Autonomic and Vascular Responses during Reactive Hyperemia in Healthy Individuals and Patients with Sickle Cell Anemia.

Background and Objectives: To compare autonomic and vascular responses during reactive hyperemia (RH) between healthy individuals and patients with sickle cell anemia (SCA). Materials and Methods: Eighteen healthy subjects and 24 SCA patients were subjected to arterial occlusion for 3 min at the lower right limb level. The pulse rate variability (PRV) and pulse wave amplitude were measured through photoplethysmography using the Angiodin® PD 3000 device, which was placed on the first finger of the lower right limb 2 min before (Basal) and 2 min after the occlusion. Pulse peak intervals were analyzed using time-frequency (wavelet transform) methods for high-frequency (HF: 0.15-0.4) and low-frequency (LF: 0.04-0.15) bands, and the LF/HF ratio was calculated. Results: The pulse wave amplitude was higher in healthy subjects compared to SCA patients, at both baseline and post-occlusion (p < 0.05). Time-frequency analysis showed that the LF/HF peak in response to the post-occlusion RH test was reached earlier in healthy subjects compared to SCA patients. Conclusions: Vasodilatory function, as measured by PPG, was lower in SCA patients compared to healthy subjects. Moreover, a cardiovascular autonomic imbalance was present in SCA patients with high sympathetic and low parasympathetic activity in the basal state and a poor response of the sympathetic nervous system to RH. Early cardiovascular sympathetic activation (10 s) and vasodilatory function in response to RH were impaired in SCA patients.

Rapid adjustments to autonomic control of cardiac rhythm at the onset of isometric exercise in healthy young adults.

Sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) influences on cardiac rhythm at the onset of exercise, a time of rapid autonomic adjustments, are clinically important areas of investigation. Continuous wavelet transform (CWT) involves time-frequency-based heart rate variability (HRV) analysis allowing investigation of autonomic influences on cardiac rhythm during short durations of exercise. Therefore, the purpose of this study was to characterize SNS and PNS influences on cardiac rhythm at the onset of isometric exercise in healthy young adults. CWT analysis was retrospectively applied to R-R interval data (electrocardiogram) previously collected from 14 healthy young adults (26 ± 2 years) who performed 30-s, one-legged, isometric, calf exercise at 70% maximal voluntary contraction (MVC; 70% MVC trial) or rested (0% MVC trial). Absolute and normalized low-frequency (aLF, nLF; 0.04-0.15 Hz) and high-frequency (aHF, nHF; 0.15-0.4 Hz) bands and LF/HF were used to analyze one 30-s baseline period and six 5-s time windows during the 30-s exercise (70% MVC) or rest (0% MVC). Statistical analysis involved two-way analysis of variance with post-hoc analysis. aHF, aLF, LF/HF, nHF, and nLF displayed a trial-time interaction (all p ≤ 0.027). In the 70% compared to the 0% MVC trial, aHF and nHF were lower after 5-30 s (all p ≤ 0.040), aLF was lower after 20-30 s (all p ≤ 0.011) and LF/HF and nLF were higher after 5-20 s (all p ≤ 0.045). These results indicate the reduction of the PNS influence on cardiac rhythm begins sooner than the augmentation of the SNS influence at the onset of isometric exercise in healthy young adults.

Blood Pressure Prediction Using Ensemble Rules during Isometric Sustained Weight Test.

BACKGROUND: Predicting beat-to-beat blood pressure has several clinical applications. While most machine learning models focus on accuracy, it is necessary to build models that explain the relationships of hemodynamical parameters with blood pressure without sacrificing accuracy, especially during exercise. OBJECTIVE: The aim of this study is to use the RuleFit model to measure the importance, interactions, and relationships among several parameters extracted from photoplethysmography (PPG) and electrocardiography (ECG) signals during a dynamic weight-bearing test (WBT) and to assess the accuracy and interpretability of the model results. METHODS: RuleFit was applied to hemodynamical ECG and PPG parameters during rest and WBT in six healthy young subjects. The WBT involves holding a 500 g weight in the left hand for 2 min. Blood pressure is taken in the opposite arm before and during exercise thereof. RESULTS: The root mean square error of the model residuals was 4.72 and 2.68 mmHg for systolic blood pressure and diastolic blood pressure, respectively, during rest and 4.59 and 4.01 mmHg, respectively, during the WBT. Furthermore, the blood pressure measurements appeared to be nonlinear, and interaction effects were observed. Moreover, blood pressure predictions based on PPG parameters showed a strong correlation with individual characteristics and responses to exercise. CONCLUSION: The RuleFit model is an excellent tool to study interactions among variables for predicting blood pressure. Compared to other models, the RuleFit model showed superior performance. RuleFit can be used for predicting and interpreting relationships among predictors extracted from PPG and ECG signals.

