Baroreflex sensitivity and heart-rate variability in prediction of total cardiac mortality after myocardial infarction. ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) Investigators

Can we identify stroke sub-type without imaging? A multidimensional analysis

Stroke is a major cause of mortality and disability worldwide, with ischemic stroke (AIS) and intracerebral haemorrhage (ICH) requiring distinct management approaches. Accurate early detection and differentiation of these subtypes is crucial for targeted treatment and improved patient outcomes. Traditionally, imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are required to distinguish between AIS and ICH. However, this study explores a non-imaging approach to differentiate between stroke subtypes. Using a retrospective dataset of 80 mild-to-moderate patients suffering stroke (68 AIS and 12 ICH), we employed principal component analysis (PCA) combined with logistic regression (LR) to evaluate 67 parameters. These parameters include baroreceptor sensitivity, and cerebral and peripheral hemodynamic variables. The PCA-LR model, validated through two-fold and six-fold cross-validation methods, effectively differentiated between AIS and ICH. BRS parameters and cerebral hemodynamic factors contributed significantly to the model's accuracy. The two-fold cross-validation approach achieved an area under the curve (AUC) of ≥0.92, while the six-fold method maintained a consistent variance explanation (AUC ≥0.79). Results suggest that this multidimensional approach may facilitate early stroke subtype identification (AIS vs ICH) without reliance on imaging, offering a promising tool for ultra-acute stroke care in prehospital settings. However, it is important to note that the model has been tested in confirmed stroke cases, and its ability to distinguish between stroke and stroke mimics remains an important limitation for broader clinical application. Future research with larger datasets is warranted to refine the model and validate its clinical applicability.

Occurrence of Dysrhythmias During Ventilatory Weaning and Its Association With Length of Mechanical Ventilation and In-hospital Complications

BACKGROUND

The occurrence of cardiac dysrhythmias during ventilatory weaning and its impact on the length of ventilation and occurrence of complications have not been systematically investigated.

OBJECTIVES

The aim of this study was to evaluate the association between cardiac dysrhythmias during weaning and the duration of ventilation and complications during ventilator weaning.

METHOD

Data on the length of ventilation and complications were collected from the medical records of 30 mechanically ventilated patients. Continuous electrocardiographic recordings were collected at baseline and during the initial weaning trial. Multiple regression analysis was used to evaluate the association between dysrhythmias and length of ventilation. The relationship between prolonged ventilation and complications was assessed using the χ 2 analysis.

RESULTS

Supraventricular ectopic beats during weaning positively predicted the length of ventilation ( P < .01). Prolonged ventilation (>7 days) is associated with the occurrence of renal insufficiency and septicemia.

CONCLUSION

The association between the occurrence of supraventricular ectopic beats during ventilator weaning and the length of ventilation requires further evaluation and tailored management to improve patient outcomes.

Association Between Cardiovascular Autonomic Function and Temporomandibular Disorders

BACKGROUND

Studies have shown that elevated stress levels associate with TMD-related pain, which suggests that alterations in autonomic tone may contribute to this pain condition.

OBJECTIVE

The aim of the study was to evaluate the sex-specific associations between autonomic nervous system (ANS) activity and TMD pain-related diagnoses in a population-based study.

METHODS

The study was part of the Northern Finland Birth Cohort 1966. Of the cohort members, 1964 (62.3% of those invited to oral health examination) were clinically examined as part of the 46-year follow-up. ANS activity was assessed by means of heart rate variability (HRV) and baroreflex sensitivity (BRS). A total of 5 TMD diagnoses were based on the modified protocol of DC/TMD (Diagnostic Criteria for TMD). Of those, pain-related diagnoses, i.e., myalgia and arthralgia, were used. In logistic regression analyses stratified by sex assigned at birth, potential confounders, i.e., education, body mass index, and number of body pain sites, were considered.

RESULTS

Those with TMD myalgia (n = 97) or arthralgia diagnoses (n = 102) had lower values of BRS while standing when adjusted for covariates among females (for myalgia OR 0.847, 95% Cl 0.744-0.964, p = 0.012) and for arthralgia (OR 0.871, 95% Cl 0.775-0.970, p = 0.021).

CONCLUSION

The results suggest that lowered baroreflex sensitivity, indicating increased sympathetic tone, associates with TMD pain, at least to some extent, in females. These findings refer to the association of stress response with TMD.

2025 Japanese Heart Rhythm Society / Japanese Circulation Society Consensus Statement on the Appropriate Use of Ambulatory and Wearable Electrocardiographs

Recently, some clinicians have been diagnosing and treating arrhythmias on the basis of electrocardiogram (ECG) devices with low accuracy. In Europe and the US, several statements on the use of ECGs have already been published by related academic societies. In addition, with the relaxation of regulations on media advertising ambulatory/wearable ECG devices, the frequency of use of simple ECG devices by the general public will increase in the future. Therefore, this statement describes the functions and features of non-invasive ambulatory or wearable ECG devices that have been approved as medical devices in Japan (and that can record ECGs remotely), as well as points to note when using them; provides an overview of data storage and security for ambulatory/wearable ECG devices and implantable loop recorders (ILRs), as well as discussing differences between their use and the use of non-invasive ambulatory/wearable ECG devices; and provides classes of recommendation for the use of these devices and their evaluation for each arrhythmia type or condition. We describe lead-based ambulatory ECG devices (classical 24-h Holter ECG monitoring), handheld ECG devices, handheld-based ECG devices using a smartphone, wearable ECG devices (smartwatch and garment ECG devices), and patch ECG devices. In addition, we provide information on methods that are not based on the original ECG, such as photoplethysmography and oscillometric blood pressure measurement, and describe the limitations of their use. We hope that the publication of this statement will lead to the appropriate use of ambulatory/wearable ECG devices in Japan.

Cardiac autonomic function in young, healthy adults: Influence of race and sex

Non-Hispanic Black (BL) adults living in the United States are more likely to develop cardiovascular disease (CVD) compared with their non-Hispanic White (WH) counterparts. Although measures of cardiac autonomic function [i.e., spontaneous cardiac baroreflex sensitivity (BRS) and heart rate variability (HRV)] have a predictive value for CVD, studies investigating racial differences in cardiac autonomic function are limited and have reported conflicting results. Furthermore, sex differences are often not considered despite BL women having a high prevalence of CVD. We hypothesized that young BL men and women would exhibit lower cardiac BRS and HRV compared with their WH counterparts. Heart rate and beat-to-beat blood pressure were continuously recorded during 5 min of supine rest in 145 young (18-33 yr), healthy, BL (37 men, 38 women) and WH (39 men, 31 women) adults to assess cardiac BRS and HRV. Overall cardiac BRS (sequence method) was higher in BL adults compared with WH adults (P < 0.001), which was mainly driven by differences between BL and WH men (BL men: 34 ± 16 vs. WH men: 21 ± 9 ms/mmHg, P < 0.001) compared with women (BL women: 27 ± 12 vs. WH women: 24 ± 11 ms/mmHg; P > 0.05). Likewise, greater HRV in BL adults, indexed by root mean square of successive differences, was primarily driven by BL men (BL men: 109 ± 59 vs. WH men: 64 ± 33 ms; P < 0.001) rather than BL women (P > 0.05). Thus, contrary to our hypothesis, these results support that reduced cardiac autonomic function does not manifest early in life among young BL adults.NEW & NOTEWORTHY Herein, we demonstrated that BL adults do not have lower cardiac autonomic function compared with WH adults. Rather BL men had greater spontaneous cardiac baroreflex sensitivity and heart rate variability compared with WH men while no differences were found among BL and WH women. These findings suggest that reduced cardiac autonomic function, which could increase the risk of cardiovascular disease, does not appear early in life in healthy BL adults.

Heart Rate Variability Modulation Through Slow-Paced Breathing in Health Care Workers with Long COVID: A Case-Control Study

BACKGROUND

Long COVID is a syndrome persisting 12+ weeks after COVID-19 infection, impacting life and work ability. Autonomic nervous system imbalance has been hypothesized as the cause. This study aims to investigate cardiovascular autonomic function in health care workers (HCWs) with Long COVID and the effectiveness of slow-paced breathing (SPB) on autonomic modulation.

METHODS

From December 1, 2022 to March 31, 2023, 6655 HCWs of the University Hospitals of Trieste (Northeast Italy) were asked to participate in the study by company-email. Inclusion/exclusion criteria were assessed. Global health status and psychosomatic disorders were evaluated through validated questionnaires. Heart rate variability was assessed by finger-photoplethysmography during spontaneous breathing and SPB, which stimulate vagal response. Long COVID HCWs (G1) were contrasted with Never infected (G2) and Fully recovered COVID-19 workers (G3).

RESULTS

There were 126 HCWs evaluated. The 58 Long COVID were assessed at a median time because COVID-19 of 419.5 days (interquartile range 269-730) and had significantly more psychosomatic symptoms and lower detectability of spontaneous systolic pressure oscillation at 0.1 Hz (Mayer wave - baroreflex arc) during spontaneous breathing compared with 53 never-infected and 14 fully-recovered HCWs (19%, 42%, and 40%, respectively, P = .027). During SPB, the increase in this parameter was close to controls (91.2%, 100%, and 100%, respectively, P = .09). No other differences in heart rate variability parameters were found among groups.

CONCLUSIONS

Resting vascular modulation was reduced in Long COVID, while during SPB, baroreflex sensitivity effectively improved. Long-term studies are needed to evaluate whether multiple sessions of breathing exercises can restore basal vascular reactivity and reduce cardiovascular risk in these patients.

