Psychophysiological reactions during the trauma-film paradigm and their predictive value for intrusions.

Background: Adequate adaptation of the autonomic nervous system (ANS) is crucial in potentially life-threatening situations. The defence cascade provides a descriptive model of progressing dominant physiological reactions in such situations, including cardiovascular parameters and body mobility. The empirical evidence for this model is scarce, and the influence of physiological reactions in this model for predicting trauma-induced intrusions is unresolved.Objectives: Using a trauma-film paradigm, we aimed to test physiological reactions to a highly stressful film as an analogue to a traumatic event along the defence cascade model. We also aimed to examine the predictive power of physiological activity for subsequent intrusive symptoms.Method: Forty-seven healthy female participants watched a stressful and a neutral film in randomized order. Heart rate (HR), heart rate variability (HRV), and body sway were measured. Participants tracked frequency, distress, and quality of subsequent intrusions in a diary for 7 consecutive days.Results: For the stressful film, we observed an initial decrease in HR, followed by an increase, before the HR stabilized at a high level, which was not found during the neutral film. No differences in HRV were observed between the two films. Body sway and trembling frequency were heightened during the stressful film. Neither HR nor HRV predicted subsequent intrusions, whereas perceived distress during the stressful film did.Conclusions: Our results suggest that the physiological trauma-analogue response is characterized by an orientation response and subsequent hyperarousal, reaching a high physiological plateau. In contrast to the assumptions of the defence cascade model, the hyperarousal was not followed by downregulation. Potential explanations are discussed. For trauma-associated intrusions in the subsequent week, psychological distress during the film seems to be more important than physiological distress. Understanding the interaction between physiological and psychological responses during threat informs the study of ANS imbalances in mental disorders such as post-traumatic stress disorder.

We used a trauma-film analogue to examine the defence cascade model and to investigate the influence of psychophysiological response on subsequent intrusions.While we found an orientation phase, upregulation phase, and coactivation indicated by heart rate, no downregulation phase was observed.None of the physiological parameters examined predicted subsequent intrusions, whereas subjective distress during the film did.

Autonomic function and its relationship with central obesity and hemodynamic variables in obese and overweight adults.

Introduction: Introduction: central obesity is associated with an autonomic dysfunction characterized by an increase in sympathetic activity and a reduction in vagal tone, leading to a decrease in heart rate variability. Objective: we aimed to analyze the relationship between the time and frequency domains of heart rate variability with central obesity, and its hemodynamic variables in normal-weight, overweight and obese adults. Methods: a total of 65 adults were evaluated (25.4 ± 3.2 years old) and distributed in 3 groups: normal weight group (NW group), overweight group (OW group) and obese group (OB group). Heart rate variability parameters at rest and both anthropometric and hemodynamic variables were recorded. Results: the results showed a positive correlation between waist circunference and LF/HF ratio in the OW (p = 0.0008; r = 0.6607; r2 = 0.4365) and OB (p = 0.0001; r = 0.8286; r2 = 0.6866) groups. The waist-to-height ratio showed significant differences with HF in the NW, OW, and OB groups. The variables related to the parasympathetic system (SDNN, RMSSD, pNN50, HF) in the OB and OW groups showed a decrease in values when compared to the NW group. Likewise, the variable related to the sympathetic system (LF) in the OB and OW groups increased its values when compared with the NW group. The LF/HF ratio increased from the NW group to the OW and OB groups (1.6 ± 0.7; 2.5 ± 1.8 and 3.3 ± 0.7). Conclusion: overweight and obese adults present a modulation of sympathetic activity predominance at rest. This increased activity is represented by the time and frequency domains of heart rate variability, having an important correlation with waist circumference and waist-to-height ratio.

Introducción: Introducción: la obesidad central se asocia con una disfunción autonómica caracterizada por una mayor actividad simpática y reducción del tono vagal, conduciendo a una disminución de la variabilidad de la frecuencia cardíaca (VFC). Objetivo: analizar la relación entre los dominios de tiempo y frecuencia de la VFC con la obesidad central y sus variables hemodinámicas en adultos con peso normal, sobrepeso y obesidad. Metodología: participaron 65 adultos (25,4 ± 3,2 años) distribuidos en 3 grupos: peso normal (grupo NW), sobrepeso (grupo OW) y obesidad (grupo OB). Se registraron los parámetros de la VFC y las variables antropométricas y hemodinámicas. Resultados: se observó una correlación positiva entre la circunferencia de la cintura y la relación LF/HF en el grupo OW (p = 0,0008; r = 0,6607; r2 = 0,4365) y OB (p = 0,0001; r = 0,8286; r2 = 0,6866). La relacion cintura/altura mostró una diferencia significativa con la HF en los grupos NW, OW y OB. La actividad parasimpática (SDNN, RMSSD, pNN50, HF) de los grupos OB y OW evidenció una disminución de los valores en comparación con el grupo NW. La actividad simpática (LF) en el grupo OB y OW presentó mayores valores que en el grupo NW. La relación LF/HF aumentó del grupo NW hacia el OW y el OB (1,6 ± 0,7; 2,5 ± 1,8 y 3,3 ± 0,7). Conclusiones: el sobrepeso y la obesidad presentan una predominancia de la actividad simpática en reposo. Este aumento de la actividad está representado en el dominio de tiempo y frecuencia de la VFC y, además, presenta una correlación importante con la circunferencia de la cintura y la relación cintura/altura.

[Association between autonomic disorders and subclinical atherosclerosis]. / Asociación de desórdenes autonómicos con aterosclerosis subclínica.

INTRODUCTION AND OBJECTIVES: Alterations of the sympathetic and parasympathetic nervous system have been proposed as precursors of the genesis and perpetuation of atherosclerosis for a long time. The objective of this study is to determine if there is an association between the presence of carotid atherosclerosis and the reduction in heart rate variability. METHODS: Using a prospective case-control design, the heart rate variability and the presence of carotid atherosclerosis was investigated in 54 patients, divided into 2groups according to the presence or absence of carotid atherosclerosis. An analysis was made of the heart rate variability variables of the frequency (spectral) domain in high frequency band, low frequency band, parasympathetic autonomic balance, and the total spectral band. RESULTS: Of the 54 individuals evaluated without previous cardiovascular disease consecutively, 26 of them (48%) presented with subclinical carotid atherosclerosis (ATE+). A reduction in heart rate variability was observed in the ATE+group represented by the low frequency (LF) spectrum (P<.0001). The parasympathetic activity specifically represented in the high frequency (HF) band was also lower in the ATE+group in the univariate analysis (P<.0001), same as the total spectral power (P<.0001), an index of integral autonomic regulation. No significant differences were found in the LF/HF analysis (P=.1598). After analysing variables with significant differences in the univariate analysis with a logistic regression model, only systolic blood preassure and the total spectral power were shown to be independent predictors of ATE+. CONCLUSION: A reduction in heart rate variability was found in subjects with carotid atherosclerosis. Some spectral components of heart rate variability, like low frequency or total spectral power, were better predictors of carotid atherosclerosis than the parasympathetic autonomic balance. In this study it seems that total spectral power is an adequate measurement for analysing autonomic function.

