Association of Anti-β 1 and Anti-M2 Antibodies with Autonomic Nervous System Modulation in Patients with Chronic Chagas Cardiomyopathy

Abstract Background: Different immune mechanisms of myocardial damage involved in the pathophysiology of Chagas disease coexist with high titers of autoantibodies induced by T. cruzi . There are few studies in the literature about the adaptive role of anti-β1 and anti-M2 antibodies in chronic Chagas cardiomyopathy (CCC). Objectives: To evaluate the association between anti-β1 and anti-M2 antibodies with heart rate variability (HRV) parameters on 24h Holter monitoring and the rate-pressure product (RPP) on cardiopulmonary exercise testing (CPET). Methods: Anti-β1 and anti-M2 antibody titers were measured by enzyme-linked immunosorbent assay (ELISA) in 64 patients affected by CCC. Analysis of HRV was performed through the time-domain indices NNs, mean NN, SDNN, SDANN, SDNN index, NNNs, RMSSD, and pNN50. Spearman's correlation coefficient was used to assess the association between antibody titers and numerical variables. The Mann-Whitney test was used for comparison between two groups. Multiple linear regression was used to identify independent variables capable of explaining anti-β1 and anti-M2 antibody titers at the 5% significance level. Results: On 24h Holter, during the period of greatest parasympathetic activation (2:00-6:00 a.m.), an inverse association was found between anti-β1 titers and SDNN (rs=-0.13, p =0.041, n=43), as well as a direct association between anti-M2 titers and SDANN ( r s=0.317, p =0.039, n=43). Regarding CPET variables, anti-β1 titers were directly associated with RPP (rs=0.371, p =0.005, n=56). The subgroup of patients with a normal chronotropic response showed higher anti-β1 titers than the subgroup with an impaired response (p=0.023). RPP was an independent explanatory variable for anti-β1 titers, although with a low coefficient of determination (R2=0.147). Conclusion: The findings of this study suggest that, in patients with CCC, anti-β1 and anti-M2 antibodies may affect HRV parameters. RPP was directly associated with higher anti-β1 titers.

Analysis of biolo artificial neural network in prediction of aerobic exercise index based on algorithm / Análise de rede neural artificial na predição do índice de exercício aeróbio baseada em algorítimo / Análisis de red neuronal artificial en la predicción del índice de ejercicio aeróbico

ABSTRACT Objective: To study the relationship between aerobic activity and cardiac autonomic nerve activity by artificial neural network algorithm and biological image fusion; because of the artificial neural network model (ANN) problems, biological image processing technology is introduced based on ANN. Methods: An Ann under biological image intelligence algorithm is proposed, a classifier suitable for electrocardiograph (ECG) screening is designed, and an ECG signal screening system is successfully established. Moreover, the data set of normal recovered ECG signals of the subjects during the experimental period is constructed, and a classifier is used to extract the characteristic data of a normal ECG signal during the experimental period. Results: The changes in resting heart rate and other physical health indicators are analyzed by combining resting physiological indicators, namely heart rate, body weight, body mass index and body fat rate. The results show that the self-designed classifier can efficiently process the ECG images, and long-term regular activities can improve the physical conditions of most people. Most subjects' body weight and body fat rate decrease with the extension of experiment time, and the resting heart rate decreases relatively. Conclusions: Certain indicators can be used to predict a person's dynamic physical health, which indicates that the experimental research of index prediction in this research has a good effect, which not only extends the application of artificial neural network but also lays a foundation for the research and implementation of ECG intelligent testing wearable devices. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Objetivo: Com o objetivo de estudar a relação entre atividade aeróbia e atividade nervosa autonômica cardíaca por algoritmo de rede neural artificial e fusão biológica de imagens, tendo em vista os problemas existentes no modelo de rede neural artificial (RNA), é introduzida a tecnologia de processamento biológico de imagens com base em ANN. Métodos: um algoritmo de inteligência biológica de imagem Ann é proposto, um classificador adequado para triagem eletrocardiográfica (ECG) é projetado e um sistema de triagem de sinal de ECG é estabelecido com sucesso. Além disso, o conjunto de dados de sinais de ECG normais recuperados dos sujeitos durante o período experimental é construído e um classificador é usado para extrair os dados característicos de um sinal de ECG normal durante o período experimental. Resultados: As alterações na frequência cardíaca em repouso e outros indicadores de saúde física são analisadas pela combinação de indicadores fisiológicos de repouso, a saber, frequência cardíaca, peso corporal, índice de massa corporal e índice de gordura corporal. Os resultados mostram que o classificador autodesenhado pode processar com eficiência as imagens de ECG, e as atividades regulares de longo prazo podem melhorar as condições físicas da maioria das pessoas. O peso corporal e a taxa de gordura corporal da maioria dos indivíduos diminuem com a extensão do tempo do experimento, e a freqüência cardíaca em repouso diminui relativamente. Conclusões: Certos indicadores podem ser usados para prever a saúde física dinâmica de uma pessoa, o que indica que a pesquisa experimental de predição de índice nesta pesquisa tem um bom efeito, que não apenas estende a aplicação da rede neural artificial, mas também estabelece uma base para a pesquisa e implementação de dispositivos vestíveis de teste inteligente de ECG. Nível de evidência II; Estudos terapêuticos- investigação dos resultados do tratamento.

