Search

Introduction: Thermal atrial fibrillation (AF) ablation exerts an additive treatment effect on the cardiac autonomic nervous system (CANS). This effect is mainly reported during ablation of the right superior pulmonary vein (RSPV), modulating the right anterior ganglionated plexus (RAGP), which contains parasympathetic innervation to the sinoatrial node in the epicardial fat pad between RSPV and superior vena cava (SVC). However, a variable response to neuromodulation after ablation is observed, with little to no effect in some patients. Our objective was to assess clinical and anatomic predictors of thermal ablation‐induced CANS changes, as assessed via variations in heart rate (HR) postablation. Methods: Consecutive paroxysmal AF patients undergoing first‐time PV isolation by the cryoballoon (CB) or radiofrequency balloon (RFB) within a 12‐month time frame and with preprocedural cardiac computed tomography (CT), were evaluated. Preablation and 24‐h postablation electrocardiograms in sinus rhythm were collected and analyzed to assess HR. Anatomic evaluation by CT included the measurement of the shortest distance between the SVC and RSPV ostium (RSPV‐SVC distance). Results: A total of 97 patients (CB, n = 50 vs. RFB, n = 47) were included, with similar baseline characteristics between both groups. A significant HR increase postablation (ΔHR ≥ 15 bpm) occurred in a total of 37 patients (38.1%), without difference in number of patients between both thermal ablation technologies (CB, 19 [51%]), RFB, 18 [49%]). Independent predictors for increased HR were RSPV‐SVC distance (odds ratio [OR]: 0.49, CI: 0.34–0.71, p value <.001), and age (OR: 0.94, CI: 0.89–0.98, p value =.003). Conclusions: Thermal balloon‐based PV isolation influences the CANS through its effect on the RAGP, especially in younger patients and patients with shorter RSPV‐SVC distance. [ABSTRACT FROM AUTHOR]

The cardiac autonomic nervous system plays a key role in maintaining normal cardiac physiology, and once disrupted, it worsens the cardiac disease states. Neuromodulation therapies have been emerging as new treatment options, and various techniques have been introduced to mitigate autonomic nervous imbalances to help cardiac patients with their disease conditions and symptoms. In this review article, we discuss various neuromodulation techniques used in clinical settings to treat cardiac diseases. [ABSTRACT FROM AUTHOR]

This study aims to analyze the vein of Marshall (VOM) in human autopsy hearts and its correlation with clinical data to elucidate the morphological substrates of atrial fibrillation (AF) and other cardiac diseases. Twenty‐three adult autopsy hearts were studied, assessing autonomic nerves by immunohistochemistry with tyrosine hydroxylase (sympathetic nerves), choline acetyltransferase (parasympathetic nerves), growth‐associated protein 43 (neural growth), and S100 (general neural marker) antibodies. Interstitial fibrosis was assessed by Masson trichrome staining. Measurements were conducted via morphometric software. The results were correlated with clinical data. Sympathetic innervation was abundant in all VOM‐adjacent regions. Subjects with a history of AF, cardiovascular cause of death, and histologically verified myocardial infarction had increased sympathetic innervation and neural growth around the VOM at the mitral isthmus. Interstitial fibrosis increased with age and heart weight was associated with AF and cardiovascular cause of death. This study increases our understanding of the cardiac autonomic innervation in the VOM area in various diseases, offering implications for the development of new therapeutic approaches targeting the autonomic nervous system. [ABSTRACT FROM AUTHOR]

Background Heart failure with reduced ejection fraction is associated with potentially deleterious imbalance of the cardiac autonomic nervous system. Sacubitril/valsartan (angiotensin receptor‐neprilysin inhibitor [ARNI]) reduces cardiovascular mortality and hospitalization for heart failure with reduced ejection fraction. Whether ARNI affects the cardiac autonomic nervous system has not been studied. Methods and Results This investigator‐initiated, prospective, single‐center cohort study compared heart rate (HR) variability, HR, deceleration capacity, and periodic repolarization dynamics as noninvasive measures of the cardiac autonomic nervous system before and after initiation of ARNI therapy. Patients underwent standardized 12‐lead Holter‐ECG, echocardiography and laboratory testing before and 3 months after start of therapy. End points were changes in HR variability (SD of normal‐to‐normal intervals, mean square of differences between consecutive R‐R intervals), HR, deceleration capacity, and periodic repolarization dynamics as well as ventricular function and NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide). Of 63 patients with heart failure with reduced ejection fraction enrolled, 48 (76.2%) patients were still on ARNI at follow‐up. SD of normal‐to‐normal intervals increased from 25 to 36 milliseconds (P

This article discusses the potential of cardiopulmonary nerve stimulation (CPNS) as a therapy for heart failure patients. It explores the mechanisms of CPNS and its effects on the cardiac autonomic nervous system. The article highlights the importance of stimulation parameters and the stimulation of ganglionated plexi. CPNS has the potential to improve cardiac function and reduce symptoms in heart failure patients, but further research is needed. The document also provides a comprehensive list of references for further research on the autonomic nervous system and its role in cardiac function and dysfunction. [Extracted from the article]

Simple Summary: The cardiac autonomic nervous system (CANS) controls all cardiac functions in physiology and pathology. The first intracardiac level of this system, namely the intrinsic cardiac nervous system (ICNS), has long been considered a pure parasympathetic efferent station, while it is now clear that it contains all the elements of a neuronal network. In the current review, we will focus on the role of the ICNS in cardiac physiology and pathology, and on the rationale and the results of therapeutic intervention performed so far at this level of cardiac neuraxis. The cardiac autonomic nervous system (CANS) plays a pivotal role in cardiac homeostasis as well as in cardiac pathology. The first level of cardiac autonomic control, the intrinsic cardiac nervous system (ICNS), is located within the epicardial fat pads and is physically organized in ganglionated plexi (GPs). The ICNS system does not only contain parasympathetic cardiac efferent neurons, as long believed, but also afferent neurons and local circuit neurons. Thanks to its high degree of connectivity, combined with neuronal plasticity and memory capacity, the ICNS allows for a beat-to-beat control of all cardiac functions and responses as well as integration with extracardiac and higher centers for longer-term cardiovascular reflexes. The present review provides a detailed overview of the current knowledge of the bidirectional connection between the ICNS and the most studied cardiac pathologies/conditions (myocardial infarction, heart failure, arrhythmias and heart transplant) and the potential therapeutic implications. Indeed, GP modulation with efferent activity inhibition, differently achieved, has been studied for atrial fibrillation and functional bradyarrhythmias, while GP modulation with efferent activity stimulation has been evaluated for myocardial infarction, heart failure and ventricular arrhythmias. Electrical therapy has the unique potential to allow for both kinds of ICNS modulation while preserving the anatomical integrity of the system. [ABSTRACT FROM AUTHOR]

A novel concept is described concerning the possible effect of right ventricular pacing stimulation being detected by the cardiac autonomic nervous system and through its afferent neuronal connection to the central autonomic nervous system (spinal cord) causing reversal or attenuation of the vasovagal reflex. This could be a direct effect of electrical stimulation or may occur by the known adverse consequences on ventricular synchrony induced by stimulation which could be right ventricular site and timing in the evolution of the vasovagal reflex dependent.

