sum test. Results: Sleep fragmentation had a significant negative impact on haemodynamic parameters related to cardiac contractility (SV p &lt; 0.001, IC p &lt; 0.001, HI p &lt; 0.001); parameters related to workload of the left ventricle (CO p &lt; 0.001, LVWI p &lt; 0.001, ACI p &lt; 0.001); parameters related to blood pressure regulation (sBP p = 0.001, TPR p &lt; 0.001); on chronotropic parameters (HR p &lt; 0.001, PEP p &lt; 0.001, LVET p &lt; 0.001) and an indicator of cardiac autonomic regulation: LF-RRI (p = 0.001). Conclusions: Acute sleep fragmentation can modify haemodynamic control and autonomic cardiovascular regulation in healthy men; the most important changes were seen in the morning hours (4:00 a.m.). Therefore, conditions of chronic sleep fragmentation (e.g. shift work, uniformed services, clinicians), might lead to disturbance in the autonomic nervous system and therefore to problems with homeostasis in the cardiovascular system. Future research is needed in standardized conditions with large-scale studies to clarify the effects of chronic sleep fragmentation.

Influence of sleep duration and sex on age-related differences in heart rate variability: Findings from program 4 of the HAIE study

Heart rate variability (HRV) is an important marker of cardiac autonomic regulation and health. We examined the influence of sleep duration and sex on HRV in younger and middle-aged adults. Cross-sectional data (888 participants, 44% women) were analyzed from Program 4 of the Healthy Aging in Industrial Environment study (HAIE). Sleep duration was measured across 14 days using Fitbit Charge monitors. Short-term EKG recordings were used to evaluate HRV in the time (RMSSD) and frequency domains (low frequency (LF) and high frequency (HF) power). Regression analysis showed age was associated with lower HRV across all HRV variables (all P < 0.001). Sex was a significant predictor for LF (β = 0.52) and HF (β = 0.54; both P < 0.001) in normalized units. Similarly, sleep duration was only associated with HF in normalized units (β = 0.06, P = 0.04). To explore this finding further, participants within each sex were separated into groups based on age (<40 and ≥ 40y) and adequate sleep duration (<7 and ≥7 h). Middle-aged women with sleep durations <7 h, but not ≥7 h, had lower HRV than younger women after adjusting for medications, respiratory frequency, and cardiorespiratory fitness (peak VO2). Middle-aged women with sleep durations <7 h also had lower RMSSD (33 ± 2 vs. 41±4 ms, P = 0.04), HF power (5.6 ± 0.1 vs. 6.0 ± 0.1 log ms2, P = 0.04), and HF in normalized units (39 ± 1 vs. 48 ± 2, P = 0.01) than middle-aged women with sleep durations ≥7 h. In contrast, middle-aged men irrespective of sleep duration had lower HRV than younger men. These results suggest that adequate sleep duration may positively influence HRV in middle-aged women but not men.

Cardiac autonomic regulation in response to functional power threshold testing in elite cyclists.

Objective: To evaluate the impact of a functional power threshold test (FTP) on cardiac autonomic regulation indicators in high performance cyclists. &#x0D; Methods: A total of 12 male elite cyclists (mean age 36.1 ± 11.2 years) were recruited. Body composition parameters were measured using bioimpedancemetry and heart rate variability (HRV) before and after the application of the FTP assessment. &#x0D; Results: We observed that a greater sympathetic nervous system (SNS) index and Stress index on baseline were correlated with a smaller decrease in the parasympathetic nervous system (PNS) activity in response to the FTP test (rho = 0.69, p = 0.013). Concerning morphological parameters, the skeletal muscle index (SMI) was the only one that was inversely correlated with ∆PNS (rho = -0.69, p = 0.02) whereas the muscle-bone index (MBI) displayed a positive correlation with ∆SNS (rho = 0.82, p = 0.001). In fully adjusted models we found that waist-to-hip ratio (beta = 7.90, CI95%[4.16, 11.63], t(8) = 4.88, p = 0.001) and SMI significantly influenced ∆PNS (beta = -1.38, CI95%[-1.84, -0.92], t(8) = -6.94, p &lt; 0.001), whereas MBI (beta = 10.26, CI95%[8.10, 12.42], t(8) = 10.96, p &lt; 0.001) and the interaction between the latter and Power achieved during FTP influenced ∆SNS (beta = -0.05, CI95%[-0.09, -4.99e-03], t(8) = -2.56, p = 0.033). &#x0D; Conclusion: Our findings indicate that the SMI had a negative effect on the ∆PNS, while the MBI was positively correlated with the ∆SNS in cyclists. These findings suggest that a higher SMI and MBI could have a detrimental impact on the cardiac autonomic response to maximal aerobic exercise in high-performance cyclists, such as FTP.