RESUMEN Objetivo: Para estudiar la relación entre la actividad aeróbica y la actividad del nervio autónomo cardíaco mediante el algoritmo de red neuronal artificial y la fusión de imágenes biológicas, ante los problemas existentes en el modelo de red neuronal artificial (ANN), se introduce la tecnología de procesamiento de imágenes biológicas basada en ANA. Métodos: Se propone un algoritmo de inteligencia de imagen biológica de Ann, se diseña un clasificador adecuado para el cribado electrocardiógrafo (ECG) y se establece con éxito un sistema de cribado de señales de ECG. Además, se construye el conjunto de datos de las señales de ECG recuperadas normales de los sujetos durante el período experimental, y se utiliza un clasificador para extraer los datos característicos de una señal de ECG normal durante el período experimental. Resultados: Los cambios en la frecuencia cardíaca en reposo y otros indicadores de salud física se analizan combinando indicadores fisiológicos en reposo, a saber, frecuencia cardíaca, peso corporal, índice de masa corporal y tasa de grasa corporal. Los resultados muestran que el clasificador de diseño propio puede procesar de manera eficiente las imágenes de ECG, y las actividades regulares a largo plazo pueden mejorar las condiciones físicas de la mayoría de las personas. El peso corporal y la tasa de grasa corporal de la mayoría de los sujetos disminuyen con la extensión del tiempo del experimento, y la frecuencia cardíaca en reposo disminuye relativamente. Conclusiones: Ciertos indicadores pueden usarse para predecir la salud física dinámica de una persona, lo que indica que la investigación experimental de predicción de índices en esta investigación tiene un buen efecto, lo que no solo extiende la aplicación de la red neuronal artificial sino que también sienta las bases para la investigación. e implementación de dispositivos portátiles de prueba inteligente de ECG. Nivel de evidencia II; Estudios terapéuticos- investigación de los resultados del tratamiento.

Autonomic function may not modulate irisin release in healthy adults: findings from a randomized cross-over study

ABSTRACT Objective Autonomic nervous system, especially the sympathetic nervous system, may stimulate the expression of peroxisome proliferator-activated receptor γ coactivator-1α, which regulates irisin. This study aimed to explore whether there was any association between autonomic function as assessed by heart rate related indices and irisin release following acute exercise. Subjects and methods Seventeen healthy adults were asked to perform an incremental exhaustive cycling as well as an incremental exhaustive running separately on different days. Heart rate was monitored, and blood samples were collected before, immediately, 10-, and 60-minutes post-exercise. Serum irisin was measured using ELISA kit. Results Markers for autonomic function, such as heart rate at rest, peak, or recovery, heart rate reserve, heart rate recovery, and chronotropic index, were comparable between cycling and running (all P > 0.10). Irisin was increased immediately following both exercise. No significant association was observed between heart rate at rest, peak, or recovery and irisin level at the corresponding time-point, as well as between heart rate reserve, heart rate recovery, or chronotropic index and exercise induced irisin release, with or without controlling for age, body mass index, and glucose (all P > 0.10). Conclusions Autonomic function might not be associated with irisin release in healthy adults. Arch Endocrinol Metab. 2020;64(3):201-4

Respostas autonômicas de recém-nascidos prematuros ao posicionamento do corpo e ruídos ambientais na unidade de terapia intensiva neonatal / Autonomic responses of premature newborns to body position and environmental noise in the neonatal intensive care unit

RESUMO Objetivo: Avaliar as respostas fisiológicas e do sistema nervoso autônomo de recém-nascidos prematuros ao posicionamento do corpo e ruídos ambientais na unidade de terapia intensiva neonatal. Métodos: Este foi um estudo quasi-experimental. O sistema nervoso autônomo de recém-nascidos foi avaliado com base na variabilidade da frequência cardíaca quando os recém-nascidos foram expostos ao ruído ambiental e colocados em diferentes posições: supina sem suporte, supina com restrição manual e prona. Resultados: Cinquenta recém-nascidos prematuros foram avaliados (idade gestacional de 32,6 ± 2,3 semanas, peso de 1.816 ± 493g e nível Brazelton de sono/vigília de 3 a 4). Identificou-se correlação positiva entre o ruído ambiental e a atividade simpática (R = 0,27; p = 0,04). O ruído ambiental médio foi de 53 ± 14dB. A frequência cardíaca foi mais elevada na posição supina do que nas posições com restrição manual e prona (148,7 ± 21,6; 141,9 ± 16 e 144 ± 13, respectivamente; p = 0,001). A atividade simpática, representada por um índice de baixa frequência, foi mais elevada na posição supina (p < 0,05) do que nas demais posições, e a atividade parassimpática (alta frequência, raiz quadrada da média dos quadrados das diferenças entre os intervalos RR normais adjacentes e porcentagem dos intervalos R-R adjacentes com diferença de duração maior que 50ms) foi mais elevada na posição prona (p < 0,05) do que nas demais posições. A complexidade dos ajustes autonômicos (entropia aproximada e entropia da amostra) foi mais baixa na posição supina do que nas demais posições. Conclusão: A posição prona e a posição com restrição manual aumentaram tanto a atividade parassimpática quanto a complexidade dos ajustes autonômicos em comparação com a posição supina, mesmo na presença de ruído ambiental maior do que o nível recomendado, o que tende a aumentar a atividade simpática.