The cardiac autonomic nervous system (CANS) plays a pivotal role in cardiac homeostasis as well as in cardiac pathology. The first level of cardiac autonomic control, the intrinsic cardiac nervous system (ICNS), is located within the epicardial fat pads and is physically organized in ganglionated plexi (GPs). The ICNS system does not only contain parasympathetic cardiac efferent neurons, as long believed, but also afferent neurons and local circuit neurons. Thanks to its high degree of connectivity, combined with neuronal plasticity and memory capacity, the ICNS allows for a beat-to-beat control of all cardiac functions and responses as well as integration with extracardiac and higher centers for longer-term cardiovascular reflexes. The present review provides a detailed overview of the current knowledge of the bidirectional connection between the ICNS and the most studied cardiac pathologies/conditions (myocardial infarction, heart failure, arrhythmias and heart transplant) and the potential therapeutic implications. Indeed, GP modulation with efferent activity inhibition, differently achieved, has been studied for atrial fibrillation and functional bradyarrhythmias, while GP modulation with efferent activity stimulation has been evaluated for myocardial infarction, heart failure and ventricular arrhythmias. Electrical therapy has the unique potential to allow for both kinds of ICNS modulation while preserving the anatomical integrity of the system.

A novel concept is described concerning the possible effect of right ventricular pacing stimulation being detected by the cardiac autonomic nervous system and through its afferent neuronal connection to the central autonomic nervous system (spinal cord) causing reversal or attenuation of the vasovagal reflex. This could be a direct effect of electrical stimulation or may occur by the known adverse consequences on ventricular synchrony induced by stimulation which could be right ventricular site and timing in the evolution of the vasovagal reflex dependent. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most common form of cardiac arrhythmia, affecting 2%–3% of the world's population. Mental and emotional stress, as well as some mental health conditions (e.g., depression) have been shown to significantly impact the heart and have been suggested to act both as independent risk factors and triggers in the onset of AF. In this paper, we review the current literature to examine the role that mental and emotional stress have in the onset of AF and summarise the current knowledge on the interaction between the brain and heart, and the cortical and subcortical pathways involved in the response to stress. Review of the evidence suggests that mental and emotional stress negatively affect the cardiac system, potentially increasing the risk for developing and/or triggering AF. Further studies are required to further understand the cortical and sub-cortical structures involved in the mental stress response and how these interact with the cardiac system, which may help in defining new strategies and interventions to prevent the development of, and improve the management of AF.

Autonomic dysregulation in cardiovascular disease plays a major role in the pathogenesis of arrhythmias. Cardiac neural control relies on complex feedback loops consisting of efferent and afferent limbs, which carry sympathetic and parasympathetic signals from the brain to the heart and sensory signals from the heart to the brain. Cardiac disease leads to neural remodeling and sympathovagal imbalances with arrhythmogenic effects. Preclinical studies of modulation at central and peripheral levels of the cardiac autonomic nervous system have yielded promising results, leading to early stage clinical studies of these techniques in atrial fibrillation and refractory ventricular arrhythmias, particularly in patients with inherited primary arrhythmia syndromes and structural heart disease. However, significant knowledge gaps in basic cardiac neurophysiology limit the success of these neuromodulatory therapies. This review discusses the recent advances in neuromodulation for cardiac arrhythmia management, with a clinical scenario-based approach aimed at bringing neurocardiology closer to the realm of the clinical electrophysiologist.

PURPOSE OF REVIEW:This review aims to describe the latest advances in autonomic neuromodulation approaches to treating cardiac arrhythmias, with a focus on ventricular arrhythmias. RECENT FINDINGS:The increasing understanding of neuronal remodeling in cardiac diseases has led to the development and improvement of novel neuromodulation therapies targeting multiple levels of the autonomic nervous system. Thoracic epidural anesthesia, spinal cord stimulation, stellate ganglion modulatory therapies, vagal stimulation, renal denervation, and interventions on the intracardiac nervous system have all been studied in preclinical models, with encouraging preliminary clinical data. The autonomic nervous system regulates all the electrical processes of the heart and plays an important role in the pathophysiology of cardiac arrhythmias. Despite recent advances in the clinical application of cardiac neuromodulation, our comprehension of the anatomy and function of the cardiac autonomic nervous system is still limited. Hopefully in the near future, more preclinical data combined with larger clinical trials will lead to further improvements in neuromodulatory treatment for heart rhythm disorders.

It is proven that music listening can have a therapeutic impact in many clinical fields. However, to assume a curative value, musical stimuli should have a therapeutic logic. This study aimed at assessing short-term effects of algorithmic music on cardiac autonomic nervous system activity. Twenty-two healthy subjects underwent a crossover study including random listening to relaxing and activating algorithmic music. Electrocardiogram (ECG) and non-invasive arterial blood pressure were continuously recorded and were later analyzed to measure Heart Rate (HR) mean, HR variability and baroreflex sensitivity (BRS). Statistical analysis was performed using a general linear model, testing for carryover, period and treatment effects. Relaxing tracks decreased HR and increased root mean square of successive squared differences of normal-to-normal (NN) intervals, proportion of interval differences of successive NN intervals greater than 50 ms, low-frequency (LF) and high-frequency (HF) power and BRS. Activating tracks caused almost no change or an opposite effect in the same variables. The difference between the effects of the two stimuli was statistically significant in all these variables. No difference was found in the standard deviation of normal-to-normal RR intervals, LFpower in normalized units and LFpower/HFpower variables. The study suggests that algorithmic relaxing music increases cardiac vagal modulation and tone. These results open interesting perspectives in various clinical areas. [ABSTRACT FROM AUTHOR]

