Riesgo cardiovascular en mujeres sanas

RESUMEN Introducción: Las enfermedades cardiovasculares son un problema de salud y una de las principales causas de muerte a nivel mundial. Presentan alta morbilidad y mortalidad en mujeres de entre 40 y 59 años, período que coincide con la menopausia natural. Objetivo: Caracterizar el riesgo cardiovascular en pacientes femeninas sanas. Métodos: Se realizó un estudio descriptivo, en 96 mujeres sanas. Fueron estudiadas variables epidemiológicas, clínicas, la valoración nutricional, circunferencia abdominal, estudios de laboratorio (triacilglicéridos, glucemia y colesterol total) y se realizó estratificación del riesgo cardiovascular. Se realizó un análisis de frecuencias y se empleó el test de ji cuadrado de Pearson para las comparaciones. Resultados: El grupo más representativo fue de 20 a 29 años de edad, los factores de riesgo con mayor incidencia fueron, la circunferencia abdominal por encima de 88 cm, IMC superior a 25 kg/m2, colesterol elevado e hipertrigliceridemia con asociación estadísticamente significativa (p< 0,000), predominaron las mujeres sin factores de riesgo en menores de 40 años, el bajo riesgo cardiovascular en todas las edades; el moderado y alto fue más significativo entre 40 y 49, y entre 50 y 59 años de edad (p< 0,000). Conclusiones: Predomina el bajo riesgo cardiovascular en mujeres menores de 40 años sin asociación de factores de riesgo; en las mayores de 40 predomina el moderado, con asociaciones entre factores de riesgo. El aumento del IMC, el colesterol elevado, la hipertrigliceridemia y la circunferencia abdominal mayor de 88 cm, fueron los factores de riesgo más importantes y estuvieron relacionados con la edad. Palabras clave: factores de riesgo; enfermedad cardiovascular; fisiología cardiovascular; identidad de género. ABSTRACT Introduction: Cardiovascular diseases are a health problem and one of the main causes of death worldwide. They present high morbidity and mortality in women between the ages of 40 and 59, a period that coincides with natural menopause. Objective: To characterize cardiovascular risk in healthy female patients. Methods: A descriptive study was carried out in 96 healthy women. Epidemiological and clinical variables, nutritional assessment, abdominal circumference, laboratory studies (triacylglycerides, glycemia and total cholesterol) were studied, and cardiovascular risk stratification was performed. A frequency analysis was performed and Pearson's chi-square test was used for comparisons. Results: The most representative group was 20 to 29 years old, the risk factors with the highest incidence were abdominal circumference above 88 cm, body mass index above 25 kg/m2, high cholesterol and hypertriglyceridemia with association statistically significant (p< 0.000), women without risk factors prevailed in those under 40 years of age, low cardiovascular risk in all ages; moderate and high was more significant between 40 and 49, and between 50 and 59 years of age (p< 0.000). Conclusions: Low cardiovascular risk predominates in women under 40 years of age without association of risk factors; in those over 40 the moderate predominates, with associations between risk factors. Increased BMI, high cholesterol, hypertriglyceridemia, and abdominal circumference greater than 88 cm were the most important risk factors and were related to age.

Cardiovascular physiology and autonomic heart control principles: the use of a station rotation strategy to recall basic cardiovascular knowledge among exercise science students

Abstract Aim: Cardiovascular physiology learned by exercise science students is often quickly forgotten. We tested whether a state rotation model would help students to recall key principles of Cardiovascular Physiology (CV). Methods: Seventy-one undergraduate students enrolled in the Exercise Physiology Course at the School of Physical Education and Sport, University of São Paulo, participated in the study. The students were randomly assigned into one of 4 stations, dedicated to recalling the concepts of the heart as a pump (e.g. preload, post-load, and contractility; station 1) and hemodynamics (e.g. serial and parallel conductance; station 2) by using the educational tool. Heart rate (HR) control by sympathetic nervous system activation (station 3) and HR control by vagal activation (station 4) were assessed by quantifying HR response to the Stroop color and word test and during face immersion in cold water, respectively. To evaluate the efficacy of the intervention, we used a Socrative app to launch eight multiple-choice questions before (PRE) and after (POST) the student's station rotation. The questions were related to the basic principles of exercise physiology and its consequences on the cardiovascular system. Results: The 4-station average score (% of corrected answers) achieved after the station rotation was higher than the score achieved before (71.21%, SD 14.50 vs. 31.07%, SD 18.04; for POST and PRE, respectively p < 0.005). Considering specific stations, the lowest score of corrected answers before the rotation was observed at station 2- hemodynamics when compared with station 1-heart as a pump and station 3/4 - autonomic control (18.9%, SD 0.9 vs. 46.5, SD 24.1 and 34.8, SD 2.1 for hemodynamics, heart as a pump and autonomic control, respectively). Interestingly, after the rotation, there was a significant increase in corrected scores for all stations (33.9, SD 9.8; 80.5, SD 4.6 and 90.2, SD 2.3, for hemodynamics, heart as a pump, and autonomic control, respectively). Conclusion: Our results suggest that the use of the educational tool was effective to recall CV principles that are essential to a better understanding of the CV responses to exercise and applying the concepts in exercise testing and prescription for different populations.