ABSTRACT Objective: Evaluate the physiological and autonomic nervous system responses of premature newborns to body position and noise in the neonatal intensive care unit. Methods: A quasi-experimental study. The autonomic nervous system of newborns was evaluated based on heart rate variability when the newborns were exposed to environmental noise and placed in different positions: supine without support, supine with manual restraint and prone. Results: Fifty premature newborns were evaluated (gestational age: 32.6 ± 2.3 weeks; weight: 1816 ± 493g; and Brazelton sleep/awake level: 3 to 4). A positive correlation was found between environmental noise and sympathetic activity (R = 0.27, p = 0.04). The mean environmental noise was 53 ± 14dB. The heart rate was higher in the supine position than in the manual restraint and prone positions (148.7 ± 21.6, 141.9 ± 16 and 144 ± 13, respectively) (p = 0.001). Sympathetic activity, represented by a low frequency index, was higher in the supine position (p < 0.05) than in the other positions, and parasympathetic activity (high frequency, root mean square of the sum of differences between normal adjacent mean R-R interval and percentage of adjacent iRR that differed by more than 50ms) was higher in the prone position (p < 0.05) than in the other positions. The complexity of the autonomic adjustments (approximate entropy and sample entropy) was lower in the supine position than in the other positions. Conclusion: The prone position and manual restraint position increased both parasympathetic activity and the complexity of autonomic adjustments in comparison to the supine position, even in the presence of higher environmental noise than the recommended level, which tends to increase sympathetic activity.

La fisiología vista desde un sistema nervioso autónomo ampliado y circadianamente organizado Bases para un enfoque Bio-Psico-Social-Ecológico de la salud y la enfermedad / THE PHYSIOLOGY OBSERVED SINCE AN AMPLIED AND CIRCADIANILLY ORGANIZED AUTONOMIC NERVOUS SYSTEM. BASIS FOR A BIO-PSICHO-SOCIAL-ECOLOGICAL APPROACH DURING HEALTH AND DISEASE

El sistema nervioso autónomo (SNA) es un componente fundamental del sistema nervioso cuya función es mantener la homeostasis y reaccionar de forma adaptativa a los cambios en el medio externo e interno. Participa en la regulación de la respiración, la circulación, la digestión, el metabolismo y el medio interno, la secreción exocrina y endocrina, las respuestas inmunes, la temperatura corporal y la reproducción. En este trabajo se analizará cómo la organización del SNA se construye en 4 niveles jerárquicos, a partir de un periodo de diferenciación crítico neonatal en el cual el medio ambiente y el vínculo afectivo con la madre juega un rol predominante. A continuación, se discutirá cómo la función del SNA cambia en las tres configuraciones corporales (vigilia, sueño de ondas lentas, sueño de movimientos oculares rápidos, REM) que se suceden durante un ciclo de 24 horas. Por último, se discutirá la aplicación de estos conceptos en la Unidad Neurofisiología del Curso de Fisiología para alumnos de 2º año de la Facultad de Ciencias Médicas, UCA, enfatizando los aspectos instrumentales destinados a aumentar la participación de los alumnos en el proceso de enseñanza

The autonomic nervous system (ANS) is a fundamental component of the nervous system whose function is to maintain homeostasis and react adaptively to changes in the external and internal environment. It participates in the regulation of respiration, circulation, digestion, metabolism and internal environment, exocrine and endocrine secretion, immune response, body temperature and reproduction. In this review article I will analyze how the organization of the ANS is built on 4 hierarchical levels, starting from a period of critical neonatal differentiation in which the environment and the affective bond with the mother plays a predominant role. Next, I will discuss how the ANS function changes in the three body configurations (wakefulness, slow wave sleep, fast eye movement, REM) that occur during a 24 hour cycle. Finally, the application of these concepts to teaching Neurophysiology at the Physiology Course for 2nd year medical students of the Faculty of Medical Sciences, Pontificia Universidad Católica Argentina, emphasizing the instrumental aspects intended to increase the participation of students in the teaching process is discussed.

Autonomic and Vascular Control in Prehypertensive Subjects with a Family History of Arterial Hypertension / Controle Autonômico e Vascular em Pré-Hipertensos com Histórico Familiar de Hipertensão Arterial

Abstract Background: Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology. Objective: To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH. Methods: Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®). The transfer function analysis was used to measure the gain and response time of baroreflex. The statistical significance adopted was p ≤ 0.05. Results: Pre-hypertensive individuals, in relation to normotensive individuals, have higher VC both at rest (3.48 ± 1.26 vs. 2.67 ± 0.72 units, p = 0.05) and peak reactive hyperemia (25, 02 ± 8.18 vs. 18.66 ± 6.07 units, p = 0.04). The indices of cardiac autonomic modulation were similar between the groups. However, in the peripheral autonomic modulation, greater variability was observed in prehypertensive patients compared to normotensive individuals (9.4 [4.9-12.7] vs. 18.3 [14.8-26.7] mmHg2; p < 0.01) and higher spectral components of very low (6.9 [2.0-11.1] vs. 13.5 [10.7-22.4] mmHg2, p = 0.01) and low frequencies (1.7 [1.0-3.0] vs. 3.0 [2.0-4.0] mmHg2, p = 0.04) of SBP. Additionally, we observed a lower gain of baroreflex control in prehypertensive patients compared to normotensive patients (12.16 ± 4.18 vs. 18.23 ± 7.11 ms/mmHg, p = 0.03), but similar delay time (-1.55 ± 0.66 vs. -1.58 ± 0.72 s, p = 0.90). Conclusion: Prehypertensive patients with FHSAH have autonomic dysfunction and increased vascular conductance when compared to normotensive patients with the same risk factor.