Background: Heart failure with reduced ejection fraction is associated with potentially deleterious imbalance of the cardiac autonomic nervous system. Sacubitril/valsartan (angiotensin receptor-neprilysin inhibitor [ARNI]) reduces cardiovascular mortality and hospitalization for heart failure with reduced ejection fraction. Whether ARNI affects the cardiac autonomic nervous system has not been studied., Methods and Results: This investigator-initiated, prospective, single-center cohort study compared heart rate (HR) variability, HR, deceleration capacity, and periodic repolarization dynamics as noninvasive measures of the cardiac autonomic nervous system before and after initiation of ARNI therapy. Patients underwent standardized 12-lead Holter-ECG, echocardiography and laboratory testing before and 3 months after start of therapy. End points were changes in HR variability (SD of normal-to-normal intervals, mean square of differences between consecutive R-R intervals), HR, deceleration capacity, and periodic repolarization dynamics as well as ventricular function and NT-proBNP (N-terminal pro-B-type natriuretic peptide). Of 63 patients with heart failure with reduced ejection fraction enrolled, 48 (76.2%) patients were still on ARNI at follow-up. SD of normal-to-normal intervals increased from 25 to 36 milliseconds ( P <0.001), mean square of differences between consecutive R-R intervals increased from 12 to 19 milliseconds ( P <0.001), HR decreased from 73±9 bpm to 67±4 bpm, ( P <0.001), and deceleration capacity increased from 2.1 to 4.4 milliseconds ( P <0.001). A trend for periodic repolarization dynamics reduction was observed (5.6 deg 2 versus 4.7 deg 2 , P =0.09). Autonomic changes were accompanied by increased left ventricular ejection fraction (29±6% versus 40±8%, P <0.001) and reduced NT-proBNP (3548 versus 685 ng/L, P <0.001). Correlation analysis showed a significant relationship between volume-unloading (as evidenced by NT-proBNP reduction) and autonomic improvement., Conclusions: Three months of ARNI therapy resulted in a significant increase in cardiac parasympathetic tone. The improvement in autonomic properties may be mediated by "volume unloading" and likely contributes to the beneficial effects of ARNI in heart failure with reduced ejection fraction., Registration: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04587947.

Pulmonary vein isolation (PVI) represents the mainstay of atrial fibrillation (AF) ablation, and PVI with cryoballoon catheter (CB) ablation (CB-A) has proven to be as effective and safe as radiofrequency ablation (RF-A). Although AF is initiated by triggers arising from the pulmonary veins (PV) and non-PV foci, the intrinsic cardiac nervous system (ICNS) plays a significant role in the induction and maintenance of AF. The ICNS is an epicardial neural system composed of ganglionated plexi (GPs) and a complex network of interconnecting neurons. In the left atrium, the major GPs are located in proximity to the PV-left atrial junction. Vagal reactions have been described as markers of autonomic modulation during PVI with both RF-A and CB-A. The occurrence of neuromodulation during PVI with CB-A may be explained by both the anatomical relationship between the GPs and the PVs and the characteristics of the CB. Due to the CB/PV size mismatch, the CB creates a wide ablation area that extends from the PV ostium toward the antrum, possibly including the GPs. Although targeted GPs ablation, as a supplemental strategy to PVI, has been associated with a better AF outcome in patients undergoing RF-A, the additional clinical benefit of neuromodulation during PVI with CB-A remains a matter of debate. In this review, we provide an overview of the anatomy of the ICNS, the relationship between the ICNS and AF pathophysiology, and the current evidence on the clinical relevance of neuromodulation during PVI with CB-A.

Background: It is increasingly popular to use heart-rate variability (HRV) to tailor training for athletes. A time-efficient method is HRV assessment during deep sleep. Aim: To validate the selection of deep-sleep segments identified by RR intervals with simultaneous electroencephalography (EEG) recordings and to compare HRV parameters of these segments with those of standard morning supine measurements. Methods: In 11 world-class alpine skiers, RR intervals were monitored during 10 nights, and simultaneous EEGs were recorded during 2-4 nights. Deep sleep was determined from the HRV signal and verified by delta power from the EEG recordings. Four further segments were chosen for HRV determination, namely, a 4-h segment from midnight to 4 AM and three 5-min segments: 1 just before awakening, 1 after waking in supine position, and 1 in standing after orthostatic challenge. Training load was recorded every day. Results: A total of 80 night and 68 morning measurements of 9 athletes were analyzed. Good correspondence between the phases selected by RR intervals vs those selected by EEG was found. Concerning root-mean-squared difference of successive RR intervals (RMSSD), a marker for parasympathetic activity, the best relationship with the morning supine measurement was found in deep sleep. Conclusion: HRV is a simple tool for approximating deep-sleep phases, and HRV measurement during deep sleep could provide a time-efficient alternative to HRV in supine position. [ABSTRACT FROM AUTHOR]

Background and Aims: Cardiovascular disease (CVD) is the leading cause of death in patients with non-alcoholic fatty liver disease (NAFLD), both with and without type 2 diabetes mellitus (T2DM). Cardiac autonomic dysfunction is a risk factor for CVD morbidity and mortality. The aim of this pilot study was to assess whether there is an association between NAFLD and impaired cardiac autonomic function.Methods and Results: Among the first 4979 participants from the Cooperative Health Research in South Tyrol (CHRIS) study, we randomly recruited 173 individuals with T2DM and 183 age- and sex-matched nondiabetic controls. Participants underwent ultrasonography and vibration-controlled transient elastography (Fibroscan®, Echosens) to assess hepatic steatosis and liver stiffness. The low-to-high-frequency (LF/HF) power ratio and other heart rate variability (HRV) measures were calculated from a 20-min resting electrocardiogram (ECG) to derive a measure of cardiac sympathetic/parasympathetic imbalance. Among the 356 individuals recruited for the study, 117 had NAFLD and T2DM, 56 had T2DM alone, 68 had NAFLD alone, and 115 subjects had neither condition. Individuals with T2DM and NAFLD (adjusted odds ratio [OR] 4.29, 95% confidence intervals [CI] 1.90-10.6) and individuals with NAFLD alone (adjusted OR 3.41, 95% CI 1.59-7.29), but not those with T2DM alone, had a substantially increased risk of having cardiac sympathetic/parasympathetic imbalance, compared with those without NAFLD and T2DM. Logistic regression models were adjusted for age, sex, body mass index (BMI), hypertension, dyslipidemia, insulin resistance, hemoglobin A1c (HbA1c), C-reactive protein (CRP), and Fibroscan®-measured liver stiffness.Conclusions: NAFLD was associated with cardiac sympathetic/parasympathetic imbalance, regardless of the presence or absence of T2DM, liver stiffness, and other potential confounding factors. [ABSTRACT FROM AUTHOR]

Heart rate variability (HRV) is an index which can accurately reflect the activity of cardiac autonomic nervous system. By improving HRV analysis via ambulatory electrocardiographic examination, the sympathetic nerve and vagus nerve tension, and their balance state can be quantitatively evaluated with a combination of time- and frequency-domain analysis. Based on the regulatory mechanism of HRV, this review intends to interpret the clinical significance of time- and frequency-domain analysis indexes. Combined with recent clinical researches and meta-analysis related to HRV in the fields of coronary atherosclerotic cardiopathy, primary hypertension, heart failure and atrial fibrillation, this paper also reviews the clinical application of HRV testing and analysis in the field of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