Heart Rate Variability Applications in Medical Specialties: A Narrative Review

HRV is clinically considered to be a surrogate measure of the asymmetrical interplay of the sympathetic and parasympathetic nervous system. While HRV has become an increasingly measured variable through commercially-available wearable devices, HRV is not routinely monitored or utilized in healthcare settings at this time. The purpose of this narrative review is to discuss and evaluate the current research and potential future applications of HRV in several medical specialties, including critical care, cardiology, pulmonology, nephrology, gastroenterology, endocrinology, infectious disease, hematology and oncology, neurology and rehabilitation, sports medicine, surgery and anesthesiology, rheumatology and chronic pain, obstetrics and gynecology, pediatrics, and psychiatry/psychology. A narrative literature review was conducted with search terms including HRV and relevant terminology to the medical specialty in question. While HRV has demonstrated promise for some diagnoses as a non-invasive, easy to use, and cost-effective metric for early disease detection, prognosis and mortality prediction, disease monitoring, and biofeedback therapy, several issues plague the current literature. Substantial heterogeneity exists in the current HRV literature which limits its applicability in clinical practice. However, applications of HRV in psychiatry, critical care, and in specific chronic diseases demonstrate sufficient evidence to warrant clinical application regardless of the surmountable research issues. More data is needed to understand the exact impact of standardizing HRV monitoring and treatment protocols on patient outcomes in each of the clinical contexts discussed in this paper.

Repeated heart rate variability monitoring after myocardial infraction - Cohort profile of the MI-ECG study

The purpose of this study was to monitor heart rate variability (HRV) parameters after myocardial infarction (MI), addressing the ongoing controversy regarding their prognostic value. HRV was measured via Holter monitoring during the acute phase around the time of discharge and again two weeks later during recovery. Our findings show that HRV parameters remained stable during the initial weeks post-MI, indicating that the timing of Holter monitoring in this period is not critical. Several HRV parameters were significantly correlated with MI type, Killip class, and left ventricular ejection fraction (LVEF), with reduced HRV observed in STEMI patients and those with decompensated heart failure. However, after adjusting for GRACE score and LVEF, the prognostic value of most HRV measures for predicting future cardiac events diminished. Notably, detrended fluctuation analysis DFA1 α2 yielded a significant hazard ratio (HR) of 0.79 when adjusted for the GRACE score. However, this significance diminished after adjusting for LVEF (HR = 0.84). In conclusion, HRV parameters reflect MI severity and correlate with clinical characteristics, but their independent predictive value for future cardiac events is limited when adjusted for established risk factors such as LVEF and GRACE score.

Baroreflex Sensitivity and Hemodynamic Parameters at Rest and in Response to Physical and Mental Stress: A Comparative Study of Patients Undergoing Different Dialysis Modalities

Introduction Cardiac arrhythmias are the leading mortal cause of end-stage kidney disease (ESKD), and autonomic dysfunction plays a predominant role. This is the first study to compare baroreflex sensitivity (BRS) and hemodynamic responses at rest and after mental and physical stimulation maneuvers between hemodialysis (HD) and peritoneal dialysis (PD) patients. Methods A total of 68 ESKD patients (34 HD and 34 PD, matched for age, sex, and dialysis vintage) were included. Continuous recordings from Finometer-PRO at rest and during mental arithmetic, orthostatic, and handgrip exercise tests were used for the calculation of BRS and hemodynamic responses in each individual. Results The two groups were similar in terms of age, sex, dialysis vintage, and major comorbidities. BRS during mental (HD: 3.59±2.62 vs. PD: 5.50±9.40 ms/mmHg, p=0.280) and physical stress tests (orthostatic: HD: 3.23±2.42 vs. PD: 2.07±2.69 ms/mmHg, p=0.777) was similar between HD and PD patients. During the mental test, both groups presented increases in systolic (SBP) and diastolic blood pressure (DBP) levels compared to rest (SBP HD: 156.3±27.7 vs. 142.7±20.0 mmHg, p<0.05; PD: 158.0±25.6 vs. 143.1±23.6 mmHg, p<0.05), but without significant between-group differences (p=0.853/p=0.611). Similarly, no significant between-group differences were noted in the other hemodynamic parameters. Mean SBP levels during the orthostatic test were significantly decreased compared to rest in both groups (HD: 135.4±26.8 vs. 142.2 ±20.1 mmHg; p<0.05; PD 135.3±21.9 vs. 143.1±23.6 mmHg; p<0.05), but the overall response was not different between groups (p=0.937). Finally, the hemodynamic responses during handgrip exercise and recovery did not differ between HD and PD. Conclusions BRS and hemodynamic responses to mental and physical stress tests were similar between HD and PD patients, suggesting that the function of the autonomic nervous system (ANS) in ESKD is not affected by dialysis modality.

Sympathetic nociceptive afferent signaling drives the chronic structural and functional autonomic remodeling after myocardial infarction

After myocardial infarction (MI), pathological autonomic remodeling, including vagal dysfunction and sympathoexcitation, occurs and predisposes to ventricular arrhythmias (VT/VF). The underlying factors that drive this remodeling, including the observed neuroinflammation and glial activation, remain unknown. We hypothesized that sympathetic nociceptive afferents underlie this remodeling post-MI. Epidural resiniferatoxin (RTX, to ablate sympathetic cardiac afferent neurons) vs. saline was administered in pigs prior to MI and autonomic and electrophysiological effects assessed four to six weeks post-infarction. Acute effects of afferent ablation after chronic MI were also assessed in a separate group of animals. Baroreflex sensitivity and vagal tone, as measured by parasympathetic neuronal activity and cardiac nociceptive responses, were improved in infarcted animals which received epidural RTX prior to MI. These animals also demonstrated reduced spinal cord inflammation and glial activation, downregulation of circulating stress and inflammatory pathways, and stabilization of electrophysiological parameters, with reduced VT/VF-inducibility. Epidural RTX after chronic MI also acutely restored vagal function and decreased VT/VF. These data suggest that cardiac spinal nociceptive afferents directly contribute to VT/VF susceptibility and MI-induced autonomic remodeling, including oxidative stress, inflammation, glial activation, and reduced vagal function, providing novel insights into the causal role of these afferents in driving sympathovagal imbalance after MI.

Metabolic improvement after exercise training in children with obesity: Possible role of the six-minute walking test

The aims of this study are to evaluate the effectiveness of an online supervised training program in modulating lipid and glucose metabolism in children with obesity and to investigate the possible role of the 6-minute walking test (6MWT) as a predictor of metabolic improvement. A total of 35 Caucasian children with obesity (aged 8-13) were enrolled in the study and tested before (T0) and after (T1) a 12-week online supervised exercise training protocol: cardiovascular fitness (by means of 6MWT), metabolic biochemical profile, lifestyle (with ad hoc questionnaires focusing on physical activity, nutrition, sedentariness, sleep hours and quality, health perception) and Cardiac Autonomic Regulation (CAR) were assessed. Spearman correlations between the variations in the studied outcomes were explored. After intervention, the distance covered during 6MWT significantly increased (p < 0.001), and nutrition quality improved slightly but significantly (p = 0.03). The improvement in the 6MWT performance was shown to be significantly correlatee with the reduction of insulin levels (r = -0.455; p = 0.02), HOMA-IR Index (r = -0.452; p = 0.02), total cholesterol values (r = -0.549; p = 0.004) and Atherogenic Index of Plasma (AIP) (r = 0.422; p = 0.04). Moreover, there was a significant correlation between the improvement in 6MWT and health perception (r = 0.578; p = 0.002). We observed that the improvement in the 6MWT performance correlates with better metabolic profile after exercise training in children with obesity suggesting the goodness of this simple test on unveil changes in pathogenetic processes underlying obesity.

Sympathetic nociceptive afferent signaling drives the chronic structural and functional autonomic remodeling after myocardial infarction

After myocardial infarction (MI), pathological autonomic remodeling, including vagal dysfunction and sympathoexcitation, occurs and predisposes to ventricular arrhythmias (VT/VF). The underlying factors that drive this remodeling, including the observed neuroinflammation and glial activation, remain unknown. We hypothesized that sympathetic nociceptive afferents underlie this remodeling post-MI. Epidural resiniferatoxin (RTX, to ablate sympathetic cardiac afferent neurons) vs. saline was administered in pigs prior to MI and autonomic and electrophysiological effects assessed four to six weeks post-infarction. Acute effects of afferent ablation after chronic MI were also assessed in a separate group of animals. Baroreflex sensitivity and vagal tone, as measured by parasympathetic neuronal activity and cardiac nociceptive responses, were improved in infarcted animals which received epidural RTX prior to MI. These animals also demonstrated reduced spinal cord inflammation and glial activation, downregulation of circulating stress and inflammatory pathways, and stabilization of electrophysiological parameters, with reduced VT/VF-inducibility. Epidural RTX after chronic MI also acutely restored vagal function and decreased VT/VF. These data suggest that cardiac spinal nociceptive afferents directly contribute to VT/VF susceptibility and MI-induced autonomic remodeling, including oxidative stress, inflammation, glial activation, and reduced vagal function, providing novel insights into the causal role of these afferents in driving sympathovagal imbalance after MI.