Smokeless tobacco: Risk factor for cardiovascular and breathing in young Indian adolescent.

BACKGROUND: Teenagers are the foremost susceptible population to smokeless tobacco usage and limited studies have surveyed the influence of smokeless tobacco on cardiac and respiratory response. OBJECTIVE: This study aims to measure consequence (cardiovascular and breathing) of smokeless tobacco usage (gutkha and chewing tobacco) among young Indian men. METHOD: On random basis, the applicants were divided into Group I (n=50) - healthy control group, Group II (n=50) - smokeless tobacco users. Anthropometric measurements and recording of blood pressure (BP), pulse wave analysis (PWV), heart rate variability (HRV) and pulmonary function test (PFT) was performed. RESULT: We observed that altogether anthropometric variables were comparable among all individuals. In blood pressure variable, except DBP, other variables for example SBP, PP and MAP were significantly increased in Group II individuals, once compare to Group I. Pulse wave analysis, (such as, AP, AIx, and SEVR), was comparable in individuals of both groups. As compare to Group I, HR was significantly increased in Group II. In HRV investigation, NN, VLF, LF, LF(nu), LF/HF were increased significantly and TSP, HF, HF(nu) were decreased significantly in Group II with compare to Group I. In PFT analysis, FVC was comparable among individuals of both the group and conversely, significant decrease in FEV1, FEV1/FVC, FEF25-75 and PEFR in Group II when compare with Group I. CONCLUSION: This study illustrate that smokeless tobacco practice has increasing adverse effects on cardiovascular as well as breathing system and become an important public health problem.

Estudio de variabilidad de la frecuencia cardiaca en pacientes con sospecha de fallas autonómicas. Utilización del Holter y el Diagrama de Poincare

El estudio de la regularidad de la Frecuencia Cardiaca, a través del Holter de 24 horas se hace desde la década de los años 60 y es bastante efectivo. Sin embargo, desde los años noventa comenzaron a efectuarse estudios cortos de Holter en pacientes sospechados de tener fallas autonómicas de control de la frecuencia cardiaca, especialmente en pacientes con comorbilidades tales como Hipertensión, Diabetes Mellitus, Aterosclerosis etc. De aquí la importancia de realizar un test de Holter de diez minutos, divididos en dos tiempos de 5 minutos, primero en decúbito dorsal y luego en bipedestación, especialmente en pacientes de más de cincuenta años o con comorbilidades presentes. Los resultados se presentan luego en gráficos de Poincare, que incluye el programa operativo del dispositivo, que permite un vistazo de la elipse con sus dos ejes, que representan las acciones simpáticas y parasimpáticas sobre la frecuencia cardiaca. Una variabilidad anormal de la frecuencia cardiaca debe ser luego estudiada más profundamente a fin de reafirmar el diagnóstico y ulteriores pasos en el tratamiento.

The variability of Cardiac Frequency is a valuable monitor of the autonomic function and is currently used as tool for study of changes of regularity through Holter 24 hours. From nighties, several researchers have been oriented to stablish relationship between VCF and autonomic failure, especially in patients with comorbidities, such as Hypertension, Diabetes Mellitus, atherosclerosis etc. Actually is well known that a lost or VCF or a minor variability, even in short traces of Holter in 10 minutes, means an autonomic failure, of baroreflex and quimioreflex resources. Hence, the importance of performing test of ten minutes Holter, five in decubitus position and five in standing, to patients of more than fifty years old, or less if comorbidities are presents, to design a Poincare diagram, which is special to indicate in quick view the prevalence of Sympathetic o Vagal action on cardiac frequency; that conduces to a more deep study of Autonomic failure, such tilt test, extended holter of 24 hours, and others medicals images resources.

Reactividad Cardiaca ante Evocación de Eventos Estresantes en Población Universitaria / Cardiac Reactivity to Evocation of Stressful Events in a University Population

Resumen La variabilidad de la frecuencia cardiaca (VFC) se utiliza como una señal fisiológica para evaluar la reactividad psicofisiológica al estrés. El análisis en el dominio de la frecuencia de esta señal se ha usado para describir el papel del sistema nervioso autónomo en los procesos de adaptación al estrés. Sin embargo, el uso de medidas de tendencia central para reportar los resultados de distintas poblaciones desestima las diferencias individuales en la reacción frente al estrés. El objetivo de esta investigación fue caracterizar la reactividad cardiaca ante la evocación de eventos estresantes en población universitaria. Participaron 94 estudiantes de nuevo ingreso a la carrera de psicología, de dos universidades de México. Los resultados indican un decremento consistente en la banda de alta frecuencia ante la evocación de eventos estresantes, en comparación con la banda de baja frecuencia. La caracterización de la respuesta autonómica al estrés presenta dos subgrupos acoplados (co-activación y co-inhibición); y uno desacoplado. Nuestros hallazgos, ratifican la viabilidad de la banda de frecuencia alta de la VFC como un indicador estable de reactividad al estrés, y resaltan la importancia de las diferencias específicas de la actividad autonómica en la caracterización de la respuesta fisiológica al estrés.

Abstract Heart rate variability (HRV) is used as a reliable physiological signal to assess psychophysiological reactivity to stress. Frequency-domain mathematical analysis of the HRV signal provides metrics that are associated with the performance of the autonomic nervous system. However, the use of measures of central tendency to report global results in different populations underestimates individual differences in the way people react to stress and the clinical importance of this response. The objective of this research was to characterize cardiac reactivity to the evocation of stressful events in a university population. The participants were 94 new psychology students from two universities in Mexico. A psychophysiological stress assessment was performed to estimate cardiac reactivity; the evaluation consisted of the following conditions: 1) Baseline; 2) Evocation of stress; and 3) Recovery. The participants were sitting with their eyes closed and without moving during every single one of the conditions. Four subgroups were created depending on the type of cardiac reactivity to stress. The results indicate a significant consistent decrease in the high-frequency band when evoking stressful events, compared to the low-frequency band. Similar responses were observed between the low-frequency band and the high-frequency band in 60.6% of the cases, suggesting that the antagonistic autonomic balance between the two divisions of the ANS was scarce. According to the autonomic space model and the type of stress reactivity of each student, there were two subgroups characterized by co-activation and co-inhibition modes; and one subgroup characterized by uncoupled response mode. Our findings confirm the viability of the high-frequency band of HRV as a stable indicator of stress reactivity. Likewise, evidence is generated in favor of using evocative stress stimuli to assess physiological reactivity like more personal stressors. Lastly, the importance of specific differences in autonomic activity to characterize the physiological response to stress and its possible clinical utility to propose interventions and select techniques that most effectively benefit vulnerable populations are highlighted.