One way to analyze the function of the autonomic nervous system (ANS) is through heart rate variability (HRV). This approach is based on the analysis of the distance between the peaks of two consecutive R waves expressed in electrocardiograms. HRV evaluations have been developed and have become more accessible and reliable through technological advances that enable the data collection in a simpler, non‐invasive, and reliable way. However, there is little information in the scientific literature on the implementation of this methodology to assess the ANS of preterm infants. In this article, we survey the barriers, potential uses, and other topics regarding the assessment of the ANS in preterm infants using HRV. [ABSTRACT FROM AUTHOR]

Objectives: Functional development of the fetal cardiac autonomic nervous system (cANS) plays a key role in fetal maturation and can be assessed through fetal heart rate variability (fHRV)‐analysis, with each HRV parameter representing different aspects of cANS activity. Current available techniques, however, are unable to assess the fHRV parameters accurately throughout the whole pregnancy. This study aims to test the feasibility of color tissue Doppler imaging (cTDI) as a new ultrasound technique for HRV analysis. Secondly, we explored time trends of fHRV parameters using this technique. Methods: 18 healthy singleton fetuses were examined sequentially every 8 weeks from 10 weeks GA onwards. From each examination, 3 cTDI recordings of the four‐chamber view of 10 seconds were retrieved to determine accurate beat‐to‐beat intervals. The fHRV parameters SDNN, RMSSD, SDNN/RMSSD, and pNN10, each representing different functional aspects of the cANS, were measured, and time trends during pregnancy were explored using spline functions within a linear mixed‐effects model. Results: In total, 77% (95% Cl 66–87%) of examinations were feasible for fHRV analysis from the first trimester onwards, which is a great improvement compared to other techniques. The technique is able to determine different maturation rates of the fHRV parameters, showing that cANS function, presumably parasympathetic activity, establishes around 20 weeks GA and matures rapidly until 30 weeks GA. Conclusions: This is the first study able to assess cANS function through fHRV analysis from the first trimester onwards. The use of cTDI to determine beat‐to‐beat intervals seems feasible in just 3 clips of 10 seconds, which holds promise for future clinical use in assessing fetal well‐being. [ABSTRACT FROM AUTHOR]

Abstract Background Premature infants may present with damage to the autonomic nervous system (ANS), which may be related to poorer neurological development. Among the techniques used to evaluate the ANS, heart rate variability (HRV) emerged as a simple, non-invasive, and easy to apply tool. The aim of the present study was to analyze and compare HRV in preterm infants at different times of hospitalization in order to verify the possible environmental relationships or clinical evolution with HRV. Methods A longitudinal, prospective, and descriptive study with non-probabilistic sampling composed of 25 collections of preterm infants of HRV at two moments: moment I (within 15 days of birth) and moment II (after 45 days post-birth). The Polar V800 heart rate monitor was used with the Polar H10 cardiac transducer to collect HRV, which was collected in the supine position for 15 min. The HRV data were analyzed by the linear method in frequency domain and time domain and by the nonlinear method using Kubios HRV analysis software, version 3.0.2. Results There was an increase in HRV values at moment II, these being statistically significant in the SD1, ApEn, and SampEn. Data related to increased sympathetic nervous system activity, parasympathetic nervous system activity, and increased index complexity. Conclusions The data demonstrate an increase in HRV values in premature infants at moment II, demonstrating a possible development in the maturation of the ANS during hospitalization. Trial registration: RBR-3x7gz8 retrospectively registered.

Background: The incidence and influence of vagal response (VR) observed during cryoballoon-based pulmonary vein isolation (CBA-based PVI) on the cardiac autonomic nervous system (CANS) and ablation outcomes in paroxysmal atrial fibrillation (PAF) remain unknown. Methods: 296 patients were treated with a 28 mm second-generation cryoballoon (Medtronic). A total of 74 patients without structural heart disease and concomitant diseases were chosen for a detailed CANS assessment with a heart rate variability (HRV) analysis. All patients were screened over a 2-year post-ablation period. Results: VR was detected in 30% of patients and included sinus arrest (64%) or severe sinus bradycardia (46%). The presence of VR was not related to PV ostial dimension, patient clinical characteristics or intraprocedural ablation details. CANS modulation, manifesting as increased median HR and decreased HRV parameters with intact sympatho-vagal balance occurred independently of VR presence or absence and sustained for at least 12 months following ablation. VR was not related with more intensive CANS modulation and did not translate into better ablation outcomes when compared to the non-VR group (74% vs. 71% at 12 months and 69% vs. 65% at 24 months respectively). Conclusions: VR is frequent during CBA-based PVI for PAF and unrelated to any additional clinical benefit.

Cardiac arrhythmias occur frequently in patients with acute stroke, with atrial fibrillation (AF) being the most common. Newly detected AF may lead to increased risk of ischemic stroke, which in turn generates stroke recurrence and adverse outcomes. Currently, most studies are focusing on the role of AF in ischemic stroke and attributing cryptogenic ischemic stroke to previously undetected AF. However, in these studies, subjects used to have neither symptoms of palpitation nor evidence of AF. A better understanding of this association will contribute to the management and therapy for patients after clinical decisions regarding stroke patients. Currently, the definition of newly detected AF has not come to an agreement, and the pathophysiology remains incompletely understood, possibly involving complex alterations in both the autonomic network and humoral regulation. Therefore, this review aims to introduce the definition and epidemiology of newly detected AF after stroke with updated information and elucidate the potential pathophysi-ology, such as autonomic imbalance, catecholamine surge, poststroke systematic inflammation, and microvesicles and microRNAs. [ABSTRACT FROM AUTHOR]