Noninvasive assessment of temporal dynamics in sympathetic and parasympathetic baroreflex responses

Objective.The baroreflex maintains cardiovascular stability by modulating heart rate, myocardial contraction, and vascular tone. However, noninvasive assessment of its sympathetic vascular and myocardial branches often overlooks their time-dependent interplay. To address this gap, we developed and implemented a noninvasive method that characterizes these baroreflex dynamics to enhance understanding of autonomic function and improve clinical assessments of cardiovascular regulation.Approach.We analyzed blood pressure and ECG recordings from 55 preoperative patients and 21 participants from the EUROBAVAR dataset. Baroreflex sensitivity (BRS) was calculated using the sequence method for interbeat interval (IBI), myocardial contractility (dP/dtmax), and systemic vascular resistance (SVR), derived through pulse contour analysis at multiple delays relative to beat-to-beat changes in systolic arterial pressure (SAP). Correlations of these BRS estimates with hemodynamic parameters and heart rate variability (HRV) were evaluated at rest and during active standing.Main results.Distinct temporal profiles of BRS for IBI, SVR, and dP/dtmaxwere identified, with significant correlations to HRV and average SVR, CO, and SAP levels at physiologically relevant delays. Orthostatic stress primarily impacted parasympathetic BRS for IBI, while BRS for SVR and dP/dtmaxshowed subtler changes, reflecting unique time-dependent associations.Significance.This approach provides a tool to comprehensively understand the baroreflex function, highlighting the latency-dependent interactions of its branches with their effectors and their adaptability to physiological challenges. Such insights could improve clinical assessments of autonomic dysfunction with altered baroreflex latencies and inform personalized strategies for managing conditions that compromise cardiovascular stability.

Physical activity, fitness, and cardiac autonomic function among adults born postterm

Recent studies have suggested that adverse outcomes of postterm birth (≥42 completed weeks of gestation), including increased cardiometabolic risk factors, impaired glucose metabolism, and obesity, may extend into adulthood. We studied interconnected determinants of cardiovascular health, including physical activity (PA; based on accelerometry for 2 weeks), muscular strength (measured by handgrip strength), cardiorespiratory fitness (CRF; measured by 4-min step test), and cardiac autonomic function (heart rate [HR] recovery, HR variability, and baroreflex sensitivity) among 46-year-old adults from the Northern Finland Birth Cohort born postterm (n = 805) and at term (n = 2645). Adults born postterm undertook vigorous PA 2.0 min day-1 (95% CI, 0.4-3.7) less than term-born adults when adjusted for sex, age, and maternal- and pregnancy-related covariates in multiple linear regression. Postterm birth was associated with reduced CRF, based on a higher peak HR (2.1 bpm; 95% CI, 0.9-3.4) and slower HR recovery 30 s after the step test (-0.7 bpm; 95% CI, -1.3 to -0.1). Postterm birth was associated with less PA of vigorous intensity and CRF and slower HR recovery in middle age. Our findings reinforce previous suggestions that postterm birth should be included as a perinatal risk factor for adult cardiometabolic disease.

The Effects of Resonance Frequency Breathing on Cardiovascular System and Brain-Cardiopulmonary Interactions

Resonance frequency (RF) is characterized as the specific frequency at which a system, equipped with delayed self-correction or negative feedback mechanisms, exhibits maximal amplitude oscillations in response to an external stimulus of a particular frequency. Emerging evidence suggests that the cardiovascular system has an inherent RF, and that breathing at this frequency can markedly enhance health and cardiovascular function. However, the efficacy of resonance frequency breathing (RFB) and the specific responses of the cardiovascular, respiratory, and central nervous systems during RFB remain unclear. In this study, we recruited 27 healthy young male subjects (aged 20-30 years) and used the corrected sliding method to accurately determine each subject's RF. We then investigated cardiovascular activity, cardiorespiratory coupling, and the brain-cardiovascular network to clarify the effects and mechanisms associated with RFB. Our results indicate that: (a) the corrected sliding method can precisely evaluate RF; (b) the reduction in blood pressure is unique to RFB and not observed in other slow-paced breathing patterns (RF + 1 and 6 breaths per minute), which we attribute to the α-wave and parasympathetic-BRS pathway; (c) during slow-paced breathing, cardiorespiratory coupling predominantly favors the respiration-to-heart direction, with the RF stage eliciting the most significant response, while brain-cardiopulmonary information transfer increases across all tasks. These findings offer valuable insights into the impact of RFB on the cardiovascular, respiratory, and central nervous systems, potentially laying the groundwork for future research to optimize respiratory training protocols and improve health outcomes.

Computational modelling of cardiac control following myocardial infarction using an in silico patient cohort

Loss of cardiac physiological function following myocardial infarction (MI) is accompanied by neural adaptations in the baroreflex that are compensatory in the short term, but then become associated with long-term disease progression. One marker of these adaptations is decreased baroreflex sensitivity, a strong predictor of post-MI mortality. The relative contributions of cardiac remodelling and neural adaptation in the sensory, central brainstem and peripheral ganglionic loci to baroreflex sensitivity changes remain underexplored. We used a computational model-based approach that accounts for the short-term dynamics of closed-loop human cardiac control to integrate disparate experimental studies on neural adaptation following MI into a unified quantitative framework. We developed an ensemble of 59 distinct model parameterizations that account for the clinically observed heterogeneity of cardiac control in healthy individuals. We simulated an in silico cohort of 35,400 patients with MI, corresponding to six scenarios of one or more loci of neural adaptation coupled with cardiac remodelling. We evaluated the range of MI-induced shifts in arterial pressure, heart rate and baroreflex curve responses. Our results show that adaptation in any single neural locus coupled with cardiac remodelling is sufficient to account for the MI-induced haemodynamic and autonomic changes observed experimentally. Of the adaptation pathways, we found that individuals with central or peripheral vagal efferent adaptation and preserved baroreceptor gain could maintain high baroreflex sensitivity after ischaemic injury. These results suggest that there are a multitude of adaptive pathways for tuning the baroreflex circuit to shift cardiac control physiology, potentially explaining patient heterogeneity post-MI. KEY POINTS: Baroreflex sensitivity is a strong indicator of post-myocardial ischaemia survival and is variable among individuals. We fine-tuned a computational model ensemble based on physiological observations to develop an in silico patient cohort consistent with the range of baroreflex responses observed experimentally. Simulation and analysis of the in silico cohort show that individuals with a functional afferent pathway and the ability to adapt along the vagal efferent pathway can maintain baroreflex sensitivity post-cardiac ischaemia.

Bioelectronic block of stellate ganglia mitigates pacing-induced heterogeneous release of catecholamine and neuropeptide Y in the infarcted pig heart

The sympathetic nervous system modulates cardiac contractile and electrophysiological function and contributes to adverse remodelling following myocardial infarction (MI). Axonal modulation therapy (AMT), directed at the sympathetic chain, blocks efferent sympathetic outflow to the heart and is a strategy to transiently and controllably mitigate chronic MI-associated sympatho-excitation. In porcine models, we evaluated scalable AMT, directed at the paravertebral chain, in blocking reflex-mediated pacing-induced sympatho-excitation post-MI. The level of sympatho-excitation was assessed by dynamic interstitial measurement of noradrenaline (NA) and neuropeptide Y (NPY). In anaesthetized normal (n = 5) and age-matched pigs 6 weeks post-MI induction (n = 10), we electrically stimulated the right sympathetic chain and determined levels of direct current block applied at the T1-T2 level sufficient to reduce the evoked changes in heart rate and/or contractility by 25-75%. Reflex-mediated neural release of NA and NPY into the interstitial space during programmed pacing (PP) was assessed using fast-scanning cyclic voltammetry and capacitive immunoprobes. Normal animals demonstrated homogeneous NA and NPY release profiles during PP. In contrast, for MI animals PP evoked differential NA and NPY release in remote and MI border zones of the left ventricle. Right-sided AMT mitigated NA and NPY pacing-induced release in the remote left ventricle with a positive correlation to increasing AMT levels. Pacing-induced NA and NPY release in the MI border zone was not mitigated by AMT. Differential effects of AMT on NA and NPY may underlie the anti-arrhythmic effects of partial stellate ganglion block in the setting of chronic MI. KEY POINTS: Programmed cardiac pacing evokes homogeneous noradrenaline (NA) and neuropeptide Y (NPY) release in equivalent areas (e.g. medial and lateral aspects) of the normal left ventricle. Programmed cardiac pacing evokes differential NA and NPY release in remote and border zones of the infarcted left ventricle. Axonal modulation therapy (AMT), using a graded direct current block applied to the stellate ganglia, can proportionally modulate cardiac sympathetic reflexes. Unilateral AMT mitigates NA and NPY release in remote left ventricular tissue, with release negatively correlated to increasing AMT levels. Heterogeneities in NA and NPY between the border and remote tissues are reduced by progressive AMT.

Firing properties of single axons with cardiac rhythmicity in the human cervical vagus nerve

Microneurographic recordings of the human cervical vagus nerve have revealed the presence of multi-unit neural activity with measurable cardiac rhythmicity. This suggests that the physiology of vagal neurones with cardiovascular regulatory function can be studied using this method. Here, the activity of cardiac rhythmic single units was discriminated from human cervical vagus nerve recordings using template-based waveform matching. The activity of 44 cardiac rhythmic neurones (22 with myelinated axons and 22 with unmyelinated axons) was isolated. By consideration of each unit's firing pattern with respect to the cardiac and respiratory cycles, the functional identification of each unit was attempted. Of note is the observation of seven cardiac rhythmic neurones with myelinated axons whose activity was recruited or enhanced by slow, deep breathing, was maximal during the nadir of respiratory sinus arrhythmia, and showed an expiratory peak. This is characteristic of cardioinhibitory efferent neurones, which are responsible for respiratory sinus arrhythmia. The remaining 15 cardiac rhythmic neurones with myelinated axons were categorised as cardiopulmonary receptors or arterial baroreceptors based on the position of their peak in firing with respect to the R-wave of the cardiac cycle. This latter method is not viable for neurones with unmyelinated axons due to their slow and unknown conduction velocities. With the exception of three neurones whose expiratory modulation implicates them as cardiac-projecting efferent neurones, this population is likely dominated by arterial baroreceptors. In conclusion, the activity of single units with cardiovascular function has been discriminated within the human cervical vagus, enabling their systematic study. KEY POINTS: Recordings of the electrical activity of the vagus nerve have recently been made at the level of the neck in humans. Examination of the gross activity of this nerve reveals subpopulations of neurones whose activity fluctuates in time with the heart's beat, suggesting that the neurones that monitor or modify cardiac function can be studied using this method. Here, the activity of individual cardiac rhythmic neurones was isolated from human vagus nerve recordings using template-based spike sorting. The relationship between this activity and the cardiac and respiratory cycles was used as a means of classifying each neurone. Neuronal firing patterns that are consistent with that of neurones that modify cardiac function, including heart-slowing 'cardioinhibitory' neurones, as well as neurones that inform the brain of cardiovascular status were observed. This approach enables, for the first time, the systematic study of the function of these neurones in humans in both health and disease.