Temporal inequality of RR intervals like a new psychophysiological indicator of mental stress / Desigualdad temporal de los intervalos RR como nuevo indicador psicofisiológico de estrés mental / Desigualdade temporal de intervalos RR como um novo indicador psicofisiológico de estresse mental

Introduction: Gini coefficient (Gini index or Gini ratio) is a parameter that is normally used in economy to measure the income distribution in a country or in the whole wide world, but it can be used to measure any kind of distribution. In the present study it is exposed an innovative proposal of application of the Gini coefficient to Heart Rate Variability (HRV) like a psychophysiological indicator of mental stress. Purpose: To assess the application of the Gini coefficient as a psychophysiological indicator of mental stress. Methods: The involved participants are 13 healthy individuals (age 19 ± 1.5 years). Heart rate was continuously recorded at rest (5 minutes) and during a mental stress (5 minutes). Linear and nonlinear methods of heart rate variability were assessed, and 2 new indicators (Sequential and Non-Sequential Gini) were calculated and proposed to measure HRV differences between states. Results: When comparing rest and mental stress conditions, a sensible decrease of the traditional indicators of the HRV was founded (p<0.05), an increase of the heart rate (p=0.004) and of the Sequential Gini (p=0.004) and Non-Sequential Gini (p=0.04). Conclusions: The results suggest that temporary inequality of the RR intervals analyzed from the Gini coefficient could be an adequate indicator of sympathetic activity present during the mental stress, with great potentialities with the objective to assess the consequences of psychosomatic affections and anxiety disorders.

Introducción: El coeficiente de Gini o índice de Gini es un parámetro que normalmente se usa en economía para medir la distribución del ingreso en un país o en todo el mundo, pero puede usarse para medir cualquier tipo de distribución. En el presente estudio se expone una propuesta innovadora de aplicación del coeficiente de Gini a la Variabilidad de la Frecuencia Cardíaca (VFC) como indicador psicofisiológico del estrés mental. Objetivo: Evaluar la aplicación del coeficiente de Gini como indicador psicofisiológico de estrés mental. Métodos: Los participantes involucrados son 13 individuos sanos (edad 19 ± 1,5 años). La frecuencia cardíaca se registró continuamente en reposo (5 minutos) y durante un estrés mental (5 minutos). Se evaluaron métodos lineales y no lineales de variabilidad de la frecuencia cardíaca, y se calcularon y propusieron 2 nuevos indicadores (Gini secuencial y no secuencial) para medir las diferencias de VFC entre estados. Resultados: Al comparar las condiciones de reposo y estrés mental, se encontró una sensible disminución de los indicadores tradicionales de la VFC (p<0,05), un aumento de la frecuencia cardiaca (p=0,004) y del Gini Secuencial (p=0,004) y Gini no secuencial (p=0,04). Conclusiones: Los resultados sugieren que la desigualdad temporal de los intervalos RR analizados a partir del coeficiente de Gini podría ser un indicador adecuado de la actividad simpática presente durante el estrés mental, con grandes potencialidades en la evaluación las consecuencias de afecciones psicosomáticas y trastornos de ansiedad.

