Dinámica no lineal de la regulación autonómica cardiovascular durante la prueba del peso sostenido en pacientes con diabetes mellitus tipo 2 / Nonlinear dynamics of cardiovascular autonomic regulation during the sustained weight test in patients with type 2 diabetes mellitus

Resumen Introducción: La dinámica no lineal de la regulación autonómica cardiovascular a partir de la variabilidad de la frecuencia cardiaca no ha sido previamente estudiada en pacientes con diabetes mellitus tipo 2 mediante la prueba del peso sostenido como inductor de hiperreactividad cardiovascular. Objetivo: Determinar las variaciones en la dinámica no lineal de la regulación autonómica cardiovascular durante la prueba del peso sostenido en pacientes con diabetes mellitus tipo 2. Método: Estudio cuasiexperimental, antes-después, con grupo control, realizado en junio-agosto de 2018 en la Facultad No. 1 de Medicina de Santiago de Cuba. Se trabajó con 15 pacientes que padecían diabetes mellitus tipo 2 sin otra enfermedad asociada y 15 sujetos sanos, a quienes se les aplicó la prueba del peso sostenido. Resultados: En los pacientes con diabetes mellitus, al realizar la prueba del peso sostenido se produjo un aumento significativo en la presión arterial sistólica, diastólica y media, y en la frecuencia cardiaca. En la entropía muestral, parámetro que evalúa la adaptabilidad de los sistemas, se produjo una disminución significativa (2.28 ± 0.33 vs. 1.83 ± 0.47 ms; p = 0.003143). El valor del estadístico C de la entropía muestral en estado basal quedó establecido en 0.973, siendo la variable con mayor capacidad predictiva. Conclusiones: Durante la prueba del peso sostenido en los pacientes con diabetes mellitus tipo 2 se produjo una disminución de la complejidad de la regulación autonómica cardiovascular; la entropía muestral basal constituyó el indicador de mayor eficacia en la identificación de alteraciones autonómicas cardiovasculares.

Abstract Introduction: The analysis of non-linear dynamics of cardiovascular autonomic regulation based on heart rate variability has not been previously studied in patients with type 2 diabetes mellitus using the sustained weight test as an inducer of cardiovascular hyperreactivity. Objective: To determine the variations in the non-linear dynamics of cardiovascular autonomic regulation during the sustained weight test in patients with type 2 diabetes mellitus. Method: A quasi-experimental, before-after study with a control group, from June-August 2018, at the No. 1 School of Medicine in Santiago de Cuba. We worked with 15 patients suffering from type 2 diabetes mellitus without other associated disease and 15 healthy subjects, to whom the sustained weight test was applied. Results: In patients with diabetes mellitus, when performing the sustained weight test, there was a significant increase in the hemodynamic parameters TAS, TAD, TAM and FC. In the sample entropy, a parameter that evaluates the adaptability of the systems, there is a significant decrease (2.28 ± 0.33 vs. 1.83 ± 0.47 ms; p = 0.003143). The value of the C statistic of the sample entropy at baseline was established at 0.973, being the variable with the highest predictive capacity. Conclusions: In patients with type 2 diabetes mellitus during the sustained weight test, there was a decrease in the complexity of cardiovascular autonomic regulation, the basal sample entropy was the indicator of greater efficacy in the identification of cardiovascular autonomic alterations.

Acute response to aerobic exercise on autonomic cardiac control of patients in phase iii of a cardiovascular rehabilitation program following coronary artery bypass grafting

Abstract Objective: The aim of the present study was to investigate the acute response to aerobic exercise on autonomic cardiac control of patients undergoing coronary artery bypass grafting (CABG). Methods: The study sample consisted of eight patients (age: 58.6±7.7 years; body mass index: 26.7±3.5 kg.m2) who underwent a successful CABG (no complications during surgery and/or in the following weeks). To assess heart rate variability (HRV), participants remained in a supine position with a 30-degree head elevation for 20 minutes. Electrocardiographic signal (protocol with three derivations) was collected from 600 Hz sample rate to obtain beat-to-beat intervals (R-R interval). This assessment was performed before, after one hour and after 24 hours of the exercise session. All patients underwent a 35 minutes aerobic exercise session (AES) (low-moderate intensity) on the cycle ergometer. Results: Significant differences were found in the time domain, with positive changes in root mean square of successive RR interval differences (rMSSD) (ms) (parasympathetic component) (one [P=0.017] and 24 hours [P=0.007] post-session). In the frequency domain, we found a significant difference in high frequency (HF) (ms2) (parasympathetic component) (one hour [P=0.048] post-session). The low frequency (LF)/HF ratio (sympathetic and parasympathetic components with a predominance of the sympathetic component) reached statistical significance only 24 hours (P=0.018) post-session. Additionally, the largest effect size was observed only for the LF/HF ratio at one (d=-0.8) and 24 hours (d=-1.3) after one AES. Conclusion: The practice of (acute) aerobic exercise improved autonomic cardiac control in patients undergoing CABG.

Sympatho-Vagal Imbalance is Associated with Sarcopenia in Male Patients with Heart Failure / Desequilíbrio Simpático-Vagal está Associado com Sarcopenia em Pacientes do Sexo Masculino com Insuficiência Cardíaca

Abstract Background: Resting sympathetic hyperactivity and impaired parasympathetic reactivation after exercise have been described in patients with heart failure (HF). However, the association of these autonomic changes in patients with HF and sarcopenia is unknown. Objective: The aim of this study was to evaluate the impact of autonomic modulation on sarcopenia in male patients with HF. Methods: We enrolled 116 male patients with HF and left ventricular ejection fraction < 40%. All patients underwent a maximal cardiopulmonary exercise testing. Maximal heart rate was recorded and delta heart rate recovery (∆HRR) was assessed at 1st and 2nd minutes after exercise. Muscle sympathetic nerve activity (MSNA) was recorded by microneurography. Dual-energy X-ray absorptiometry was used to measure body composition and sarcopenia was defined by the sum of appendicular lean muscle mass (ALM) divided by height in meters squared and handgrip strength. Results: Sarcopenia was identified in 33 patients (28%). Patients with sarcopenia had higher MSNA than those without (47 [41-52] vs. 40 [34-48] bursts/min, p = 0.028). Sarcopenic patients showed lower ∆HRR at 1st (15 [10-21] vs. 22 [16-30] beats/min, p < 0.001) and 2nd min (25 [19-39] vs. 35 [24-48] beats/min, p = 0.017) than non-sarcopenic. There was a positive correlation between ALM and ∆HRR at 1st (r = 0.26, p = 0.008) and 2nd min (r = 0.25, p = 0.012). We observed a negative correlation between ALM and MSNA (r = -0.29, p = 0.003). Conclusion: Sympatho-vagal imbalance seems to be associated with sarcopenia in male patients with HF. These results highlight the importance of a therapeutic approach in patients with muscle wasting and increased peripheral sympathetic outflow.