Modelling neurocardiac physiology and diseases using human pluripotent stem cells: current progress and future prospects

Throughout our lifetime the heart executes cycles of contraction and relaxation to meet the body's ever-changing metabolic needs. This vital function is continuously regulated by the autonomic nervous system. Cardiovascular dysfunction and autonomic dysregulation are also closely associated; however, the degrees of cause and effect are not always readily discernible. Thus, to better understand cardiovascular disorders, it is crucial to develop model systems that can be used to study the neurocardiac interaction in healthy and diseased states. Human pluripotent stem cell (hiPSC) technology offers a unique human-based modelling system that allows for studies of disease effects on the cells of the heart and autonomic neurons as well as of their interaction. In this review, we summarize current understanding of the embryonic development of the autonomic, cardiac and neurocardiac systems, their regulation, as well as recent progress of in vitro modelling systems based on hiPSCs. We further discuss the advantages and limitations of hiPSC-based models in neurocardiac research.

Bayliss Starling Prize Lecture 2023: Neuropeptide-Y being 'unsympathetic' to the broken hearted

William Bayliss and Ernest Starling are not only famous as pioneers in cardiovascular physiology, but also responsible for the discovery of the first hormone (from the Greek 'excite or arouse'), the intestinal signalling molecule and neuropeptide secretin in 1902. Our research group focuses on neuropeptides and neuromodulators that influence cardiovascular autonomic control as potential biomarkers in disease and tractable targets for therapeutic intervention. Acute myocardial infarction (AMI) and chronic heart failure (CHF) result in high levels of cardiac sympathetic stimulation, which is a poor prognostic indicator. Although beta-blockers improve mortality in these conditions by preventing the action of the neurotransmitter noradrenaline, a substantial residual risk remains. Recently, we have identified the sympathetic co-transmitter neuropeptide-Y (NPY) as being released during AMI, leading to larger infarcts and life-threatening arrhythmia in both animal models and patients. Here, we discuss recently published data demonstrating that peripheral venous NPY levels are associated with heart failure hospitalisation and mortality after AMI, and all cause cardiovascular mortality in CHF, even when adjusting for known risk factors (including brain natriuretic peptide). We have investigated the mechanistic basis for these observations in human and rat stellate ganglia and cardiac tissue, manipulating NPY neurochemistry at the same time as using state-of-the-art imaging techniques, to establish the receptor pathways responsible for NPY signalling. We propose NPY as a new mechanistic biomarker in AMI and CHF patients and aim to determine whether specific NPY receptor blockers can prevent arrhythmia and attenuate the development of heart failure.

Variability of baroreceptor reflex assessed by tilt table test in a patient undergoing pulmonary vein isolation

BACKGROUND

The autonomic nervous system (ANS) plays a significant role in atrial fibrillation (AF). Catheter ablation (CA) affects the ANS balance. The assessment of baroreceptor (BR) function is an established method to measure parasympathetic activity; however, it has been rarely used in patients undergoing CA of AF.

AIMS

This study is to assess changes in BR function caused by CA and to compare these changes between two different types of CA: point-by-point radiofrequency (RF) versus cryoballoon (CB).

METHODS

In this observational, prospective, single center study, 78 patients (25 females, mean age 58 ± 9) with paroxysmal AF and first CA were included: 39 patients (RF group) and 39 (CB group). The BR function was assessed non-invasively using tilt testing and three parameters: event count (BREC) depicting overall BR activity, slope mean depicting BR sensitivity (BRS), and BR effectiveness index (BEI).

RESULTS

The groups did not differ in clinical or demographic data. Before CA, tilting caused a marked decrease in BR function parameters in the whole study group (BREC (29 ± 14.0-50.0 vs 28 ± 9.0-44.0, p < 0.068), BRS (10.2 ± 7.1-13.2 vs 5.8 ± 4.9-8.5; p < 0.001), and BEI (52.9 ± 39.9-65.5 vs 39.6 ± 23.6-52.1; p < 0.001), supine vs tilting, respectively). These changes were similar in the both groups. After CA, BR function decreased in the whole group (BREC 12.0 ± 3.0-22.0 vs 6.0 ± 3.0-18.0, p = 0.004; BRS 4.8 ± 3.6-6.8 vs 4.0 ± 3.0-5.8, p = 0.014; BEI 18.7 ± 8.3-27.4 vs 12.0 ± 5.1-21.0, p = 0.009). BREC was significantly more decreased in the CB vs RF. Similar trend was noted for BRS and BEI.

CONCLUSIONS

CA significantly affects BR function. These changes were more pronounced following CB rather than RF CA.

Circulating neuropeptide Y dynamics and performance during exercise in heart failure patients with contemporary medical and device therapy

High cardiac sympathetic drive and release of the sympathetic cotransmitter neuropeptide Y (NPY) are significant features of congestive heart failure (CHF), in which resting venous NPY levels are known to be associated with mortality. However, whether circulating NPY levels increase during exercise in CHF when they are already elevated is controversial. We sought to establish the dynamics of circulating NPY levels in CHF patients treated with contemporary medical therapy and devices in relationship to indices of performance linked to long-term prognosis. CHF patients (n = 15) underwent cardiopulmonary exercise testing with venous blood sampling at rest, peak exercise and recovery. These patients had significantly higher resting venous NPY levels compared with an age- and sex-matched control group of patients (n = 16) with normal left ventricular function (40 ± 6.9 vs. 9.0 ± 4.6 pg/mL, respectively; P < 0.0001). In CHF patients, NPY levels increased significantly from baseline to peak exercise (to 93.5 ± 42.1 pg/mL; P = 0.0004) and remained elevated during recovery (86.8 ± 44.6 pg/mL; P = 0.0018). The peak (r = 0.58, P = 0.0222) and recovery (r = 0.56, P = 0.0304) NPY levels and the ability to increase NPY from baseline (r = 0.53, P = 0.0427) showed significant positive correlations with heart rate recovery at 1 min, but not with peak oxygen consumption. In CHF patients, the ability to increase NPY levels on exertion is correlated with heart rate recovery, a known prognostic indicator for mortality. These findings suggest that NPY dynamics during exercise might provide valuable insights into sympathetic responses and prognosis in CHF patients.

Hypertension increases sympathetic neuron activity by enhancing intraganglionic cholinergic collateral connections

Autonomic dysregulation, including sympathetic hyperactivity, is a common feature of hypertension (HT) and other cardiovascular diseases. The CNS plays a role in driving chronic sympathetic activation in disease, but several lines of evidence suggest that neuroplasticity in the periphery may also contribute. The potential contribution of postganglionic sympathetic neurons to sustained sympathetic hyperactivity is not well understood. We recently discovered that noradrenergic sympathetic neurons in the stellate ganglion (SG) have excitatory cholinergic collateral connections to other neurons within the ganglion. We hypothesize that remodelling of these neurons and increased cholinergic collateral transmission contributes to sustained sympathetic hyperactivity in cardiovascular diseases, including HT. To test that hypothesis, we examined the activity of sympathetic neurons in isolated SG under control conditions and after 1 week of HT induced by peripheral angiotensin II infusion, using whole-cell patch clamp recordings. Despite the absence of central inputs, we observed elevated spontaneous activity and synaptic transmission in sympathetic SG neurons from hypertensive mice that required generation of action potentials. Genetically disrupting cholinergic transmission in noradrenergic neurons decreased basal neuronal activity and prevented angiotensin II-mediated enhancement of activity. Similar changes in activity, driven by increased collateral transmission, were identified in cardiac projecting neurons and neurons projecting to brown adipose tissue. These changes were not driven by altered A-type K+ currents. This suggests that HT stimulates increased activity throughout the intraganglionic network of collateral connections, contributing to the sustained sympathetic hyperactivity characteristic in cardiovascular disease. KEY POINTS: Sympathetic neurons in ganglia isolated from angiotensin II-treated hypertensive mice are more active than neurons from control mice despite the absence of central activation. The enhanced activity is the result of a ganglionic network of cholinergic collaterals, rather than altered intrinsic excitability. Increased neuronal activity was observed in both cardiac neurons and brown adipose tissue-projecting neurons, which are not involved in cardiovascular homeostasis.

