Muscle blood flow in heart failure : interaction between central and local factors

A intolerância ao exercício é uma característica marcante da insuficiência cardíaca. Diversos mecanismos, como anormalidades no metabolismo muscular, no consumo de oxigênio do músculo e principalmente no fluxo sangüíneo muscular, têm sido documentados em pacientes com insuficiência cardíaca. Contudo, a relação entre a tolerância ao exercício e perfusão muscular no exercício é ainda controversa neste estado. Diversos mecanismos têm sido propostos na participação da regulação da hiperemia relacionada ao exercício, incluindo os mecanismos neural, endotelial e a bomba muscular. O propósito desta revisão é apresentar as evidências experimentais e clínicas com relação ao controle da perfusão muscular no exercício na insuficiência cardíaca. Existe um consenso geral de que a insuficiência cardíaca crônica esteja associada à vasoconstrição periférica e à marcante elevação da atividade do sistema nervoso autônomo simpático. Evidências recentes sugerem, ainda, que a modulação inadequada da atividade vasoconstritora simpática, a disfunção endotelial e os mecanismos anormais de controle da bomba muscular podem ser responsáveis pela resposta vasodilatadora inadequada ao exercício nesses pacientes. Contudo, a interação entre os mecanismos de controle do fluxo sangüíneo muscular no exercício e, sobretudo, como esses mecanismos afetam a tolerância ao exercício na insuficiência cardíaca ainda precisam ser melhor investigados.Exercise intolerance is a hallmark of heart failure. Several mechanisms, such as abnormalities in muscle metabolism, muscle oxygen uptake and especially muscle blood flow have been documented in patients with heart failure. However, the relation between exercise tolerance and muscle perfusion during exercise is still controversial in this state. Several mechanisms have been proposed to be involved in the regulation of exercise hyperemia, including neural, endothelial and muscle pump mechanisms. The purpose of this review is to present experimental and clinical evidence regarding muscle perfusion control during exercise in heart failure. There is a general consensus that chronic heart failure is associated with peripheral vasoconstriction and marked elevation in sympathetic nervous system activity. Recent evidence also suggests that impaired modulation of sympathetic vasoconstriction, endothelial dysfunction and abnormal muscle pump mechanisms may be responsible for the blunted vasodilator responses to exercise in these patients. However, the interactions between muscle blood flow control mechanisms during exercise and especially how these factors affect exercise tolerance still need to be investigated in heart failure

