Cardiac Baroreflex, HRV, and Statistics: An Interdisciplinary Approach in Hypertension

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

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

Progressive Additive Benefits of Prehabilitation and Subsequent Bariatric Surgery on Cardiac Autonomic Regulation as Assessed by Means of a Simple Unitary Composite Index: Preliminary Data from an Observational Study

Obesity is associated with an increased risk of several chronic comorbidities, which may also be determined by dysfunctional autonomic nervous system (ANS). The influence of bariatric surgery (BS) on ANS balance was explored in previous studies, but with high heterogeneity in both the assessment timing and methods employed. In the present observational study, we applied a clinical protocol which considers two subsequent phases. Twenty-nine non-diabetic obese subjects were studied at baseline (T0), after one month of lifestyle modification (prehabilitation) (phase 1-T1), and after eight months following BS (phase 2-T2). ANS regulation was assessed across the three study epochs by means of ANSI, a single composite percent-ranked proxy of autonomic balance, being free of gender and age bias, economical and simple to apply in a clinical setting. The aim of the present study was to investigate the effects of the clinical protocol based on prehabilitation and subsequent BS on the ANS regulation by means of ANSI. Potential intertwined correlations with metabolic parameters were also investigated. Notably, we observed a progressive improvement in ANS control, even by employing ANSI. Moreover, the reduction in the markers of sympathetic overactivity was found to significantly correlate with the amelioration in some metabolic parameters (fasting glucose, insulin levels, and waist circumference), as well as in stress and tiredness perception. In conclusion, this study provides convincing evidence that a unitary proxy of cardiac autonomic regulation (CAR) may reflect the progressive improvement in autonomic regulation following behavioral and surgical interventions in obese patients. Intriguingly, this might contribute to reducing cardiovascular and metabolic risk.

Baroreflex control model for cardiovascular system subjected to postural changes under normal and orthostatic conditions

Baroreflex dysfunction is one of the common causes associated with the cardiovascular system. The buffering capability and baroreflex gain influences large variation in blood pressure for short term control. For regulating the blood pressure, an integrated analytical model for baroreflex control along with the cardiovascular system is presented to study the complex interactions between autonomic nervous system and cardiovascular system. In the proposed model, the autonomic nervous system utilizes sympathetic and parasympathetic nerve activities. This comprises a heart modeled by Mulier's approach, systemic vasculature, baroreceptor sensor using stress-strain based Voigt model and Hodgkin-Huxley based autonomic nervous control. This model can handle the distribution of total blood volume changes under the influence of gravity upon postural changes by means of short term baroreflex control. The simulation is carried out for the integrated model along with (i) non pulsatile and (ii) pulsatile model of heart. The proposed model is validated for supine to standing position under influence of gravity. To show the efficiency of the proposed model, the simulation is carried out further for (i) postural changes like supine to standing and standing to supine under normal condition and (ii) Orthostatic hypotension and hypertension conditions. Also the robustness of the proposed pulsatile model is tested by introducing disturbance signal in mean arterial pressure under various postural changes.

Evidence of Better Autonomic, Metabolic and Psychological Profile in Breast Cancer Survivors Meeting Current Physical Activity Recommendations: An Observational Study

The increased cardiometabolic risk observed in breast cancer survivors (BCS) is due to multiple mechanisms: Hormonal and immunological dysfunction are well-identified ones, while cardiac autonomic regulation (CAR) is less recognized but may play a new complementary role particularly relevant when considering conditions and behaviors associated with a better prognosis in BCS, such as physical training. This observational study investigated a group of consecutive (172) BCS subdivided in two groups: those who reached the physical activity goals above 600 (MET·min/week) and those who did not. We assessed CAR by autoregressive spectral analysis of cardiovascular variabilities (considering in particular the unitary autonomic nervous system index—ANSI), body mass composition, stress perception and lifestyle in order to verify possible differences due to execution of physical activity. Subjects who spontaneously met physical activity recommendations presented a better autonomic, metabolic and psychological profile compared to those who did not. Lower physical activity volume, poor metabolic parameters, increased stress and fatigue perception may cluster together, leading to worsened CAR. This control mechanism may play a complementary role in determining the increased cardiometabolic risk observed in BCS. Furthermore, it may also explain, albeit in part, the better prognosis observed in patients following interventions aiming to improve the sympathetic–parasympathetic balance, such as physical training, using a personalized medicine approach.