Resumo Fundamento: Hiperatividade simpática de repouso e uma reativação parassimpática diminuída pós-exercício têm sido descritas em pacientes com insuficiência cardíaca (IC). No entanto, a associação dessas alterações autonômicas em pacientes com IC sarcopênicos ainda não são conhecidas. Objetivo: O objetivo deste estudo foi avaliar o impacto da modulação autonômica sobre sarcopenia em pacientes com IC do sexo masculino. Métodos: Foram estudados 116 pacientes com IC e fração de ejeção ventricular esquerda inferior a 40%. Todos os pacientes foram submetidos ao teste de exercício cardiopulmonar máximo. A frequência cardíaca máxima foi registrada, e o delta de recuperação da frequência cardíaca (∆RFC) foi avaliado no primeiro e no segundo minuto após o exercício. A atividade nervosa simpática muscular (ANSM) foi registrada por microneurografia. A Absorciometria Radiológica de Dupla Energia foi usada para medir composição cpororal, e a sarcopenia definida como a soma da massa muscular apendicular (MMA) dividida pela altura em metros ao quadrado e força da mão. Resultados: A sarcopenia foi identificada em 33 pacientes (28%). Os pacientes com sarcopenia apresentaram maior ANSM que aqueles sem sarcopenia - 47 (41-52) vs. 40 (34-48) impulsos (bursts)/min, p = 0,028). Pacientes sarcopênicos apresentaram ∆RFC mais baixo no primeiro [15 (10-21) vs. 22 (16-30) batimentos/min, p < 0,001) e no segundo [25 (19-39) vs. 35 (24-48) batimentos/min, p = 0,017) minuto que pacientes não sarcopênicos. Observou-se uma correlação positiva entre a MMA e a ANSM (r = -0,29; p = 0,003). Conclusão: Um desequilíbrio simpático-vagal parece estar associado com sarcopenia em pacientes com IC do sexo masculino. Esses resultados destacam a importância de uma abordagem terapêutica em pacientes com perda muscular e fluxo simpático periférico aumentado.

Changes in Cardiac Autonomic Modulation in Women with Breast Cancer Using Aromatase Inhibitors and the Relation with Biochemical Variables / Alterações na Modulação Autonômica Cardíaca em Mulheres com Câncer de Mama em Uso de Inibidores de Aromatase e sua Relação com Variáveis Bioquímicas

Abstract Background: The use of autonomic modulation as a predictor of cardiovascular risk in women with breast cancer is important. Objective: To evaluate the cardiac autonomic modulation of postmenopausal women using aromatase inhibitors for breast cancer treatment, as well as its relation with the following biochemical variables. Methods: Postmenopausal women who did not have breast cancer (n = 33) and postmenopausal women with breast cancer (n = 15). For evaluation of the autonomic modulation the heart rate was recorded beat-to-beat for 30 minutes and the series of RR intervals obtained were used to calculate the following heart rate variability indices: Mean RR ms, SDNN (standard deviation of all normal RR intervals, expressed in milliseconds) ms, Mean HR, RMSSD (square root of the mean of the squared differences between adjacent normal RR interval) ms, NN50 (number of pairs of successive NNs that differ by more than 50 ms) count, pNN50% (proportion of NN50 divided by total number of NNs), RRtri (RR triangular), TINN (triangular interpolation of NN interval) ms, SD1 ms, SD2 ms, LF ms2, HF ms2, LH/HF ms2. The values of biochemical variables (fasting glycemia, triglycerides, HDL-cholesterol, and C-reactive protein) were analyzed by blood sample. Results: Lower values of heart rate variability indices were observed in postmenopausal women with breast cancer in relation to postmenopausal women who did not have breast cancer: Mean RR (p = 0.03); SDNN (p = 0.03); RMSSD (p = 0.03); NN50 count (p = 0.03); pNN50 % (p = 0.03); RRtri (p = 0.02); SD1 (p = 0.01); SD2 (p = 0.02); LF ms2 (p = 0.01); HF ms2 (p = 0.03).There was an inversely proportional correlation between the indices SDNN, SD2, and HFms2 with triglycerides (SDNN p = 0.04; SD2 p = 0.04; HF ms2 p = 0.04). No statistically significant correlations were found between heart rate variability indices and others variables. Statistical significance was set at 5% for all analyses. Conclusion: Women with breast cancer present reduced autonomic modulation and in these women of heart rate variability indices are inversely correlated with triglyceride values.