Avaliação do melhor ambiente para o teste de caminhada de seis minutos

Introdução: o objetivo do teste de caminhada de seis minutos (TC6) é avaliar a capacidade cardiorrespiratória por meio de um teste de baixo custo e de fácil administração, sendo bem tolerado por diferentes populações, e que reflita a realização das atividades da vida diária. Entretanto, poucos estudos têm sido realizados para determinar a diferença entre a realização do TC6 em ambientes fechados e ao ar livre. Objetivo: o presente estudo teve como objetivo comparar a distância percorrida no TC6 realizado em ambientes fechado e ao ar livre e avaliar as seguintes variáveis fisiológicas: frequência cardíaca, pressão arterial e a sensação subjetiva de falta de ar, utilizando a escala de percepção de esforço de Borg.Materiais e métodos Um ensaio clínico randomizado prospectivo foi conduzido envolvendo oito mulheres saudáveis não praticantes de atividade física regular, com média de idade de 23,75 ± 1,67 anos. As participantes realizaram o TC6 nos dois ambientes com um intervalo de 30 minutos entre os testes. A ordem dos testes foi determinada aleatoriamente. Resultados: a distância média percorrida foi de 578 ± 50,07 m ao ar livre e 579,95 ± 45,35 m no ambiente fechado (p = 0,932). As variáveis fisiológicas médias foram 82,25 ± 11,02 bpm (fechado) versus 84,38 ± 9,42 bpm (ar livre) para a frequência cardíaca, 121,88 ± 10,28 mmHg (fechado) versus 118,75 ± 19,40 mmHg (ar livre) para a pressão arterial sistólica, 81,88 ± 9,74 mmHg (fechado) versus 80,50 ± 7,89 mmHg (ar livre) para a pressão arterial diastólica e uma pontuação média de 12 pontos na escala de esforço percebido em ambos os ambientes. Conclusão: os dados demonstraram que não há diferenças nas distâncias percorridas ou entre as variáveis fisiológicas dos participantes durante o TC6 nos ambientes fechado e ao ar livre.Introduction: the purpose of the six-minute walk test (6MWT) is to evaluate cardiopulmonary capacity using a low-cost test that is easy to administer, generally well tolerated by different populations and reflects one’s performance on activities of daily living. However, few studies have been conducted to determine the difference between performing the 6MWT indoors and outdoors. Objective: the aim of the present study was to compare the distance covered on the 6MWT performed indoors and outdoors and evaluate the following physiological variables: heart rate, blood pressure and the subjective sensation of shortness of breath, using the Borg perceived exertion scale.Materials and methods A prospective, randomized, clinical trial was conducted involving eight healthy females not engaged in regular physical activity, with mean age 23.75 ± 1.67 years. Each subject performed the 6MWT indoors and outdoors with a 30-minute interval between tests. The order of the tests was determined randomly.Results The mean distance traveled was 578 ± 50.07 m on the outdoor trial and 579.95 ± 45.35 m on the indoor trial (p = 0.932). The mean physiological variables were 82.25 ± 11.02 bpm (indoors) versus 84.38 ± 9.42 bpm (outdoors) for heart rate, 121.88 ± 10.28 mmHg (indoors)versus 118.75 ± 19.40 mmHg (outdoors) for systolic blood pressure, 81.88 ± 9.74 mmHg (indoors) versus 80.50 ± 7.89 mmHg (outdoors) for diastolic blood pressure and a mean score of 12 on the perceived exertion score in both environments. Conclusions: the present data demonstrate no differences in the distance walked on the 6MWT or the physiologic variables of participants between the indoor and outdoor trials

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals

BACKGROUND:Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution.OBJECTIVES:The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals.METHOD:Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion.RESULTS:At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs. IES, 6±3, p<0.01).CONCLUSION:Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FIPE-HCPA, Porto Alegre, BrazilUniversidade Federal de São Paulo (UNIFESP) Cardiovascular Surgery DepartmentHospital de Clinicas de Porto AlegreUniversidade de Brasilia Physical Therapy DepartmentUNIFESP, Cardiovascular Surgery DepartmentSciEL

Interferential electrical stimulation improves peripheral vasodilatation in healthy individuals

BACKGROUND: Interferential electrical stimulation (IES), which may be linked to greater penetration of deep tissue, may restore blood flow by sympathetic nervous modulation; however, studies have found no association between the frequency and duration of the application and blood flow. We hypothesized that 30 min of IES applied to the ganglion stellate region might improve blood flow redistribution.OBJECTIVES: The purpose of this study was to determine the effect of IES on metaboreflex activation in healthy individuals.METHOD: Interferential electrical stimulation or a placebo stimulus (same protocol without electrical output) was applied to the stellate ganglion region in eleven healthy subjects (age 25±1.3 years) prior to exercise. Mean blood pressure (MBP), heart rate (HR), calf blood flow (CBF) and calf vascular resistance (CVR) were measured throughout exercise protocols (submaximal static handgrip exercise) and with recovery periods with or without postexercise circulatory occlusion (PECO+ and PECO -, respectively). Muscle metaboreflex control of calf vascular resistance was estimated by subtracting the area under the curve when circulation was occluded from the area under the curve from the AUC without circulatory occlusion.RESULTS:At peak exercise, increases in mean blood pressure were attenuated by IES (p<0.05), and the effect persisted under both the PECO+ and PECO- treatments. IES promoted higher CBF and lower CVR during exercise and recovery. Likewise, IES induced a reduction in the estimated muscle metaboreflex control (placebo, 21±5 units vs.IES, 6±3, p<0.01).CONCLUSION: Acute application of IES prior to exercise attenuates the increase in blood pressure and vasoconstriction during exercise and metaboreflex activation in healthy subjects