Uso de mascarillas faciales y frecuencia cardiaca en adultos de 18 a 60 años / Use of face masks and heart rate in adults aged 18 to 60 years / Uso de máscara facial e freqüência cardíaca em adultos de 18-60 anos de idade

Objetivo. Evaluar la influencia del uso de mascarillas faciales sobre la frecuencia cardiaca (FC) en reposo y en la actividad física en adultos de 18 a 60 años, en la ciudad de Lima, durante la pandemia por la COVID-19 en el 2020. Métodos. Se realizó un estudio de tipo experimental, analítico, prospectivo y transversal. Para la recopilación de datos se realizó una encuesta virtual vía Google forms, con una serie de preguntas e indicaciones para la correcta medida de la FC en diferentes situaciones: reposo, inmediatamente posterior a la actividad y 5 min posterior a la actividad física con y sin el uso de mascarillas (KN95, tela, quirúrgica y N95). Para el presente estudio se analizaron las posibles causas del aumento de la FC, por lo que fueron elegidos 60 adultos asintomáticos, 40 mujeres y 20 hombres, en el rango de edades entre 18 hasta 60 años. Resultados. Se obtuvo que la diferencia de la FC promedio con y sin uso de mascarilla inmediatamente posterior a la actividad física aumentó signifcativamente dependiendo del tipo de mascarilla. Con respecto a la KN95, se presenció un aumento de hasta en 9,6 latidos/min, mientras las mascarillas en tela, quirúrgica y N95 mostraron un aumento de 5,9, 5,6 y 7,4 latidos/min, respectivamente, bajo las mismas condiciones, calculándose en una media de 112,7 latidos/min por sobre 10,6 latidos/min en reposo, evidenciándose un incremento en hasta 7 % de su valor en reposo. Conclusión. Se comprobó que el uso de la mascarilla ejerce una notable influencia en la FC, inmediatamente y 5 minutos posterior terminada la actividad física, siendo la KN95 la mascarilla facial más utilizada y la de mayor influencia en el pulso cardiaco

Objective. To evaluate the influence of the use of face masks on resting heart rate (HR) and physical activity in adults aged 18 to 60 years, in the city of Lima, during the COVID-19 pandemic in 2020. Methods. An experimental, analytical, prospective and cross-sectional study was carried out. For data collection, a virtual survey was carried out via Google Forms, with a series of questions and indications for the correct measurement of HR in different situations: at rest, immediately after activity and 5 min after physical activity with and without the use of masks (KN95, fabric, surgical and N95). For the present study, the possible causes of increased HR were analyzed, so 60 asymptomatic adults, 40 women and 20 men, in the age range of 18 to 60 years, were selected. Results. It was found that the difference in mean HR with and without mask use immediately after physical activity increased signifcantly depending on the type of mask. With respect to the KN95, an increase of up to 9.6 beats/min was observed, while the fabric, surgical and N95 masks showed an increase of 5.9, 5.6 and 7.4 beats/min, respectively, under the same conditions, calculating an average of 112.7 beats/ min over 10.6 beats/min at rest, showing an increase of up to 7% of its value at rest. Results. It was obtained that the difference in the average HR with and without mask use immediately after physical activity increased signifcantly depending on the type of mask. With respect to KN95, an increase of up to 9,6 beats/min was observed, while cloth, surgical and N95 masks showed an increase of 5,9, 5,6 and 7,4 beats/min, respectively, under the same conditions, calculated at an average of 112.7 beats/min over 10,6 beats/min at rest, evidencing an increase in up to 7 % of their value at rest. Conclusion. It was found that the use of the face mask exerts a notable influence on HR, immediately and 5 minutes after the end of the physical activity, being the KN95 the most used face mask and the one with the greatest influence on the cardiac pulse.

Objetivo. Avaliar o influence do uso de máscaras faciais em repouso de freqüência cardíaca (FC) e atividade física em adultos de 18-60 anos de idade, na cidade de Lima, durante a pandemia da COVID-19 em 2020. Métodos. Foi realizado um estudo experimental, analítico, prospectivo e de corte transversal. Para a coleta de dados, foi realizada uma pesquisa virtual através de formulários Google, com uma série de perguntas e indicações para a medição correta de RH em diferentes situações: em repouso, imediatamente após o repouso, imediatamente após o exercício, e imediatamente após o exercício. situações: em repouso, imediatamente após a atividade e 5 minutos após a atividade física com e sem o uso de máscaras (KN95, tecido, cirúrgico e N95). Para o presente estudo, foram analisadas as possíveis causas do aumento do RH e foram selecionados 60 adultos assintomáticos, 40 mulheres e 20 homens, na faixa etária de 18 a 60 anos. Resultados. Descobriu-se que a diferença em HR com e sem o uso da máscara imediatamente após a atividade física aumentou significativamente, dependendo do tipo de máscara. Com respeito ao KN95, foi testemunhado um aumento de até 9,6 batidas/min, enquanto o tecido, as máscaras cirúrgicas e N95 mostraram um aumento de 5,9, 5,6 e 7,4 batimentos/min, respectivamente, nas mesmas condições, com uma média de 112,7 batimentos/min acima de 10,6 batimentos/min em repouso, mostrando um aumento de até 7% de seu valor de repouso. Conclusão. Verificou-se que o uso da máscara facial exerce uma influência notável na FC, imediatamente e 5 minutos após o final da atividade física, sendo a KN95 a máscara facial mais usada e a que tem maior influência no pulso cardíaco.

Cardiovascular autonomic neuropathy in patients with diabetes mellitus. / Neuropatía autonómica cardiovascular en pacientes con diabetes mellitus.

Cardiovascular autonomic neuropathy associated with diabetes mellitus is caused by an impairment of the autonomic system. The prevalence of this condition ranges from 20% to 65%, depending on the duration of the diabetes mellitus. Clinically, the autonomic function disorder is associated with resting tachycardia, exercise intolerance, orthostatic hypotension, intraoperative cardiovascular instability, silent myocardial ischemia and increased mortality. For the diagnosis, the integrity of the parasympathetic and sympathetic nervous system is assessed. Parasympathetic activity is examined by measuring heart rate variability in response to deep breathing, standing and the Valsalva manoeuvre. Sympathetic integrity is examined by measuring blood pressure in response to standing and isometric exercise. The treatment includes the metabolic control of diabetes mellitus and of the cardiovascular risk factors. Treating symptoms such as orthostatic hypotension requires special attention.