Neurocardiology: translational advancements and potential

In our original white paper published in the The Journal of Physiology in 2016, we set out our knowledge of the structural and functional organization of cardiac autonomic control, how it remodels during disease, and approaches to exploit such knowledge for autonomic regulation therapy. The aim of this update is to build on this original blueprint, highlighting the significant progress which has been made in the field since and major challenges and opportunities that exist with regard to translation. Imbalances in autonomic responses, while beneficial in the short term, ultimately contribute to the evolution of cardiac pathology. As our understanding emerges of where and how to target in terms of actuators (including the heart and intracardiac nervous system (ICNS), stellate ganglia, dorsal root ganglia (DRG), vagus nerve, brainstem, and even higher centres), there is also a need to develop sensor technology to respond to appropriate biomarkers (electrophysiological, mechanical, and molecular) such that closed-loop autonomic regulation therapies can evolve. The goal is to work with endogenous control systems, rather than in opposition to them, to improve outcomes.

A Body-Temperature-Triggered In Situ Softening Peripheral Nerve Electrode for Chronic Robust Neuromodulation

Implantable peripheral nerve electrodes are crucial for monitoring health and alleviating symptoms of chronic diseases. Advanced compliant electrodes have been developed because of their biomechanical compatibility. However, these mechanically tissue-like electrodes suffer from unmanageable operating forces, leading to high risks of nerve injury and fragile electrode-tissue interfaces. Here, a peripheral nerve electrode is developed that simultaneously fulfills the criteria of body temperature softening and tissue-like modulus (less than 0.8 MPa at 37 °C) after implantation. The central core is altered from the tri-arm crosslinker to the star-branched monomer to kill two birds (close the translation temperature to 37 °C and decrease the modulus after implantation) with one stone. Furthermore, the decreased interfacial impedance (325.1 ± 46.9 Ω at 1 kHz) and increased charge storage capacity (111.2 ± 5.8 mC cm-2) are achieved by an in situ electrografted conductive polymer on the strain-insensitive conductive network of Au nanotubes. The electrodes are readily wrapped around nerves and applied for long-term stimulation in vivo with minimal inflammation. Neuromodulation experiments demonstrate their potential clinical utility, including vagus nerve stimulation in rats to suppress seizures and alleviation of cardiac remodeling in a canine model of myocardial infarction.

Baroreflex Sensitivity and Long-Term Dementia Risk in Older Adults

BACKGROUND

Increased blood pressure (BP) variability is linked to dementia risk, but the relationship between baroreflex sensitivity (BRS), a fundamental mechanism for maintaining stable BP, and dementia risk is undetermined.

METHODS

We tested the hypothesis that impaired BRS is associated with increased dementia risk in 1819 older adults (63% women; age, 71.0±6.3 years) from the community-based Rotterdam Study. Cardiac BRS was determined from a 5-minute beat-to-beat BP recording at supine rest between 1997 and 1999. Cardiac BRS measures the correlation between changes in consecutive beat-to-beat systolic BP and subsequent responses in heartbeat intervals, with a higher value indicating better BRS. The primary outcome was incident dementia ascertained from baseline through January 1, 2020; the secondary outcome was all-cause mortality.

RESULTS

During a median follow-up of 14.8 years, 421 participants developed dementia. The association of cardiac BRS with dementia risk differed by antihypertensive medication use (Pinteraction=0.03) and was only observed in participants not taking antihypertensives. Specifically, in those not taking antihypertensive medication, reduced BRS was associated with a higher risk of dementia (adjusted hazard ratio comparing bottom versus top quintiles, 1.60 [95% CI, 1.07-2.40]; Ptrend=0.02). Reduced BRS was also associated with an increased risk of death (corresponding hazard ratio, 1.76 [95% CI, 1.32-2.35]). The association remained after adjusting for average BP and BP variability.

CONCLUSIONS

Impaired BRS partly explains hypertension-related brain damage and excessive dementia risk beyond conventional BP measures, making it a potential novel biomarker for the early detection and prevention of dementia.

Acute right-sided transcutaneous vagus nerve stimulation improves cardio-vagal baroreflex gain in patients with chronic heart failure

PURPOSE

The aim of this paper is to investigate the acute effects of short-term transcutaneous vagus nerve stimulation (tVNS) on cardio-vagal baroreflex gain and heart rate variability in patients with chronic heart failure (CHF).

METHODS

A total of 16 adults with CHF and left ventricular ejection fraction (LVEF) < 50% in sinus rhythm were enrolled (65 ± 8 years, 63% men, LVEF 40 ± 5%, 88% on beta-blockers, 50% on quadruple CHF therapy). Over a single experimental session, after a 10-min baseline recording, each patient underwent two trials of 10-min tVNS (Parasym Device, 200 µs, 30 Hz, 1 mA below discomfort threshold) at either the right or left tragus in a randomized order, separated by a 10-min recovery.

RESULTS

Compared with baseline, tVNS did not affect heart rate, blood pressure, and respiratory rate (p > 0.05), and no patients complained of discomfort or any adverse effect. Right-sided tVNS was associated with a significant increase in cardio-vagal baroreflex gain (from 5.6 ± 3.1 to 7.5 ± 3.8 ms/mmHg, ∆ 1.9 ± 1.6 ms/mmHg, p < 0.001), while no change was observed with left-sided tVNS (∆ 0.5 ± 2.0 ms/mmHg, p = 0.914). These findings were independent of stimulation-side order (excluding any carry-over effect) and consistent across sex, LVEF category, and HF etiology subgroups (p-value for interaction > 0.05).

CONCLUSIONS

Acute right-sided tVNS increases cardio-vagal baroreflex gain in patients with CHF and LVEF < 50%, with no tolerability concerns.

Cardiac Autonomic Neuropathy in Diabetes Mellitus: Pathogenesis, Epidemiology, Diagnosis and Clinical Implications: A Narrative Review

Background: Cardiac autonomic neuropathy (CAN) is a serious but sometimes underdiagnosed complications of Diabetes Mellitus (DM). Because of the subtle onset and non-specific symptoms that can be mistaken for other conditions, CAN is frequently underdiagnosed despite the serious consequences that can appear. Its significance as an independent risk factor for cardiovascular events, including arrhythmias, sudden cardiac death, and silent myocardial ischemia, is being demonstrated by recent studies. The objective of this review article is to highlight the reasons why CAN is underdiagnosed and its association with decreased cardiovascular risk and promote clinical awareness. This review article summarizes the epidemiology, influence on the cardiovascular system and diagnostic methods of CAN, and the clinical implications of diabetic neuropathy. This review analyzes available data from papers relevant to the topic of diabetic neuropathy, cardiac autonomic neuropathy, and cardiovascular system implications. Conclusions: CAN is still underdiagnosed despite its clinical impact because routine screening is lacking, and healthcare providers are not aware of it. To improve outcomes for people with DM, it is necessary to introduce standardized diagnostic procedures into clinical practice and increase the knowledge about CAN.

Joint Analysis of Cardiovascular Control and Shear Wave Elastography to Determine Carotid Plaque Vulnerability

Background/Objectives: Carotid artery stenosis (CAS) is one of the main causes of stroke, and the vulnerability of plaque has been proved to be a determinant. A joint analysis of shear wave elastography, a radiofrequency echo-based wall tracking technique for arterial stiffness evaluation, and of autonomic and baroreflex function is proposed to noninvasively, preoperatively assess plaque vulnerability in asymptomatic CAS patients scheduled for carotid endarterectomy. Methods: Elastographic markers of arterial stiffness were derived preoperatively in 78 CAS patients (age: 74.2 + 7.7 years, 27 females). Autonomic and baroreflex markers were also assessed by means of an analysis of the beat-to-beat fluctuations in heart period and systolic arterial pressure, derived at rest in supine position (REST) and during active standing. Postoperative analysis identified 36 patients with vulnerable plaque (VULN) and 42 with stable plaque (STABLE). Results: Baroreflex sensitivity (BRS) at a respiratory rate decreased during STAND only in VULN patients, being much higher at REST compared to STABLE levels. Autonomic indexes were not helpful in separating experimental conditions and/or populations. The Young's modulus (YM) of the plaque was lower in the VULN group than in the STABLE one. Cardiovascular control and elastographic markers were significantly correlated only in VULN patients. A multivariate logistic regression model built combining YM and BRS at the respiratory rate improved the prediction of plaque vulnerability, reporting an area under the ROC curve of 0.694. Conclusions: Noninvasive techniques assessing shear wave elastography and baroreflex control could contribute to the early detection of plaque vulnerability in patients with asymptomatic CAS.

Bilateral tDCS over the DLPFC enhances baroreceptor reflex sensitivity and inhibits blood pressure-related hypoalgesia

OBJECTIVE

This study investigated the impact of transcranial direct stimulation (tDCS) on pain perception, baroreflex sensitivity (BRS), and blood pressure (BP)-related hypoalgesia.

METHOD

Fifty-eight healthy participants were randomized to receive 1) bi-hemispheric tDCS over the dorsolateral prefrontal cortex (DLPFC) at 2 mA for 20 min, or 2) non-stimulation (Sham). Pain measures (threshold, tolerance, intensity and unpleasantness), emotional state (anxiety and mood), continuous BP, and electrocardiogram (ECG) data were recorded before, during, and after stimulation.

RESULTS

tDCS stimulation was followed by increases in BRS, pain intensity and unpleasantness. Anxiety decreased in the Sham group, but not in the tDCS group. Positive correlations between BP and pain threshold and tolerance before stimulation were observed. These remained during stimulation in the Sham group, but not in the tDCS group. Moreover, negative associations between BRS and BP only persisted in the Sham group.

DISCUSSION

The results suggest that bilateral tDCS over the DLPFC enhances BRS and modulates pain perception and BP-related mechanisms. tDCS increases pain perception by inhibiting BP-related hypoalgesia and preventing habituation of anxiety.

SIGNIFICANCE

Low BRS is a powerful prognostic factor of cardiovascular disease, such that its increase via tDCS may be a new therapeutic strategy for cardiovascular health promotion.