Oxidative damage induced by cigarette smoke exposure in mice : impact on lung tissue and diaphragm muscle

Objetivo: Avaliar o dano oxidativo (oxidação lipídica, oxidação proteica, thiobarbituric acid-reactive substances [TBARS, substâncias reativas ao ácido tiobarbitúrico], e carbonilação) e inflamação (expressão de phosphorylated AMP-activated protein kinase e de phosphorylated mammalian target of rapamycin (p-AMPK e p-mTOR, respectivamente) em tecido pulmonar e músculos do diafragma em camundongos C57BL/6 machos expostos à fumaça de cigarro (FC) por 7, 15, 30, 45 ou 60 dias. Métodos: Trinta e seis camundongos machos da espécie C57BL/6 foram divididos em seis grupos (n = 6/grupo): grupo controle e 5 grupos expostos a FC por 7, 15, 30, 45 e 60 dias, respectivamente. Resultados: Comparados aos camundongos controle, os camundongos expostos à FC apresentaram menor peso corporal em 30 dias. Nos camundongos expostos à FC (comparados aos controle) as maiores diferenças (aumentos) nos níveis de TBARS foram observados no dia 7 no músculo diafragma, comparado ao dia 45 em tecido pulmonar; as maiores diferenças (aumentos) nos níveis de carbonilas foram observados no dia 7 em ambos os tipos de tecido; e os níveis de sulfidrilas foram menores, nos dois tipos de tecidos, em todos os tempos. No tecido pulmonar e no músculo diafragma, a expressão de p-AMPK exibiu um comportamento semelhante ao dos níveis de TBARS. A expressão de p-mTOR foi maior que o valor controle nos dias 7 e 15 no tecido pulmonar, assim como no dia 45 no músculo diafragma. Conclusões: Nossos dados demonstram que a exposição à FC produz dano oxidativo tanto no tecido pulmonar quanto (primariamente) no tecido muscular, tendo um efeito adicional no músculo respiratório, como é frequentemente observado em fumantes com DPOC.Objective: To evaluate oxidative damage (lipid oxidation, protein oxidation, thiobarbituric acid-reactive substances [TBARS], and carbonylation) and inflammation (expression of phosphorylated AMP-activated protein kinase and mammalian target of rapamycin [p-AMPK and p-mTOR, respectively]) in the lung parenchyma and diaphragm muscles of male C57BL-6 mice exposed to cigarette smoke (CS) for 7, 15, 30, 45, or 60 days. Methods: Thirty-six male C57BL-6 mice were divided into six groups (n = 6/group): a control group; and five groups exposed to CS for 7, 15, 30, 45, and 60 days, respectively. Results: Compared with control mice, CS-exposed mice presented lower body weights at 30 days. In CS-exposed mice (compared with control mice), the greatest differences (increases) in TBARS levels were observed on day 7 in diaphragm-muscle, compared with day 45 in lung tissue; the greatest differences (increases) in carbonyl levels were observed on day 7 in both tissue types; and sulfhydryl levels were lower, in both tissue types, at all time points. In lung tissue and diaphragm muscle, p-AMPK expression exhibited behavior similar to that of TBARS. Expression of p-mTOR was higher than the control value on days 7 and 15 in lung tissue, as it was on day 45 in diaphragm muscle. Conclusion: Our data demonstrate that CS exposure produces oxidative damage, not only in lung tissue but also (primarily) in muscle tissue, having an additional effect on respiratory muscle, as is frequently observed in smokers with COPD

Effects of transcutaneous electrical nerve stimulation (TENS) on arterial stiffness and blood pressure in resistant hypertensive individuals: study protocol for a randomized controlled trial