Medición objetiva del comportamiento sedentario y la actividad física, y de sus efectos en la variabilidad de la frecuencia cardiaca, en adultos jóvenes que residen en una altitud moderada / Objective measurement of sedentary behavior and physical activity, and their effects on heart rate variability, in young adults that live in a moderate altitude

Resumen Antecedentes: El ejercicio físico y el entrenamiento de resistencia aeróbica se han asociado con un aumento de la variabilidad de la frecuencia cardiaca, mientras que el tiempo sedentario se ha asociado con una disminución de la variabilidad de la frecuencia cardiaca. Objetivo: Determinar si la variabilidad de la frecuencia cardiaca medida durante el reposo se relaciona con el tiempo sedentario y el tiempo utilizado en diferentes intensidades de actividad física, determinadas a través de un método objetivo (acelerometría), en un grupo de adultos sanos que residen a una altura de 2600 metros sobre el nivel del mar (m.s.n.m.). Método: Se realizaron mediciones de acelerometría a 99 individuos durante una semana y una medición de variabilidad de la frecuencia cardiaca en reposo. De acuerdo con la acelerometría, se realizó una división en tiempo sedentario y tiempo de actividad física de intensidad ligera, moderada y vigorosa. Para analizar la variabilidad de la frecuencia cardiaca se utilizaron parámetros en el dominio del tiempo (intervalos normales [NN], desviación estándar de los intervalos normales [SDNN], raíz cuadrada del promedio de las diferencias al cuadrado entre intervalos normales adyacentes [RMSSD]) y de la frecuencia (potencia de la baja frecuencia [LF], potencia de la alta frecuencia [HF], LF/HF) para analizar la variabilidad de la frecuencia cardiaca. Mediante de modelos de regresión se buscó la asociación entre las variables de actividad física y de variabilidad de la frecuencia cardiaca. Resultados: Se presentó una asociación negativa entre los intervalos NN, la SDNN y el tiempo sedentario, así como asociaciones positivas entre el intervalo NN y la actividad física ligera, moderada y vigorosa, al igual que entre la actividad física vigorosa y las potencias de LF y HF. Todas las asociaciones anteriores fueron significativas (p< 0.05). Conclusiones: En adultos jóvenes que residen a 2600 m.s.n.m., el tiempo sedentario reduce la variabilidad de la frecuencia cardiaca, mientras que la actividad física vigorosa aumenta dicha variabilidad.

Abstract Background: Physical exercise and aerobic resistance training have been associated with increased heart rate variability, while sedentary time has been associated with decreased heart rate variability. Objective: To determine if heart rate variability measured at rest is related to sedentary time and time used in various intensities of physical activity, established through an objective method (accelerometry), in a group of healthy adults who live 2,600 meters above sea level. Method: Accelerometer measurements were taken in 99 individuals during one week along with one measurement of heart rate variability at rest. Time was divided into sedentary time and time spent in light, moderate and vigorous physical activity. Time (NN interval, SDNN, RMSSD) and frequency (LF, HF, LF/HF) domain parameters were used to analyze heart rate variability. Using regression models, an association was sought between the physical activity and heart rate variability variables. Results: There was a negative association between NN intervals, SDNN and sedentary time, as well as positive associations between the NN interval and light, moderate and vigorous physical activity, and between vigorous physical activity and LF and HF power. All the foregoing associations were significant (p< 0.05). Conclusions: In young adults living 2,600 meters above sea level, sedentary time reduces heart rate variability, while vigorous physical activity increases this variability.

Cardiac autonomic function in Chagas disease: a narrative review / Função autonômica cardíaca na doença de Chagas: uma revisão narrativa / Función autonómica cardíaca en la enfermedad de Chagas: una revisión narrativa

Chagas disease (CD) is a severe health problem in countries of Latin America, including Brazil, and is characterised as an acute and chronic infection. CD can affect several organs and cellular tissues, in particular the heart, which can lead to sudden death. This work aimed to review the literature regarding cardiac autonomic function assessed by Heart Rate Variability (HRV) in CD in adult individuals. The search was carried out using the electronic databases PubMed, SciELO, and Web of Science between January 2013 and October 2020. A total of 19 articles were found, of which 14 were included in this review. HRV was demonstrated at baseline conditions, physical exercise, and cardiac rehabilitation. Quantifying CD progression assessed by HRV is an effective method to detect changes in the cardiac autonomic nervous system, even in asymptomatic individuals. Physical exercise can improve autonomic function in CD. Further clinical studies are needed to assess the anatomical-functional, metabolic, and immunological parameters associated with CD evaluated by HRV.

A doença de Chagas (DC) é um grave problema de saúde em países da América Latina, incluindo o Brasil, sendo caracterizada como infecção aguda e crônica. A DC pode afetar vários órgãos e tecidos celulares, em particular o coração, podendo levar à morte súbita. O objetivo deste trabalho foi revisar a literatura relacionada à função autonômica cardíaca avaliada pela Variabilidade da Frequência Cardíaca (VFC) na DC em indivíduos adultos. A busca foi realizada nas bases de dados eletrônicas PubMed, SciELO e Web of Science entre o período de janeiro de 2013 a outubro de 2020. Foram encontrados 19 artigos, dos quais 14 foram incluídos nesta revisão. A VFC foi demonstrada em condições basais, exercícios físicos e reabilitação cardíaca. Quantificar a progressão da DC avaliada pela VFC é um método eficaz para detectar alterações no sistema nervoso autônomo cardíaco, mesmo em indivíduos assintomáticos. O exercício físico pode melhorar a função autonômica na DC. Mais estudos clínicos são necessários para avaliar os parâmetros anátomo-funcionais, metabólicos e imunológicos associados à DC e avaliados pela VFC.

La enfermedad de Chagas (EC) es un grave problema de salud que enfrenta los países de América Latina y se caracteriza por ser una infección aguda y crónica. La EC puede afectar varios órganos y tejidos celulares, en particular el corazón, y puede provocar la muerte súbita. El objetivo de este estudio fue revisar la literatura que relaciona la función autónoma cardíaca evaluada por la Variabilidad de la Frecuencia Cardíaca (VFC) en la EC en individuos adultos. La búsqueda se realizó en las bases de datos electrónicas PubMed, SciELO y Web of Science desde enero de 2013 hasta octubre de 2020. Se encontraron 19 artículos, de los cuales 14 fueron incluidos en esta revisión. La VFC se ha demostrado en condiciones basales, ejercicio físico y rehabilitación cardíaca. La cuantificación de la progresión de la EC evaluada por la VFC es un método eficaz para detectar cambios en el sistema nervioso autónomo cardíaco, incluso en individuos asintomáticos. El ejercicio físico puede mejorar la función autónoma en la EC. Se necesitan más estudios clínicos para evaluar los parámetros anatómico-funcionales, metabólicos e inmunológicos asociados con la EC y evaluados por la VFC.

Correlation of serum uric acid with heart rate variability in hypertension.