Resumo Fundamentos: A modulação autonômica como um preditor de risco cardiovascular em mulheres com câncer de mama é importante. Objetivos: Avaliar a modulação autonômica em mulheres pós-menopausa em uso de inibidores de aromatase como tratamento de câncer de mama, e sua relação com algumas variáveis bioquímicas. Métodos: Foram avaliadas mulheres pós-menopausa sem câncer de mama (n = 33) e mulheres pós-menopausa com câncer de mama (n = 15). Para avaliação da modulação autonômica, a frequência cardíaca (FC) foi registrada batimento a batimento por 30 minutos, e as séries de intervalos RR obtidas foram usadas para o cálculo dos seguintes índices de variabilidade da frequência cardíaca: média de RR ms, SDNN (desvio padrão de todos os intervalos RR normais) ms, FC, RMSSD (raiz quadrada da média das diferenças ao quadrado entre os intervalos RR normais adjacentes) ms, contagem NN50 (número de pares de NNs sucessivos que se diferem em mais de 50 ms), pNN50% (proporção de NN50 dividida pelo número total de NNs), RRtri (RR triangular), TINN (interpolação triangular do intervalo NN) ms, DP1 ms, DP2 ms, LF (baixa frequência) ms2, HF (alta frequência) ms2, LH/HF ms2. Os valores das variáveis bioquímicas (glicemia de jejum, triglicerídeos, HDL-colesterol, e proteína C reativa) foram analisadas das amostras de sangue. O nível de significância adotado nas análises estatísticas foi de 5%. Resultados: As mulheres pós-menopausa com câncer de mama apresentaram menores índices de variabilidade da frequência cardíaca em comparação àquelas sem câncer de mama: média de RR (p = 0,03); SDNN (p = 0,03); RMSSD (p = 0,03); contagem NN50 (p = 0,03); pNN50% (p = 0,03); RRtri (p = 0,02), DP1 (p = 0,01), DP2 (p = 0,02); LF ms2 (p = 0,01); HF ms2 (p = -0,03). Observou-se uma correlação inversamente proporcional dos índices SDNN, DP2 e HF ms2 com triglicerídeos (SDNN p = 0,04, DP2 p = 0,04; HF ms2 0,04). Não houve correlação significativa entre os índices de variabilidade da frequência cardíaca e as demais variáveis. Conclusão: Mulheres com câncer de mama apresentam modulação autonômica diminuída e índices de variabilidade da FC inversamente correlacionados com valores de triglicerídeos.

Women with Polycystic Ovarian Syndrome Exhibit Reduced Baroreflex Sensitivity That May Be Associated with Increased Body Fat / Mulheres com Síndrome do Ovário Policístico Apresentam menor Sensibilidade Barorreflexa, a Qual Pode Estar Associada ao Aumento da Gordura Corporal

Abstract Background: Polycystic ovarian syndrome (PCOS) women have a high prevalence of obesity and alterations in cardiovascular autonomic control, mainly modifications in heart rate variability (HRV) autonomic modulation. However, there are few studies about other autonomic control parameters, such as blood pressure variability (BPV) and baroreflex sensitivity (BRS). In addition, there are still doubts about the obesity real contribution in altering autonomic control in these women. Objective: To investigate BPV and BRS autonomic modulation alterations in PCOS women, as well as, to evaluate whether these alterations are due PCOS or increased body fat. Methods: We studied 30 eutrophic volunteers [body mass index (BMI) < 25 kg/m2] without PCOS (control group) and 60 volunteers with PCOS divided into: eutrophic (BMI < 25 kg/m2, N = 30) and obese women (BMI > 30 kg/m2, N = 30). All volunteers were submitted to anthropometric evaluation, hemodynamic and cardiorespiratory parameters record at rest and during physical exercise, analysis of HRV, BPV and spontaneous BRS. The differences in p less than 5% (p < 0.05) were considered statistically significant. Results: Related to eutrophics groups, there were no differences in autonomic parameters evaluated. The comparison between the PCOS groups showed that both PCOS groups did not differ in the BPV analysis. Although, the obese PCOS group presented lower values of spontaneous BRS and HRV, in low frequency and high frequency oscillations in absolute units. Conclusion: Our results suggest that obesity did little to alter HRV in women with PCOS, but it may influence the spontaneous BRS.

Resumo Fundamento: As mulheres com síndrome do ovário policístico (SOP) apresentam alta prevalência de obesidade e alterações no controle autonômico cardiovascular, principalmente modificações na modulação autonômica da variabilidade da frequência cardíaca (VFC). No entanto, existem poucos estudos sobre outros parâmetros de controle autonômico, como a variabilidade da pressão arterial (VPA) e a sensibilidade barorreflexa (SBR). Além disso, ainda há dúvidas sobre a real contribuição da obesidade na alteração do controle autonômico dessas mulheres. Objetivo: Investigar as alterações da modulação autonômica da VPA e SBR em mulheres com SOP, bem como avaliar se essas alterações se devem à SOP ou ao aumento da gordura corporal. Métodos: Foram estudadas 30 voluntárias com peso normal [índice de massa corporal (IMC) < 25 kg/m2] sem SOP (grupo controle) e 60 voluntárias com SOP, divididas em: mulheres com peso normal (IMC < 25 kg/m2, N = 30) e mulheres obesas (IMC > 30 kg/m2, N = 30). Todas as voluntárias foram submetidas à avaliação antropométrica, com registro de parâmetros hemodinâmicos e cardiorrespiratórios em repouso e durante exercício físico, e análise da VFC, VPA e SBR espontânea. As diferenças de p < 5% (p < 0,05) foram consideradas estatisticamente significantes. Resultados: Em relação aos grupos com peso normal, não houve diferenças nos parâmetros autonômicos avaliados. A comparação entre os grupos SOP mostrou que ambos os grupos não diferiram na análise da VPA. No entanto, o grupo SOP obeso apresentou menores valores de SBR espontânea e VFC nas oscilações de baixa e alta frequências, em unidades absolutas. Conclusão: Nossos resultados sugerem que a obesidade pouco influenciou a VFC em mulheres com SOP, mas pode afetar a SBR espontânea.

Effects of a new approach of aerobic interval training on cardiac autonomic modulation and cardiovascular parameters of metabolic syndrome subjects

ABSTRACT Objective: To evaluate the effects of 16 weeks of periodized aerobic interval training (AIT) on cardiac autonomic modulation and cardiovascular parameters of metabolic syndrome (Mets) individuals. Subjects and methods: The sample was composed of 52 subjects with a diagnosis of Mets, allocated into two groups: AIT (AITG; n = 26) and control (CG; n = 26). The AITG was submitted to a periodized AIT program, over 16 weeks, while CG was not submitted to any training program. To evaluate the autonomic modulation and cardiovascular parameters in both groups, heart rate variability (HRV) indices, blood pressure (BP), and heart rate (HR) were measured at the beginning and end of the training. Results: Statistically significant differences were not observed in HFms2 (high frequency in milisseconds), LFnu (low frequency in normality unit), HFnu (high frequency in normality unit), and LF/HF ratio indices, or in the cardiovascular parameters BP and HR when comparing the AITG with the CG. However, significant increases in rMSSD (root-means square differences of successive R-R intervals), LFms2 (low frequency in milliseconds), and SDNN (standard deviation of normal to normal intervals) were observed in the AITG. Conclusion: Periodized AIT promoted positive effects on autonomic modulation of Mets subjects, characterized by an increase in the parasympathetic, sympathetic, and global modulation of this population. Additionally, cardiovascular parameter alterations were not observed in Mets subjects submitted to periodized AIT.