Prefrontal tDCS modulates autonomic responses in COVID-19 inpatients

Backgroundmaladaptive changes in the autonomic nervous system (ANS) have been observed in short and long-term phases of COVID-19 infection. Identifying effective treatments to modulate autonomic imbalance could be a strategy for preventing and reducing disease severity and induced complications. Objectiveto investigate the efficacy, safety, and feasibility of a single session of bihemispheric prefrontal tDCS on indicators of cardiac autonomic regulation and mood of COVID-19 inpatients. Methodspatients were randomized to receive a single 30-min session of bihemispheric active tDCS over the dorsolateral prefrontal cortex (2 mA; n = 20) or sham (n = 20). Changes in time [post-pre intervention] in heart rate variability (HRV), mood, heart rate, respiratory rate, and oxygen saturation were compared between groups. Additionally, clinical worsening indicators and the occurrence of falls and skin injuries were evaluated. The Brunoni Adverse Effects Questionary was employed after the intervention. Resultsthere was a large effect size (Hedges’ g = 0.7) of intervention on HRV frequency parameters, suggesting alterations in cardiac autonomic regulation. An increment in oxygen saturation was observed in the active group but not in the sham after the intervention (P = 0.045). There were no group differences regarding mood, incidence and intensity of adverse effects, no occurrence of skin lesions, falls, or clinical worsening. Conclusionsa single prefrontal tDCS session is safe and feasible to modulate indicators of cardiac autonomic regulation in acute COVID-19 inpatients. Further research comprising a thorough assessment of autonomic function and inflammatory biomarkers is required to verify its potential to manage autonomic dysfunctions, mitigate inflammatory responses and enhance clinical outcomes.

Age Prediction in Healthy Subjects Using RR Intervals and Heart Rate Variability: A Pilot Study Based on Deep Learning

Autonomic cardiac regulation is affected by advancing age and can be observed by variations in R-peak to R-peak intervals (RRIs). Heart rate variability (HRV) has been investigated as a physiological marker for predicting age using machine learning. However, deep learning-based age prediction has rarely been performed using RRI data. In this study, age prediction was demonstrated in a healthy population based on RRIs using deep learning. The RRI data were extracted from 1093 healthy subjects and applied to a modified ResNet model to classify four age groups. The HRV features were evaluated using this RRI dataset to establish an HRV-based prediction model as a benchmark. In addition, an age prediction model was developed that combines RRI and HRV data. The adaptive synthetic algorithm was used because of class imbalance and a hybrid loss function that combined classification loss and mean squared error functions was implemented. Comparisons suggest that the RRI model can perform similarly to the HRV and combined models, demonstrating the potential of the RRI-based deep learning model for automated age prediction. However, these models showed limited efficacy in predicting all age groups, indicating the need for significant improvement before they can be considered reliable age prediction methods.

Disrupted resting-state functional connectivity of the thalamus in patients with coronary heart disease

BackgroundAlthough homeostasis of the cardiovascular system is regulated by the cerebral cortex via the autonomic nervous system, the role of abnormal brain functional connectivity (FC) networks in patients with cardiac dysfunction remains unclear. Here, we report thalamus-based FC alterations and their relationship with clinical characteristics in patients with coronary heart disease (CHD). MethodsWe employed resting-state functional magnetic resonance imaging (rs-fMRI) to acquire imaging data in twenty-six patients with CHD alongside sixteen healthy controls (HCs). Next, we performed a thalamus-based FC analysis to profile abnormal FC patterns in the whole brain. Subsequently, the mean time series of the brain regions that survived in the FC analysis were used to determine correlations with clinical parameters in patients with CHD. ResultsWe found no statistically significant differences in demographic and clinical data between patients with CHD and HCs. Patients with CHD showed decreased FC patterns between bilateral thalami and left hemisphere, encompassing supplementary motor area, superior frontal gyrus, superior parietal gyrus, inferior parietal gyrus, middle cingulate cortex, lingual gyrus and calcarine sulcus. ConclusionsThese findings not only have implications in clarifying the relationship between cerebral functional imbalance and cardiovascular system, but also provide valuable insights to guide future evaluation and management of cardiac autonomic regulation via the brain-heart axis.