Introdução: O coeficiente de Gini ou índice de Gini é um parâmetro normalmente usado em economia para medir a distribuição de renda em um país ou no mundo, mas pode ser usado para medir qualquer tipo de distribuição. No presente estudo, apresenta-se uma proposta inovadora de aplicação do coeficiente de Gini à Variabilidade da Frequência Cardíaca (VFC) como indicador psicofisiológico de estresse mental.Objetivo: Avaliar a aplicação do coeficiente de Gini como indicador psicofisiológico de estresse mental.Métodos: Os participantes envolvidos são 13 indivíduos saudáveis ​​(idade 19 ± 1,5 anos). A frequência cardíaca foi registrada continuamente em repouso (5 minutos) e durante o estresse mental (5 minutos). Métodos lineares e não lineares de variabilidade da frequência cardíaca foram avaliados e 2 novos indicadores (gini sequencial e não sequencial) foram calculados e propostos para medir as diferenças na VFC entre os estados.Resultados: Ao comparar as condições de repouso e estresse mental, foi encontrada diminuição significativa nos indicadores tradicionais da VFC (p<0,05), aumento da frequência cardíaca (p=0,004) e do Gini Sequencial (p= 0,004) e não - Gini sequencial (p=0,04).Conclusões: Os resultados sugerem que a desigualdade temporal dos intervalos RR analisados ​​a partir do coeficiente de Gini pode ser um indicador adequado da atividade simpática presente durante o estresse mental, com grande potencial na avaliação das consequências de condições psicossomáticas e transtornos de ansiedade.

Theil Entropy as a Non-Lineal Analysis for Spectral Inequality of Physiological Oscillations.

Theil entropy is a statistical measure used in economics to quantify income inequalities. However, it can be applied to any data distribution including biological signals. In this work, we applied different spectral methods on heart rate variability signals and cellular calcium oscillations previously to Theil entropy analysis. The behavior of Theil entropy and its decomposable property was investigated using exponents in the range of [-1, 2], on the spectrum of synthetic and physiological signals. Our results suggest that the best spectral decomposition method to analyze the spectral inequality of physiological oscillations is the Lomb-Scargle method, followed by Theil entropy analysis. Moreover, our results showed that the exponents that provide more information to describe the spectral inequality in the tested signals were zero, one, and two. It was also observed that the intra-band component is the one that contributes the most to total inequality for the studied oscillations. More in detail, we found that in the state of mental stress, the inequality determined by the Theil entropy analysis of heart rate increases with respect to the resting state. Likewise, the same analytical approach shows that cellular calcium oscillations present on developing interneurons display greater inequality distribution when inhibition of a neurotransmitter system is in place. In conclusion, we propose that Theil entropy is useful for analyzing spectral inequality and to explore its origin in physiological signals.

Early cardiovascular sympathetic reflex activation is independent of occlusion time during reactive hyperemia / La activación temprana del reflejo simpático cardiovascular es independiente del tiempo de oclusión durante la hiperemia reactiva / A ativação precoce do reflexo simpático cardiovascular é independente do tempo de oclusão durante a hiperemia reativa

Purpose: The aim of the present study was to investigate the role of occlusion time in dynamic changes of autonomic activation during reactive hyperemia. Methods: Healthy subjects (n = 30) in the age range of 18­25 years participated in this study. Vascular reactivity was assessed by measuring the dynamic changes in finger pulse volume amplitude (PVA) and  pulse transit time relative to the RR intervals in the test (occluded arm) and control arm (contralateral non-occluded arm) during 1, 3 and 5 minute of occlusion using two separate Photoplethysmographic sensors. Heart Rate Variability was computed from a simultaneously acquired ECG signal to monitor the dynamic changes in cardiac autonomic nervous activity. Time-varying analysis of all signals were shown every 1 second in average response graphs. Results: Time-varying analysis of vascular and autonomic response during reactive hyperemia demonstrated the presence of a characteristic response pattern with an increase in the Sympathetic index and a decrease in Parasympathetic index at 8 to 10 seconds, an increase in heart rate at 20 seconds and a progressive increase in PVA during the first 60 seconds after occlusion regardless of the time spent in the procedure. Moreover, a decrease in pulse transits time relative to RR intervals,  followed by an increase regardless of the occlusion time was evidenced.  Conclusions: Early cardiovascular sympathetic activation is independent of occlusion time during reactive hyperemia, which suggests this is a vascular autonomic reflex response involved in the generation of the physiological phenomenon of reactive hyperemia.