The effects of cataract surgery on autonomic heart rate control: a prospective cross-sectional and analytical study

OBJECTIVES: We aimed to evaluate the effects of cataract surgery on cardiac autonomic modulation. METHODS: A cross-sectional and analytical study was conducted at the Hospital Maria Braido in the city of São Caetano do Sul, São Paulo, between 2015 and 2016. We investigated 19 patients of both sexes who were all over 50 years old; all patients had a diagnosis of senile or bilateral cataracts and were recommended to undergo implantation of the intraocular lens. Heart rate variability (HRV) was evaluated before, during and after cataract surgery. RESULTS: There were no significant changes in the time and geometric domains of HRV before, during or after surgery. The high-frequency (HF) band in normalized units (nu) on the spectral analysis significantly increased (p=0.02, Cohen's d=0.9, large effect size). However, the low-frequency (LF) band in nu significantly decreased during surgery (p=0.02, Cohen's d=0.9, large effect size). CONCLUSION: Throughout the intraocular lens implantation cataract surgery, there was an increase in parasympathetic modulation and a decrease in the sympathetic component of the heart rate (HR). We propose that this result is attributable to the supine position of the patients during surgery and the trigeminal reflex.

Autonomic dysfunction in patients with central serous chorioretinopathy / Disfunção autonômica em pacientes com coriorretinopatia serosa central

Abstract Objetive: To evaluate the association between sympathetic nervous system activity and blood pressure variability with central serous chorioretinopathy (CSC). Methods: We performed an individual, observational, and cross-sectional study involving 11 patients with CSC and 16 healthy individuals in similar age range. Participants underwent spectral power analysis of heart rate variability (HRV) at the Hypertension Department of Heart Institute at the University of São Paulo. Results: We demonstrated sympathetic activity predominance in CSC group and found that the LF (low frequency) of heart rate variability was significantly higher in this group (p = 0.04). when compared to control group. The CSC group's mean LF / HF (high frequency) ratio was higher than the control group but was not statistically significant (p = 0.2). Blood pressure variability was higher in CSC patients than in normal patients (p = 0.055), whereas heart rate variability was lower in these patients when compared to normal patients, although no statistical significance was found (p = 0.2). Spontaneous baroreflex function was significantly reduced in patients with CSC when compared to healthy individuals (p = 0.04). Conclusion: Autonomic dysfunction and a predominance of sympathetic modulation were observed in CSC patients.

Resumo Objetivo: Avaliar a associação entre a atividade do sistema nervoso simpático e a variabilidade da pressão arterial com a coriorretinopatia serosa central (CSC). Métodos: Estudo individuado, observacional e transversal envolvendo 11 pacientes com CSC e 16 indivíduos saudáveis de idade semelhante. Os participantes foram submetidos à análise de poder espectral da variabilidade da freqüência cardíaca no Departamento de Hipertensão do Instituto do Coração da Universidade de São Paulo. Resultados: Observamos o predomínio da atividade simpática no grupo com CSC, evidenciado pelo LF da variabilidade da freqüência cardíaca significativamente maior neste grupo (P = 0.04) quando comparado ao grupo controle. A média da relação LF / HF e a variabilidade da pressão arterial foram maiores nos pacientes com CSC do que nos pacientes normais (P = 0,2 e P = 0,055, respectivamente), enquanto a variabilidade da freqüência cardíaca foi menor nesses pacientes quando comparados aos pacientes normais (P = 0,2), embora não tenha sido encontrada significância estatística. A função barorreflexa espontânea também foi significativamente reduzida nos pacientes com CSC quando comparados aos indivíduos saudáveis (P= 0,04). Conclusão: Concluímos que há sinais de disfunção autonômica e predomínio da modulação simpática nos pacientes com CSC.

Relação entre ansiedade e modulação autonômica cardíaca / Relationship between anxiety and autonomic heart modulation

A ansiedade é caracterizada pelo sentimento de tensão, nervosismo, apreensão e preocupação que pode alterar a modulação do sistema nervoso autônomo sobre a condução elétrica ligada ao coração, determinando a intensidade nos batimentos cardíacos modificando a variabilidade da frequência cardíaca que é um importante indicador de condições normais e patológicas. Assim, o objetivo do estudo foi analisar a relação existente entre a ansiedade e o processo de regulação autonômica cardíaca. Este estudo trata-se de uma revisão integrativa desenvolvido por meio de buscas nas bases de dados da Lilacs, Medline e SciELO, com os descritores em ciências da saúde e operador booleano: ansiedade AND frequência cardíaca e, ansiedade AND sistema nervoso autônomo. A busca foi realizada durante o mês de setembro de 2017, sendo incluídos artigos disponíveis na íntegra; em português e inglês e; publicados nos últimos 06 anos. Excluiu-se artigos que não fossem originais, teses, dissertações e monografias. Obteve-se um total de 10 artigos, nos quais observou-se que a ansiedade altera a resposta autonômica, assim quando o corpo entra em tensão, aumenta-se a frequência cardíaca, o predomínio do sistema simpático e no relaxamento ocorre o domínio parassimpático. Assim indivíduos portadores de ansiedade apresentam menor variação na frequência cardíaca e possuem uma capacidade menor de interação social. Com isto, evidencia-se uma baixa adaptação do sistema nervoso autônomo em casos de ansiedade, sendo que a variabilidade da frequência cardíaca encontra-se reduzida; condição esta que pode ser classificada como patológica.