Suitability of the muscle O2 resaturation parameters most used for assessing reactive hyperemia: a near-infrared spectroscopy study / Adequação de parâmetros de ressaturação muscular de O2 mais utilizados na avaliação da hiperemia reativa: um estudo por espectroscopia no infravermelho próximo

Abstract Background There is a spectrum of possibilities for analyzing muscle O2 resaturation parameters for measurement of reactive hyperemia in microvasculature. However, there is no consensus with respect to the responsiveness of these O2 resaturation parameters for assessing reactive hyperemia. Objectives This study investigates the responsiveness of the most utilized muscle O2 resaturation parameters to assess reactive hyperemia in the microvasculature of a clinical group known to exhibit impairments of tissue O2 saturation (StO2). Methods Twenty-three healthy young adults, twenty-nine healthy older adults, and thirty-five older adults at risk of cardiovascular disease (CVD) were recruited. Near-infrared spectroscopy (NIRS) was used to assess StO2 after a 5-min arterial occlusion challenge and the following parameters were analyzed: StO2slope_10s, StO2slope_30s, and StO2slope_until_baseline (upslope of StO2 over 10s and 30s and until StO2 reaches the baseline value); time to StO2baseline and time to StO2max (time taken for StO2 to reach baseline and peak values, respectively); ∆StO2reperfusion (the difference between minimum and maximum StO2 values); total area under the curve (StO2AUCt); and AUC above the baseline value (StO2AUC_above_base). Results Only StO2slope_10s was significantly slower in older adults at risk for CVD compared to healthy young individuals (p < 0.001) and to healthy older adults (p < 0.001). Conversely, time to StO2max was significantly longer in healthy young individuals than in older adult at CVD risk. Conclusions Our findings suggest that StO2slope_10s may be a measure of reactive hyperemia, which provides clinical insight into microvascular function assessment.

Resumo Contexto Existe um espectro de possibilidades na análise dos parâmetros de ressaturação de O2 muscular como uma medida de hiperemia reativa na microvasculatura. No entanto, não há consenso com relação à responsividade desses parâmetros de ressaturação de O2 para avaliação de hiperemia reativa. Objetivos Este estudo investigou a capacidade de resposta dos parâmetros de ressaturação muscular de O2 mais utilizados para avaliar a hiperemia reativa na microvasculatura de um grupo clínico conhecido por apresentar comprometimento da saturação de O2 (StO2). Métodos Foram recrutados 23 jovens saudáveis, 29 idosos saudáveis e 35 idosos com risco para doença cardiovascular. A espectroscopia no infravermelho próximo foi usada para avaliar a StO2 após um teste de oclusão arterial de 5 minutos, no qual os seguintes parâmetros foram analisados: StO2slope_10s, StO2slope_30s e StO2slope_until_baseline (inclinação da StO2 em 10 s, 30 s e até StO2 atingir valores basais); tempo para StO2baseline e tempo para StO2máx (o tempo necessário para StO2 atingir os valores da linha de base e o máximo, respectivamente); ∆StO2reperfusão (a diferença entre o valor de StO2mínimo e StO2máximo); área total sob a curva (StO2AUCt); e área sob a curva acima do valor da linha de base (StO2AUC_above_base). Resultados Apenas StO2slope_10s foi significativamente mais lento em idosos em risco de doença cardiovascular comparados com indivíduos jovens saudáveis (p < 0,001) e idosos saudáveis (p < 0,001). Por outro lado, o tempo para StO2max foi significativamente maior em indivíduos jovens saudáveis do que em idosos em risco de doença cardiovascular. Conclusões Nossos achados sugerem que StO2slope_10s pode ser uma medida de hiperemia reativa, que fornece informações clínicas sobre a avaliação da função microvascular.

Bradycardia in athletes: does the type of sport make any difference? - a systematic review / Bradicardia em atletas: a modalidade esportiva importa? - uma revisão sistemática / Bradicardia en atletas: ¿la modalidad deportiva importa? - una revisión sistemática

ABSTRACT Bradycardia in athletes can range from moderate to severe, and the factors that contribute to slow heart rate are complex. Studies investigating the mechanisms associated with this condition are controversial, and may be linked to the form of exercise practiced. A systematic literature review was conducted to discuss bradycardia mechanisms in athletes who practice different forms of sport. The databases consulted were Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus and PEDro. The search included English language articles published up to January 2019, that evaluated athletes who practiced different forms of sport. One hundred and ninety-three articles were found, ten of which met the inclusion criteria, with 1549 male and female athletes who practiced diverse forms of sport. Resting heart rate and cardiac structure were studied in association with the form of sport practiced, through heart rate variability, electrocardiogram, echocardiogram and pharmacological blockade. The studies suggest that a slow resting heart rate cannot be explained by increased vagal modulation alone, but also includes changes in cardiac structure. According to the studies, different sports seem to produce different cardiac responses, and the bradycardia found in athletes can be explained by non-autonomic and autonomic mechanisms, depending on the type of effort or the form of sport practiced. However, the mechanism underlying the slow heart rate in each form of sport is still unclear. Level of evidence II; Prognostic studies - Investigating the effect of a patient characteristic on the outcome of disease.

RESUMO A bradicardia em atletas pode variar de moderada a grave, e os fatores que contribuem para a redução da frequência cardíaca são complexos. Estudos que investigam os mecanismos associados à bradicardia são controversos e, possivelmente, ligados ao tipo de exercício. Realizou-se uma pesquisa bibliográfica sistemática para discutir os mecanismos de bradicardia em atletas de diferentes modalidades esportivas. As bases de dados consultadas foram Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus e PEDro. Foram incluídos artigos em inglês, que avaliaram atletas de diferentes modalidades esportivas, publicados até janeiro de 2019. Cento e noventa e três artigos foram encontrados e dez preencheram os critérios de inclusão, perfazendo 1.549 homens e mulheres atletas de diversas modalidades esportivas. A frequência cardíaca em repouso e a estrutura cardíaca foram estudadas em associação com a modalidade esportiva, por variabilidade da frequência cardíaca, eletrocardiograma, ecocardiograma e bloqueio farmacológico. Os estudos sugerem que a redução da frequência cardíaca em repouso não é explicada apenas pelo aumento da modulação vagal, mas também por alterações da estrutura cardíaca. De acordo com os estudos, diferentes esportes parecem produzir diferentes respostas cardíacas e a bradicardia encontrada em atletas pode ser explicada por mecanismos não autonômicos e autonômicos. Este achado parece depender do tipo de esforço ou modalidade esportiva praticada. No entanto, o mecanismo envolvido na redução da frequência cardíaca em cada modalidade esportiva ainda não está claro. Nível de evidência II; Estudos prognósticos - Investigação do efeito de característica de um paciente sobre o desfecho da doença.