Objective: In two independent study arms, we determine the effects of strength training (ST) and high-intensity interval training (HIIT) overload on cardiac autonomic modulation by measuring heart rate (HR) and vagal heart rate variability (HRV).Methods: In the study, 37 well-trained athletes (ST: 7 female, 12 male; HIIT: 9 female, 9 male) were subjected to orthostatic tests (HR and HRV recordings) each day during a 4-day baseline period, a 6-day overload microcycle, and a 4-day recovery period. Discipline-specific performance was assessed before and 1 and 4 days after training.Results: Following ST overload, supine HR, and vagal HRV (Ln RMSSD) were clearly increased and decreased (small effects), respectively, and the standing recordings remained unchanged. In contrast, HIIT overload resulted in decreased HR and increased Ln RMSSD in the standing position (small effects), whereas supine recordings remained unaltered. During the recovery period, these responses were reversed (ST: small effects, HIIT: trivial to small effects). The correlations between changes in HR, vagal HRV measures, and performance were weak or inconsistent. At the group and individual levels, moderate to strong negative correlations were found between HR and Ln RMSSD when analyzing changes between testing days (ST: supine and standing position, HIIT: standing position) and individual time series, respectively. Use of rolling 2–4-day averages enabled more precise estimation of mean changes with smaller confidence intervals compared to single-day values of HR or Ln RMSSD. However, the use of averaged values displayed unclear effects for evaluating associations between HR, vagal HRV measures, and performance changes, and have the potential to be detrimental for classification of individual short-term responses.Conclusion: Measures of HR and Ln RMSSD during an orthostatic test could reveal different autonomic responses following ST or HIIT which may not be discovered by supine or standing measures alone. However, these autonomic changes were not consistently related to short-term changes in performance and the use of rolling averages may alter these relationships differently on group and individual level.

Left cardiac sympathetic denervation (LCSD) is a surgical antiadrenergic intervention with a strong antiarrhythmic effect, supported by preclinical as well as clinical data. The mechanism of action of LCSD in structurally normal hearts with increased arrhythmic susceptibility (such as those of patients with channelopathies) is not limited to the antagonism of acute catecholamines release in the heart. LCSD also conveys a strong anti-fibrillatory action that was first demonstrated over 40 years ago and provides the rationale for its use in almost any cardiac condition at increased risk of ventricular fibrillation. The molecular mechanisms involved in the final antiarrhythmic effect of LCSD turned out to be much broader than anticipated. Beside the vagotonic effect at different levels of the neuraxis, other new mechanisms have been recently proposed, such as the antagonism of neuronal remodeling, the antagonism of neuropeptide Y effects, and the correction of neuronal nitric oxide synthase (nNOS) imbalance. The beneficial effects of LCSD have never been associated with a detectable deterioration of cardiac performance. Finally, patients express a high degree of satisfaction with the procedure. In this review, we focus on the rationale, results and our personal approach to LCSD in patients with channelopathies such as long QT syndrome and catecholaminergic polymorphic ventricular tachycardia.

The cardiac autonomic nervous system (CANS) is associated with modulation of cardiac electrophysiology and arrhythmogenesis. In this mini review, we will briefly introduce cardiac autonomic anatomy and autonomic activity in ventricular arrhythmias (VAs) and discuss novel approaches of CANS modulation for treating VAs. Studies over the decades have provided a better understanding of cardiac autonomic innervation and revealed overwhelming evidence of the relationship between autonomic tone and VAs. A high sympathetic tone and low parasympathetic (vagal) tone are considered as the major triggers of VAs in patients with myocardial ischemia, which can cause sudden cardiac death. In recent years, novel methods of autonomic neuromodulation have been investigated to prevent VAs, and they have been verified as being beneficial for malignant VAs in animal models and humans. The clinical outcome of autonomic neuromodulation depends on the level of cardiac neuraxis, stimulation parameters, and patient’s pathological status. Since autonomic modulation for VA treatment is still in the early stage of clinical application, more basic and clinical studies should be performed to clarify these mechanisms and optimize autonomic neuromodulation therapies for patients with VAs in the future.

Aims: The purpose of this study was to evaluate the contribution in the acute loss in vagal innervation after ablation with the second generation cryoballoon (CB-A) in each distinct pulmonary vein (PV) by means of external cardiac vagal stimulation (ECVS) by positioning a catheter in the internal jugular vein in a cohort of 60 patients. Methods: Sixty patients, 50 starting from the left superior pulmonary vein (LSPV) and 10 from the right superior pulmonary vein with symptomatic paroxysmal atrial fibrillation (PAF), having undergone ECVS before the first and after each PV ablation by means of CB-A ablation, were included. Results: The ECVS performed pre-ablation provoked cardioinhibitory responses in all cases with mean pause duration of 10251.83 ms ± 2826.23 ms. At the end of the procedure, the vagal reactions (VR) were significantly diminished. Specifically, compared against the initial pause, responses were 8957.06 ± 2711.66 ms (p < 0.01) after left superior PV, 10017.36 ± 9127.0 ms (p = 0.88) after left inferior PV, 6020.16 ± 3780.709 ms (p < 0.001) after right inferior PV and 1687.5 ± 2183.7 ms (p < 0.001) after right superior PV. Noteworthy, if starting with ablation in the RSPV, VR was immediately reduced by 90.34%, 990.7 ± 379.78 ms (p < 0.001) as compared to baseline response. Conclusions: Although not directly targeting the ganglion plexuses, AF ablation with the CB-A causes a significant acute loss in parasympathetic innervation. The RSPV showed to be associated with the most significant reduction of acute loss in parasympathetic innervation. [ABSTRACT FROM AUTHOR]

Aims: Acute lymphoblastic leukemia (ALL) is one of the leading malignancies in children worldwide. The cardiotoxicity of anti-cancer treatments leads to a dysfunction of the cardiac autonomic nervous system. Protection strategies, with dexrazoxane treatments, were used to counter these adverse effects. The aim of this study was to investigate the effects of the treatments on the cardiac autonomic nervous system. Methods and results: A total of 203 cALL survivors were included in our analyses and were classified into 3 categories based on the prognostic risk group: standard risk, high risk with and without dexrazoxane. A 24-h Holter monitoring was performed to study the cardiac autonomic nervous system. The frequency domain heart rate variability (HRV) was used to validate the cardiac autonomic nervous system modifications. Other analyses were performed using linear HRV indexes in the time domain and non-linear indexes. A frequency domain HRV parameters analysis revealed significant differences on an overall time-period of 24 h. A repeated measures ANOVA indicated a group-effect for the low frequency (p = 0.029), high frequency (p = 0.03) and LF/HF ratio (p = 0.029). Significant differences in the time domain and in the non-linear power spectral density HRV parameters were also observed. Conclusion: Anti-cancer treatments induced significant changes in the cardiac autonomic nervous system. The HRV was sensitive enough to detect cardiac autonomic nervous system alterations depending on the cALL risk category. Protection strategies (i.e., dexrazoxane treatments), which were used to counter the adverse effects of doxorubicin, could prevent changes observed in the cardiac autonomic nervous system. [ABSTRACT FROM AUTHOR]