The anxiety is characterized by the sensation of tension, nervousness, apprehension and worry that can alter the modulation of autonomic nervous system on the electrical conduction linked to the heart, determining the intensity in the heart beats modifying the heart rate variability, which is an important indicator of conditions normal and pathological. Thus, the study objective is to analyze the relationship between anxiety and the process of autonomic cardiac regulation. This study is an integrative review developed through searches in the databases of Lilacs, Medline and SciELO, with the descriptors in health sciences and boolean operator: anxiety AND heart rate and anxiety AND autonomic nervous system. The search was performed during the month of September of 2017, being included articles available in full; in Portuguese and English and; published in the last 6 years. Was excluded articles that were not original, theses, dissertations and monographs. Was obtained a total of 10 articles, in which it was observed that anxiety alters the autonomic response, so when the body is in tension, increases your heart rate, the predominance of the sympathetic system and in the relaxation occurs the domain of the parasympathetic. Thus, individuals with anxiety present lower variation in heart rate and have a lower capacity for social interaction. With this, it is evident a low adaptation of the autonomic nervous system in cases of anxiety, being that the variability of the heart rate is reduced; condition that can be classified as pathological.

Effects of Coexistence Hypertension and Type II Diabetes on Heart Rate Variability and Cardiorespiratory Fitness / Efeitos da Coexistência de Diabetes Tipo 2 e Hipertensão sobre a Variabilidade da Frequência Cardíaca e Capacidade Cardiorrespiratória

Abstract Background: Type 2 diabetes Mellitus (T2DM) is associated with cardiac autonomic dysfunction, which is an independent predictor of mortality in chronic diseases. However, whether the coexistence of systemic arterial hypertension (HTN) with DMT2 alters cardiac autonomic modulation remains unknown. Objective: To evaluate the influence of HTN on cardiac autonomic modulation and cardiorespiratory fitness in subjects with DMT2. Methods: 60 patients of both genders were evaluated and allocated to two groups: DMT2 patients (n = 32; 51 ± 7.5 years old) and DMT2 + HTN patients (n = 28; 51 ± 6.9 years old). RR intervals were obtained during rest in supine position. Linear and nonlinear indices of heart rate variability (HRV) were computed using Kubios HRV software. Pulmonary gas exchange was measured breath-by-breath, using a portable telemetric system during maximal incremental exercise testing on a cycle ergometer. Statistical analysis included Shapiro-Wilk test followed by Student's t Test, Pearson correlation and linear regression. Results: We found that patients in the DMT2+HTN group showed lower values of mean RR intervals (801.1 vs 871.5 ms), Shannon entropy (3 vs 3.2) and fractal dimension SD 1 (9.5 vs 14.5), when contrasted with patients in the DMT2 group. Negative correlations were found between some HRV nonlinear indices and exercise capacity indices. Conclusion: HTN negatively affects the cardiac autonomic function in diabetic patients, who are already prone to develop autonomic dysfunction. Strategies are need to improve cardiac autonomic functionality in this population.

Resumo Fundamento: A diabetes mellitus tipo 2 (DM2) está associada com disfunção autonômica cardíaca, que é um preditor independente de mortalidade em doenças crônicas. No entanto, ainda não se sabe se a coexistência de hipertensão arterial sistêmica (HAS) e DM2 altera a modulação cardíaca autonômica. Objetivos: O objetivo deste estudo foi avaliar a influência de HAS sobre a modulação da função autonômica cardíaca e capacidade cardiopulmonar em indivíduos com DM2. Métodos: 60 pacientes de ambos os sexos foram avaliados e alocados em dois grupos; pacientes DM2 (n = 32; 51 ± 7,5 anos) e pacientes DM2 + HAS (n = 28; 51 ± 6,9 anos). Intervalos RR foram obtidos durante repouso e em posição supina. Índices lineares e não lineares da variabilidade da frequência cardíaca (VFC) foram registrados utilizando-se o programa Kubios HRV software. A troca gasosa pulmonar foi medida a cada inspiração, utilizando-se um sistema telemétrico portátil durante o teste incremental máximo de exercício em cicloergômetro. A análise estatística incluiu o teste Shapiro-Wilk seguido do teste t de Student, a correlação de Pearson e a regressão linear. Resultados: Encontramos que pacientes do grupo DM2+HAS apresentaram valores mais baixos de intervalos RR (801,1 vs 871,5 ms), entropia de Shannon (3,0 vs 3,2) e DP1 da dimensão fractal em comparação aos pacientes do grupo DM2. Foram encontradas correlações negativas entre alguns índices não lineares da VFC e índices da capacidade do exercício. Conclusão: A HAS afeta negativamente a função autonômica cardíaca em pacientes diabéticos, os quais já são propensos a desenvolverem disfunção autonômica. Estratégias são necessárias para melhorar a função autonômica cardíaca nessa população.

Complexity of autonomic nervous system function in individuals with COPD / Complexidade do sistema nervoso autônomo em indivíduos com DPOC

ABSTRACT Objective: To evaluate autonomic modulation in individuals with COPD, compared with healthy controls, via recurrence plots (RPs) and linear heart rate variability (HRV) indices. Methods: We analyzed data on 74 volunteers, who were divided into two groups: COPD (n = 43) and control (n = 31). For calculation of HRV indices, heart rate was measured beat-by-beat during 30 min of supine rest using a heart-rate meter. We analyzed linear indices in the time and frequency domains, as well as indices derived from the RPs. Results: In comparison with the control group, the COPD group showed significant increases in the indices derived from the RPs, as well as significant reductions in the linear indices in the time and frequency domains. No significant differences were observed in the linear indices in the frequency domains expressed in normalized units or in the low frequency/high frequency ratio. Conclusions: Individuals with COPD show a reduction in both sympathetic and parasympathetic activity, associated with decreased complexity of autonomic nervous system function, as identified by RPs, which provide important complementary information in the detection of autonomic changes in this population.