Heart Rate Variability and Integrative Therapies

Because of its noninvasiveness and convenience, measuring heart rate variability (HRV) as an indicator for health or illness has become increasingly popular. HRV can serve as an important indicator of cardiac autonomic regulation, and decreased HRV has been demonstrated in a variety of clinical conditions, such as cardiovascular disease, depression, and cancer-related fatigue. Many nonpharmacologic interventions have been clinically shown to improve HRV. This includes exercise, forest bathing or greenspace exposure, auricular vagus stimulation, biofeedback or paced slow breathing, and acupuncture.

Uterine activity modifies the response of the fetal autonomic nervous system at preterm active labor.

The autonomic nervous system of preterm fetuses has a different level of maturity than term fetuses. Thus, their autonomic response to transient hypoxemia caused by uterine contractions in labor may differ. This study aims to compare the behavior of the fetal autonomic response to uterine contractions between preterm and term active labor using a novel time-frequency analysis of fetal heart rate variability (FHRV). We performed a case-control study using fetal R-R and uterine activity time series obtained by abdominal electrical recordings from 18 women in active preterm labor (32-36 weeks of gestation) and 19 in active term labor (39-40 weeks of gestation). We analyzed 20 minutes of the fetal R-R time series by applying a Continuous Wavelet Transform (CWT) to obtain frequency (HF, 0.2-1Hz; LF, 0.05-0.2Hz) and time-frequency (Flux0, Flux90, and Flux45) domain features. Time domain FHRV features (SDNN, RMSSD, meanNN) were also calculated. In addition, ultra-short FHRV analysis was performed by segmenting the fetal R-R time series according to episodes of the uterine contraction and quiescent periods. No significant differences between preterm and term labor were found for FHRV features when calculated over 20 minutes. However, we found significant differences when segmenting between uterine contraction and quiescent periods. In the preterm group, the LF, Flux0, and Flux45 were higher during the average contraction episode compared with the average quiescent period (p<0.01), while in term fetuses, vagally mediated FHRV features (HF and RMSSD) were higher during the average contraction episode (p<0.05). The meanNN was lower during the strongest contraction in preterm fetuses compared to their consecutive quiescent period (p=0.008). The average autonomic response to contractions in preterm fetuses shows sympathetic predominance, while term fetuses respond through parasympathetic activity. Comparison between groups during the strongest contraction showed a diminished fetal autonomic response in the preterm group. Thus, separating contraction and quiescent periods during labor allows for identifying differences in the autonomic nervous system cardiac regulation between preterm and term fetuses.

Psychological Intervention Based on Mental Relaxation to Manage Stress in Female Junior Elite Soccer Team: Improvement in Cardiac Autonomic Control, Perception of Stress and Overall Health.

Chronic stress may represent one of the most important factors that negatively affects the health and performance of athletes. Finding a way to introduce psychological strategies to manage stress in everyday training routines is challenging, particularly in junior teams. We also must consider that a stress management intervention should be regarded as "efficacious" only if its application results in improvement of the complex underlying pathogenetic substratum, which considers mechanistically interrelated factors, such as immunological, endocrine and autonomic controls further to psychological functioning and behavior. In this study, we investigated the feasibility of implementing, in a standard training routine of the junior team of the Italian major soccer league, a stress management program based on mental relaxation training (MRT). We evaluated its effects on stress perception and cardiac autonomic regulation as assessed by means of ANSI, a single composite percentile-ranked proxy of autonomic balance, which is free of gender and age bias, economical, and simple to apply in a clinical setting. We observed that the simple employed MRT intervention was feasible in a female junior soccer team and was associated with a reduced perception of stress, an improved perception of overall health, and a betterment of cardiac autonomic control. This data may corroborate the scientific literature that indicates psychological intervention based on MRT as an efficacious strategy to improve performance, managing negative stress effects on cardiac autonomic control.