Objetivo: El objetivo del presente estudio fue investigar el papel del tiempo de oclusión en los cambios dinámicos de la activación autónoma durante la hiperemia reactiva.Métodos: Participaron en este estudio sujetos sanos (n = 30) en el rango de edad de 18 a 25 años. La reactividad vascular se evaluó midiendo los cambios dinámicos en la amplitud del volumen del pulso del dedo (PVA) y el tiempo de tránsito del pulso en relación con los intervalos RR en la prueba (brazo ocluido) y el brazo de control (brazo contralateral no ocluido) durante 1, 3 y 5 minutos. de oclusión utilizando dos sensores fotopletismográficos separados. La variabilidad de la frecuencia cardíaca se calculó a partir de una señal de ECG adquirida simultáneamente para controlar los cambios dinámicos en la actividad nerviosa autónoma cardíaca. El análisis variable en el tiempo de todas las señales se mostró cada segundo en gráficos de respuesta promedio.Resultados: El análisis variable en el tiempo de la respuesta vascular y autonómica durante la hiperemia reactiva demostró la presencia de un patrón de respuesta característico con un aumento en el índice simpático y una disminución en el índice parasimpático a los 8 a 10 segundos, un aumento en la frecuencia cardíaca a los 20 segundos y un aumento progresivo de PVA durante los primeros 60 segundos después de la oclusión independientemente del tiempo transcurrido en el procedimiento. Además, se evidenció una disminución en el tiempo de tránsitos del pulso en relación con los intervalos RR, seguido de un aumento independientemente del tiempo de oclusión.Conclusiones: La activación simpática cardiovascular temprana es independiente del tiempo de oclusión durante la hiperemia reactiva, lo que sugiere que se trata de una respuesta refleja autonómica vascular involucrada en la generación del fenómeno fisiológico de hiperemia reactiva.

Objetivo: O objetivo do presente estudo foi investigar o papel do tempo de oclusão nas mudanças dinâmicas da ativação autonômica durante a hiperemia reativa.Métodos: Participaram deste estudo indivíduos saudáveis ​​(n = 30) na faixa etária de 18 a 25 anos. A reatividade vascular foi avaliada medindo as mudanças dinâmicas na amplitude do volume do pulso do dedo (PVA) e tempo de trânsito do pulso em relação aos intervalos RR no teste (braço ocluído) e braço controle (braço não ocluído contralateral) durante 1, 3 e 5 minutos de oclusão usando dois sensores fotopletismográficos separados. A variabilidade da frequência cardíaca foi calculada a partir de um sinal de ECG adquirido simultaneamente para monitorar as mudanças dinâmicas na atividade nervosa autonômica cardíaca. A análise variável no tempo de todos os sinais foi mostrada a cada 1 segundo em gráficos de resposta média.Resultados: A análise variável no tempo da resposta vascular e autonômica durante a hiperemia reativa demonstrou a presença de um padrão de resposta característico com um aumento no índice simpático e uma diminuição no índice parassimpático em 8 a 10 segundos, um aumento na frequência cardíaca em 20 segundos e aumento progressivo do PVA durante os primeiros 60 segundos após a oclusão, independentemente do tempo despendido no procedimento. Além disso, foi evidenciada uma diminuição no tempo de trânsito de pulso em relação aos intervalos RR, seguida de um aumento independente do tempo de oclusão.Conclusões: A ativação simpática cardiovascular precoce independe do tempo de oclusão durante a hiperemia reativa, o que sugere que se trata de uma resposta reflexa autonômica vascular envolvida na geração do fenômeno fisiológico de hiperemia reativa.

Dynamics of cardiac autonomic regulation during isometric sustained weight test in hypertensive patients