Safety and tolerability of the M2 muscarinic acetylcholine receptor modulator BAY 2413555 in heart failure with reduced ejection fraction in the REMOTE-HF study

BAY 2413555 is a novel selective and reversible positive allosteric modulator of the type 2 muscarinic acetylcholine (M2) receptor, aimed at enhancing parasympathetic signaling and restoring cardiac autonomic balance for the treatment of heart failure (HF). This study tested the safety, tolerability and pharmacokinetics of this novel therapeutic option. REMOTE-HF was a multicenter, double-blind, randomized, placebo-controlled, phase Ib dose-titration study with two active arms. Study participants had an established diagnosis of HF with NYHA Class I-III and LVEF ≤ 45%. Patients were required to have an implanted cardiac defibrillator (ICD) or cardiac resynchronization therapy (CRT) device because of the potential for bradycardia or AV conduction delay, which may be induced by BAY 2413555. The study period included a screening and run-in period, followed by a treatment period of over 28 days, consisting of two parts, A and B, comprising 14 days each. Participants were randomized into 1 of 3 arms: a placebo arm and two BAY 2413555 arms-one receiving 1.25 mg in both Part A and Part B (BAY 1.25 mg-1.25 mg) and the other receiving 1.25 mg in Part A followed by 5 mg in Part B (BAY 1.25 mg-5 mg). The primary safety endpoint was the number of participants with treatment-emergent adverse events (TEAEs). Secondary endpoints included number of participants with high degree AV block or symptomatic pauses/ bradycardia and changes from baseline in resting heart rate after 2 and 4 weeks of dosing with BAY 2413555. Changes from baseline in heart rate recovery (HRR) at 1 and 2 min after exercise testing and chronotropic reserve (CR) were also assessed. Of the anticipated 129 participants, 22 participants were randomized: 7 to placebo, 8 to BAY 1.25 mg-1.25 mg, and 7 to BAY 1.25 mg-5 mg. The study was terminated early based on new and unexpected preclinical findings from a chronic animal toxicology study in monkeys in which evidence of increased vascular inflammation was observed, leading to a no longer favorable risk-benefit balance for the intended long-term (i.e., life-long) treatment of heart failure patients. Comparable adverse events were not encountered in REMOTE-HF. Overall, until the termination of the study, BAY 2413555 was safe and well tolerated, with no deaths or TEAEs leading to discontinuation, and no symptomatic bradycardia or AV blocks observed. There was a larger change in the mean HRR at 60 s in the pooled BAY 2413555 treatment arms in Part A (1.25 mg) compared to the placebo (+ 7.3 vs. -6.7 bpm), indicating enhanced cardiac parasympathetic activity. Administration of 1.25 mg and 5 mg BAY 2413555 was safe and well tolerated in both active treatment arms, with no concerning safety findings observed. However, due to the limited number of subjects resulting from early termination, the results should be considered with caution and viewed as exploratory. There were promising signs of target engagement, providing grounds for further exploration of the mechanism.

Whole-Body Cold Stimulation Improves Cardiac Autonomic Control Independently of the Employed Temperature

Background/Objectives: The autonomic nervous system (ANS) is considered one of the mechanisms mediating the benefits of whole-body cold stimulation (WBC). Nevertheless, different treatment protocols, different methodologies employed to assess the ANS, and, in particular, difficulties in interpreting the numerous variables obtained represent important barriers to understanding the effects of WBC on the ANS. The present study aimed to explore the effects of WBC on cardiac autonomic control (CAR) as assessed using a single composite percentile-ranked proxy of autonomic balance (ANSI), considering two different WBC temperatures and the same WBC protocol. Methods: Heart rate variability (HRV) was employed to assess the ANS in 23 subjects with obesity who underwent 10 WBC sessions, studied before and after 2 min WBC at -55 °C (15 subjects) or 2 min WBC at -110 °C (8 subjects) both at the first session (T1) and the last one (T10). To overcome some important barriers in data interpretation and age/sex bias, we considered the Autonomic Nervous System Index (ANSI), a single composite percentile-ranked proxy of autonomic control. Results: We observed an improvement in CAR independently of the employed temperature. Both treatments, without distinction, caused a significant increase in the ANSI post-WBC treatment both at T1 and T10 and a significant betterment of the total power of the RR interval variability from pre- to post-treatment at T1 and overall from T1 to T10. Conclusions: WBC was capable of inducing an immediate change in the ANS control (pre- vs. post-treatment both at T1 and T10) and a long-term modulation in cardiac autonomic control (T1-pre vs. T10-pre).

Comparison of the impact of carotid endarterectomy and stenting on autonomic and baroreflex regulations: a one-year follow-up randomized study

Patients with carotid stenosis can receive indication for either carotid endarterectomy (CEA) or carotid artery stenting (CAS), with both techniques having an impact on the autonomic function and baroreflex control.Seventy carotid stenosis patients randomly assigned to CEA or CAS were enrolled. After exclusion of some recordings, 33 CEA (age 67.79 ± 5.32 yrs, 26 males) and 25 CAS (age 70.32 ± 3.63 yrs, 14 males) were admitted to analysis. Autonomic and baroreflex sensitivity markers were derived from the analysis of heart period and systolic arterial pressure spontaneous variability derived in supine position and during active standing (STAND), before (PRE) the intervention and after a 6 and 12-month follow-up (FU6, FU12).CEA had a preserved response of autonomic and baroreflex control to STAND in PRE and FU6, suggesting an early improvement. CAS had a similar response at PRE but a blunted one at the follow-ups. When directly compared, the two groups had a similar autonomic function, with CAS having a reduced baroreflex control in PRE and lower autonomic function at FU6. All the differences disappeared at the long-term follow-up, showing a similar long term effect of the surgical procedures, suggesting that CEA and CAS induced a similar long-term impairment of autonomic and baroreflex controls.

Impact of neonatal hyperoxia on adult cardiac autonomic function in rats: Role of angiotensin II type 1 receptor activation

Individuals born preterm present altered cardiac autonomic function, a risk factor to heart diseases. Neonatal renin-angiotensin-system activation contributes to adult cardiomyopathy in rats exposed to neonatal hyperoxia, a well-established model of preterm birth-related conditions. Central angiotensin II receptor activation is a key modulator of the autonomic drive to the heart. Whether neonatal hyperoxia leads to alteration of the cardiac autonomic function through activation of the angiotensin II receptor type 1 (AT1) is unknown and was examined in the present study. Sprague-Dawley pups were exposed to hyperoxia or room air from postnatal days 3-10. AT1 antagonist losartan or water was given orally postnatal days 8-10. Blood pressure, autonomic function, left ventricular sympathetic innervation, β-adrenergic-receptors expression, and AT1 expression in the solitary-tract-nucleus were examined in adult rats. Neonatal hyperoxia led to loss of day-night blood pressure variation, decreased heart rate variability, increased sympathovagal balance, increased AT1 expression in the solitary-tract, decreased left ventricle sympathetic innervation, and increased β1-adrenergic-receptor protein expression. Losartan prevented the autonomic changes and AT1 expression in the solitary-tract but did not impact the loss of circadian blood pressure variation nor the changes in sympathetic innervation and in β1-adrenergic-receptor expression. In conclusion, neonatal hyperoxia leads to both central autonomic and cardiac sympathetic changes, partly programmed by neonatal activation of the renin-angiotensin system.

Adiposity and cardiac autonomic function in children with a family history of obesity

PURPOSE

Data on associations between adiposity and heart rate variability (HRV) in prepubertal children are limited. We examined the associations between adiposity indices and HRV, independent of lifestyle behaviors, comparing multiple indicators of adiposity, and explored differences between boys and girls.

METHODS

Data stem from 469 participants of the QUALITY cohort (630 children aged 8-10 years with a parental history of obesity). Adiposity indices included waist-to-height ratio, body mass index (BMI) percentiles and categories (overweight, obesity), dual-energy x-ray absorptiometry (DEXA) defined fat mass percentage and android/gynoid ratio. HRV indices in the frequency and the spectral domain were derived from a daytime 3-h Holter recording. Multivariable linear regression models were adjusted for age, sex, Tanner stage, physical activity, screen time, and fitness. Interactions between sex and adiposity were tested.

RESULTS

Greater adiposity was associated with decreased parasympathetic modulation and increased sympathetic dominance. Waist-to-height ratio was associated with lower parasympathetic activity: root mean square of the successive differences (RMSSD) [B =  -23.32, 95% confidence interval (CI) -42.42, -4.22], pNN50 (B =  -16.93, 95% CI - 28.58, - 5.27), LF/HF ratio (B = 1.83, 95% CI 0.97-2.70). Patterns of association were similar for android/gynoid ratio. Overweight was not associated with altered HRV. Obesity was negatively associated with RMSSD and pNN50 and positively with LF/HF ratio. Greater fat mass percentage was associated with lower RMSSD, pNN50, and HF, and increased LF/HF ratio. There were no differences between boys and girls.

CONCLUSIONS

Specific markers of adiposity relate to altered HRV in childhood, with waist-to-height ratio being potentially a more relevant marker of HRV than BMI and more pragmatic than percent body fat.

TRIAL REGISTRATION

NCT03356262, 11 November 2017.

Abnormal Autonomic Nervous Regulation in Patients with Globus Pharyngeus

BACKGROUND

Globus pharyngeus could be described as a benign sensation of lump or foreign object in the throat. The etiology of the globus as a solitary syndrome is still unknown, but it is proposed that stress could have an important role in symptom emergence.