Background: Premature infants may present with damage to the autonomic nervous system (ANS), which may be related to poorer neurological development. Among the techniques used to evaluate the ANS, heart rate variability (HRV) emerged as a simple, non-invasive, and easy to apply tool. The aim of the present study was to analyze and compare HRV in preterm infants at different times of hospitalization in order to verify the possible environmental relationships or clinical evolution with HRV.Methods: A longitudinal, prospective, and descriptive study with non-probabilistic sampling composed of 25 collections of preterm infants of HRV at two moments: moment I (within 15 days of birth) and moment II (after 45 days post-birth). The Polar V800 heart rate monitor was used with the Polar H10 cardiac transducer to collect HRV, which was collected in the supine position for 15 min. The HRV data were analyzed by the linear method in frequency domain and time domain and by the nonlinear method using Kubios HRV analysis software, version 3.0.2.Results: There was an increase in HRV values at moment II, these being statistically significant in the SD1, ApEn, and SampEn. Data related to increased sympathetic nervous system activity, parasympathetic nervous system activity, and increased index complexity.Conclusions: The data demonstrate an increase in HRV values in premature infants at moment II, demonstrating a possible development in the maturation of the ANS during hospitalization.Trial Registration: RBR-3x7gz8 retrospectively registered. [ABSTRACT FROM AUTHOR]

This study evaluated the associations between cardiac autonomic nervous system (ANS) activity and cardiometabolic disease (CMD) risk factors among black South African children. The participants included 34 black South African children (11.85 ± 0.89 y). CMD risk factors included waist circumference (WC), hip circumference (HC), body mass index z-score (BMI z-score), blood pressure (SBP, DBP), total cholesterol (TC), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), fasting glucose (FG), fasting insulin (FINS), and vessel stiffness index (SI). Heart rate variability was used to quantify cardiac ANS activity. lnRMSSD, pNN50 and lnSD1 were inversely associated with FINS (r = −0.33, p = 0.05; r = −0.36, p = 0.03; r = −0.41, p = 0.01), WC (r = −0.45, p = 0.01; r = −0.39, p = 0.02; r = −0.45, p = 0.01), and HC (r = −0.41, p = 0.01; r = −0.36, p = 0.03; r = −0.43, p = 0.01). HDL was positively associated with lnRMSSD (r = 0.37; p = 0.03) and lnSD1 (r = 0.37; p = 0.03) while, LDL was negatively associated with HF (r = −0.41; p = 0.01). Regression analysis identified WC as the primary predictor for parasympathetic modulation in time domain (lnRMSSD: r2 = 0.21, p = 0.01; pNN50: r2 = 0.18, p = 0.01) and non-linear domain (lnSD1: r2 = 0.21, p = 0.01). Elevated resting parasympathetic activity in children is associated with lower CMD risk factors and an elevation in the protective HDL. [ABSTRACT FROM AUTHOR]

Objective: In two independent study arms, we determine the effects of strength training (ST) and high-intensity interval training (HIIT) overload on cardiac autonomic modulation by measuring heart rate (HR) and vagal heart rate variability (HRV). Methods: In the study, 37 well-trained athletes (ST: 7 female, 12 male; HIIT: 9 female, 9 male) were subjected to orthostatic tests (HR and HRV recordings) each day during a 4-day baseline period, a 6-day overload microcycle, and a 4-day recovery period. Discipline-specific performance was assessed before and 1 and 4 days after training. Results: Following ST overload, supine HR, and vagal HRV (Ln RMSSD) were clearly increased and decreased (small effects), respectively, and the standing recordings remained unchanged. In contrast, HIIT overload resulted in decreased HR and increased Ln RMSSD in the standing position (small effects), whereas supine recordings remained unaltered. During the recovery period, these responses were reversed (ST: small effects, HIIT: trivial to small effects). The correlations between changes in HR, vagal HRV measures, and performance were weak or inconsistent. At the group and individual levels, moderate to strong negative correlations were found between HR and Ln RMSSD when analyzing changes between testing days (ST: supine and standing position, HIIT: standing position) and individual time series, respectively. Use of rolling 2–4-day averages enabled more precise estimation of mean changes with smaller confidence intervals compared to single-day values of HR or Ln RMSSD. However, the use of averaged values displayed unclear effects for evaluating associations between HR, vagal HRV measures, and performance changes, and have the potential to be detrimental for classification of individual short-term responses. Conclusion: Measures of HR and Ln RMSSD during an orthostatic test could reveal different autonomic responses following ST or HIIT which may not be discovered by supine or standing measures alone. However, these autonomic changes were not consistently related to short-term changes in performance and the use of rolling averages may alter these relationships differently on group and individual level. [ABSTRACT FROM AUTHOR]

The cardiac autonomic nervous system (CANS) is associated with modulation of cardiac electrophysiology and arrhythmogenesis. In this mini review, we will briefly introduce cardiac autonomic anatomy and autonomic activity in ventricular arrhythmias (VAs) and discuss novel approaches of CANS modulation for treating VAs. Studies over the decades have provided a better understanding of cardiac autonomic innervation and revealed overwhelming evidence of the relationship between autonomic tone and VAs. A high sympathetic tone and low parasympathetic (vagal) tone are considered as the major triggers of VAs in patients with myocardial ischemia, which can cause sudden cardiac death. In recent years, novel methods of autonomic neuromodulation have been investigated to prevent VAs, and they have been verified as being beneficial for malignant VAs in animal models and humans. The clinical outcome of autonomic neuromodulation depends on the level of cardiac neuraxis, stimulation parameters, and patient's pathological status. Since autonomic modulation for VA treatment is still in the early stage of clinical application, more basic and clinical studies should be performed to clarify these mechanisms and optimize autonomic neuromodulation therapies for patients with VAs in the future. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to investigate the impact of 3 isocaloric exercise programs on cardiac autonomic nervous system (ANS) functioning in children. Methods: One hundred nine children (39% boys and 61% girls) aged 10–13 years (mean 11.07 ± 0.81) were conveniently assigned to 1 of 4 groups as follows: Moderate-intensity continuous training (MICT; n = 29) at 65–70% of the predicted maximum heart rate (MHR), High-intensity interval training (HIIT; n = 29) at > 80% of the predicted MHR, HIIT and MICT combined on alternate weeks (ALT; n = 27), and a control group (n = 24). Morning ANS activity was assessed via analysis of heart rate variability (HRV), with the patient in supine position for 10 min, before and after the exercise intervention. Data Analysis: A 2-way analysis of variance was used to evaluate the effects of training on all HRV parameters (p < 0.05/4 = 0.0125). Results: After 5 weeks of training, significant improvements were observed for ln of the standard deviation of normal-to-normal intervals (p < 0.0001), ln of the root mean square of successive difference (p < 0.0001), and ln of standard deviation 1 (p < 0.0001), with superior results reported in the HIIT group (effect size [ES] = 2.22, 2.69, and 2.69) compared with the MICT (ES = 1.67, 1.75, and 1.75) and ALT (ES = 0.87, 1.06, and 1.06) groups, respectively. Conclusion: Short-term HIIT seems to induce superior alterations in cardiac ANS activity compared to MICT and ALT in children through enhanced vagal activity. [ABSTRACT FROM AUTHOR]