RESUMO Objetivo: Avaliar a modulação autonômica de indivíduos com DPOC, comparados com um grupo controle saudável, por meio do plot de recorrência (PR) associado a métodos lineares da variabilidade da frequência cardíaca (VFC). Métodos: Foram avaliados dados de 74 voluntários, os quais foram divididos em grupos DPOC (n = 43) e controle (n = 31). Para a análise dos índices de VFC, a frequência cardíaca dos voluntários foi registrada, batimento a batimento, por meio de um cardiofrequencímetro com os voluntários em repouso na posição supina por 30 min. Foram avaliados índices lineares nos domínios de tempo e de frequência, assim como índices obtidos por meio do PR. Resultados: No grupo DPOC, em comparação com o grupo controle, houve aumentos significativos em índices obtidos do PR, assim como houve reduções significativas nos índices lineares nos domínios de tempo e de frequência. Não foram observadas diferenças significativas nos índices lineares nos domínios de frequência em unidades normalizadas e na relação entre os componentes de alta e baixa frequência. Conclusões: Indivíduos com DPOC apresentam uma diminuição tanto da atividade simpática quanto da parassimpática, associada a uma redução da complexidade do sistema nervoso autônomo, identificada pelo PR, que fornece informações complementares importantes na detecção de alterações autonômicas nessa população.

Influence of expiratory positive airway pressure on cardiac autonomic modulation at rest and in submaximal exercise in COPD patients

The aim of this study was to evaluate the effect of expiratory positive airway pressure (EPAP) on heart rate variability (HRV) indices at rest and during 6-min walk test (6MWT) in chronic obstructive pulmonary disease (COPD) patients. Fifteen moderate to severe COPD patients were randomized and evaluated with and without (Non-EPAP) a 5 cmH2O EPAP device. Respiratory rate (RR) was collected at rest (5 min), during the 6MWT (5 min), and at recovery (5 min). Indices of HRV were computed in the time domain, in the frequency domain, and nonlinear analysis. For EPAP and Non-EPAP during the 6MWT, we found an increased mean heart rate (HR) (P=0.001; P=0.001) while mean RR (P=0.001; P=0.015) and RR tri index decreased (P=0.006; P=0.028). Peripheral oxygen saturation (P=0.019) increased at rest only in the EPAP group. In EPAP, correlations were found between forced expiratory volume in 1 s (FEV1) and low frequency (LF) sympathetic tonus (P=0.05; r=-0.49), FEV1 and high frequency (HF) parasympathetic tonus at rest (P=0.05; r=0.49), lactate at rest and LF during the 6MWT (P=0.02; r=-0.57), and lactate at rest and HF during 6MWT (P=0.02; r=0.56). Through a linear regression model, we found that lactate at rest explained 27% of the alterations of LF during 6MWT. The use of 5 cmH2O EPAP improved autonomic cardiac modulation and its complexity at rest in COPD patients. Although it did not influence the performance of the 6MWT, the EPAP device caused alterations in resting lactate concentration with an effect on sympatho-vagal control during the test.

Impaired baroreflex sensitivity and increased systolic blood pressure variability in chronic post-ischemic stroke

OBJECTIVES: Acute post-stroke patients present cardiovascular autonomic dysfunction, which manifests as lower heart rate variability and impaired baroreflex sensitivity. However, few studies performed to date have evaluated cardiovascular autonomic function in chronic post-stroke patients. The aim of this study was to evaluate cardiovascular autonomic modulation in chronic post-ischemic stroke patients. METHODS: The seventeen enrolled subjects were divided into a stroke group (SG, n=10, 5±1 years after stroke) and a control group (CG, n=7). Non-invasive curves for blood pressure were continuously recorded (Finometer®) for 15 minutes while the subject was in a supine position. Heart rate variability and blood pressure variability were analyzed in the time and frequency domains. RESULTS: No differences were observed in systolic and diastolic pressure and heart rate between post-stroke patients and healthy individuals. The SG group had lower indexes for heart rate variability in the time domain (standard deviation of normal to normal R-R intervals, SDNN; variance of normal to normal R-R intervals, VarNN; and root mean square differences of successive R-R intervals, RMSSD) and a lower high-frequency band for heart rate variability than was observed in the CG. Systolic blood pressure variability and the low-frequency band for systolic pressure were higher in post-stroke patients, while the alpha index was lower in the SG than in the CG. CONCLUSION: After ischemic stroke, affected patients present chronically reduced heart rate variability, impaired cardiac vagal modulation, increased systolic blood pressure variability and higher sympathetic vascular modulation along with impaired baroreflex sensitivity, which can increase the risk of cardiovascular events, despite adequate blood pressure control.

ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice

OBJECTIVES: The present study aimed to investigate cardiovascular autonomic modulation and angiotensin II (Ang II) activity in diabetic mice that were genetically engineered to harbor two or three copies of the angiotensin-converting enzyme gene. METHODS: Diabetic and non-diabetic mice harboring 2 or 3 copies of the angiotensin-converting enzyme gene were used in the present study. Animals were divided into 4 groups: diabetic groups with two and three copies of the angiotensin-converting enzyme gene (2CD and 3CD) and the respective age-matched non-diabetic groups (2C and 3C). Hemodynamic, cardiovascular, and autonomic parameters as well as renal Ang II expression were evaluated. RESULTS: Heart rate was lower in diabetic animals than in non-diabetic animals. Autonomic modulation analysis indicated that the 3CD group showed increased sympathetic modulation and decreased vagal modulation of heart rate variability, eliciting increased cardiac sympathovagal balance, compared with all the other groups. Concurrent diabetes and either angiotensin-converting enzyme polymorphism resulted in a significant increase in Ang II expression in the renal cortex. CONCLUSION: Data indicates that a small increase in angiotensin-converting enzyme activity in diabetic animals leads to greater impairment of autonomic function, as demonstrated by increased sympathetic modulation and reduced cardiac vagal modulation along with increased renal expression of Ang II.