Resumo Fundamento: Indivíduos com histórico familiar de hipertensão arterial sistêmica (HFHAS) e/ou pré-hipertensão apresentam maior risco de desenvolver essa patologia. Objetivo: Avaliar as funções autonômica e vascular de pré-hipertensos com HFHAS. Métodos: Vinte e cinco voluntários jovens com HFHAS, sendo 14 normotensos e 11 pré-hipertensos foram submetidos à avaliação da função vascular, por meio da condutância vascular do antebraço (CV) durante repouso e hiperemia reativa (Hokanson®), e da modulação autonômica cardíaca e periférica, quantificada, respectivamente, por meio da análise espectral da frequência cardíaca (ECG) e da pressão arterial sistólica (PAS) (FinometerPRO®). A análise da função de transferência foi utilizada para mensurar o ganho e o tempo de resposta do barorreflexo. A significância estatística adotada foi p ≤ 0,05. Resultados: Pré-hipertensos, em relação aos normotensos, tem maior CV tanto em repouso (3,48 ± 1,26 vs. 2,67 ± 0,72 unidades; p = 0,05) quanto no pico hiperemia reativa (25,02 ± 8,18 vs. 18,66 ± 6,07 unidades; p = 0,04). Os índices da modulação autonômica cardíaca foram semelhantes entre os grupos. Entretanto, na modulação autonômica periférica, foi observado, nos pré-hipertensos em relação aos normotensos, maior variabilidade (9,4 [4,9-12,7] vs. 18,3 [14,8-26,7] mmHg2; p < 0,01) e maiores componentes espectrais de muito baixa (6,9 [2,0-11,1] vs. 13,5 [10,7-22,4] mmHg2; p = 0,01) e baixa frequências (1,7 [1,0-3,0] vs. 3,0 [2,0-4,0] mmHg2; p = 0,04) da PAS. Adicionalmente, observamos menor ganho do controle barorreflexo nos pré-hipertensos em relação aos normotensos (12,16 ± 4,18 vs. 18,23 ± 7,11 ms/mmHg; p = 0,03), porém, tempo de retardo semelhante (-1,55 ± 0,66 vs. -1,58 ± 0.72 s; p = 0,90). Conclusão: Pré-hipertensos com HFHAS tem disfunção autonômica e condutância vascular aumentada quando comparados a normotensos com o mesmo fator de risco.

Relationship between heart rate variability and subclinical thyroid disorders of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

The association between subclinical thyroid dysfunctions and autonomic modulation changes has been described by many studies with conflicting results. We aimed to analyze the association between subclinical hyperthyroidism (SCHyper), subclinical hypothyroidism (SCHypo), and heart rate variability (HRV) using the baseline from ELSA-Brasil. SCHyper and SCHypo were classified by use of medication to treat thyroid disorders, thyrotropin levels respectively above and under the reference range, and normal free thyroxine levels. For HRV, the participants underwent 10 min in supine position and the R-R intervals of the final 5 min were selected for analysis. We first used linear regression models to report crude data and then, multivariate adjustment for sociodemographic (age, sex, and race) and cardiovascular risk factors (hypertension, dyslipidemia, diabetes, smoking, body mass index, use of alcohol, and leisure physical activity) using the euthyroid group as reference. From 9270 subjects (median age, 50; interquartile range: 44-56), 8623 (93.0%) were classified as euthyroid, 136 (1.5%) as SCHyper, and 511 (5.5%) as SCHypo. Compared to euthyroid subjects, SCHyper participants presented significantly higher heart rate (68.8 vs 66.5 for euthyroidism, P=0.007) and shorter R-R intervals (871.4 vs 901.6, P=0.007). Although SCHyper was associated with lower standard deviation of NN interval (SDNN) (β: -0.070; 95% confidence interval (95%CI): -0.014 to -0.009) and low-frequency (LF) (β: -0.242, 95%CI: -0.426 to -0.058) compared to the euthyroid group, these differences lost significance after multivariate adjustment for confounders. No significant differences were found for HRV in SCHypo. No association was found between HRV and SCHyper or SCHypo compared to euthyroid subjects in this sample of apparently healthy subjects.

Resting spontaneous baroreflex sensitivity and cardiac autonomic control in anabolic androgenic steroid users

OBJECTIVES: Misuse of anabolic androgenic steroids in athletes is a strategy used to enhance strength and skeletal muscle hypertrophy. However, its abuse leads to an imbalance in muscle sympathetic nerve activity, increased vascular resistance, and increased blood pressure. However, the mechanisms underlying these alterations are still unknown. Therefore, we tested whether anabolic androgenic steroids could impair resting baroreflex sensitivity and cardiac sympathovagal control. In addition, we evaluate pulse wave velocity to ascertain the arterial stiffness of large vessels. METHODS: Fourteen male anabolic androgenic steroid users and 12 nonusers were studied. Heart rate, blood pressure, and respiratory rate were recorded. Baroreflex sensitivity was estimated by the sequence method, and cardiac autonomic control by analysis of the R-R interval. Pulse wave velocity was measured using a noninvasive automatic device. RESULTS: Mean spontaneous baroreflex sensitivity, baroreflex sensitivity to activation of the baroreceptors, and baroreflex sensitivity to deactivation of the baroreceptors were significantly lower in users than in nonusers. In the spectral analysis of heart rate variability, high frequency activity was lower, while low frequency activity was higher in users than in nonusers. Moreover, the sympathovagal balance was higher in users. Users showed higher pulse wave velocity than nonusers showing arterial stiffness of large vessels. Single linear regression analysis showed significant correlations between mean blood pressure and baroreflex sensitivity and pulse wave velocity. CONCLUSIONS: Our results provide evidence for lower baroreflex sensitivity and sympathovagal imbalance in anabolic androgenic steroid users. Moreover, anabolic androgenic steroid users showed arterial stiffness. Together, these alterations might be the mechanisms triggering the increased blood pressure in this population.