The effects of a 3-day mountain bike cycling race on the autonomic nervous system (ANS) and heart rate variability in amateur cyclists: a prospective quantitative research design

BackgroundThe acute and chronic adaptation of endurance athletes’ hearts shows that increased volume of endurance exercise might cause an acute reduction in cardiac function, causing a physiological cascade that leads to the release of cardiac biomarkers specific to cardiomyocyte stress. Heart rate variability (HRV) is a valuable tool used as a physiological measurement to evaluate the autonomic nervous system (ANS). It is frequently used to assess cardiac autonomic regulation, determining a patient’s risk for unfavorable events. This study set out to determine the changes in the ANS by participating in a 3-day mountain bike cycling race in amateur cyclists using HRV as an outcome measure.MethodsSixteen healthy participants (male and female) participating in a 3-day mountain bike cycling race underwent five-minute resting electrocardiography recordings in a supine position 2 days before the race (baseline testing). In addition, HRV measurements were recorded after each race day and 24 h post-race (recovery).ResultsTime-domain and frequency-domain measures showed significant changes from baseline HRV parameters after each race day (p ≤ 0.05). In addition, our data revealed that the mean heart rate and R–R variability intervals did not return to baseline values after 24 h of recovery. Thus, autonomic nervous system (ANS) alterations may be due to changes in cardiac sympatho-vagal balance.ConclusionsThe main strength of this study is using HRV as a measuring and screening tool to assess cardiac autonomic activity, whereby the state of the ANS before and after endurance races can be measured. Thus, physicians, athletes, and coaches can determine the stress of endurance races on the ANS and plan recovery strategies. The reasoning is that if the ANS is in a state of sub-optimal function, susceptible amateur athletes might be at risk for a cardiovascular event or maladaptation due to the endurance race.

Effects of chronic secondhand smoke exposure on cardiovascular regulation and the role of soluble epoxide hydrolase in mice.

Background: Secondhand smoke (SHS) is a significant risk factor for cardiovascular morbidity and mortality with an estimated 80% of SHS-related deaths attributed to cardiovascular causes. Public health measures and smoking bans have been successful both in reducing SHS exposure and improving cardiovascular outcomes in non-smokers. Soluble epoxide hydrolase (sEH) inhibitors have been shown to attenuate tobacco exposure-induced lung inflammatory responses, making them a promising target for mitigating SHS exposure-induced cardiovascular outcomes. Objectives: The objectives of this study were to determine 1) effects of environmentally relevant SHS exposure on cardiac autonomic function and blood pressure (BP) regulation and 2) whether prophylactic administration of an sEH inhibitor (TPPU) can reduce the adverse cardiovascular effects of SHS exposure. Methods: Male C57BL/6J mice (11weeks old) implanted with BP/electrocardiogram (ECG) telemetry devices were exposed to filtered air or 3mg/m3 of SHS (6hr/d, 5d/wk) for 12weeks, followed by 4weeks of recovery in filtered air. Some mice received TPPU in drinking water (15mg/L) throughout SHS exposure. BP, heart rate (HR), HR variability (HRV), baroreflex sensitivity (BRS), and BP variability were determined monthly. Results: SHS exposure significantly decreased 1) short-term HRV by ∼20% (p < 0.05) within 4weeks; 2) overall HRV with maximum effect at 12weeks (-15%, p < 0.05); 3) pulse pressure (-8%, p < 0.05) as early as week 4; and 4) BRS with maximum effect at 12weeks (-11%, p < 0.05). Four weeks of recovery following 12weeks of SHS ameliorated all SHS-induced cardiovascular detriments. Importantly, mice exposed to TPPU in drinking water during SHS-related exposure were protected from SHS cardiovascular consequences. Discussion: The data suggest that 1) environmental relevant SHS exposure significantly alters cardiac autonomic function and BP regulation; 2) cardiovascular consequences from SHS can be reversed by discontinuing SHS exposure; and 3) inhibiting sEH can prevent SHS-induced cardiovascular consequences.