BACKGROUND: Autonomic dysfunction with dominant sympathetic tone is a common finding among hypertensives and prehypertensives. Uric acid is one of the independent predictors of hypertension. There are very few studies which have shown a relationship between the autonomic tone and uric acid generation pathway among prehypertensives and hypertensives. Aim of the study was to estimate and correlate serum uric acid levels with autonomic function as measured by heart rate variability (HRV) among prehypertensives and hypertensives. METHODS: Cross-sectional study of three groups, prehypertensives, hypertensives and normotensives, classified according to Joint National Committee VII criteria, with 35 subjects in each group were included in this study. Serum uric acid levels were estimated by using colorimetric assay kit. HRV was analyzed after recording lead II Electrocardiogram using RMS Vagus HRV software (RMS, India). One-way ANOVA and Pearson's correlation was done using SPSS 18.0 software. RESULTS: Mean uric acid levels were 5.62±2.21mg/dL in normal subjects, 7.06±2.87mg/dL in prehypertensives and 9.77±2.04mg/dL in hypertensives. There was statistically significant negative correlation between uric acid and time domain parameters of HRV in the whole sample and among prehypertensives and positive correlation with low frequency power (LF) in ms(2) and n.u. CONCLUSIONS: Serum uric acid levels were high in prehypertensives and hypertensives as compared to normal subjects. Further, there was statistically significant correlation seen between uric acid levels and sympathetic domain parameters particularly among prehypertensives.

Respuesta autonómica cardiovascular al estrés mental inducido por la prueba de cálculo aritmético / Autonomic cardiovascular response to mental stress induced by the arithmetic computation test

Introducción: El estrés mental agudo, así como los estados de ansiedad inducidos para influenciar la reactividad psicofisiológica en jóvenes sanos, aportan cambios en los patrones nerviosos que pueden ser medidos mediante la variabilidad de la frecuencia cardiaca. Objetivo: Determinar las diferencias en los parámetros lineales del balance autonómico cardiovascular en individuos jóvenes en estado basal y durante la prueba de cálculo aritmético. Métodos: Se realizó un estudio cuasi-experimental, sin grupo control de tipo antes y después, en el Laboratorio de Ciencias Básicas Biomédicas de la Universidad de Ciencias Médicas de Santiago de Cuba. Población y muestra de 10 sujetos. Se registró el trazado electrocardiográfico (5 min) durante el reposo y luego durante la prueba de cálculo aritmético. Resultados: Existieron diferencias significativas entre ambos estados en las variables frecuencia cardiaca (p = 0,005); mínima (p = 0,007); máxima (p = 0,005); intervalo RR (p = 0,005); stress index (p = 0,028); índice simpático (p = 0,005); bajas frecuencias (p = 0,005); relación LF/HF (p = 0,005); RMSSD (p = 0,007); NN50 (p = 0,008); pNN50 (p = 0,005); índice parasimpático (p = 0,005) y altas frecuencias (p = 0,005). El estrés mental provocó una disminución parasimpática y un predominio simpático uniforme en todos los sujetos participantes en el estudio. Conclusiones: Durante el estrés mental inducido por la prueba de cálculo aritmético la dinámica lineal de la respuesta autonómica cardiovascular experimenta un aumento en la actividad simpática y una disminución del tono parasimpático, traduciendo una respuesta adaptativa en la regulación de la función cardiovascular por el sistema nervioso autónomo(AU)

Introduction: Acute mental stress and states of anxiety induced to influence psychophysiological reactivity in healthy young people, result in changes in nervous patterns which may be measured in terms of heart rate variability. Objective: Determine the differences in linear parameters for autonomic cardiovascular balance in young individuals at baseline and during the arithmetic computation test. Methods: A non-observational quasi-experimental before-after study without a control group was conducted at the Basic Biomedical Sciences Laboratory of the University of Medical Sciences of Santiago de Cuba. The study population and sample was 10 subjects. The electrocardiographic tracing (5 min) was recorded at rest and then during the arithmetic computation test. Results: Significant differences were found between the two states as to the variables heart rate (p = 0.005), minimum (p = 0.007), maximum (p = 0.005), RR interval (p = 0.005), stress index (p = 0.028), sympathetic index (p = 0.005), low frequencies (p = 0.005), LF/HF ratio (p = 0.005), RMSSD (p = 0.007), NN50 (p = 0.008), pNN50 (p = 0.005), parasympathetic index (p = 0.005) and high frequencies (p = 0.005). Mental stress caused a parasympathetic reduction and uniform sympathetic predominance in all the subjects participating in the study. Conclusions: During the mental stress induced by the arithmetic computation test, the linear dynamic of the autonomic cardiovascular response experiences an increase in sympathetic activity and a reduction in parasympathetic tone, displaying an adaptive response in cardiovascular function regulation by the autonomous nervous system(AU)

Disfunción diastólica y relación con arritmias: un vínculo más allá de la fibrilación auricular / Diastolic dysfunction and its relationship with arrhythmias: more than just linked to atrial fibrillation

Resumen Introducción: La falla cardíaca es un problema de salud pública, cuya prevalencia aumenta con la edad. Hasta el 50% de los casos tiene fracción de eyección preservada. Pocos estudios evalúan arritmias en este tipo de población. Se conoce una asociación con fibrilación auricular, pero se ignora qué otro tipo de arritmias pueden estar presentes. Objetivo: Describir arritmias por medio de monitorización Holter de 24 horas en pacientes con disfunción diastólica. Materiales y métodos: Se realizó un estudio observacional, descriptivo y retrospectivo, en el que se evaluaron y compararon los parámetros de la monitorización Holter de 24 horas en pacientes con disfunción diastólica, provenientes de un solo centro y residentes en Medellín, durante el año 2017. Resultados: 67 pacientes tenían disfunción diastólica; la mayoría correspondió a mujeres (65.7%). El promedio de edad fue 71 años, el índice de masa corporal fue de 26,8 y las comorbilidades más frecuentes fueron hipertensión arterial (68,7%), fibrilación auricular (19,4%) y enfermedad coronaria (19,4%). El promedio de fracción de eyección fue de 58%; el 67,2% tenía disfunción diastólica tipo I y el promedio del volumen de la aurícula izquierda fue de 33 ml/m2. Las arritmias más frecuentes fueron taquicardia atrial no sostenida (40,3%), fibrilación auricular (10,4%), taquicardia ventricular monomórfica (7,5%) y taquicardia por reentrada intranodal (1.5%). Se presentó bloqueo AV de primer grado (22,4%) y bloqueo sinoatrial (1,5%). El promedio de variabilidad de la frecuencia cardíaca fue 126.23. Conclusiones: En pacientes con disfunción diastólica tipo I y II se documentaron varios tipos de arritmias más allá de la fibrilación auricular. No hubo alteraciones en la variabilidad de la frecuencia cardíaca y tampoco en el tiempo de QTc. Dada la existencia de trasfondo fisiopatológico común, se debe evaluar en estudios futuros la relación entre arritmias y disfunción diastólica, además de su potencial tratamiento y modificación de su curso clínico.