Dependence of Heart Rate Variability Indices on the Mean Heart Rate in Women with Well-Controlled Type 2 Diabetes

Heart rate variability (HRV) is a method used to evaluate the presence of cardiac autonomic neuropathy (CAN) because it is usually attributed to oscillations in cardiac autonomic nerve activity. Recent studies in other pathologies suggest that HRV indices are strongly related to mean heart rate, and this does not depend on autonomic activity only. This study aimed to evaluate the correlation between the mean heart rate and the HRV indices in women patients with well-controlled T2DM and a control group. HRV was evaluated in 19 T2DM women and 44 healthy women during basal supine position and two maneuvers: active standing and rhythmic breathing. Time-domain (SDNN, RMSSD, pNN20) and frequency-domain (LF, HF, LF/HF) indices were obtained. Our results show that meanNN, age, and the maneuvers are the main predictors of most HRV indices, while the diabetic condition was a predictor only for pNN20. Given the known reduced HRV in patients with T2DM, it is clinically important that much of the HRV indices are dependent on heart rate irrespective of the presence of T2DM. Moreover, the multiple regression analyses evidenced the multifactorial etiology of HRV.

Heart rate variability modifications in response to different types of exercise training in athletes

PURPOSE

Spectral analysis of heart rate variability (HRV) is a long-standing technique to indirectly assess neural cardiac regulation. This article specifically addressed how spectral analysis of HRV could help to understand neural cardiovascular adaptations to long-term exercise training and inform us on training status in athletes.

METHODS

We reviewed literature searching for articles investigating resting cardiovascular adaptations to long-tem exercise training through spectral analysis of HRV in athletes, from amateur to world class categories, practicing different sport disciplines, focusing, in particular, on a series of work performed over time in our laboratory, which may highlight how different types of exercise training differently affect neural cardiac regulation.

RESULTS

Spectral analysis of HRV has been shown its capability of detecting different adaptational changes in cardiac autonomic nervous system (ANS) regulation attending physical training in athletes of different sport disciplines. Studies showed that spectral analysis of HRV provide results that are sport-dependent and differ at individual level. ANS adaptations to exercise training are presented and discussed.

CONCLUSIONS

Reported studies indicate that spectral analysis of HRV is an effective tool to monitor and optimize the training process and also to predict athletic achievements in competitions. Cardiac ANS adaptations are strongly dependant on the type of training being performed. The individual nature of cardiac ANS adaptations should be considered to properly interpret the observed findings.

Altered Cardiac Autonomic Regulation in Overweight and Obese Subjects: The Role of Age-and-Gender-Adjusted Statistical Indicators of Heart Rate Variability and Cardiac Baroreflex

In the context of functional determinants of cardiovascular risk, a simple excess in body weight, as indexed by a rise in body mass index (BMI), plays a significant, well-recognized causal role. Conversely, BMI reductions toward normal result in an improvement of risk. Obesity is associated with impaired cardiac autonomic regulation (CAR), through either vagal or sympathetic mechanisms, which could favor the tendency to foster hypertension. Here we study the changing properties of the relationship between increasing grades of BMI and CAR in a population of 756 healthy subjects (age 35.9 ± 12.41 years, 37.4% males, 21.6% overweight, and 16% obese). Evaluation of CAR is based on autoregressive spectral analysis of short-term RR interval and systolic arterial pressure variability, from which a multitude of indices, treated overall as autonomic nervous system (ANS) proxies, is derived. Inspection of the study hypothesis that elevated BMI conditions associate significantly with alterations of CAR, independently of age and gender, is carried out using a mix of statistical transformations, exploratory factor analysis, non-parametric testing procedures, and graphical tools particularly well suited to address alterations of CAR as a disturbed process. In particular, to remove the effects of the inter-individual variability, deriving from components like age, gender or ethnicity, and to reduce the number of ANS proxies, we set up six age-and-gender-adjusted CAR indicators, corresponding to four ANS latent domains (oscillatory, amplitude, pressure, and pulse), cardiac baroreflex regulation, and autonomic nervous system index (ANSI). An impairment of the CAR indicators is overall evident in the overweight group and more marked in the obesity group. Empirical evidence is strong (9/9 concordant non-parametric test results) for pressure domain, almost strong (8/9) for ANSI, medium-strong for baroreflex (6/9) and pulse (7/9), weak for oscillatory (2/9) and amplitude (1/9) domains. In addition, the distribution of the CAR indicators corresponding to pressure, pulse, baroreflex, and ANSI is skewed toward the unfavorable abscissa extremity, particularly in the obese group. The significant association of increased BMI with progressive impairments of CAR regarding specifically the pressure domain and the overall ANS performance might underscore the strong hypertensive tendency observed in obesity.