A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an athlete's individual responses to training to optimize the scheduling of training and recovery strategies. Resting and exercise-related heart rate measures have received growing interest in recent decades and are considered potentially useful within multivariate response monitoring, as they provide non-invasive and time-efficient insights into the status of the autonomic nervous system (ANS) and aerobic fitness. In team sports, the practical implementation of athlete monitoring systems poses a particular challenge due to the complex and multidimensional structure of game demands and player and team performance, as well as logistic reasons, such as the typically large number of players and busy training and competition schedules. In this regard, exercise-related heart rate measures are likely the most applicable markers, as they can be routinely assessed during warm-ups using short (3–5 min) submaximal exercise protocols for an entire squad with common chest strap-based team monitoring devices. However, a comprehensive and meaningful monitoring of the training process requires the accurate separation of various types of responses, such as strain, recovery, and adaptation, which may all affect heart rate measures. Therefore, additional information on the training context (such as the training phase, training load, and intensity distribution) combined with multivariate analysis, which includes markers of (perceived) wellness and fatigue, should be considered when interpreting changes in heart rate indices. The aim of this article is to outline current limitations of heart rate monitoring, discuss methodological considerations of univariate and multivariate approaches, illustrate the influence of different analytical concepts on assessing meaningful changes in heart rate responses, and provide case examples for contextualizing heart rate measures using simple heuristics. To overcome current knowledge deficits and methodological inconsistencies, future investigations should systematically evaluate the validity and usefulness of the various approaches available to guide and improve the implementation of decision-support systems in (team) sports practice.

Microgravity-induced alterations in the autonomic nervous system (ANS) contribute to derangements in both the mechanical and electrophysiological function of the cardiovascular system, leading to severe symptoms in humans following space travel. Because the ANS forms embryonically from neural crest (NC) progenitors, we hypothesized that microgravity can impair NC-derived cardiac structures. Accordingly, we conducted in vitro simulated microgravity experiments employing NC genetic lineage tracing in mice with cKitCreERT2/+, Isl1nLacZ, and Wnt1-Cre reporter alleles. Inducible fate mapping in adult mouse hearts and pluripotent stem cells (iPSCs) demonstrated reduced cKitCreERT2/+-mediated labeling of both NC-derived cardiomyocytes and autonomic neurons (P < 0.0005 vs. controls). Whole transcriptome analysis, suggested that this effect was associated with repressed cardiac NC- and upregulated mesoderm-related gene expression profiles, coupled with abnormal bone morphogenetic protein (BMP)/transforming growth factor beta (TGF-β) and Wnt/β-catenin signaling. To separate the manifestations of simulated microgravity on NC versus mesodermal-cardiac derivatives, we conducted Isl1nLacZ lineage analyses, which indicated an approximately 3-fold expansion (P < 0.05) in mesoderm-derived Isl-1+ pacemaker sinoatrial nodal cells; and an approximately 3-fold reduction (P < 0.05) in cardiac NC-derived ANS cells, including sympathetic nerves and Isl-1+ cardiac ganglia. Finally, NC-specific fate mapping with a Wnt1-Cre reporter iPSC model of murine NC development confirmed that simulated microgravity directly impacted the in vitro development of cardiac NC progenitors and their contribution to the sympathetic and parasympathetic innervation of the iPSC-derived myocardium. Altogether, these findings reveal an important role for gravity in the development of NCs and their postnatal derivatives, and have important therapeutic implications for human space exploration, providing insights into cellular and molecular mechanisms of microgravity-induced cardiomyopathies/channelopathies. [ABSTRACT FROM AUTHOR]

Reduced heart rate (HR) variability in preterm infants compared with full-term infants suggests that autonomic cardiac control is developmentally delayed. However, the association between developmental changes in myocardial repolarization and gestational age remains unknown. This study investigated the association between the myocardial repolarization lability index, namely the QT variability index (QTVI) = log10 [(QTv/QTm2)/(HRv/HRm2)], and the perinatal profile of healthy 1-month-old infants. We included 209 infants (143 boys and 87 girls; mean gestational weeks at birth, 38.6 ± 1.7) who were born in university hospitals between 2014 and 2015 without apparent cardiac disease. We compared the ECG variability indices in 28 infants born before 37 gestational weeks (mean gestational weeks at birth, 35.6 ± 1.1 as preterm) and 181 infants born at the average number of gestational weeks (mean gestational weeks at birth, 38.8 ± 1.1 as controls). There was a negative correlation between the QTVI and gestational weeks (r = − 0.460, p = 0.035). QTVI values in preterm infants were larger than those in the controls (0.01 ± 0.50 vs. −0.26 ± 0.48, p = 0.023). In conclusion, the QTVI is negatively correlated with gestational age. The QTVI can serve as an index of the maturity of the cardiac autonomic nervous system and myocardial depolarization. [ABSTRACT FROM AUTHOR]

A comprehensive monitoring of fitness, fatigue, and performance is crucial for understanding an athlete's individual responses to training to optimize the scheduling of training and recovery strategies. Resting and exercise-related heart rate measures have received growing interest in recent decades and are considered potentially useful within multivariate response monitoring, as they provide non-invasive and time-efficient insights into the status of the autonomic nervous system (ANS) and aerobic fitness. In team sports, the practical implementation of athlete monitoring systems poses a particular challenge due to the complex and multidimensional structure of game demands and player and team performance, as well as logistic reasons, such as the typically large number of players and busy training and competition schedules. In this regard, exercise-related heart rate measures are likely the most applicable markers, as they can be routinely assessed during warm-ups using short (3-5min) submaximal exercise protocols for an entire squad with common chest strap-based team monitoring devices. However, a comprehensive and meaningful monitoring of the training process requires the accurate separation of various types of responses, such as strain, recovery, and adaptation, which may all affect heart rate measures. Therefore, additional information on the training context (such as the training phase, training load, and intensity distribution) combined with multivariate analysis, which includes markers of (perceived) wellness and fatigue, should be considered when interpreting changes in heart rate indices. The aim of this article is to outline current limitations of heart rate monitoring, discuss methodological considerations of univariate and multivariate approaches, illustrate the influence of different analytical concepts on assessing meaningful changes in heart rate responses, and provide case examples for contextualizing heart rate measures using simple heuristics. To overcome current knowledge deficits and methodological inconsistencies, future investigations should systematically evaluate the validity and usefulness of the various approaches available to guide and improve the implementation of decision-support systems in (team) sports practice. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Survival after surgical repair of a ventricular septal defect (VSD) is good, but, as in almost all congenital heart diseases, late complications are frequent in adulthood. The exact mechanisms, timing and who is at risk are not fully understood. Altered cardiac autonomic nervous system (ANS) activity might play a role in these long-term sequelae. The aim of this study was to extensively evaluate children late after VSD repair including their cardiac ANS activity, cardiac function and exercise capacity. METHODS: Thirty-three patients after surgical VSD repair and 66 healthy age-matched controls underwent 24-h monitoring of ANS control and cardiac output using impedance cardiography, detailed echocardiography and cardiopulmonary exercise testing. RESULTS: Ambulatory cardiac ANS control was not different between the patients and the controls. Right ventricular function, exercise capacity and ambulatory cardiac output were decreased in patients compared with the controls. No relationships were found between cardiac ANS activity and cardiac function. CONCLUSIONS: Long (average time after repair was 9.9 years) after successful surgical correction of a VSD, cardiac ANS control is not different from the controls. Right ventricular function and exercise capacity are impaired in VSD patients. Post-surgical outcome in these patients may be less benign than presently assumed; therefore, follow-up should be continued into adulthood to detect adverse outcomes in a timely fashion. [ABSTRACT FROM AUTHOR]