RESUMEN La bradicardia en atletas puede variar de moderada a grave, y los factores que contribuyen para la reducción de la frecuencia cardíaca son complejos. Los estudios que investigan los mecanismos asociados a la bradicardia son controvertidos y, posiblemente, vinculados al tipo de ejercicio. Se realizó una investigación bibliográfica sistemática para discutir los mecanismos de bradicardia en atletas de diferentes modalidades deportivas. Las bases de datos consultadas fueron Pubmed (MEDLINE), Clinical Trials, Cochrane, Scopus, Web of Science, SciELO, Sport Discus y PEDro. Se incluyeron artículos en inglés, que evaluaron a atletas de diferentes modalidades deportivas, publicados hasta enero de 2019. Se encontraron ciento noventa y tres artículos y diez cumplieron con los criterios de inclusión, totalizando 1549 hombres y mujeres atletas de diversas modalidades deportivas. La frecuencia cardíaca en reposo y la estructura cardíaca fueron estudiadas en asociación con la modalidad deportiva, por variabilidad de la frecuencia cardíaca, electrocardiograma, ecocardiograma y bloqueo farmacológico. Los estudios sugieren que la reducción de la frecuencia cardíaca en reposo no es explicada sólo por el aumento de la modulación vagal, sino también por alteraciones de la estructura cardíaca. De acuerdo con los estudios, los diferentes deportes parecen producir diferentes respuestas cardíacas y la bradicardia encontrada en atletas puede explicarse por mecanismos no autonómicos y autonómicos. Este hallazgo parece depender del tipo de esfuerzo o modalidad deportiva practicada. Sin embargo, el mecanismo involucrado en la reducción de la frecuencia cardíaca en cada modalidad deportiva aún no está claro. Nivel de evidencia II; Estudios pronósticos - investigación del efecto de característica de un paciente sobre el desenlace de la enfermedad.

Predictive maximal heart rate equations in child and adolescent athletes: a systematic review / Equações preditivas de frequência cardíaca máxima em crianças e adolescentes atletas: uma revisão sistemática / Ecuaciones predictivas de frecuencia cardíaca máxima en niños y adolescentes atletas: una revisión sistemática

Abstract Introduction: The maximal heart rate (HRmax) is considered the highest value of HR achieved during a physical effort close to exhaustion. Objective: To evaluate the applicability of the predictive HRmax equations during exercise tests in child and adolescent athletes through a systematic review. Methods: It is a systematic review, through Scopus, Pubmed, Lilacs, Scielo and PEDro. The included studies compared the measured and estimated HRmax predictive equations during exercise tests in child and adolescent athletes. The following search strategy was used: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise capacity OR Heart rate OR Heart rate OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Results: From a total of 1,664 articles, only 4 were included. All compared the measured HRmax values with those estimated by the "220 - age" equation; 3 used the formula "208 - (0.7 x age)", and only 1 used the "223 - (1.44 x age)" equation. Although all of them stated that the "220 - age" equation overestimates HRmax, the formula "208 - (0.7 x age") underestimated (2 articles) and overestimated (1 study) the measured results, while the equation "213 - (1.44 x age) was also not adequate. Conclusion: The use of predictive HRmax equations for child and adolescent athletes does not seem to be recommended. The use of cohort points for these estimates is carefully recommended.

Resumo Introdução: A frequência cardíaca máxima (FCmáx) é denominada o maior valor de FC alcançada durante um esforço físico intenso. Objetivo: Avaliar a aplicabilidade das equações preditivas de FCmáx durante testes de exercício em crianças e adolescentes atletas. Métodos: Trata-se de uma revisão sistemática, através do Scopus, Pubmed, Lilacs, Scielo e PEDro. Foram incluídos estudos que compararam a FCmáx medida e a estimada por equações preditivas durante testes de exercício em crianças e adolescentes atletas. Utilizou-se a seguinte estratégia de busca: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise tolerance OR Exercise capacity AND Heart rate OR Heart rates OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Resultados: De um total de 1664 artigos, apenas 4 foram incluídos. Todos os estudos compararam os valores medidos de FCmáx com os estimados pela equação "220 - idade", 3 utilizaram a fórmula "208 - (0,7 x idade)" e apenas 1 a equação "223 - (1,44 x idade)". Embora todos demonstraram que a equação "220 - idade" superestima a FCmáx, a fórmula "208 - (0,7 x idade") subestimou (2 artigos) e superestimou (1 estudo) os resultados medidos, enquanto a equação "213 - (1,44 x idade) também não foi adequada. Conclusão: O uso de equações preditivas de FCmáx em crianças e adolescentes atletas não parece indicado. Recomenda-se cuidadosamente a utilização de pontos de coorte para essas estimativas.

Resumen Introducción: La frecuencia cardiaca máxima (FCmáx) se denomina el mayor valor de FC alcanzado durante un esfuerzo físico cercano al agotamiento. Objetivo: Evaluar la aplicabilidad de las ecuaciones predictivas de FCmáx durante las pruebas de ejercicio en niños y adolescentes atletas. Métodos: Se trata de una revisión sistemática, a través del Scopus, Pubmed, Lilacs, Scielo y PEDro. Se incluyeron estudios que compararon la FCmáx medida y la estimada por ecuaciones predictivas durante pruebas de ejercicio en niños y adolescentes atletas. Se utilizó la siguiente estrategia de búsqueda: "Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise tolerance OR Exercise capacity AND Heart rate OR Heart rates OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations". Resultados: De un total de 1664 artículos, sólo 4 fueron incluidos. Todos los estudios compararon los valores medidos de FCmáx con los estimados por la ecuación "220 - edad", 3 utilizaron la fórmula "208 - (0,7 x edad)" y sólo 1 la ecuación "223 - (1,44 x edad". Aunque todos demostraron que la ecuación "220 - edad" sobreestima la FCmáx, la fórmula "208 - (0,7 x edad") subestimó (2 artículos) y sobreestimó (1 estudio) los resultados medidos, mientras que la ecuación "213 - (1,44 x edad) tampoco fue adecuada. Conclusión: El uso de ecuaciones predictivas de FCmáx en niños y adolescentes atletas no parece indicado. Se recomienda cuidadosamente el uso de puntos de cohorte para estas estimaciones.