Sensitivity, Specificity and Predictive Value of Heart Rate Variability Indices in Type 1 Diabetes Mellitus / Sensibilidade, Especificidade e Valor Preditivo dos Índices da Variabilidade da Frequência Cardíaca no Diabetes Mellitus Tipo 1

Abstract Background: Heart rate variability (HRV) indices may detect autonomic changes with good diagnostic accuracy. Type diabetes mellitus (DM) individuals may have changes in autonomic modulation; however, studies of this nature in this population are still scarce. Objective: To compare HRV indices between and assess their prognostic value by measurements of sensitivity, specificity and predictive values in young individuals with type 1 DM and healthy volunteers. Methods: In this cross-sectional study, physical and clinical assessment was performed in 39 young patients with type 1 DM and 43 young healthy controls. For HRV analysis, beat-to-beat heart rate variability was measured in dorsal decubitus, using a Polar S810i heart rate monitor, for 30 minutes. The following indices were calculated: SDNN, RMSSD, PNN50, TINN, RRTri, LF ms2, HF ms2, LF un, HF un, LF/HF, SD1, SD2, SD1/SD2, and ApEn. Results: Type 1 DM subjects showed a decrease in sympathetic and parasympathetic activities, and overall variability of autonomic nervous system. The RMSSD, SDNN, PNN50, LF ms2, HF ms2, RRTri, SD1 and SD2 indices showed greater diagnostic accuracy in discriminating diabetic from healthy individuals. Conclusion: Type 1 DM individuals have changes in autonomic modulation. The SDNN, RMSSD, PNN50, RRtri, LF ms2, HF ms2, SD1 and SD2 indices may be alternative tools to discriminate individuals with type 1 DM.

Resumo Fundamento: Alguns índices da variabilidade da frequência cardíaca (VFC) podem ser capazes de detectar alterações autonômicas com boa acurácia diagnóstica. Indivíduos com Diabetes Mellitus (DM) tipo 1 podem apresentar alterações na modulação autonômica, contudo, estudos dessa natureza são incipientes nesses sujeitos. Objetivo: Comparar diferentes índices da VFC e avaliar seu valor prognóstico por medidas da sensibilidade, especificidade e valores preditivos em jovens com DM tipo 1 e jovens controles saudáveis. Métodos: Neste estudo transversal, foram realizadas avaliações físicas e clínicas em 39 jovens com DM tipo 1 e 43 jovens saudáveis. Para análise da VFC, a frequência cardíaca foi captada batimento a batimento usando um monitor de frequência acardíaca, PolarS810i, por 30 minutos com os voluntários em decúbito dorsal. Foram calculados os índices: SDNN, RMSSD, PNN50, TINN, RRTri, LF ms2, HF ms2, LF un, HF um, LF/HF, SD1, SD2, SD1/SD2, ApEn. Resultados: Indivíduos com DM tipo 1 apresentam redução na atividade simpática, parassimpática e na variabilidade global do sistema nervoso autônomo. Índices RMSSD, SDNN, PNN50, LF ms2, HF ms2, RRTri, SD1 e SD2 representam melhor acurácia diagnóstica para discriminar indivíduos diabéticos de saudáveis. Conclusão: Indivíduos com DM tipo 1 apresentam alterações na modulação autonômica e os índices SDNN, RMSSD, PNN50, RRtri, LF ms2, HF ms2, SD1 e SD2 podem ser uma opção utilizada para discriminar indivíduos com DM tipo 1.

Time course of changes in heart rate and blood pressure variability in rats with myocardial infarction

Our aim was to determine the time course of changes in autonomic balance in the acute (1 and 3 days), sub-acute (7 days) and chronic (28 days) phases of myocardial infarction (MI) in rats. Autonomic balance was assessed by temporal and spectral analyses of blood pressure variability (BPV) and heart rate variability (HRV). Pulsatile blood pressure (BP) recordings (30 min) were obtained in awake and unrestrained male Wistar rats (N = 77; 8-10 weeks old) with MI (coronary ligature) or sham operation (SO). Data are reported as means±SE. The high frequency (HF) component (n.u.) of HRV was significantly lower in MI-1- (P<0.01) and MI-3-day rats (P<0.05) than in their time-control groups (SO-1=68±4 vs MI-1=35.3±4.3; SO-3=71±5.8 vs MI-3=45.2±3.8), without differences thereafter (SO-7=69.2±4.8 vs MI-7=56±5.8; SO-28=73±4 vs MI-28=66±6.6). A sharp reduction (P<0.05) of BPV (mmHg2) was observed in the first week after MI (SO-1=8.55±0.80; SO-3=9.11±1.08; SO-7=7.92±1.10 vs MI-1=5.63±0.73; MI-3=5.93±0.30; MI-7=5.30±0.25). Normal BPV, however, was observed 4 weeks after MI (SO-28=8.60±0.66 vs MI-28=8.43±0.56 mmHg2; P>0.05). This reduction was mainly due to attenuation of the low frequency (LF) band of BPV in absolute and normalized units (SO-1=39.3±7%; SO-3=55±4.5%; SO-7=46.8±4.5%; SO-28=45.7±5%; MI-1=13±3.5%; MI-3=35±4.7%; MI-7=25±2.8%; MI-28=21.4±2.8%). The results suggest that the reduction in HRV was associated with decrease of the HF component of HRV suggesting recovery of the vagal control of heartbeats along the post-infarction healing period. The depression of BPV was more dependent on the attenuation of the LF component, which is linked to the baroreflex modulation of the autonomic balance.

Autonomic and Renal Alterations in the Offspring of Sleep-Restricted Mothers During Late Pregnancy

OBJECTIVES: Considering that changes in the maternal environment may result in changes in progeny, the aim of this study was to investigate the influence of sleep restriction during the last week of pregnancy on renal function and autonomic responses in male descendants at an adult age. METHODS: After confirmation of pregnancy, female Wistar rats were randomly assigned to either a control or a sleep restriction group. The sleep-restricted rats were subjected to sleep restriction using the multiple platforms method for over 20 hours per day between the 14th and 20th day of pregnancy. After delivery, the litters were limited to 6 offspring that were designated as offspring from control and offspring from sleep-restricted mothers. Indirect measurements of systolic blood pressure (BPi), renal plasma flow, glomerular filtration rate, glomerular area and number of glomeruli per field were evaluated at three months of age. Direct measurements of cardiovascular function (heart rate and mean arterial pressure), cardiac sympathetic tone, cardiac parasympathetic tone, and baroreflex sensitivity were evaluated at four months of age. RESULTS: The sleep-restricted offspring presented increases in BPi, glomerular filtration rate and glomerular area compared with the control offspring. The sleep-restricted offspring also showed higher basal heart rate, increased mean arterial pressure, increased sympathetic cardiac tone, decreased parasympathetic cardiac tone and reduced baroreflex sensitivity. CONCLUSIONS: Our data suggest that reductions in sleep during the last week of pregnancy lead to alterations in cardiovascular autonomic regulation and renal morpho-functional changes in offspring, triggering increases in blood pressure.