Effects of resistance training protocols on nonlinear analysis of heart rate variability in metabolic syndrome

Despite the various standard non-linear measurements used in autonomic modulation (AM) assessments usually being applied to long time-series, such analyses can sometimes be applied to shorter term series. To overcome this disadvantage, chaotic global methods were formulated by putting together heart rate variability (HRV) linear methods. Chaos provides information about vegetative function control related to cardiovascular risks. Applying this method can be useful to investigate the complexity of the health condition after resistance training protocols, as a therapeutic intervention in AM in metabolic syndrome individuals (MetS). This study aimed to compare the effects of two resistance training programs (conventional vs functional) in MetS using nonlinear analysis of AM. MetS subjects (n=50) of both sexes aged 40 to 60 years were randomly divided into two programs; a group of 12 people served as a control group. Both groups performed 30 sessions of training. AM was assessed in the chaos domain by chaotic global techniques. The main results showed that both resistance training, functional and conventional, increased chaos when compared to the control group, respectively, observed by chaotic forward parameter (CFP)1 (13.9±17.9 vs 12.8±14.4 vs -2.23±7.96; P≤0.05) and CFP3 (15.4±19.8 vs 21.9±13.2 vs -4.82±11.4; P≤0.05). In addition, 30 sessions of both resistance programs increased chaos, and non-linear analysis enabled discrimination of AM after interventions when compared to the control group.

Monitorização do sistema nervoso autônomo em ambiente de cuidados intensivos como ferramenta de prognóstico. Revisão sistemática / Autonomic nervous system monitoring in intensive care as a prognostic tool. Systematic review

RESUMO Objetivo: Apresentar uma revisão sistemática do uso da monitorização do sistema nervoso autônomo como ferramenta de prognóstico, verificando a variabilidade da frequência cardíaca nas unidades de cuidados intensivos. Métodos: Revisão de literatura publicada até julho de 2016 na PubMed/MEDLINE de estudos realizados em unidades de cuidados intensivos, sobre a monitorização do sistema nervoso autônomo, por meio da análise da variabilidade da frequência cardíaca, como ferramenta de prognóstico - estudo da mortalidade. Foram utilizados os seguintes termos em inglês no campo de pesquisa: ("autonomic nervous system" OR "heart rate variability") AND ("intensive care" OR "critical care" OR "emergency care" OR "ICU") AND ("prognosis" OR "prognoses" OR "mortality"). Resultados: A probabilidade de morte nos doentes aumentou com a diminuição da variabilidade da frequência cardíaca, estudada por meio da variância da frequência cardíaca, desacoplamento cardíaco, volatilidade da frequência cardíaca, integer heart rate variability, desvio padrão de todos os intervalos RR normais, raiz quadrada da média do quadrado das diferenças entre intervalos RR adjacentes, poder total, componente de baixa frequência, componente de muito baixa frequência, razão entre o componente de baixa frequência e o componente de alta frequência), razão entre expoentes fractais de curto e longo prazo, entropia de Shannon, entropia multiescalar e entropia aproximada. Conclusão: Nos doentes internados em unidades de cuidados intensivos, independentemente da patologia que motivou o internamento, a variabilidade da frequência cardíaca varia de forma inversa com a gravidade clínica e com o prognóstico.

ABSTRACT Objective: To present a systematic review of the use of autonomic nervous system monitoring as a prognostic tool in intensive care units by assessing heart rate variability. Methods: Literature review of studies published until July 2016 listed in PubMed/Medline and conducted in intensive care units, on autonomic nervous system monitoring, via analysis of heart rate variability as a prognostic tool (mortality study). The following English terms were entered in the search field: ("autonomic nervous system" OR "heart rate variability") AND ("intensive care" OR "critical care" OR "emergency care" OR "ICU") AND ("prognosis" OR "prognoses" OR "mortality"). Results: There was an increased likelihood of death in patients who had a decrease in heart rate variability as analyzed via heart rate variance, cardiac uncoupling, heart rate volatility, integer heart rate variability, standard deviation of NN intervals, root mean square of successive differences, total power, low frequency, very low frequency, low frequency/high frequency ratio, ratio of short-term to long-term fractal exponents, Shannon entropy, multiscale entropy and approximate entropy. Conclusion: In patients admitted to intensive care units, regardless of the pathology, heart rate variability varies inversely with clinical severity and prognosis.

Recurrence plots: a new tool for quantification of cardiac autonomic nervous system recovery after transplant

Abstract Objective: To evaluate a possible evolutionary post-heart transplant return of autonomic function using quantitative and qualitative information from recurrence plots. Methods: Using electrocardiography, 102 RR tachograms of 45 patients (64.4% male) who underwent heart transplantation and that were available in the database were analyzed at different follow-up periods. The RR tachograms were collected from patients in the supine position for about 20 minutes. A time series with 1000 RR intervals was analyzed, a recurrence plot was created, and the following quantitative variables were evaluated: percentage of determinism, percentage of recurrence, average diagonal length, Shannon entropy, and sample entropy, as well as the visual qualitative aspect. Results: Quantitative and qualitative signs of heart rate variability recovery were observed after transplantation. Conclusion: There is evidence that autonomic innervation of the heart begins to happen gradually after transplantation. Quantitative and qualitative analyses of recurrence can be useful tools for monitoring cardiac transplant patients and detecting the gradual return of heart rate variability.