BACKGROUND: Autonomic disturbances are a common phenomenon in patients’ post-stroke, characterized by hypo function of the para-sympathetic and/or overactive sympathetic system. The impact of autonomic disturbances on physical therapy tasks during the rehabilitation period has not yet been assessed. OBJECTIVE: To describe the response of the cardiac autonomic nervous system during different tasks, among patients and age-matched healthy controls. METHODS: Nineteen patients in the subacute phase post first-ever ischemic stroke, and 16 controls. The Polar advanced heart rate monitor (RS800CX) was used to record RR intervals at rest, during paced breathing exercise, while performing different types of muscle contractions, and during single and dual task conditions. RESULTS: RR intervals and heart-rate variability (HRV) parameters were significantly lower among patients post stroke, both at rest and during most of the activities tested. Among the control group a significant autonomic adaptation was seen in the form of reduced RR intervals and HRV during muscle contraction and a significant increase in these parameters during slow breathing, no significant changes were observed among patients post stroke. CONCLUSION: Patients post-stroke experience hyper sympathetic function at rest and less adaptive cardiac autonomic control during different activities, which all may have an impact on rehabilitation outcomes. [ABSTRACT FROM AUTHOR]

Background: Poor exercise capacity is an important negative prognostic marker in patients with chronic obstructive pulmonary disease (COPD). Heart rate variability (HRV) responses can indicate alterations in cardiac autonomic control. Nevertheless, it remains unclear whether these abnormalities are related to cardiorespiratory responses to exercise in these patients. Objective: To evaluate whether HRV at rest and submaximal exercise are related to impaired cardiopulmonary responses to exercise in COPD patients. Methods: Fifteen men (66.2 ±8.7 years) with COPD (FEV1: 55.1 ±19.2%) were assessed. The R-R interval (RRi) data collection was performed at rest (stand position) and during the six- minute walk test (6MWT). All patients performed a symptom-limited cardiopulmonary exercise test on a cycle ergometer. The HRV changes from rest to submaximal exercise (Δrest-6MWT) were calculated. Results: We found significant correlations between low frequency (LF) and high frequency (HF) Δ rest-6MWT with Δ oxyhemoglobin saturation by pulse oximetry (r = -0.64 and r = 0.65, respectively; p <0.05), minute ventilation/carbon dioxide output relationship from beginning to peak exercise (r = -0.52 and r = 0.53, p <0.05), and exercise ventilatory power (r = 0.52 and r = -0.53, p <0.05). Interestingly, there was a strong positive correlation (r = 0.82, p <0.05) between six-minute walk distance (6MWD) and Δ LF/HF from rest to exercise. Conclusion: HRV analysis in the transition from rest to submaximal exercise is associated with exercise ventilatory and hemodynamic abnormalities in COPD patients. Rehabilitative strategies to improve HRV responses may provide an important tool to clinical practice in these patients. [ABSTRACT FROM AUTHOR]

We aimed to explore the association between occupational noise exposure duration and heart rate variability (HRV) and the underlying mechanism. A total of 449 subjects in a manufacturing company in Wuhan, China were included in our study and six candidate miRNAs (miR-200a-3p, miR-200b-3p, miR-200c-3p, miR-1-3p, miR-92a-3p and miR-21–5p) were tested among 200 individuals. Information combining the work histories and the occupational noise monitoring records were used to calculate the exposure of occupational noise, HRV indices were measured by using 3-channel digital Holter monitors, including the standard deviation of all normal R-R intervals (SDNN), the root mean of the square of successive differences between adjacent normal NN intervals (r-MSSD), SDNN index, low-frequency power (LF), high-frequency power (HF) and TP (total power). We found a significant linear negative dose-response relationship between occupational noise exposure duration and HRV indices (P for overall <0.05, P for nonlinear >0.05), including SDNN, r-MSSD, SDNN index, LF and HF. In the continuous models, the β (95% CIs) for each 1-year occupational noise exposure were −0.002 (−0.004, −0.001) for SDNN, −0.002 (−0.004, −0.001) for r-MSSD, −0.002 (−0.004, −0.001) for SDNN index, and −0.006 (−0.012, −0.001) for HF. Meanwhile, we also found that occupational noise exposure duration was significantly associated with lower expression of five miRNAs, when adjusting for other covariates. The β (95% CIs) were −0.039 (−0.067, −0.011) for miRNA-200c-3p, −0.053 (−0.083, −0.022) for miRNA-200a-3p, −0.044 (−0.070, −0.019) for miRNA-200b-3p, −0.032 (−0.048, −0.017) for miRNA-92a-3p, and −0.063 (−0.089, −0.038) for miRNA-21–5p in the continuous models. In addition, we found a positive association between miRNA-1-3p and LF (β = 0.039, 95% CI = 0.002, 0.080). Our study suggests that occupational noise exposure duration is associated with cardiac autonomic dysfunction, and the role of miRNAs in noise induced HRV reduction needs to be confirmed in future studies. [Display omitted] • Occupational noise exposure duration is associated with reduced SDNN, SDNN index, and HF. • Occupational noise exposure duration is associated with lower miR-200c-3p, miR-200a-3p, miR-200b-3p, miR-92a-3p, and miR-21–5p. • The role of miRNAs in noise induced HRV reduction needs to be confirmed. [ABSTRACT FROM AUTHOR]