Background: The Sustained Weight Test (SWT) is an isometric exercise test that has great practical value for carrying out massive studies on hypertension, however, is insufficient knowledge of the dynamics of cardiac autonomic regulation during this test. The aim of this study was to determine variations in the dynamics of cardiac autonomic regulation and in hemodynamic response during SWT in hypertensive subjects. Methods: A quasi-experimental study was conducted on 15 hypertensive patients of both sexes, paired with 30 normotensive individuals, measuring arterial blood pressure, entropy sample and the Heart Rate Variability (HRV) in time-frequency with the Continuous Wavelet Transform Morlet-type (CWT  morlet) through the electrocardiographic signal of the polygraph AD Instruments in the functional states of Rest and SWT. Results: A significant increase in heart rate and blood pressure was found, as well as a decrease in sample entropy in the functional states of normotensive and hypertensive patients. In hypertensive patients, an early response pattern increased with multiple fluctuations during SWT in the time-frequency analysis of HRV with the CWT morlet. Conclusions: SWT produces an increase in blood pressure, which is more frequent and evident in hypertensive subjects. Cardiac autonomic regulation during SWT increases the sympathetic and decreases the parasympathetic components, manifesting itself in hypertensive patients with a pattern of imbalance in the regulation of both sympathetic and parasympathetic response.

Cardiac vagal imbalance to the isometric sustained weight test in adolescents with emotional eating behavior.

PURPOSE: To assess the relationship between emotional eating behavior and heart rate variability in Spanish adolescents during an isometric exercise test. METHODS: Participants included 52 adolescents aged between 13 and 18 years old. Heart rate was continuously recorded at rest (2 minutes) and during the sustained weight test (2 minutes). Linear and nonlinear methods of heart rate variability were assessed and related to the emotional eating behavior divided in two clusters. RESULTS: Statistically significant differences were observed in linear and non-linear parameters of heart rate variability comparing rest and sustained weight test. An increase in the value of emotional eating in overweight adolescents was founded. During the sustained weight test, there were differences between the two emotional eating clusters regarding the variables peak high frequency power, normalized low frequency power, normalized high frequency power, low frequency/high frequency ratio, and sample entropy. A positive correlation between the emotional eating behavior and the peak high frequency power was observed, though the prediction capacity of the high frequency waves is low it is observed that there is a good fit to the regression line. CONCLUSION: Results of this study shows that there was a relationship between vagal tone and emotional eating behavior in adolescents during an isometric exercise, with excessive parasympathetic predominance and sympathetic withdrawal during a physical effort.

Introduction of Application of Gini Coefficient to Heart Rate Variability Spectrum for Mental Stress Evaluation / Introdução da Aplicação do Coeficiente de Gini ao Espectro de Variabilidade da Frequência Cardíaca para Avaliação do Estresse Mental

Abstract Background: The Gini coefficient is a statistical tool generally used by economists to quantify income inequality. However, it can be applied to any kind of data with unequal distribution, including heart rate variability (HRV). Objectives: To assess the application of the Gini coefficient to measure inequality in power spectral density of RR intervals, and to use this application as a psychophysiological indicator of mental stress. Methods: Thirteen healthy subjects (19 ± 1.5 years) participated in this study, and their RR intervals were obtained by electrocardiogram during rest (five minutes) and during mental stress (arithmetic challenge; five minutes). These RR intervals were used to obtain the estimates of power spectral densities (PSD). The limits for the PSD bands were defined from 0.15 to 0.40 Hz for high frequency band (HF), from 0.04 to 0.15 Hz for low frequency band (LF), from 0.04 to 0.085 Hz for first low frequency sub-band (LF1) and from 0.085 to 0.15 Hz for second low frequency sub-band (LF2). The spectral Gini coefficient (SpG) was proposed to measure the inequality in the power distribution of the RR intervals in each of above-mentioned HRV bands. SpG from each band was compared with its respective traditional index of HRV during the conditions of rest and mental stress. All the differences were considered statistically significant for p < 0.05. Results: There was a significant decrease in HF power (p = 0.046), as well as significant increases in heart rate (p = 0.004), LF power (p = 0.033), LF2 power (p = 0.019) and LF/HF (p = 0.002) during mental stress. There was also a significant increase in SpG(LF) (p = 0.009) and SpG(LF2) (p = 0.033) during mental stress. Coefficient of variation showed SpG has more homogeneity compared to the traditional index of HRV during mental stress. Conclusions: This pilot study suggested that spectral inequality of Heart Rate Variability analyzed using the Gini coefficient seems to be an independent and homogeneous psychophysiological indicator of mental stress. Also, HR, LF/HF, SpG(LF) of HRV are possibly important, reliable and valid indicators of mental stress.