El electrocardiograma: una oportunidad de aprendizaje / The electrocardiogram: a learning opportunity

Resumen Actualmente, en la formación médica la enseñanza de la interpretación electrocardiográfica ha adquirido un papel secundario, y algunos médicos consideran que solo el especialista puede ser competente en esta área. Se muestra un abordaje sistemático para guiar a los estudiantes en la obtención, interpretación y aplicación de esta herramienta diagnóstica.

Abstract Currently, among the medical curricula, electrocardiogram interpretation has undergone a fallback, and some physicians consider that only the specialists can be competent in this area. A systematic approach is shown in order to aid students to obtain, interpret and execute a clinical application of this diagnostic test.

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

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

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

Non-linear indices of heart rate variability during endodontic treatment

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

Hemodynamic responses during and after multiple sets of stretching exercises performed with and without the Valsalva maneuver

OBJECTIVE: This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver. METHODS: Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise. RESULTS: The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product. CONCLUSIONS: Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises. .

Advances in the Mechanism of Action of Natriuretic Peptides at a Cellular Level.

Background: Natriuretic peptides have a vast array of different actions at numerous sites throughout the human body. There have been rapid advances in understanding their mechanism of action in recent years and this review aimed to collate all available information on this field in order to present the current evidence-base. Method: A two-step process utilising a Medline/PubMed systematic search was conducted. The initial search was undertaken using elementary phrases. The search produced over 4000 published papers on the topic of the mechanisms of action of natriuretic peptides. The resultant abstracts were analysed and appropriate papers were selected. The secondary search was performed by (1) using the reference lists of the chosen articles and (2) by using PubMed weblink for related articles. The studies were selected if they were in English language published in the past 30 years (1983-2013) and included the appropriate topics. All of the reports regarding the intracellular and pharmacological mechanisms of action of natriuretic peptides were selected. Conclusions: This review has collected all information on the recent advances in our understanding of the intracellular pathways that allow these peptides to bring about natriuresis, vasodilatation and their many other effects. Although offering significant pharmacological potential, this field remains poorly understood and there is a need for more research using newer research techniques.

Respostas agudas de pressão arterial e variabilidade da frequência cardíaca são dependentes do volume total do exercício aeróbio em adultos saudáveis / Acute blood pressure and heart rate variability responses in healthy adults are dependent on the total volume of aerobic exercise

A hipotensão pós-exercício (HPE) é um fenômeno de relevância clínica, mas dúvidas persistem no tocante ao efeito do modo e da forma de execução (contínua vs. acumulada) do exercício aeróbio para sua manifestação, bem como o papel do controle autonômico cardíaco como mecanismo fisiológico associado à HPE. Assim, a presente tese objetivou: a) investigar a HPE induzida por sessões aeróbias de exercício isocalórico contínuo e acumulado; b) comparar as respostas de pressão arterial sistólica (PAS) e diastólica (PAD) após teste cardiopulmonar de exercício máximo (TCPE) em três modalidades; c) verificar a influência do modo de exercício e do controle autonômico cardíaco em repouso sobre a reativação vagal após TCPE. No primeiro estudo, 10 homens saudáveis (idade: 27,6 ± 3,5 anos) realizaram TCPEs de corrida e ciclismo para medida do consumo de oxigênio de pico (VO2pico) e sessões contínuas (400 kcal) e acumuladas (2 x 200 kcal) de corrida e ciclismo à 75%VO2reserva. A PAS e PAD reduziram similarmente após exercício contínuo e acumulado (4,6 ± 2,3 vs. 5,2 ± 2,3 mmHg, 2,6 ± 2,5 vs. 3,6 ± 2,5 mmHg, respectivamente, P > 0,05). Porém, a corrida provocou maior declínio na PAS do que o ciclismo (P < 0.05). A atividade simpática (componente de baixa frequência, LF) e parassimpática (componente de alta frequência, HF) aumentou (P < 0,001) e diminuiu (P < 0,001) em relação à sessão controle, elevando o balanço simpato-vagal (razão LF:HF) (P < 0,001) que foi inversamente correlacionado ao ΔPAS e ΔPAD (r = -0,41 a -0,70; P < 0.05). No segundo e terceiro estudos, 20 homens saudáveis (idade: 21.2 ± 3.0 anos) realizaram três TCPEs (ciclismo, caminhada e corrida). No segundo estudo, investigou-se a resposta aguda da PA, débito cardíaco (Q), resistência vascular periférica (RVP), sensibilidade do barorreflexo arterial (SBR), variabilidade da frequência cardíaca (VFC) e dispêndio energético durante 60 min após os TCPEs e sessão controle...

Postexercise hypotension (PEH) is a phenomenon of clinical relevance, but doubts persist regarding the effect of the mode and manner of execution (continuous vs. cumulative) of aerobic exercise for its manifestation, as well as the role of cardiac autonomic control as physiological mechanisms associated with PEH. Thus, this thesis aimed to: a) investigate the PEH elicited by isocaloric bouts of continuous and accumulative aerobic exercise; b) to compare the acute responses of systolic (SBP) and diastolic blood pressure (DBP) after maximal cardiopulmonary exercise tests (CPET) performed using three exercise modalities; and c) to determine the influence of exercise mode and cardiac autonomic control at rest on the vagal reactivation after CPET. In the first study, ten healthy men (age: 27.6 ± 3.5 yrs) performed maximal CPETs to determine the peak oxygen uptake (VO2peak), and continuous (400 kcal) and accumulated (2 x 200 kcal) exercise bouts of running and cycling at 75% VO2reserve. The SBP and DBP decreased similarly after continuous and accumulated exercise (4.6 ± 2.3 vs. 5.2 ± 2.3 mmHg, 2.6 ± 2.5 vs. 3.6 ± 2.5 mmHg, respectively, P > 0.05). However, running elicited greater SBP reductions than cycling (P < 0.05). The sympathetic (low frequency component, LF) and parasympathetic (high frequency component, HF) activity increased (P < 0.001) and decreased (P < 0.001) from baseline, increasing the sympathovagal balance (LF:HF ratio) (P < 0.001) that was inversely related to ΔSBP and ΔDBP (r = -0.41 to -0.70; P < 0.05). In the second and third studies, 20 healthy men (age: 21.2 ± 3.0 yrs) performed three CPETs (cycling, walking and running). The second study investigated the acute response of BP, cardiac output (Q), peripheral vascular resistance (PVR), spontaneous baroreflex sensitivity (SBR), heart rate variability (HRV) and energy expenditure during 60 min after exercise and a control session...