Background: Resistant hypertension (RH) treatment requires an adequate and intense therapeutic approach. However, the results are not always satisfactory despite intensive treatment. Of the different pathophysiological mechanisms involved in the pathogenesis of RH, sympathetic overstimulation and therapies that block the sympathetic system have been widely studied. These approaches, however, are invasive and expensive. Another possible approach is by transcutaneous electrical nerve stimulation (TENS), a noninvasive method that modulates activity by using low-frequency transcutaneous electrical stimulation to inhibit primary afferent pathways. Thus, the current study will evaluate the effect of applying TENS in the cervicothoracic region of subjects with RH and will seek to develop a new low-cost and readily available therapy to treat this group of hypertensive individuals. Methods/design: This is a randomized, single blind (subject), parallel-assignment study controlled with a sham group and including participants aged 40 to 70 years with resistant hypertension. The trial has two arms: the treatment and control (sham group). The treatment group will be submitted to the stimulation procedure (TENS). The sham group will not be submitted to stimulation. The primary outcomes will be a reduction in the peripheral blood pressure and adverse events. The secondary outcomes will be a reduction the central blood pressure. The study will last 30 days. The sample size was calculated assuming an alpha error of 5 % to reject the null hypothesis with a statistical power of 80 %, thereby resulting in 28 participants per group (intervention versus sham). Discussion: In recent decades, RH has become very common and costly. Adequate control requires several drugs, and in many cases, treatment is not successful. Sympathetic nervous system inhibition by renal denervation and central inhibition have significant effects in reducing BP; however, these treatments are costly and invasive. Another type of sympathetic nervous system inhibition can also be noninvasively achieved by electric current. Therefore, the application of TENS may be a new therapeutic option for treating resistant hypertensive individuals. Trial Registration: Clinical Trials NCT0236597

Pocket Rehab - mHealth-based rehabilitation program for patients with cardiovascular disease as a prevention and treatment strategy for COVID-19 victims : an international multicentric collaborative study

Pacientes com doença cardiovascular e fatores de risco para doença cardiovascular (DCV) têm sido afetados com mais frequência e mais gravemente pelo novo coronavírus. Isso agravou o cenário anterior de subutilização dos programas de reabilitação cardiovascular (RCV) antes da pandemia, exigindo alternativas otimizadas de RCV, como por exemplo aquelas baseadas em aplicativos móveis (mHeath), não apenas por gerar benefícios bem estabelecidos, mas agora também para manter esses pacientes clinicamente estáveis, diminuindo a chance de eventos cardiovasculares e risco de contaminação naqueles não infectados pelo vírus, bem como tratando dos sobreviventes da COVID-19, tendo em vista as disfunções adicionais que tem sido descritas nos sistemas respiratório, cardiovascular e muscular. Serão realizados dois estudos: o estudo 1, qualitativo, de concordância e reprodutibilidade. Criação aplicativo baseado em tecnologia móvel (mHealth), para dar suporte a um programa otimizado (capaz de avaliar após COVID-19) de reabilitação cardiovascular (RCV) em ambiente domiciliar, desenvolvido pela Universidade do Luxemburgo (Centro 4), integrando instrumentos reconhecidos internacionalmente, como o EXPERT Tool, Hasselt University (Centro 3) e PACERProject, University of Miami (Centro 2). O aplicativo será testado e avaliado por profissionais de saúde nos dois centros colaboradores do estudo (Centro 2 e Centro 3) e na instituição executora - Universidade de Brasília (Centro 1)

Ativação dos músculos inspiratórios durante e após exercício : efeito metabólico e na redistribuição do fluxo sangüíneo