Resumo Fundamento: O coeficiente de Gini é um instrumento estatístico geralmente usado por economistas para quantificar a desigualdade de renda. No entanto, ele pode ser aplicado a qualquer tipo de dados com distribuição desigual, incluindo a variabilidade da frequência cardíaca (VFC). Objetivos: Avaliar a aplicação do coeficiente de Gini para medir a desigualdade na densidade espectral de potência de intervalos RR, e usar esta aplicação como um indicador psicofisiológico do estresse mental. Métodos: Treze indivíduos saudáveis (19 ± 1,5 anos) participaram deste estudo, e seus intervalos RR foram obtidos por eletrocardiograma durante repouso (cinco minutos) e durante estresse mental (desafio aritmético; cinco minutos). Esses intervalos RR foram utilizados para obter as estimativas de densidades espectrais de potência (PSD). Os limites para as bandas PSD foram definidos de 0,15 a 0,40 Hz para banda de alta frequência (HF), de 0,04 a 0,15 Hz para banda de baixa frequência (LF), de 0,04 a 0,085 Hz para a primeira sub-banda de baixa frequência (LF1) e de 0,085 a 0,15 Hz para a segunda sub-banda de baixa frequência (LF2). O coeficiente de Gini espectral (SpG) foi proposto para medir a desigualdade na distribuição de potência dos intervalos RR em cada uma das bandas de VFC mencionadas acima. O SpG de cada banda foi comparado com seu respectivo índice tradicional de VFC durante as condições de repouso e de estresse mental. Todas as diferenças foram consideradas estatisticamente significativas para p < 0,05. Resultados: Houve uma diminuição significativa no poder de FC (p=0,046), bem como aumentos significativos na frequência cardíaca (p = 0,004), potência da LF (p = 0,033), potência da LF2 (p = 0,019) e LF/HF (p = 0,002) durante estresse mental. Houve também um aumento significativo de SpG(LF) (p = 0,009) e SpG(LF2) (p = 0,033) durante estresse mental. O coeficiente de variação mostrou que o SpG tem mais homogeneidade em comparação com o índice tradicional de VFC durante o estresse mental. Conclusões: Este estudo piloto sugeriu que a desigualdade espectral da VFC analisada pelo coeficiente de Gini parece ser um indicador psicofisiológico independente e homogêneo de estresse mental. Além disso, FC, LF/HF, SpG(LF) da VFC são possivelmente indicadores importantes, confiáveis e válidos de estresse mental.

Introduction of Application of Gini Coefficient to Heart Rate Variability Spectrum for Mental Stress Evaluation.

BACKGROUND: The Gini coefficient is a statistical tool generally used by economists to quantify income inequality. However, it can be applied to any kind of data with unequal distribution, including heart rate variability (HRV). OBJECTIVES: To assess the application of the Gini coefficient to measure inequality in power spectral density of RR intervals, and to use this application as a psychophysiological indicator of mental stress. METHODS: Thirteen healthy subjects (19 ± 1.5 years) participated in this study, and their RR intervals were obtained by electrocardiogram during rest (five minutes) and during mental stress (arithmetic challenge; five minutes). These RR intervals were used to obtain the estimates of power spectral densities (PSD). The limits for the PSD bands were defined from 0.15 to 0.40 Hz for high frequency band (HF), from 0.04 to 0.15 Hz for low frequency band (LF), from 0.04 to 0.085 Hz for first low frequency sub-band (LF1) and from 0.085 to 0.15 Hz for second low frequency sub-band (LF2). The spectral Gini coefficient (SpG) was proposed to measure the inequality in the power distribution of the RR intervals in each of above-mentioned HRV bands. SpG from each band was compared with its respective traditional index of HRV during the conditions of rest and mental stress. All the differences were considered statistically significant for p < 0.05. RESULTS: There was a significant decrease in HF power (p = 0.046), as well as significant increases in heart rate (p = 0.004), LF power (p = 0.033), LF2 power (p = 0.019) and LF/HF (p = 0.002) during mental stress. There was also a significant increase in SpG(LF) (p = 0.009) and SpG(LF2) (p = 0.033) during mental stress. Coefficient of variation showed SpG has more homogeneity compared to the traditional index of HRV during mental stress. CONCLUSIONS: This pilot study suggested that spectral inequality of Heart Rate Variability analyzed using the Gini coefficient seems to be an independent and homogeneous psychophysiological indicator of mental stress. Also, HR, LF/HF, SpG(LF) of HRV are possibly important, reliable and valid indicators of mental stress.