Neurofisiología de la empatía: una revisión de investigaciones / Neurophysiology of empathy: a review of investigations

La empatía es un constructo con múltiples definiciones y modelos explicativos, los cuales se han conformado a partir de observaciones e investigaciones en humanos y otros animales. En el presente, se revisaron estudios en humanos sanos, que vincula empatía con conducta motora, sistema nervioso autónomo y central. La evidencia presentada apoya la asociación entre empatía y el sistema de neuronas en espejo, la imitación facial, el contagio pupilar, el sistema autonómico, la interocepción, la conectividad neuronal, la ínsula, el cíngulo, entre otras. Finalmente, esta revisión incentiva el estudio, investigación y desarrollo de las múltiples áreas y disciplinas que tratan con la empatía.

Impact of malnutrition on cardiac autonomic modulation in children / Impacto da desnutrição na modulação autonômica cardíaca em crianças

Abstract Objective: To compare the autonomic behavior between malnourished children and a control group using analysis of heart rate variability (HRV). Method: Data were analyzed from 70 children who were divided into two groups: malnourished and eutrophic, according to the Z-score nutritional status for height and age. For analysis of HRV indices, heart rate was recorded beat to beat with the child in the supine position for 20 min. The analysis of these indices was performed using linear methods, analyzed in the time and frequency domains. Student's t-test for unpaired data and the Mann-Whitney test were used to compare variables between groups, with a significance level of 5%. Results: A reduction in systolic and diastolic blood pressure and an increase in heart rate were found in malnourished children compared to eutrophic children. The HRV indices suggested that malnourished children present reductions in both sympathetic and parasympathetic autonomic nervous system activity. The SDNN, rMSSD, NN50, pNN50, SD1, SD2, TINN, LF (ms2), and HF (ms2) indices were lower in malnourished children. Conclusion: Malnourished children present changes in cardiac autonomic modulation, characterized by reductions in both sympathetic and parasympathetic activity, as well as increased heart rate and decreased blood pressure.

Resumo Objetivo: Avaliar a modulação autonômica cardíaca de crianças desnutridas por meio da variabilidade da frequência cardíaca (VFC). Método: Foram analisadas 70 crianças com média de 3,71 anos, que foram distribuídas em dois grupos, de acordo com o estado nutricional: desnutridas (n = 35) e eutróficas (n = 35), seguindo o escore Z, para estatura e idade. Para análise dos índices da VFC, a frequência cardíaca foi captada batimento a batimento com as crianças em decúbito dorsal por 20 minutos. A análise desses índices foi feita por meio de métodos lineares, analisados nos domínios do tempo e da frequência. Teste t de Student para dados não pareados e teste de Mann-Whitney foram aplicados para comparar as variáveis entre os grupos, com nível de significância de 5%. Resultados: Redução da pressão arterial sistólica e diastólica e aumento na frequência cardíaca foram encontrados nas crianças desnutridas quando comparada com as eutróficas. Os índices da VFC sugerem que crianças desnutridas apresentam uma redução da modulação simpática e parassimpática do sistema nervoso autônomo. Os índices SDNN, rMSSD, NN50, pNN50, SD1, SD2, TINN, BF e AF em ms2 foram menores nas crianças desnutridas. Conclusão: Crianças desnutridas apresentam modificações na modulação autonômica cardíaca caracterizadas por depressão no componente simpático e no parassimpático, bem como aumento na frequência cardíaca e diminuição da pressão arterial.

Cardiovascular coupling during graded postural challenge: comparison between linear tools and joint symbolic analysis

ABSTRACT Background A joint symbolic analysis (JSA) is applied to assess the strength of the cardiovascular coupling from spontaneous beat-to-beat variability of the heart period (HP) and the systolic arterial pressure (SAP) during an experimental protocol inducing a gradual baroreflex unloading evoked by postural change (i.e. graded head-up tilt). Method: The adopted JSA can quantify the degree of association between the HP and SAP variabilities as a function of the time scale of the HP and SAP patterns. Traditional linear tools assessing the HP-SAP coupling strength, such as squared correlation coefficient, squared coherence function, and percentage of baroreflex sequences, were computed as well for comparison. Results: We found that: i) JSA indicated that the strength of the cardiovascular coupling at slow temporal scales gradually increased with the magnitude of the orthostatic challenge, while that at fast temporal scales gradually decreased; ii) the squared correlation coefficient and percentage of baroreflex sequences did not detect this behavior; iii) even though squared coherence function could measure the magnitude of the HP-SAP coupling as a function of the time scale, it was less powerful than JSA owing to the larger dispersion of the frequency domain indexes. Conclusion: Due to its peculiar features and high statistical power, JSA deserves applications to pathological groups in which the link between HP and SAP variabilities is lost or decreased due to the overall depression or impairment of the cardiovascular control.

Sevoflurane preconditioning during myocardial ischemia-reperfusion reduces infarct size and preserves autonomic control of circulation in rats

ABSTRACT PURPOSE: To investigate the myocardial ischemia-reperfusion with sevoflurane anesthetic preconditioning (APC) would present beneficial effects on autonomic and cardiac function indexes after the acute phase of a myocardial ischemia-reperfusion. METHODS: Twenty Wistar rats were allocated in three groups: control (CON, n=10), myocardial infarction with sevoflurane (SEV, n=5) and infarcted without sevoflurane (INF, n=5). Myocardial ischemia (60 min) and reperfusion were performed by temporary coronary occlusion. Twenty-one days later, the systolic and diastolic function were evaluated by echocardiography; spectral analysis of the systolic arterial pressure (SAPV) and heart rate variability (HRV) were assessed. After the recording period, the infarct size (IS) was evaluated. RESULTS: The INF group presented greater cardiac dysfunction and increased sympathetic modulation of the SAPV, as well as decreased alpha index and worse vagal modulation of the HRV. The SEV group exhibited attenuation of the systolic and diastolic dysfunction and preserved vagal modulation (square root of the mean squared differences of successive R-R intervals and high frequency) of HRV, as well as a smaller IS. CONCLUSION: Sevoflurane preconditioning better preserved the cardiac function and autonomic modulation of the heart in post-acute myocardial infarction period.