Introdução: Em indivíduos saudáveis, a ativação dos músculos inspiratórios pode reduzir fluxo sangüíneo periférico mediado pela ação do metaboreflexo muscular inspiratório. Objetivos: Testar a hipótese de que ativação dos músculos inspiratórios durante a recuperação do exercício máximo contribuiria para clearance, além de conduzir redução dos níveis de lactato em indivíduos saudáveis. Avaliar o efeito da ativação dos músculos inspiratórios sobre a resposta do fluxo sangüíneo nos membros em repouso e em exercício em pacientes com insuficiência cardíaca e fraqueza muscular inspiratória (IC) comparado com indivíduos saudáveis e se o treinamento muscular inspiratório é capaz de atenuar esta resposta. Métodos: Doze indivíduos saudáveis realizaram dois testes cardiopulmonares máximos seguidos de 20 min de recuperação com e sem carga inspiratória para avaliação dos níveis de lactato. Em 18 pacientes com IC e 10 individuos saudáveis, a fadiga dos músculos inspiratórios foi induzida pela adição de carga inspiratória de 60% da pressão inspiratória máxima, enquanto que o fluxo de sangue da panturrilha em repouso (FSP) e antebraço em exercício (FSA) foram medidos através de pletismografia. Para os pacientes com IC, foram realizadas também medidas após 4 semanas de treinamento muscular inspiratório. Resultados: A ativação dos músculos inspiratórios reduziu o nível de lactato de recuperação em comparação à situação sem resistência inspiratória. Com fadiga muscular inspiratória, os pacientes com IC apresentaram maior redução do FSP (55 ± 12 % vs. 14 ± 5%, p < 0,01) e atenuação do aumento do FSA em exercício (6,9 ± 2,0 vs. 11,2 ± 1,1 ml/min.100ml; p = 0.01) quando comparado aos indivíduos saudáveis. Após 4 semanas de treinamento muscularinspiratório, os pacientes com IC melhoraram o FSP (1,19 ± 0,3 vs. 2,0 ± 1,0 ml/min.100ml; p = 0.01) e FSA em exercício (6,9 ± 2,0 vs. 9,8 ± 2,8 ml/min.100ml; p = 0.01) com fadiga do músculo inspiratório. Conclusões: Esses dados são consistentes com a noção de que os músculos inspiratórios podem ser consumidores de lactato durante a recuperação do exercício e que a fadiga dos músculos inspiratórios resulta em redução do fluxo de sangue para membros em repouso e em exercício. Em pacientes com IC, o treinamento muscular inspiratório melhora a redistribuição do fluxo de sangüíneo.Background: In healthy subjects, inspiratory muscle activation may reduce peripheral blood flow, a response know as the inspiratory muscle-mediated metaboreflex. Objectives: We tested the hypothesis that inspiratory muscle activation during recovery of intense exercise would contribute to lactate clearance. We also evaluated the effect of inspiratory muscle activation on blood flow response to the resting and exercising limbs in patients with chronic heart failure and inspiratory muscle weakness (CHF) compared with healthy subjects and whether inspiratory muscle training attenuates this effect. Methods: Twelve healthy men underwent 2 maximal incremental exercise tests followed of the 20 min recovery period with and without inspiratory resistance for the evaluation of blood lactate levels. In 18 patients with CHF and 10 healthy volunteers, inspiratory muscle fatigue was induced by the addition of inspiratory load of 60% of maximal inspiratory pressure, while blood flow to the resting calf (CBF) and exercising forearm (FBF) were measured by venous occlusion plethysmography. For the patients with CHF, measurements were also made after a 4-week program of inspiratory muscle training. Results: Inspiratory muscle activation reduced lactate levels during recovery of intense exercise. With inspiratory muscle fatigue, CHF patients presented a more marked reduction in resting CBF (mean ± SD 55 ± 12 vs. 14 ± 5 %, P < 0.01%) and showed an attenuated rise in FBF (6.9 ± 2.0 vs 11.2 ± 1.1 ml/min.100ml; P = 0.01) when compared to controls. After 4 weeks of inspiratory muscle training, CHF patients improved resting CBF (1.19 ± 0.3 vs 2.0 ± 1.0 ml/min.100ml; P =0.01) and exercise FBF (6.9 ± 2.0 vs 9.8 ± 2.8 ml/min.100ml; P = 0.01) with inspiratory muscle fatigue. Conclusions: These data are consistent with the notion that inspiratory muscles may be net consumers of lactate during recovery from intense exercise. In patients with CHF, the induction of inspiratory muscle fatigue results in marked reduction of blood flow to resting and exercising limbs. Inspiratory muscle training improves blood flow redistribution in these patients