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.

Algoritmo para la detección de puntos clínicos de interés de la onda de pulso arterial / Algorithm for the detection of clinical points of interest of the arterial pulse wave

Introducción: La aplicación de métodos para la detección de puntos clínicos de interés de la onda de pulso permite la obtención de parámetros como el índice de rigidez vascular y el de reflexión que facilitan la evaluación de los efectos vasculares del envejecimiento, la hipertensión y la aterosclerosis. Por esto es necesaria la adecuada localización del inicio, pico sistólico, incisura dicrota y el pico diastólico de la onda de pulso arterial. Objetivo: Desarrollar un algoritmo para la localización del inicio, pico sistólico, incisura dicrota y el pico diastólico de la onda de pulso arterial. Método: El algoritmo presentado utiliza la primera derivada unido a condicionales móviles para eliminar puntos no deseados, al igual que intervalos no confiables. El algoritmo fue evaluado utilizando la anotación de un experto, con 5 registros de onda de pulso arterial de 5 minutos (5236 anotaciones) y contaminadas a diferente relaciones señal ruido (15, 12 and 9 dB). Resultados: Cuando se comparó con las anotaciones de un experto el algoritmo detecto estos puntos fiduciales con una sensibilidad promedio, predictividad positiva y exactitud del 100 por ciento y mostró errores menores de 10ms. En señales de onda de pulso arterial contaminadas con ruido en ambos casos el error relativo fue menor que 2 por ciento respecto a un periodo de muestreo de 800ms. Conclusiones: el algoritmo provee una simple pero precisa detección de los puntos clínicos de interés de la onda de pulso arterial, robusto a ruido y artefactos de movimiento que pudiera ser utilizado en la evaluación del índice de rigidez y de reflexión vascular(AU)

Introduction: The application of methods for the detection of clinical points of interest of the pulse wave allows obtaining parameters such as the index of vascular rigidity and reflection that facilitate the evaluation of the vascular effects of aging, hypertension and atherosclerosis. For this reason, the appropriate localization of the onset, systolic peak, dicrotic notchs and the diastolic peak of the arterial pulse wave is necessary. Objective: To develop an algorithm for the localization of the onset, systolic peak, dicrotic notchs and the diastolic peak of the arterial pulse wave. Method: The presented algorithm uses the first derivative linked to mobile conditionals to eliminate unwanted points, as well as unreliable intervals. The algorithm was evaluated using the annotation of an expert, with 5 records of arterial pulse wave of 5 minutes (5236 annotations) and contaminated at different signal-to-noise ratios (15, 12 and 9 dB). Results: When compared with the annotations of an expert, the algorithm detected these fiducial points with an average sensitivity, positive predictivity and 100 percent accuracy and showed errors of less than 10ms. In arterial pulse wave signals contaminated with noise in both cases the relative error was less than 2 percent with respect to a sampling period of 800ms. Conclusions: the algorithm provides a simple but accurate detection of the clinical points of interest of the arterial pulse wave, robust to noise and movement artifacts that could be used in the evaluation of the stiffness index and vascular reflection(AU)

Algoritmo para la detección de puntos clínicos de interés de la onda de pulso arterial / Algorithm for the detection of clinical points of interest of the arterial pulse wave