Relação entre variabilidade da frequência cardíaca e aumento no desempenho físico em jogadores de futebol / The correlation between heart rate variability and improvement in soccer player's physical performance

O objetivo deste estudo foi analisar se a variabilidade da frequência cardíaca (VFC) analisada no período inicial da pré-temporada de futebol apresenta relação com a melhora do desempenho físico ao longo deste período. Dez jogadores de futebol fizeram parte da amostra. O desempenho foi analisado através dos seguintes testes: Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1), sprint de 30 m e salto vertical, aplicados antes e após seis semanas da pré-temporada. As medidas de VFC foram realizadas em repouso, na posição supina, durante dez minutos. O teste de Spearman foi usado para investigar as possíveis relações entre VFC e melhora no desempenho e o teste T de Student para verificar as mudanças no desempenho e na VFC. A inferência prática baseada em magnitudes (analise qualitativa) foi aplicada para verificar as chances dos valores encontrados serem positivos, irrelevantes e negativos. Houve melhora significante do desempenho para o Yo-Yo IR1 (P< 0,001) e Sprint de 30 m (P< 0,001). A análise qualitativa revelou que a mudança do desempenho no Yo-Yo IR1 foi "muito provavelmente positiva", para o Sprint de 30 m foi "quase certamente positiva" e para o salto vertical foi "inconclusiva". Houve forte correlação entre um índice parassimpático da VFC e a variação no desempenho [r = 0,85; P = 0,003 (IC95% =0,49 - 0,97)]. Em conclusão, esse estudo mostrou uma correlação forte entre índices parassimpáticos da VFC analisados antes do treinamento, com a melhora do desempenho no Yo-Yo IR1 durante a pré-temporada em atletas de futebol.

The aim of this study was to analyze whether the heart rate variability (HRV), assessed at the beginning of a soccer preseason, reveals a correlation with the improvement of physical performance over this training period. Ten soccer players took part in the study. Their performance was evaluated by the following tests: the Yo-Yo intermittent recovery test, Level 1(Yo-Yo IR1); the 30-m sprint time, and the vertical jump; all were conducted before and after six weeks of pre-season. The HRV measurements were performed at rest in the supine position for ten minutes. The Spearman Rank Correlation test was used to investigate any possible relationship between HRV and improvements in performance, while the Student's t-test verified the changes in both performance and HRV. The Magnitude-Based Inferences approach (qualitative analysis) was applied to verify the possibilities of the observed values being positive, negative or inconclusive. There were significant improvements in Yo-Yo IR1 performance (P< 0.001) and in the 30-m sprint time (P< 0.001). The qualitative analysis revealed that the differences in Yo-Yo IR1 performance were very likely positive, were almost certainly positive for the sprint, but were inconclusive for the vertical jump. There was a strong correlation between one parasympathetic index and the change in performance [r = 0.85 P = 0.003 (IC95% = 0.49 - 0.97)]. In conclusion, this study revealed a strong correlation between parasympathetic indices of HRV (analyzed before the training) with the performance improvement in Yo-Yo IR1 in football athletes during pre-season.

Respostas pressóricas pós-exercícios aeróbios executados em diferentes ergômetros / Blood pressure responses post aerobic exercises on different ergometers

Introdução. São poucos os achados no que tange à influência dos esforços aeróbios sobre os valores pressóricos no período pós-esforço.Objetivo. Verificar o efeito hipotensivo agudo após uma sessão de treino aeróbio, em diferentes ergômetros, com a mesma intensidade e a mesma duração. Método. Estudo transversal em indivíduos normotensos e praticantes regulares de exercícios físicos no mínimohavia seis meses. Cada avaliado realizou três visitas, não consecutivas, ao local de realização dos testes. Em uma das visitas, o sujeito executou o exercício em cicloergômetro, em outra, realizou o exercício em esteira rolante e, no terceiro dia, não foram realizadas atividades e serviu de controle para o estudo. A intensidade estipulada para a realização doexercício foi determinada em 60% e 70% da frequência cardíaca de reserva e a duração do esforço foi 30 minutos. Resultados. Participaram do estudo sete indivíduos (três homens e quatro mulheres) com 21,2 ± 2,5 anos de idade. Não foram encontradas respostas hipotensivas significativas em exercícios com cicloergômetro ou com esteirarolante entre si e sem atividade física. Conclusão. A ausência de resposta hipotensiva da atividade aeróbia na amostra estudada pode ser atribuída ao número pequeno de indivíduos avaliados e às características usadas na avaliação.

Introduction. The chronic effects of the aerobic exercises on the blood pressure is well known. However, there are few studies about the post-acute effects. Objective. The present study aimed to evaluate the acute hypotensive effect of one session of aerobic trainingon different ergometers with the same intensity and duration.Method. Cross-sectional study in men and women, all non-hypertensive and physically active for at least six months. Every subject visited the test site in three non-consecutive days. Following a random order, they exercised in the cycle ergometer and treadmill or stayed at rest (control group). The training ranged from 60% to 70% of heartrate reserve and lasted 30 minutes. Results. Three men and four women (21.2 ± 2.5 years old) participated in the study. The hypotensive responseswere not different in the groups. Conclusion. New studies are needed with a larger sample and different intensities, duration and ergometer.