Symbolic analysis of heart rate variability and its interaction with p-value of normality tests applied on RR intervals / Análise simbólica da variabilidade da frequência cardíaca e sua interação com valor-p de testes de normalidade aplicado em intervalos RR

OBJECTIVE: A previous study suggested that the p-value of normality test applied to RR intervals is an index able to quantify Heart Rate Variability (HRV) through correlation of traditional time and frequency domain indices. We investigate the association between the p-value of normality test applied in RR intervals and symbolic analysis of HRV. METHOD: We evaluated 32 healthy women between 18 and 30 years old. RR intervals were used for HRV analysis and we performed symbolic analysis, where RR intervals are joined by symbols. Sets of three consecutive symbols (RR intervals) were grouped into four types of clusters, as follows: 1. Three equal symbols (zero variation); 2: two equal, one divergent symbol (one variation); 3. Three different symbols monotonically ascending or descending (two like variations); 4. Three different symbols, forming a peak or a trough (two unlike variations). Frequency of occurrence of each type of cluster was calculated. Normality tests were applied to all RR intervals and the p-value was calculated. We computed the correlations between the p-value of normality test and symbolic analysis of HRV. RESULTS: Correlation coefficients between the p-value of normality test from Kolmorogov-Smirnov test and the four types of clusters showed no correlation for any of them. Likewise, the correlation coefficient index between the p-value of normality test calculated from the Shapiro-Wilk test and symbolic analysis produced no significant results for any of the four types of clusters. CONCLUSION: There was no significant correlation between the p-value of normality test and HRV symbolic analysis. The physiological significance of this result is that the PNT is not related to chaotic behavior of HRV.

OBJETIVO: Um estudo anterior sugeriu que o valor "p" do teste de normalidade (PNT) aplicado a intervalos RR é um índice capaz de quantificar variabilidade da frequência cardíaca através da correlação tradicional dos índices de tempo e frequência. Investigamos a associação entre o teste PNT aplicado a intervalos RR e a análise simbólica da variabilidade da frequência cardíaca. MÉTODO: Foram avaliadas 32 mulheres saudáveis entre 18 e 30 anos de idade. Os intervalos RR foram utilizados para análise da variabilidade da frequência cardíaca; foi realizada uma análise simbólica, onde intervalos RR são unidos por símbolos. Grupos de três símbolos consecutivos foram agrupados em quatro tipos de aglomerados, a saber: 1: três símbolos iguais (variação zero); 2: dois símbolos iguais, um divergente (uma variação); 3: três símbolos diferentes, monotonicamente crescentes ou decrescentes (duas variações iguais); 4: três símbolos diferentes, formando um pico ou uma calha (duas variações desiguais). Foi calculada a frequência de ocorrência de cada tipo de cluster. Testes de normalidade foram aplicados a todos os intervalos RR e o valor de "p" foi calculado. Calculamos as correlações entre o PNT e análise simbólica de HRV. RESULTADOS: Os coeficientes de correlação entre PNT de teste Kolmorogov-Smirnov e os quatro tipos de clusters não mostraram correlação com qualquer um deles. Da mesma forma, o coeficiente de correlação entre o índice PNT calculado a partir do teste de Shapiro-Wilk e a análise simbólica não produziu resultados significativos para qualquer dos quatro tipos de aglomerados. CONCLUSÃO: Não houve correlação significativa entre o PNT e análise simbólica da variabilidade da frequência cardíaca. O significado fisiológico deste resultado é que o PNT não está relacionado ao comportamento caótico da VFC.

Correlation between heart rate variability and pulmonary function adjusted by confounding factors in healthy adults

The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.

Non-linear indices of heart rate variability during endodontic treatment

Abstract Dental treatment promotes psychosomatic change that can influence the procedure and compromise the general well-being of the patient. In this context, it highlights the importance of evaluating the function of the autonomic nervous system in individuals undergoing endodontic treatment. Thus, this manuscript aimed to analyse cardiac autonomic modulation, through non-linear indices of heart rate variability (HRV) during endodontic treatment. Analysis of 50 subjects of either sex aged between 18 and 40 years diagnosed with irreversible pulp necrosis of lower molars undergoing endodontic treatment was undertaken. We carried out fractal and symbolic analysis of HRV, which was recorded in the first session of the endodontic treatment at four intervals: T1: 0-10 min before the onset of the treatment session; T2: 0-10 min after the application of anaesthesia; T3: throughout the period of treatment; and T4: 0-30 min after the end of the treatment session. There was reduction of α1 in T2 compared to T1 and T4 (p < 0.0001). The α2 index also reduced in T2 compared to T3 (p = 0.0035). There was an increase in the α1/α2 ratio in T4 compared to T2 and T3 (p = 0.0003). It was found that 0V% was significantly lower in T2 (p = 0.002), while 2UV% was significantly higher (p < 0.0001) when compared to other points in time. In conclusion, HRV is reduced during endodontic treatment, and after applying local anaesthetic the parasympathetic component of HRV increases. These data indicate that endodontic treatment acutely overcharges the heart, supporting the stress involved in this situation.