Introducción: La aplicación de métodos para la detección de puntos clínicos de interés de la onda de pulso permite la obtención de parámetros como el índice de rigidez vascular y el de reflexión que facilitan la evaluación de los efectos vasculares del envejecimiento, la hipertensión y la aterosclerosis. Por esto es necesaria la adecuada localización del inicio, pico sistólico, incisura dicrota y el pico diastólico de la onda de pulso arterial. Objetivo: Desarrollar un algoritmo para la localización del inicio, pico sistólico, incisura dicrota y el pico diastólico de la onda de pulso arterial. Método: El algoritmo presentado utiliza la primera derivada unido a condicionales móviles para eliminar puntos no deseados, al igual que intervalos no confiables. El algoritmo fue evaluado utilizando la anotación de un experto, con 5 registros de onda de pulso arterial de 5 minutos (5236 anotaciones) y contaminadas a diferente relaciones señal ruido (15, 12 and 9 dB). Resultados: Cuando se comparó con las anotaciones de un experto el algoritmo detecto estos puntos fiduciales con una sensibilidad promedio, predictividad positiva y exactitud del 100 por ciento y mostró errores menores de 10ms. En señales de onda de pulso arterial contaminadas con ruido en ambos casos el error relativo fue menor que 2 por ciento respecto a un periodo de muestreo de 800ms. Conclusiones: el algoritmo provee una simple pero precisa detección de los puntos clínicos de interés de la onda de pulso arterial, robusto a ruido y artefactos de movimiento que pudiera ser utilizado en la evaluación del índice de rigidez y de reflexión vascular(AU)

Introduction: The application of methods for the detection of clinical points of interest of the pulse wave allows obtaining parameters such as the index of vascular rigidity and reflection that facilitate the evaluation of the vascular effects of aging, hypertension and atherosclerosis. For this reason, the appropriate localization of the onset, systolic peak, dicrotic notchs and the diastolic peak of the arterial pulse wave is necessary. Objective: To develop an algorithm for the localization of the onset, systolic peak, dicrotic notchs and the diastolic peak of the arterial pulse wave. Method: The presented algorithm uses the first derivative linked to mobile conditionals to eliminate unwanted points, as well as unreliable intervals. The algorithm was evaluated using the annotation of an expert, with 5 records of arterial pulse wave of 5 minutes (5236 annotations) and contaminated at different signal-to-noise ratios (15, 12 and 9 dB). Results: When compared with the annotations of an expert, the algorithm detected these fiducial points with an average sensitivity, positive predictivity and 100 percent accuracy and showed errors of less than 10ms. In arterial pulse wave signals contaminated with noise in both cases the relative error was less than 2 percent with respect to a sampling period of 800ms. Conclusions: the algorithm provides a simple but accurate detection of the clinical points of interest of the arterial pulse wave, robust to noise and movement artifacts that could be used in the evaluation of the stiffness index and vascular reflection(AU)

Evaluación del estado nutricional y vascular en estudiantes y atletas de beisbol de alto rendimiento / Assessment of the nutritional and vascular state in students and high-performance baseball athletes

Introducción: La evaluación del estado vascular es uno de los pilares en la prevención de las enfermedades cardiovasculares en atletas de elite y en la población general. Los índices de reflexión y rigidez arterial de la onda de pulso constituyen elementos objetivos que favorecen su evaluación. Objetivo: Caracterizar desde los puntos de vista antropométrico-nutricional y vascular a deportistas de beisbol de alto rendimiento. Método: Se realizó un estudio analítico transversal, entre enero y marzo de 2016, en 28 sujetos: 14 atletas de beisbol de alto rendimiento, categoría juvenil (edad: χ̅=18,2±1,4), y 14 estudiantes de medicina (edad: χ̅=18,1±1,7). Se realizó una evaluación antropométrico-nutricional y se determinaron los índices de reflexión y rigidez arterial de las ondas del pulso mediante el polígrafo PowerLab® (ADInstruments) del Laboratorio de Ciencias Básicas Biomédicas de la Universidad de Ciencias Médicas de Santiago de Cuba. Resultados: Se encontraron incrementos significativos en la talla (p=0,001), el peso (p<0,001), el índice de masa corporal (p=0,003) y en las presiones arteriales de los deportistas con respecto a los estudiantes. A pesar de no existir diferencias significativas entre los valores del índice de reflexión (p=0,085), se observó un incremento de los valores del de rigidez arterial (p=0,02) en los estudiantes (χ̅=6,1) respecto a los deportistas (χ̅=5,6). Conclusiones: Existió un aumento la presión arterial y el estado nutricional en los atletas comparado con los estudiantes, que contrasta con la menor rigidez arterial en los atletas. Lo que sugiere que en este tipo de actividad de alto rendimiento operan mecanismos fisiológicos protectores contra las enfermedades cardiovasculares(AU)