Comportamiento de la presión pulmonar y función del ventrículo derecho intraesfuerzo / Pulmonary Artery Pressure and Right Ventricular Function during Exercise

Introducción El comportamiento fisiológico de la presión pulmonar durante el ejercicio continúa sin establecerse con precisión. La literatura es discordante con respecto a los valores considerados patológicos de presión pulmonar intraesfuerzo (PPI) en ausencia de valvulopatía mitral e incluso, las últimas guías no recomiendan utilizar la presión pulmonar media ≥ 30 mmHg con el esfuerzo para definir hipertensión pulmonar. Es escasa la información disponible en relación a la respuesta hemodinámica y funcional del ventrículo derecho (VD) con el esfuerzo y tampoco sobre el hecho de si podría discriminar entre una respuesta fisiológica o patológica de la presión pulmonar. Objetivo Determinar el comportamiento de la PPI y comparar los parámetros ecocardiográficos de función sistólica y diastólica del VD en relación a sus niveles. Material y Métodos Se incluyeron 94 pacientes sin cardiopatías significativas, con adecuada factibilidad para estimar presión pulmonar sistólica (PPS) basal y en máxima carga durate el eco-estrés en ejercicio. De acuerdo al valor de presión pulmonar con el ejercicio, la población fue estratificada en dos grupos: a) PI < 50 mmHg / Hg (56) y b) PI ≥ 50 mm. (38) Se compararon las variables de función sistólica (onda S del Doppler tisular) y diastólica (Doppler pulsado en tracto de entrada y Doppler tisular de pared lateral) del VD. Resultados El 40% de la población analizada alcanzó una PPI ≥ 50 mm/Hg y se relacionó con mayor edad, sexo femenino y valores elevados de PPS basal. Los parámetros de función diastólica del VD no demostraron diferencias significativas. El grupo conPPI ≥ 50 mmHg presentó un menor incremento de la onda S del Doppler tisular como expresión de una disminución de la respuesta compensadora contráctil del VD. Conclusiones Un porcentaje elevado de la población estudiada desarrolló una PPI ≥ 50 mmHg. En relación al VD, no se observaron diferencias significativas en las variables de función diastólica y el grupo con PPI ≥ 50 mmHg presentó una menor respuesta sistólica compensadora con las cargas, como expresión de disfunción sub-clínica.

Background The physiological behavior of pulmonary artery pressure during exercise has not been precisely established yet. There is lack of agreement in the published literature about the abnormal values of pulmonary artery pressure (PAP) during exercise in the absence of mitral valve disease. Indeed, the last guidelines do not recommend using mean pulmonary artery pressure value ≥ 30 mmHg during exercise to define pulmonary hypertension. There is scarce information about the hemodynamic and functional response of the right ventricle (RV) during exercise and if it is useful to discriminate between a physiological or abnormal response of the pulmonary artery pressure. Objectives To determine the behavior of PAP during exercise and to compare the echocardiographic parameters of systolic and diastolic RV function in relation to PAP levels. Material and Methods A total of 94 patients without significant heart disease were included. Systolic pulmonary artery pressure (SPAP) at rest and maximum exercise during dobutamine stress echocardiography was adequately measured in all patients. The population was divided into two groups according to the value of pulmonary artery pressure during exercise: a) PAP <50 mmHg (56) b) PAP ≥50 mmHg (38). We also compared the variables of RV systolic function (S-wave measured by tissue Doppler imaging) and diastolic function (using pulsed Doppler echocardiography in the inlet tract and tissue Doppler echocardiography in the lateral wall). Results During exercise, 40% of the analyzed population reached a PAP ≥50 mm mmHg This value was associated with greater age, female gender and elevated values of SPAP at rest. The parameters of RV diastolic function did not present significant differences. The group with PAP ≥ 50 mmHg during exercise presented a less increase in the S-wave measured by tissue Doppler imaging as an expression of a compensatory reduced RV contractile performance. Conclusions A high percentage of the population developed PAP ≥50 mmHg during exercise. The variables of RV diastolic function did not show significant differences and the group with PAP ≥50 mmHg during exercise presented compensatory reduced RV contractile performance as an expression of subclinical dysfunction.

Fisiología cardiovascular aplicada en caninos con insuficiencia cardiaca / Applied cardiovascular physiology in dogs with heart dailure

La insuficiencia cardiaca está relacionada con anormalidades de la contracción y relajación ventricular. Recientes publicaciones han mostrado que la mayoría de los pacientes con enfermedades cardiacas coexiste alteraciones de la función sistólica y diastólica. Actualmente, hay muchas ambigüedades en el uso de términos clínicos y fisiológicos usados cotidianamente con respecto a este tema. Este artículo pretende revisar algunos conceptos fisiológicos del sistema cardiovascular.

Congestive heart failure is related to abnormal ventricular contraction and relaxation. Recent publications show that the alteration of systolic and diastolic function coexists in most patients with heart diseases. There are currently several ambiguities in the daily use of clinical and physiological terms regarding this topic. This paper aims to review certain physiological concepts of the cardiovascular system.

Cardiovascular and autonomic responses after exercise sessions with different intensities and durations

BACKGROUND: Several studies have reported the phenomenon of post-exercise hypotension. However, the factors that cause this drop in blood pressure after a single exercise session are still unknown. OBJECTIVE: To investigate the effects of aerobic exercise on the acute blood pressure response and to investigate the indicators of autonomic activity after exercise. METHODS: Ten male subjects (aged 25 ± 1 years) underwent four experimental exercise sessions and a control session on a cycle ergometer. The blood pressure and heart rate variability of each subject were measured at rest and at 60 min after the end of the sessions. RESULTS: Post-exercise hypotension was not observed in any experimental sessions (P > 0.05). The index of parasympathetic neural activity, the RMSSD, only remained lower than that during the pre-exercise session after the high-intensity session (Δ = -19 ± 3.7 for 15-20 min post-exercise). In addition, this value varied significantly (P < 0.05) between the high- and low-intensity sessions (Δ = -30.7 ± 4.0 for the high intensity session, and Δ = -9.9 ± 2.5 for the low intensity session). CONCLUSION: The present study did not find a reduction in blood pressure after exercise in normotensive, physically active young adults. However, the measurements of the indicators of autonomic neural activity revealed that in exercise of greater intensity the parasympathetic recovery tends to be slower and that sympathetic withdrawal can apparently compensate for this delay in recovery.