Obstructive and Central Sleep Apnea in First Ever Ischemic Stroke are Associated with Different Time Course and Autonomic Activation

INTRODUCTION

Sleep-related breathing disorders are highly prevalent in patients with ischemic stroke. Among sleep-disordered breathing disorders, obstructive sleep apnea is the most represented one, but central sleep apnea, isolated or in the context of a periodic breathing/Cheyne-Stokes respiration, is frequently reported in these patients. Altered baroreflex responses have been reported in the acute phases of a cerebral event.

METHODS

We conducted, in a group of patients with ischemic stroke (n=60), a prospective 3-month follow-up physiological study to describe the breathing pattern during sleep and baroreflex sensitivity in the acute phase and in the recovery phase.

RESULTS

In the acute phase, within 10 days from the onset of symptoms, 22.4% of patients had a normal breathing pattern, 40.3% had an obstructive pattern, 16.4% had a central pattern, and 29.9% showed a mixed pattern. Smaller variations in the Apnea-Hypopnea Index were found in normal breathing and obstructive groups (ΔAHI 2.1±4.1 and -2.8±11.6, respectively) in comparison with central and mixed patterns (ΔAHI -6.9±15.1 and -12.5±13.1, respectively; ANOVA p=0.01). The obstructive pattern became the most frequent pattern, in 38.3% of patients at baseline and 61.7% of patients at follow-up. Modification of baroreflex sensitivity over time was influenced by the site of the lesion and by the sleep disorder pattern in the acute phase (MANOVA p=0.005).

CONCLUSION

We suggest that a down-regulation of autonomic activity, possibly related to reduced vagal modulation, may help the recovery after stroke, or a transitory disconnection from the cortical node that participates in the regulation of sympathetic outflow.

Streamlining Analysis of RR Interval Variability in Elite Soccer Players: Preliminary Experience with a Composite Indicator of Cardiac Autonomic Regulation

It is well recognized that regular physical activity may improve cardiac autonomic regulation preventing chronic non-communicable diseases. Accordingly, the assessment of cardiac autonomic regulation (CAR) with non-invasive techniques, such as RR interval Variability (V) might be of practical interest. We studied 56 soccer players (21.2 ± 4.2 years.) and 56 controls (22.2 ± 1.5 years.) and used a ranked Autonomic Nervous System Index (ANSI), resulting from the combination of multivariate statistical methodologies applied to spectral analysis derived indices from RRV. We hypothesized that ANSI would be higher in soccer players as compared to controls (p < 0.001) and that values would be greatest in defenders and midfielders, who are known to run longer distances during competitions. Conversely in the intrinsically stationary goalkeepers ANSI would be similar to controls. Our data show that it is possible to assess the overall level of autonomic performance in soccer players as compared to the general population, using a ranked composite autonomic proxy (ANSI). This approach suggests as well that CAR is better in those players who during competitions run for a greater distance. We conclude that it is possible to highlight the differences in autonomic profile due to distinct exercise routines, using ANSI, a simple ranked, composite autonomic proxy.