Influence of Smoking Consumption and Nicotine Dependence Degree in Cardiac Autonomic Modulation / Influência do Consumo Tabagístico e Grau de Dependência Nicotínica na Modulação Autonômica Cardíaca

Abstract Background: Smoking consumption alters cardiac autonomic function. Objective: Assess the influence of the intensity of smoking and the nicotine dependence degree in cardiac autonomic modulation evaluated through index of heart rate variability (HRV). Methods: 83 smokers, of both genders, between 50 and 70 years of age and with normal lung function were divided according to the intensity of smoking consumption (moderate and severe) and the nicotine dependency degree (mild, moderate and severe). The indexes of HRV were analyzed in rest condition, in linear methods in the time domain (TD), the frequency domain (FD) and through the Poincaré plot. For the comparison of smoking consumption, unpaired t test or Mann-Whitney was employed. For the analysis between the nicotine dependency degrees, we used the One-way ANOVA test, followed by Tukey's post test or Kruskal-Wallis followed by Dunn's test. The significance level was p < 0,05. Results: Differences were only found when compared to the different intensities of smoking consumption in the indexes in the FD. LFun (62.89 ± 15.24 vs 75.45 ± 10.28), which corresponds to low frequency spectrum component in normalized units; HFun (37.11 ± 15.24 vs 24.55 ± 10.28), which corresponds to high frequency spectrum component in normalized units and in the LF/HF ratio (2.21 ± 1.47 vs 4.07 ± 2.94). However, in the evaluation of nicotine dependency, significant differences were not observed (p > 0.05). Conclusion: Only the intensity of smoking consumption had an influence over the cardiac autonomic modulation of the assessed tobacco smokers. Tobacco smokers with severe intensity of smoking consumption presented a lower autonomic modulation than those with moderate intensity.

Resumo Fundamento: O tabagismo altera a função autonômica cardíaca. Objetivo: Avaliar a influência da intensidade do consumo tabagístico e do grau de dependência nicotínica na modulação autonômica cardíaca avaliada por meio de índices de variabilidade da frequência cardíaca (VFC). Métodos: 83 tabagistas, de ambos os sexos, faixa etária entre 50 e 70 anos de idade e com função pulmonar normal foram divididos de acordo com a intensidade do consumo tabagístico (moderado e grave) e o grau de dependência nicotínica (leve, moderado e grave). Os índices de VFC foram analisados em condição de repouso, em métodos lineares no domínio do tempo (DT), domínio da frequência (DF) e pelo plot de Poincaré. Para comparação do consumo tabagístico, foi utilizado teste t não pareado ou Mann-Whitney. Para análise entre os graus de dependência nicotínica, foi utilizado teste One-way ANOVA seguido de pós-teste de Tukey ou Kruskal-Wallis seguido pelo teste de Dunn. O nível de significância foi de p < 0,05. Resultados: Diferenças só foram encontradas quando comparadas às diferentes intensidades do consumo tabagístico nos índices no DF: LFun (62,89 ± 15,24 vs 75,45 ± 10,28), que corresponde ao componente espectral de baixa frequência em unidades normalizadas; HFun (37,11 ± 15,24 vs 24,55 ± 10,28), que corresponde ao componente espectral de alta frequência em unidades normalizadas e na relação LF/HF (2,21 ± 1,47 vs 4,07 ± 2,94). No entanto, na avaliação da dependência nicotínica não foram observadas diferenças significativas (p > 0,05). Conclusão: Apenas a intensidade do consumo tabagístico promoveu influências sobre a modulação autonômica cardíaca dos tabagistas avaliados. Tabagistas com intensidade de consumo tabagístico grave apresentaram menor modulação autonômica do que tabagistas moderados.

Avaliação diagnóstica da insuficiência autonômica / Diagnostic evaluation of autonomic failure

A síncope postural é uma perda transitória da consciência secundária à redução do fluxo sanguíneo cerebral e normalmente ocorre durante a ortostase. Transtornos do controle da homeostase circulatória sãofrequentemente incapacitantes e de difícil tratamento. O reconhecimento dos vários subgrupos de insuficiênciaautonômica é útil na definição do tratamento mais apropriado da desordem específica do paciente. Em conjunto com a síncope reflexa, a hipotensão ortostática (por insuficiência autonômica ou secundária a uma afecção crônica) responde pelas principais categorias fisiopatológicas de síncope postural. A incapacidade de identificar a causa subjacente da síncope pode resultar em aumento da morbidade, redução da qualidade de vida e aumento dos custos com os cuidados de saúde. Uma história clínica direcionada, associada a exame físico e eletrocardiografia, pode diagnosticar a maioria dos transtornos de controle circulatório. Em casos mais complexos, a análise do sistema nervoso simpático e as respostas circulatórias durante o teste de inclinação podem auxiliar no diagnóstico diferencial...

Postural syncope is a transient loss of consciousness secondary to a reduction in cerebral blood flow and is typically precipitated by standing. Disorders of circulatory homeostasis are frequently disabling and difficult to treat. Recognizing the various subgroups of autonomic insufficiency is helpful to choose the treatment that is bestsuited for the patient’s specific disorder. Along with reflex syncope, orthostatic hypotension (due to autonomicfailure or secondary to chronic disease) is responsible for the main pathophysiological categories of posturalsyncope. Failure to identify the underlying cause of postural syncope may result increased morbidity, impairedquality of life and increase in healthcare costs. With a detailed clinical history in addition to physical examination and electrocardiography, most circulatory control disorders may be diagnosed. In more complex cases, the analysisof the sympathetic nervous system and circulatory responses during head-up tilting can support the differentialdiagnosis...