Cardiovascular responses to passive static flexibility exercises are influenced by the stretched muscle mass and the Valsalva maneuver

BACKGROUND: The respiratory pattern is often modified or even blocked during flexibility exercises, but little is known about the cardiovascular response to concomitant stretching and the Valsalva maneuver (VM) in healthy subjects. OBJECTIVES: This study evaluated the heart rate (HR), systolic blood pressure (SBP), and rate-pressure product (RPP) during and after large and small muscle group flexibility exercises performed simultaneously with the VM. METHODS: Asymptomatic volunteers (N = 22) with the following characteristics were recruited: age, 22 ± 3 years; weight, 73 ± 6 kg; height, 175 ± 5 cm; HR at rest, 66 ± 9 BPM; and SBP at rest, 113 ± 10 mmHg. They performed two exercises: four sets of passive static stretching for 30 s of the dorsi-flexion (DF) of the gastrocnemius and the hip flexion (HF) of the ischio-tibialis. The exercises were performed with (V+) or without (V-) the VM in a counterbalanced order. The SBP and HR were measured, and the RPP was calculated before the exercise session, at the end of each set, and during a 30-min post-exercise recovery period. RESULTS: The within-group comparisons showed that only the SBP and RPP increased throughout the sets (p<0.05), but no post-exercise hypotension was detected. The between-group comparisons showed that greater SBP increases were related to the VM and to a larger stretched muscle mass. Differences for a given set were identified for the HR (the HFV+ and HFV- values were higher than the DFV+ and DFV- values by approximately 12 BPM), SBP (the HFV+ value was higher than the DFV+ and DFV- values by approximately 12 to 15 mmHg), and RPP (the HFV+ value was higher than the HFV- value by approximately 2000 mmHGxBPM, and the HFV+ value was higher than the DFV+ and DFV- values by approximately 4000 mmHGxBPM). CONCLUSION: Both the stretched muscle mass and the VM influence acute cardiovascular responses to multiple-set passive stretching exercise sessions.

A influência do exercício físico no perfil lipídico e na aptidão física em mulheres idosas / The influence of exercise in the lipidic profile and in the physical fitness in elderly women

Resumo Objetivo: Avaliar a influência do nível de atividade física no perfil lipídico, na glicose sanguínea, na composição corporal, na aptidão cardiovascular (VO2max), na aptidão muscular e na agilidade/equilíbrio em mulheres idosas. Métodos: Para verificar interferência do nível de atividade física nos níveis lipídicos, glicêmicos, de composição corporal e de aptidão física, foi utilizado o teste t de Student independente, precedido do teste de normalidade de Shapiro-Wilks. Foram avaliadas 23 mulheres com mais de 60 anos, divididas em um grupo ativo (GA) e grupo inativo (GI) segundo classificação do IPAQ. Resultados: Mulheres idosas do grupo ativo apresentaram valores significativamente superiores no teste de agilidade/equilíbrio e idade média superior ao do grupo inativo. Além disso, o grupo ativo apresentou valores superiores na massa de gordura, massa corporal magra e força de membros inferiores, mas não estatisticamente significativos. De forma inversa, o colesterol total, triglicérides e a glicose sanguínea mostraram-se inferiores no grupo ativo, mas também não estatisticamente significativos. As demais variáveis antropométricas, perfil qualitativo alimentar, e demais testes de aptidão física não mostraram diferenças entre os grupos. Conclusão: Conclui-se que a adoção e manutenção de um estilo de vida ativo, mesmo em idades avançadas, por meio da atividade física, têm efeitos benéficos na manutenção da independência de pessoas idosas.

Abstract Objective: To value the influence of the level of physical activity in the lipid profiles, the levels of glucose in the blood stream, the body composition, the muscular and cardiovascular fitness aptitudes (VO²max), and the agility/equilibrium in elderly women Methods: In order to verify the interference of the level of physical exercises on the levels of lipid and glucose, on body composition and on physical aptitude, the independent Student test was used, after the normality Shapiro-Wilks test. Twenty-three women over 60 years old were evaluated in two groups, an active group and an inactive one, according to a classification by IPAQ. Results: Active women presented significantly higher values in the agility/equilibrium tests and middle age superior to that of the inactive group. Besides, the active group presented superior fatness mass, slim body mass, strength in inferior members, which were not, however, statistically significant. In the reverse form, the total cholesterol, triglycerids and they showed the blood glucose inferior in the active group, but also not statistically significant. You were varying the rest antropométricas, qualitative food profile, and too many tests of physical aptitude did not show differences between the groups.Conclusions: The conclusion is that adopting and keeping up an active lifestyle by means of physical activities, even in advanced age, has benefic effects in prolonging the independence of the elderly.

Hipotensão pós-exercício aeróbio: uma revisão sistemática / Post-exercise hypotension: a systematic review

Diversos estudos investigaram os efeitos hipotensores após uma sessão de exercício aeróbio em humanos. No entanto, vários aspectos permanecem obscuros em relação à hipotensão pós-exercício (HPE), uma vez que diversas variáveis podem influenciar a resposta hipotensora, como intensidade, duração, tipo de exercício, estado clínico, faixa etária, etnia, sexo e estado de treinamento. Nesse sentido, o objetivo do presente estudo foi revisar sistematicamente a literatura, relacionando as principais variáveis da prescrição de uma sessão de exercício aeróbio e a HPE, assim como apresentar os possíveis mecanismos envolvidos. Foram encontrados 55 estudos que abrangeram a temática HPE e exercício aeróbio em humanos. A ocorrência da HPE está bem estabelecida na literatura, já que vários estudos identificaram reduções da pressão arterial em normotensos e hipertensos. Porém, os possíveis moduladores das respostas hipotensoras, como intensidade e duração da sessão de exercício, ainda são contraditórios. Em relação ao tipo de exercício, porém, existem indicativos de que os realizados de forma intermitente e que utilizam maior massa muscular podem acarretar maior HPE. Além disso, hipertensos devem apresentar maior magnitude e duração da HPE. Contudo, existem lacunas em relação aos diversos mecanismos fisiológicos envolvidos, que parecem ser diferentes entre normotensos e hipertensos.