Abstract Introduction: Heart failure is a public health problem, with a prevalence that increases with age. Up to 50% of cases have a preserve ejection fraction. Few studies have evaluated arrhythmias in this population type. It is known that there is an association with atrial fibrillation, but other types of arrhythmias that could be present are ignored. Objective: To describe arrhythmias using 24 hour Holter monitoring in patients with diastolic dysfunction. Materials and methods: An observational, descriptive, and retrospective study was performed in which the parameters from 24 hour Holter monitoring were evaluated and compared in patients with diastolic dysfunction from a single centre and resident in Medellin, during the year 2017. Results: A total of 67 patients had diastolic dysfunction, in which the majority (65.7%) were women. The mean age was 71 years, with a mean body mass index of 26.8. The most frequent comorbidities were arterial hypertension (68.7%), atrial fibrillation (19.4%), and coronary disease (19.4%). The mean ejection fraction was 58%; 67.2% had a type I diastolic dysfunction, and the mean atrial volume was 33 ml/m2. The most common arrhythmias were discontinuous atrial flutter (40.3%), atrial fibrillation (10.4%), monomorphic ventricular tachycardia (7.5%) and nodal re-entrant tachycardia (1.5%). First degree AV block (22.4%) and sinoatrial block (1.5%) were observed. The mean heart rate variability was 126.23. Conclusions: Several types of arrhythmias other than atrial fibrillation were documented in patients with type I and type II diastolic dysfunction. There were no changes in the heart rate variability or in the QTc time. Given the existence of a common pathophysiological background, further studies are needed in order to evaluate the relationship between arrhythmias and diastolic dysfunction, as well as any potential treatment and modification of its clinical course.

Diferencias en los parámetros lineales del balance autonómico basal entre estudiantes de medicina y atletas juveniles de béisbol / Differences in linear parameters of the basal autonomic balance between medical students and young baseball players

RESUMEN Introducción: La modulación autonómica cardiovascular puede ser considerada como una herramienta útil en la determinación del estado fisiológico de la interacción entre los sistemas nervioso autónomo y cardiovascular. Objetivo: Determinar las diferencias en los parámetros lineales del balance autonómico basal entre estudiantes de medicina y atletas juveniles de béisbol. Método: Se realizó un estudio analítico de tipo transversal en el Laboratorio de Ciencias Básicas Biomédicas de la Facultad Nº. 1 de la Universidad de Ciencias Médicas de Santiago de Cuba. Universo y muestra de 36 individuos (Grupo 1: 18 atletas juveniles de béisbol de alto rendimiento, Grupo 2: 18 estudiantes de medicina). Los datos fueron recolectados mediante de polígrafo PowerLab de 8 canales, y fueron procesados usando el software Kubios® versión 3.0.4 Premium. Resultados: Existieron diferencias significativas en los valores de pNN50 (p=0,009), índice de estrés (stress index [p=0,044]), y en los índices parasimpático (p=0,005) y simpático (p=0,001) entre estudiantes y atletas. La capacidad discriminatoria del índice parasimpático para asociarse con la mejor forma física de los atletas fue buena (área bajo la curva 0,784). El punto de corte óptimo por encima del cual el índice parasimpático se asocia al grupo de los atletas, quedó establecido en 0,57. Conclusiones: El índice parasimpático se asoció con el grupo de atletas, lo que evidencia el predominio vagal en la modulación de la actividad cardíaca en los sujetos de este grupo.

ABSTRACT Introduction: Cardiovascular autonomic modulation can be considered a useful tool in determining the physiological state of the interaction between the autonomic nervous system and the cardiovascular system. Objective: To determine the differences in linear parameters of the basal autonomic balance between medical students and young baseball players. Method: A cross-sectional analytical study was carried out in the Biomedical Basic Sciences Laboratory, Faculty No.1, of the Universidad de Ciencias Médicas in Santiago de Cuba. The population and sample consisted of 36 individuals (Group 1: 18 high-performance young baseball athletes, Group 2: 18 medical students). Data was collected using an 8-channel PowerLab polygraph and it was processed using the Kubios® Software version 3.0.4 Premium. Results: There were significant differences in the values between students and athletes: pNN50 (p=0.009), stress index (p=0.044) and in parasympathetic (p=0.005) and sympathetic (p=0.001) indexes. The discriminatory ability of the parasympathetic index to be associated with the best physical fitness of the athletes was good (area under the curve 0.784). The optimum cut-off point above which the parasympathetic index is associated with the group of athletes was set at 0.57. Conclusions: The parasympathetic index was associated with the group of athletes, showing the vagal predominance in the modulation of cardiac activity in the individuals belonging to this group.

Regulación autonómica cardiovascular durante la prueba del peso sostenido en pacientes sanos y diabéticos tipo 2 / Autonomic cardiovascular regulation during the sustained weight test in healthy subjects and type 2 diabetic patients

Introducción: En la actualidad se hace imprescindible el estudio de la diabetes mellitus tipo 2 a partir de técnicas poco costosas en función de la carga sanitaria que representa, es entonces donde la prueba del peso sostenido gana valor como ejercicio isométrico estático cubano en el estudio de la variabilidad de la frecuencia cardíaca. Objetivo: Determinar las respuestas electrofisiológicas autonómicas y hemodinámicas en estado basal y durante la prueba del peso sostenido en pacientes sanos y con diabetes tipo 2. Métodos: Se realizó un estudio en la Universidad de Ciencias Médicas de Santiago de Cuba, no observacional, cuasi-experimental, de tipo antes-después con grupo control de 60 pacientes (30 sanos y 60 con diabetes mellitus tipo 2). Resultados: Los diabéticos presentaron mayor IMC (p = 0,004). En estado basal se experimentaron diferencias significativas entre pacientes sanos y diabéticos. En la mayoría, los parámetros de la variabilidad de la frecuencia cardíaca analizados y durante la prueba del peso sostenido, solo se observaron diferencias significativas en las variables TAS (p = 0,022), BF (p = 0,001) y AF (p = 0,015). Al realizar la prueba del peso sostenido se encontraron variaciones muy significativas (p < 0,001) de los parámetros hemodinámicos, y variaciones significativas de AF (p = 0,023) y BF/AF (p = 0,046) en pacientes sanos; y en diabéticos, diferencias significativas de las variables hemodinámicas. Conclusiones: Se determinó una menor respuesta en pacientes diabéticos con respecto a los sanos del sistema nervioso autónomo, lo que expresa un deterioro de este y una disminución de la actividad simpática y parasimpática(AU)

Introduction: At present it is indispensable to study type 2 diabetes mellitus with low-cost techniques due to the health load it represents. In this context the sustained weight test acquires great value as a Cuban static isometric exercise for the study of heart rate variability. Objective: Determine autonomic and hemodynamic electrophysiological responses at baseline state and during the sustained weight test in healthy subjects and type 2 diabetic patients. Methods: A non-observational quasi-experimental before-after study was conducted at the University of Medical Sciences of Santiago de Cuba based on a control group of 60 patients (30 healthy and 30 with type 2 diabetes mellitus). Results: Diabetics had a higher BMI (p = 0.004). At baseline state significant differences were found between healthy subjects and diabetic patients. In most of the heart rate variability parameters analyzed and during the sustained weight tests, the only variables that showed significant differences were SBP (p = 0.022), FB (p = 0.001) and FA (p = 0.015). The results obtained from the sustained weight test were the following: very significant variations of hemodynamic parameters (p < 0.001), significant FA (p = 0.023) and FB/FA (p = 0.046) variations in healthy subjects, and significant differences in hemodynamic variables in diabetic patients. Conclusions: A lower response by the autonomic nervous system was determined in diabetic patients versus healthy subjects, signaling deterioration of that system and reduced sympathetic and parasympathetic activity(AU)