AIMS

To evaluate the autonomic nervous regulation in patients with globus compared to healthy controls in reaction to stress.

METHODS

Patients included in the study were diagnosed based on ROME IV criteria for Disorders of Gut Brain Interaction. Besides globus, the patients did not suffer any other substantial medical condition. As a control group, measurement of healthy volunteers was performed. Both groups underwent the same stress protocol assessment in the same laboratory settings. The protocol consist of two types of stressors: cold pressor test and mental arithmetic test to test different types of autonomic reactivity.

RESULTS

Baroreflex sensitivity was significantly decreased in patients compared to controls in all phases of the protocol. Low-frequency band of systolic blood pressure variability was significantly increased during both stress phases in patients compared to controls. High-frequency band of heart rate variability was significantly decreased in patients compared to controls during the both of the stress phases.

CONCLUSION

The results of this study shows discrete abnormalities in complex autonomic reflex control which are predominantly manifested in response to stressful stimuli indicating altered neurocardiac regulation as a reaction to stress associated with globus pharynegus. This fact could have an important role in the personalized management of globus patients such as biofeedback.

Baroreflex activation therapy through electrical carotid sinus stimulation

An imbalance between cardiovascular parasympathetic and sympathetic activity towards sympathetic predominance has been implicated in the pathogenesis of treatment-resistant arterial hypertension and heart failure. Arterial baroreceptors control efferent cardiovascular autonomic activity and have, therefore, been recognized as potential treatment targets. Baroreflex activation therapy through electrical carotid sinus stimulation is a device-based approach to modulate cardiovascular autonomic activity. Electrical carotid sinus stimulation lowered blood pressure in various hypertensive animal models and improved cardiac remodeling and survival in preclinical models of heart failure. In human mechanistic profiling studies, electrical carotid sinus stimulation lowered blood pressure through sympathetic inhibition with substantial inter-individual variability. The first-generation device reduced blood pressure in controlled and uncontrolled clinical trials. Controlled clinical trials proving efficacy in blood pressure reduction in patients with hypertension do not exist for the currently available second-generation carotid sinus stimulator. Investigations in heart failure patients showed improved symptoms, quality of life, and natriuretic peptide biomarkers. Electrical carotid sinus stimulation is an interesting technology to modulate cardiovascular autonomic control. However, controlled trials with hard clinical endpoints are required.

Prognostic Value of Ultra-Short Heart Rate Variability Measures Obtained from Electrocardiogram Recordings of Hospitalized Patients Diagnosed with Non-ST-Elevation Myocardial Infarction

Background: Myocardial infarction (MI) is a common emergency with high rates of morbidity and mortality. Current risk stratification scores for non-ST-elevation MI (NSTEMI) use subjective or delayed information. Heart rate variability was shown to correlate with prognosis following MI. This study aimed to evaluate ultra-short heart rate variability (usHRV) as a prognostic factor in NSTEMI patients. Methods: A retrospective analysis was performed on 183 NSTEMI patients admitted to Rambam Health Care Campus in 2014. usHRV measures, including the standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences (RMSSD), were calculated. Logistic regression assessed whether clinical, laboratory, or usHRV parameters predicted severe in-hospital complications like heart failure (HF), atrial flutter/fibrillation (AFL/AF), ventricular tachycardia/fibrillation (VT/VF), and atrioventricular block (AVB). Both Cox and logistic regression were used for survival analysis. Results: Of 183 patients (71.6% male, mean age 67.1), 35 (19%) died within 2 years. In-hospital complications included 39 cases (21.3%) of HF, 3 cases (1.6%) of VT/VF, and 9 cases (4.9%) of AVB. Lower usHRV was significantly associated with higher mortality at 2 years and showed marginal significance at 90 days and 1 year. Increased usHRV was linked to a higher risk of in-hospital ventricular arrhythmia (VT/VF). Conclusions: Overall, this study is in agreement with previous research, showing a correlation between low usHRV and a higher mortality risk. However, the association between usHRV and the risk of VT/VF demands further investigation. More expansive prospective studies are needed to strengthen the observed associations.

Treating heart failure by targeting the vagus nerve

Increased sympathetic and reduced parasympathetic nerve activity is associated with disease progression and poor outcomes in patients with chronic heart failure. The demonstration that markers of autonomic imbalance and vagal dysfunction, such as reduced heart rate variability and baroreflex sensitivity, hold prognostic value in patients with chronic heart failure despite modern therapies encourages the research for neuromodulation strategies targeting the vagus nerve. However, the approaches tested so far have yielded inconclusive results. This review aims to summarize the current knowledge about the role of the parasympathetic nervous system in chronic heart failure, describing the pathophysiological background, the methods of assessment, and the rationale, limits, and future perspectives of parasympathetic stimulation either by drugs or bioelectronic devices.

Emotional Awareness Is Correlated With Ambulatory Heart Rate Variability: A Replication and Extension

OBJECTIVE

In healthy volunteers, a positive association has previously been observed between emotional awareness (EA), the ability to identify and describe emotional experiences in oneself and others, and resting heart rate variability (HRV), which is dominated by vagus nerve activity. The current study aimed to investigate the EA-HRV association across multiple assessments in a "real-world" ambulatory context in patients with long QT syndrome (LQTS) who are at genetic risk for sudden cardiac death.

METHODS

Participants (157 LQTS patients; Mean Age = 35.1, SD Age = 10.4; 115 women) completed the levels of emotional awareness scale (LEAS) on one occasion, which served as our measure of EA. In an ecological momentary assessment study involving 10 assessments per day over 3 days, multiple 5-minute ECG assessments (mean = 24.6, SD = 5.1) were obtained in each patient using a Holter monitor, from which high-frequency HRV (HF-HRV) was computed on each occasion.

RESULTS

There was a significant positive association between LEAS scores and HF-HRV controlling for biobehavioral covariates. We also detected a similar inverse relation between EA and mean heart rate.

CONCLUSION

These findings suggest that, in patients with a well-defined genetic risk for ventricular arrhythmia and sudden death, the ability to experience emotions in a complex and differentiated way covaries with greater parasympathetic influences on the heart. These findings are consistent with the overlapping neural substrates of EA and HRV and their common contribution to adaptive emotional responding, consistent with the Neurovisceral Integration Model.

Autonomic reactivity to mental stress is associated with cardiovascular mortality

Aims

The mechanisms linking acute psychological stress to cardiovascular disease (CVD) mortality are incompletely understood. We studied the relationship of electrocardiographic measures of autonomic dysfunction during acute mental stress provocation and CVD death.

Methods and results

In a pooled cohort of 765 participants with stable CVD from two related studies, we collected Holter data during standardized laboratory-based mental stress testing with a speech task and followed them for events. We assessed autonomic function using low-frequency (LF) heart rate variability (HRV) in 5-min intervals before, during, and after stress induction, and specifically examined changes from rest to stress. We employed cause-specific survival models to examine its association with CVD and all-cause mortality, controlling for demographic and CVD risk factors. The mean (SD) age was 58 (10) years, 35% were women, and 44% self-identified as Black. After a median follow-up of 5.6 years, 37 (5%) died from CVD causes. A stress-induced LF HRV decrease (67% of sample), vs. increase, was associated with a hazard ratio (HR) of 3.48 (95% confidence interval-3.25, 3.73) for CVD mortality. Low rest LF HRV (bottom quartile) was also independently associated with CVD mortality, HR = 1.75 (1.58, 1.94), vs. normal rest LF HRV (upper three quartiles). The combination of stress-induced LF HRV decrease and low rest LF HRV was associated with HR = 5.73 (5.33, 6.15) vs. the normal stress/rest LF HRV reference. We found similar results with HF HRV.

Conclusion

Stress-induced LF HRV decrease and low rest LF HRV are both independently and additively associated with a higher CVD mortality risk. Additional research is needed to assess whether targeting autonomic dysfunction may improve CVD outcomes.

Noninvasive Assessment of Temporal Dynamics in Sympathetic and Parasympathetic Baroreflex Responses

Background

The baroreflex system is crucial for cardiovascular regulation and autonomic homeostasis. A comprehensive assessment requires understanding the simultaneous temporal dynamics of its multiple functional branches, which traditional methods often overlook.

Objective

To develop and validate a noninvasive method for simultaneously assessing the temporal dynamics of sympathetic and parasympathetic baroreflexes using pulse contour analysis and the sequence method.

Methods

Beat-to-beat blood pressure and ECG recordings were analyzed from 55 preoperative cardiothoracic surgery patients in the supine position and 21 subjects from the EUROBAVAR dataset in both supine and standing positions. Systolic arterial pressure (SAP), interbeat interval (IBI), cardiac output (CO), myocardial contraction (dP/dtmax), and systemic vascular resistance (SVR) were estimated using pulse contour analysis. Baroreflex sensitivity (BRS) was calculated via the sequence method and correlated with hemodynamic and heart rate variability (HRV) parameters.

Results

Parasympathetic BRS for IBI was correlated with the root mean square of successive differences of ECG RR intervals (RMSSD-HRV) at 0-beat delay. Sympathetic BRS for SVR strongly correlated with SVR, CO, and RMSSD-HRV, particularly at 3-beat delay, and was uniquely associated with SAP at 1-beat delay. Sympathetic BRS for dP/dtmax correlated with dP/dtmax at 1-beat delay. In contrast, BRS for CO correlated with CO and SVR at 0- and 3-beat delays. Postural changes mainly affected parasympathetically-mediated BRS for IBI and, to a lesser extent, the sympathetic vascular and myocardial branches.

Conclusions

This method effectively captures multiple baroreflex responses and their temporal dynamics, revealing distinct autonomic mechanisms and the impact of postural changes. Further validation is warranted.