Several studies have investigated the hypotensor effects after an aerobic exercise session in humans. However, many aspects remain unclear concerning post-exercise hypotension (PEH), once many variables can influence on the hypotensor response, such as intensity, duration, type of exercise, clinical status, age, ethnic group, sex and training level. Therefore, the aim of the present study was to systematically review the literature, relating the main prescription variables of an aerobic exercise session to PEH, as well as to present the possible mechanisms involved. Fifty-five studies which approached PEH and aerobic exercise in humans have been found. PEH occurrence is well-established in the literature, once many studies have identified reduction in blood pressure in normotensive and hypertensive individuals. Nevertheless, the possible modulators of the hypotensive responses, such as intensity and duration of the exercise session, are contradictory yet. Concerning the type of exercise, there are indications that intermittent exercise which uses greater muscular mass may lead to higher PEH. Additionally, hypertensive patients should present greater magnitude and PEH duration. However, there are some gaps regarding the several physiological mechanisms involved, which seem to be different between normotensive and hypertensive individuals.

Efeitos do pós-condicionamento isquêmico na função ventricular esquerda de corações isolados de ratos / Effects of ischemic postconditioning on left ventricular function of isolated rat hearts

OBJETIVO: Avaliar os efeitos do pós-condicionamento isquêmico na função ventricular esquerda de corações isolados de ratos. MÉTODOS: Corações isolados de 24 ratos Wistar foram submetidos a perfusão pelo método de Langendorff modificado e distribuídos em três grupos: Grupo I - controle (n=8); Grupo II - três ciclos de pós-condicionamento de 10/10s (n=8); Grupo III - três ciclos de pós-condicionamento de 30/30s (n=8). Após estabilização de 15min, os corações foram submetidos a 20min de isquemia e subseqüentes 20min de reperfusão. A freqüência cardíaca (FC), o fluxo coronariano (FCo), a pressão sistólica (PS), a contratilidade (+dP/dt max) e a velocidade de relaxamento (-dP/dt max) miocárdico foram medidas nos tempos 0 (pré-isquemia) e 5, 10, 15 e 20min de reperfusão. Utilizado método estatístico ANOVA com Teste de Tukey para diferenças entre grupos, com significância menor que 0,05 (P< 0,05). RESULTADOS: A FC, em bpm, reduziu em todos os grupos após 20min de reperfusão, sem diferença estatística (GI 232,5 + 36,8; GII 241,8 + 46,7; GIII 249,4 + 40,4; P>0,05). O mesmo ocorreu com a PS, em mmHg, (GI 132,6 + 49,3; GII 140,8 + 43,1; GIII 112,6 + 33,2; P>0,05), FCo, em ml/min, (GI 18,5 + 4,6; GII 21,4 + 4,4; GIII 22,1 + 9,0; P>0,05) e -dP/dt max, em mmHg/s, (GI 1490,6 + 512,0; GII 1770,4 + 406,6; GIII 1399,1 + 327,4, P>0,05). A +dP/dt max, em mmHg/s, reduziu significativamente exceto no Grupo II (GI 1409,0 + 415,2; GII 1917,3 + 403,1; GIII 1344,8 + 355,8), (GII vs. GI, P=0,04) e (GII vs. GIII, P=0,02). CONCLUSÃO: O pós-condicionamento isquêmico com três ciclos de 10/10s de reperfusão/isquemia foi capaz de preservar a contratilidade miocárdica em corações isolados de ratos após 20min de isquemia.

OBJECTIVE: To assess the effects of ischemic postconditioning on left ventricular function in isolated rat hearts. METHODS: Twenty-four Wistar rats were used. These hearts underwent perfusion by modified LANGERDORFF method and distributed into three groups: GI - control (n=8); GII - three cycles of postconditioning of 10/10s (n=8); GIII three cycles of postconditioning of 30/30s (n=8). After a 15min stabilization period, all hearts underwent 20min of global ischemia following 20min of reperfusion. In the times 0 (control), 5, 10, 15 and 20min of reperfusion, the heart rate (HR), the coronary flow (CoF), the systolic pressure, the (+dP/dt max) contractility and (-dP/dt max) velocity of relaxation were measured. Data were analyzed by ANOVA method followed by Tukey's test for differences between groups and P < 0.05 was considered significant. RESULTS: The HR (bpm) decreased in all groups after 20min of reperfusion without statistical differences among them (GI 232.5+36.8; GII 241.8+46.7; GIII 249.4+40.4;P>0.05). The same occurred with the systolic pressure (mmHg) (GI 132.6+49.3; GII 140.8+43.1; GIII 112.6+33.2; P>0.05), coronary blood flow (GI 18.5+4.6; GII 21.4+4.4; GIII 22.1+9.0; P>0.05) and -dP/dt max (mmHg) (GI 1490.6+512.0; GII 1770.4+406.6; GIII 1399.1+327.4; P>0.05). The +dP/dt max (mmHg) decreased significantly in all groups except in group II (GI 1409.0+415.2, GII 1917.3+403.1, GIII 1344.8+355.8) (GII vs GI, P= 0.04; GII vs GIII, P= 0.02). CONCLUSION: The ischemic postconditioning by three cycles of reperfusion/ischemia of 10/10s demonstrated to be effective for preservation of the myocardial contractility in isolated rat hearts which had undergone 20min of ischemia.