La Variabilidad de la Frecuencia Cardíaca (VFC) como medida Objetiva de la Atención Sostenida en el Salón de Clase / The Variability of Heart Rate (HRV) as an Objective Measurement of Sustained Attention in the Classroom

El objetivo que se propone en el presente informe es probar la hipótesis teórica de que el tiempo de atención sostenida en los estudiantes en el salón de clase puede ser medida por la respuesta autonómica de la VFC. 10 sujetos participaron del experimento. La VFC fue observada por medio del análisis de series temporales en segmentos de cinco (5) minutos hasta completar la ventana de observación para medias móviles simples de 60 minutos. Se analizaron las series RR en los dominios de tiempo, de frecuencia e índices no lineares.

The objective proposed in this report is to test the theoretical hypothesis that the time of attention sustained by students in the classroom can be measured by the autonomic response of the VFC. 10 subjects participated in the experiment. HRV was observed by means of the analysis of time series in segments of five (5) minutes until completing the observation window for simple moving averages of 60 minutes. The RR series were analyzed in the time, frequency and non-linear index domains.

Comparación del sueño ligero y profundo por medio de la variabilidad de la frecuencia cardíaca

El análisis de la variabilidad de la frecuencia cardiaca (VFC) permite evaluar de forma no invasiva la actividad cardiovascular. La VFC presenta diferencias entre el sueño MOR y NMOR. Aunque, existen inconsistencias en el procedimiento de evaluación de la VFC en el sueño NMOR, hay estudios que lo dividen en sueño ligero y profundo mientras que otros no lo hacen. Nuestro objetivo fue determinar si había diferencias entre estos dos tipos de sueño en 12 medidas de la VFC. Se obtuvo la polisomnografía de 24 voluntarios sanos durante dos noches consecutivas. Se encontraron diferencias significativas entre ambos sueños en las medidas del dominio de tiempo DENN y LogVFC y en las del dominio no lineal DE2 y α1. Estas medidas se caracterizan por proporcionar indicadores de la variabilidad en el funcionamiento cardiaco. Se concluye que al menos con estas medidas se justificaría la división del sueño NMOR en ligero y profundo

Heart rate variability (HRV) analysis allows a non-invasive assessment of the cardiovascular activity. It has been reported that HRV shows differences between REM and NREM sleep. However, there are inconsistencies in the HRV evaluation of NREM sleep, since there are studies that divide it into light and deep sleep and others do not. The objective of this research was to determine if there were differences between these two types of sleep in 12 measures of HRV. Polysomnography of 24 healthy volunteers was obtained during two consecutive nights. Significant differences were found between both sleep types in the measurements of the time domain SDNN and LogHRV, also in measurements of the non-linear domain SD2 and α1. These measures are characterized by providing indicators of the variability in cardiac function. It is concluded that at least these measures would justify the division of the NREM sleep in light and deep sleep

Variabilidad de la frecuencia cardiaca como factor predictor de las enfermedades cardiovasculares / Heart rate variability as a predictive factor of cardiovascular diseases

Resumen La variabilidad de la frecuencia cardiaca se conoce como la variación en el tiempo que transcurre entre los intervalos RR del electrocardiograma y refleja la actividad del sistema nervioso autónomo sobre la función cardiaca. Su aumento se considera un factor protector para el corazón y su medición podría ser una herramienta predictiva temprana o diagnóstica en enfermedades cardiovasculares. El sistema nervioso autónomo genera efectos inotrópicos y cronotrópicos en la función cardiaca, que pueden aumentar o disminuir esta variabilidad. Existen diversos métodos de medición de la variabilidad de la frecuencia cardiaca; el más común es el Holter seguido por el sistema POLAR, además se han desarrollado programas de software clínico (Kubios®, Sinus Core®) que han demostrado validez en estas mediciones. La variabilidad de la frecuencia cardiaca puede emplearse como factor predictor en la aparición de eventos coronarios, accidentes cerebrovasculares y muerte súbita, entre otros.

Abstract Heart rate variability is defined as the variation in time between the RR intervals of the electrocardiogram, and reflects the activity of the autonomous nervous system over cardiac function. Its increase is considered as a protective factor for the heart, and its measurement could be used as a tool for the early prediction or diagnosis of cardiovascular diseases. The autonomous nervous system generates inotropic and chronotropic effects on cardiac function, which can increase or decrease this variability. There are several methods for measuring heart rate variability. The most common is the Holter device, followed by the Polar system. Clinical computer programs have also been developed (Kubios®, Sinus Core®) that have shown to be valid in the measurements. Heart rate variability may be used as a predictive factor for the appearance of coronary events, including among others, cerebrovascular accidents and sudden death.

Respuesta autonómica cardiovascular durante la prueba isométrica cubana del peso sostenido / Cardiovascular autonomic response during the Cuban dynamic weight-bearing test

RESUMEN Introducción: La prueba del peso sostenido (PPS) es un ejercicio isométrico cubano, similar a la de handgrip, de mucha utilidad para inducir modificaciones hemodinámicas que permiten identificar la hiperreactividad cardiovascular en poblaciones de riesgo. Sin embargo, los cambios en la respuesta autonómica cardiovascular durante la PPS no se encuentran totalmente dilucidados. Objetivo: Determinar la respuesta autonómica cardiovascular durante la prueba isométrica cubana del peso sostenido. Método: Estudio cuasi-experimental (crossover) con 16 sujetos sanos, donde se evaluaron la presión arterial y la variabilidad de la frecuencia cardíaca, 5 minutos antes (reposo) y durante la PPS (2 minutos de maniobra y 3 minutos de recuperación), a través del análisis frecuencial (Fourier) y en tiempo-frecuencia (wavelet) de las bandas de altas (HF: 0,15-0,4 Hz) y bajas frecuencias (LF: 0,04-0,15 Hz), así como el análisis temporal y no-lineal (entropía de Shannon) de la serie de intervalos RR. Resultados: Aunque no existieron diferencias significativas (p>0,05) en los indicadores temporales (SDNN, RMSSD, pNN50), ni en los frecuenciales (LF, HF, LF/HF), se encontraron incrementos (p<0,05) de la presión arterial y una disminución significativa (p<0,05) de la complejidad (entropía) en la PPS con respecto al reposo, asociados con un pico en la LF y la relación LF/HF alrededor de los 2 minutos reflejados con los métodos en tiempo-frecuencia. Conclusiones: Existió un incremento dinámico en la respuesta simpática cardiovascular durante la PPS que se asocian a una disminución de la complejidad de este proceso fisiológico, lo que no es evidente con los métodos lineales tradicionales de la variabilidad de la frecuencia cardíaca.