Association between ablation-induced baroreceptor reflex modification and procedure efficacy in patients with atrial fibrillation

Background

The autonomic nervous system (ANS) plays a significant role in atrial fibrillation (AF). Catheter ablation (CA) is a well-established treatment method for AF and significantly affects the ANS, including baroreceptor (BR) function. However, little is known about the changes in BR function caused by radiofrequency (RF) or cryoballoon energy (CB) and its impact on future AF recurrences.

Purpose

To assess 1-year efficacy of CA of AF in relation to BR function modification and type of ablation energy used.

Methods

The study group consisted of 78 patients (25 females, mean age 58 ± 9 years) with paroxysmal AF and first CA (39 patients in the RF group and 39 in the CB group). The BR function was assessed non-invasively, using tilt testing before and after CA, and three BR parameters were calculated: event count (BREC) depicting overall BR activity, slope mean depicting BR sensitivity (BRS), and BR effectiveness index (BEI). The efficacy of CA was assessed during 1-year follow-up, which consisted of ambulatory visits and 24-h Holter ECG recordings at 3, 6, and 12 months after CA. The quality of life was assessed by using a dedicated scale [University of Toronto Atrial Fibrillation Severity Scale (AFSS)].

Results

The two groups did not show differences in terms of clinical or demographic data. One-year follow-up was completed for 35 (89.7%) patients from the CB group and for 34 (87.2%) from the RF group. The rates of efficacy of CB and RF were similar [31/35 (88.6%) vs. 26/34 (76.5%), respectively]. After CA, the BR function decreased in both groups, with a significantly greater decrease in the CB group. The changes in BR parameters were similar in both responders and non-responders after CA in the whole group [BREC 10.0 (2.0-24.0) vs. 12.0 (4.0-21.5), p = 0.939; BRS 5.4 (3.7-6.5) vs. 4.8 (3.6-7.2), p = 0.809; BEI 24.8 (15.9-27.4) vs. 17.5 (8.9-27.5), p = 0.508, respectively]. According to the AFSS, the AF symptoms were significantly reduced in both groups to a similar extent.

Conclusions

CA for AF significantly decreased the BR function, especially in patients undergoing CB. There was no correlation between CA-induced changes in BR parameters and ablation outcome.

Renal autonomic dynamics in hypertension: how can we evaluate sympathetic activity for renal denervation?

This review explores the various pathophysiological factors influencing antihypertensive effects, involving the regulation of vascular resistance, plasma volume, cardiac function, and the autonomic nervous system, emphasizing the interconnected processes regulating blood pressure (BP). The kidney's pivotal role in BP control and its potential contribution to hypertension is complicated but important to understand the effective mechanisms of renal denervation (RDN), which may be a promising treatment for resistant hypertension. Excessive stimulation of the sympathetic nervous system or the renin-angiotensin-aldosterone system (RAAS) can elevate BP through various physiological changes, contributing to chronic hypertension. Renal sympathetic efferent nerve activation leads to elevated norepinephrine levels and subsequent cascading effects on vasoconstriction, renin release, and sodium reabsorption. RDN reduces BP in resistant hypertension by potentially disrupting sensory afferent nerves, decreasing feedback activation to the central nervous system, and reducing efferent sympathetic nerve activity in the heart and other structures. RDN may also modulate central sympathetic outflow and inhibit renal renin-angiotensin system overactivation. While evidence for RDN efficacy in hypertension is increasing, accurate patient selection becomes crucial, considering complex interactions that vary among patients. This review also discusses methods to evaluate autonomic nerve activity from the golden standard to new potential examination for finding out optimization in stimulation parameters or rigorous patient selection based on appropriate biomarkers.

Association of hyperventilation-induced heart rate variability and sudden unexpected death in epilepsy in drug-resistant epilepsy

BACKGROUND

 Within the general epilepsy population, the incidence of Sudden Unexpected Death in Epilepsy (SUDEP) ranges from approximately 0.35 to 2.3 per 1,000 individuals per year.

OBJECTIVE

 We aimed to evaluate the relationship between SUDEP risk factors and heart rate variability (HRV) parameters as a potential biomarker of SUDEP in patients with drug-resistant epilepsy (DRE).

METHODS

 There were 52 patients diagnosed with DRE and under follow-up, and controls including 45 healthy subjects, included in the study. Hyperventilation-induced HRV (HRVHV) parameters, including the standard deviation of all RR intervals (SDRR), mean heart rate (HR), root mean squares of successive differences (RMSSD), SD of mean NN intervals recordings (SDANN), and HRV triangular index, were assessed during resting. To predict the risk of SUDEP, the relationship between HRV parameters and SUDEP risks was evaluated using the Risk Assessment for Sudden Death in Epilepsy (SUDEP-7) Risk Inventory.

RESULTS

 No statistically significant difference was found in sympathetic skin response (SSR) latency and amplitudes between the patient and control groups. In comparing healthy control subjects with patients experiencing DRE, we observed significant decreases in SDRRHV and hyperventilation-induced RMSSD (RMSSDHV) values, specifically within HRVHV. Notably, a significant correlation emerged concerning the RMSSDHV values (p < 0.01), when examining the correlation between the SUDEP-7 inventory and HRVHV parameters.

CONCLUSION

 This correlation between RMSSDHV and the SUDEP-7 Risk Inventory in patients with DRE represents a novel and consequential finding, suggesting its potential as an indicator of SUDEP risk.

Protective role of acetylcholine and the cholinergic system in the injured heart

This review explores the roles of the cholinergic system in the heart, comprising the neuronal and non-neuronal cholinergic systems. Both systems are essential for maintaining cardiac homeostasis by regulating the release of acetylcholine (ACh). A reduction in ACh release is associated with the early onset of cardiovascular diseases (CVDs), and increasing evidence supports the protective roles of ACh against CVD. We address the challenges and limitations of current strategies to elevate ACh levels, including vagus nerve stimulation and pharmacological interventions such as cholinesterase inhibitors. Additionally, we introduce alternative strategies to increase ACh in the heart, such as stem cell therapy, gene therapy, microRNAs, and nanoparticle drug delivery methods. These findings offer new insights into advanced treatments for regenerating the injured human heart.

Frequency-Domain Features and Low-Frequency Synchronization of Photoplethysmographic Waveform Variability and Heart Rate Variability with Increasing Severity of Cardiovascular Diseases

Objective-Heart rate variability (HRV) and photoplethysmographic waveform variability (PPGV) are available approaches for assessing the state of cardiovascular autonomic regulation. The goal of our study was to compare the frequency-domain features and low-frequency (LF) synchronization of the PPGV and HRV with increasing severity of cardiovascular diseases. Methods-Our study included 998 electrocardiogram (ECG) and finger photoplethysmogram (PPG) recordings from subjects, classified into five categories: 53 recordings from healthy subjects, aged 28.1 ± 6.2 years, 536 recordings from patients with hypertension (HTN), 49.0 ± 8.8 years old, 185 recordings from individuals with stable coronary artery disease (CAD) (63.9 ± 9.3 years old), 104 recordings from patients with myocardial infarction (MI) that occurred three months prior to the recordings (PMI) (65.1 ± 11.0 years old), and 120 recordings from study subjects with acute myocardial infarction (AMI) (64.7 ± 11.5 years old). Spectral analyses of the HRV and PPGV were carried out, along with an assessment of the synchronization strength between LF oscillations of the HRV and of PPGV (synchronization index). Results-Changes in all frequency-domain indices and the synchronization index were observed along the following gradient: healthy subjects → patients with HTN → patients with CAD → patients with PMI → patients with AMI. Similar frequency-domain indices of the PPGV and HRV show little relationship with each other. Conclusions-The frequency-domain indices of the PPGV are highly sensitive to the development of any cardiovascular disease and, therefore, are superior to the HRV indices in this regard. The S index is an independent parameter from the frequency-domain indices.

Revealing alterations in heart rate fluctuations during the progression of Chagas disease

Introduction

The heart rate variability (HRV) continually evolves throughout life, reflecting modifications in the architecture of the sinoatrial node (SAN) and in the regulation of heart rate by the autonomic nervous system (ANS). Both can be considerably affected by Chagas disease, causing important changes in the complex nature of HRV. We aim to evaluate the ability of an index based on the false nearest neighbors method (FN10) to reflect these changes during disease progression.

Methods

We perform a retrospective, descriptive, and cross-sectional study analyzing HRV time series of participants with Chagas disease. We determine the dependence of FN10 on age and sex in a healthy population, and then evaluate FN10 in individuals with Chagas disease.

Results and discussion

In the healthy population, FN10 has a scaling behavior with age, which is independent of sex. In Chagas disease, some individuals show FN10 values significantly above those seen in the healthy population. We relate the findings to the pathophysiological mechanisms that determine the progression of the disease. The results indicate that FN10 may be a candidate prognostic biomarker for heart disease.

Cardiac Neuroanatomy and Fundamentals of Neurocardiology

Cardiac control is mediated via nested-feedback reflex control networks involving the intrinsic cardiac ganglia, intra-thoracic extra-cardiac ganglia, spinal cord, brainstem, and higher centers. This control system is optimized to respond to normal physiologic stressors; however, it can be catastrophically disrupted by pathologic events such as myocardial ischemia. In fact, it is now recognized that cardiac disease progression reflects the dynamic interplay between adverse remodeling of the cardiac substrate coupled with autonomic dysregulation. With advances in understanding of this network dynamic in normal and pathologic states, neuroscience-based neuromodulation therapies can be devised for the management of acute and chronic cardiac pathologies.