Papel do sistema nervoso autônomonas arritmias cardíacas / Role of the autonomic nervous system in cardiac arrhythmias

As arritmias cardíacas apresentam comportamento eletrofisiológico, manifestação clínica, prognóstico e resposta terapêutica diferentes na população. Sendo assim, a compreensão dos mecanismos envolvidos na gênese da anormalidade do ritmo cardíaco é fundamental para nortear a terapêutica. O sistema nervoso autônomo participa ativamente da eletrofisiologia da célula cardíaca e dos mecanismos relacionados ao desencadeamento das arritmias cardíacas. Dentre as arritmias supraventriculares, a fibrilação atrial merece destaque. Estudos avaliando a variabilidade da frequência cardíaca demonstram importante modificação autonômica antecedendo um quadro defibrilação atrial. Tanto a ativação simpática quanto a estimulação parassimpática podem participar da manutenção dessa arritmia. Além disso, métodos que reduzem a inervação autonômica também reduzem a incidência de arritmias atriais, sugerindo que a neuromodulação possa ser uma ferramenta promissora no controle dessa arritmia. As arritmias ventriculares também se relacionam ao comportamento autonômico. O infarto agudo do miocárdio ocasiona denervação das fibras simpáticas na cicatriz e as áreas de intensa fibrose perdem a capacidade de responderem a estimulação simpática; entretanto asregiões próximas a cicatriz apresentam um encurtamento do período refratário para a estimulação simpática de forma heterogênica predispondo a ocorrência da ectopias ventriculares. Dessa forma, a investigação do sistema nervoso autônomo no desencadeamento e manutenção das arritmias cardíacas é uma linha de pesquisa promissora e a maior compreensão dos mecanismos autonômicos irá propiciar novas ferramentas de controle das anormalidades do ritmo cardíaco...

Cardiac arrhythmias present varying electrophysiological behavior, clinical manifestation, prognosis, and therapeutic response in the population. An understanding of the mechanisms involved in the genesis of heart rhythm disorders is there fore essential for guiding the therapy. The autonomic nervous system plays an active role in the electrophysiology of the cardiac cells and the mechanisms that trigger cardiac arrhythmias. Atrial fibrillation, one of the supraventricular arrhythmias, deserves special attention. Studies to evaluate heart rate variability have demonstrated important modifications preceding an episode of atrial fibrillation. Both sympathetic activation and parasympathetic stimulation can play a role in the persistence of this arrhythmia. More over, methods that reduce autonomic innervation also reduce the incidence of atrial arrhythmias, suggesting that neuromodulation can be a promising tool in the control of this arrhythmia. Ventricular arrhythmias are also related to autonomic behavior. Acute myocardial infarction leads to denervation of the sympathetic fibers in the scar tissue, and the areas of intense fibrosis lose their capacity to respond to sympathetic stimulation, while the regions close to thescar tissue present heterogeneous refractory period shortening for sympathetic stimulation, predisposing to the occurrence of ventricular ectopic beats. Thus, the investigation of the autonomic nervous system in the triggering and persistence of heart arrhythmias is a promising line of research, and a better understanding of the autonomic mechanisms involved will provide new tools for the control of heart rhythm disorders...

Resposta ao estresse: l. homeostase e teoria da alostase / Stress response: l. homestasis and allostasis theory / Respuesta al estrés: l. homeostasis y teoría de la alostasis

Os seres vivos desenvolvem ao longo de sua história evolutiva mecanismos de enfrentamento às condições adversas originadas tanto no ambiente geofísico como no ambiente social. Esta resposta adaptativa é coordenada e envolve diferentes sistemas funcionais, particularmente, os sistemas nervoso, endócrino e imune, e é denominada de resposta ao estresse e deve atender a duas demandas principais da vida: sobrevivência e reprodução. Esta revisão tem o objetivo de discutir o emprego do conceito clássico de homeostase e um conceito alternativo, alostase, que inclui os mecanismos preditivos e reativos de regulação, assim como os diferentes níveis de impacto dos estressores crônicos, resultando em sobrecarga alostática que pode ou não se seguir de falha alostática. Os mecanismos neurais, hormonais, imunes, sistêmicos e moleculares, que compreendem os sistemas alóstaticos subjacentes à resposta ao estresse são também apresentados.

Over the course of their evolution organisms developed mechanisms to cope with challenging situations originating from both physical and social environments. These adaptive mechanisms are coordinated and involve the sequential and/or simultaneous recruitment of different functional systems, mainly neural, endocrine and immune, the so-called stress response. They operate to maintain physiological variables at suitable. This review aims to discuss the use of the classical homeostasis concept and allostasis, an alternative model, which includes reactive and predictive mechanisms, as well as the different levels of impact of the chronic stressor, resulting in allostatic overload or allostatic failure. The organizing role of neural, hormonal, immune, systemic and molecular mechanisms, which comprise the allostatic systems underlying the stress response, is also presented.

Los seres vivos desarrollan a lo largo de su historia evolutiva mecanismos de enfrentamiento a las condiciones adversas originadas tanto en el ambiente geofísico como en el ambiente social. Esta respuesta adaptativa es coordinada y envuelve distintos sistemas funcionales, particularmente, el sistema nervioso, endócrino e inmune y es denominada de respuesta al estrés y debe atender a las dos demandas principales de la vida: supervivencia y reproducción. Esta revisión tiene como objetivo de discutir el empleo del concepto clásico de homeostasis y una concepto alternativa, alostasis, que incluye los mecanismos y el impacto de los agentes de estresores crónicos resultando en sobrecarga alostática o falla alostática. Los mecanismos neuronales, hormonales e inmunes, sistémicos y moleculares que comprenden los sistemas alóstaticos subyacentes a la respuesta al estrés son también presentados.