ABSTRACT Introduction: The dynamic weight-bearing test (WBT) is a Cuban isometric exercise, similar to the hand grip test, which is very useful to induce hemodynamic modifications to identify cardiovascular hyperreactivity in at-risk populations. However, changes in the cardiovascular autonomic response during weight-bearing test are poorly understood. Objective: To determine the cardiovascular autonomic response during the Cuban dynamic WBT. Method: Quasi-experimental crossover trial with 16 healthy subjects; blood pressure and heart rate variability were assessed, 5 minutes before (rest) and during the WBT (2 minutes for maneuver and 3 minutes for recovery), through the frequency (Fourier) and time-frequency (Wavelet) analysis of high-frequency (HF: 0.15-0.4 Hz) and low-frequency (LF: 0.04-0.15 Hz) bands, as well as temporal and non-linear analysis (Shannon entropy) of the RR interval series. Results: Although temporal indicators (SDNN, RMSSD, pNN50) showed no significant differences (p>0.05) nor the frequencies (LF, HF, LF/HF); we found an increase (p<0.05) in blood pressure and a significant decrease (p<0.05) in complexity (entropy) in the WBT with respect to rest, associated with an HF peak and LF/HF ratio at nearly 2 minutes reflected with the time-frequency methods. Conclusions: There was a dynamic increase in the cardiovascular sympathetic response during the WBT associated with a decrease in the complexity of this physiological process, which is not evident with the traditional linear methods of heart rate variability.

Sympathetic activity is negatively associated to uremic state and hemodynamic instability during hemodialysis sessions / La actividad simpática está negativamente asociada al estado urémico y a la inestabilidad hemodinámica durante las sesiones de hemodiálisis

INTRODUCTION: Hemodynamic instabilities, characterized by oscillations of blood pressure, are common during hemodialysis sessions (HD), culminating in intradialytic hypotension owing to volume withdrawal from the cardiovascular system. The ability to carry out immediate adjusts in cardiovascular system, mainly mediated by the autonomic nervous system, is essential to the maintenance of hemodynamic stability during HD. OBJECTIVE: This study aimed to investigate the relationship between the sympathetic activity, and the hemodynamic stability from chronic kidney disease (CKD) patients during the HD, as well as the relationship between sympathetic activity and the uremic state. METHODS: Fourteen CKD patients (08 women and 06 men) with no history of recurrent ID episodes had the successive RR intervals recorded during HD. Blood pressure measurements were recorded at regular intervals of 30 minutes along 4 hours of each session. Hemodynamic stability was established by the standard deviation (SD), coefficient of variation (CV) and the Delta (difference between the highest and the lowest measure) of systolic (SBP), diastolic (DBP), and mean (MBP) blood pressures, as well as the pulse pressure (PP) from the 8 recordings obtained during each session. As a measure of autonomic heart control, the log-transformed low frequency (lnLFnu) spectral band was used. The uremic state was established by the mean of uremia from the last 12 months. Pearson's correlation was used to analyze the correlation between the studied variables. RESULTS: The lnLFnu values were negatively associated SD (SBP [r = -0.480; p = 0.010], PP [r = -0.504; p = 0.006] and MBP [r = -0.449; p = 0.017]), CV (SBP [r = -0.390; p = 0.040]) and delta (SBP [r = -0.438; p = 0.020], PP [r = -0.490; p = 0.008] and MBP [r = -0.382; p = 0.045]). lnLFnu was also negatively associated to the uremic state (r = -0.601; p = 0.01). CONCLUSIONS: Our results indicate that higher values of the lnLFnu are associated with better hemodynamic stability (i.e., smaller blood pressure oscillations) during HD sessions, in turn, the mean of blood urea concentration in the last 12 months, defined here as the uremic state, was associated with lower values of the lnLFnu during HD sessions

INTRODUCCIÓN: La inestabilidad hemodinámica, que se caracteriza por las oscilaciones de la presión arterial, es frecuente durante las sesiones de hemodiáilisis (HD) y tiene como resultado la hipotensión intradialítica, causada por una disminución en el volumen sanguíneo del sistema cardiovascular. Es esencial poder realizar ajustes inmediatos en el sistema cardiovascular, mediados principalmente por el sistema nervioso autónomo, a fin de mantener la estabilidad hemodinámica durante la hemodiálisis. OBJETIVO: El objetivo de nuestro estudio fue investigar la relación entre la actividad del sistema nervioso simpático y la estabilidad hemodinámica en pacientes con enfermedad renal crónica (ERC) durante las sesiones de hemoterapia; asimismo, se indagó sobre la relación entre la actividad del sistema nervioso simpático y el estado urémico. MATERIAL Y MÉTODOS: Se registraron, durante las sesiones de hemodiálisis, los intervalos RR sucesivos de 14 pacientes con enfermad renal crónica (8 mujeres y 6 hombres) sin antecedentes de episodios recurrentes de hipotensión intradialítica (HI). Se realizaron registros de la tensión arterial en intervalos regulares de 30 minutos durante 4 horas en cada sesión. La estabilidad hemodinámica se estableció mediante la desviación estándar, el coeficiente de variación (CV) y delta (diferencia entre la medida más alta y la más baja) de la tensión arterial sistólica (TAS), la diastólica (TAD) y la media (TAM), así como la tensión diferencial (TD) a partir de los ocho registros obtenidos durante cada sesión. Se utilizó el análisis espectral de transformaciones logarítmicas de baja frecuencia (LnLFnu, por su sigla en inglés) expresados en unidades normalizadas mediante transformación logarítmica. El estado urémico se determinó a través del promedio de los valores de uremia obtenidos durante los últimos doce meses. Se utilizó el coeficiente de correlación de Pearson para analizar las variables estudiadas. RESULTADOS: Mediante los distintos cálculos, se hallaron las siguientes correlaciones negativas con los valores de lnLFnu : SD (TAS [r = -0,480; p = 0,010]; TD [r = -0,504; p = 0,006] , y TAM [r = -0,449; p = 0,017]); CV (TAS [r = -0,390; p = 0,040]); y delta (TAS [r = -0,438; p = 0,020]; TD [r = -0,490; p = 0,008], y TAM [r = -0,382; p = 0,045]). También se observó una correlación negativa entre lnLFnu y el estado urémico (r = -0,601; p = 0,01). CONCLUSIONES: Nuestros resultados indican que los valores más elevados de LnLFnu se asocian con una mejor estabilidad hemodinámica, es decir, menor oscilación de la tensión arterial, durante las sesiones de hemodiálisis. A su vez, el promedio de concentración de urea en sangre registrado durante los últimos doce meses, al cual definimos como el estado urémico, se relacionó con valores más bajos de LnLFnu durante las sesiones de hemodiálisis