Speed and Grade Increment During Cardiopulmonary Treadmill Testing: Impact on Exercise Prescription

Maximal oxygen uptake (VO2max) and both first (VT1) and second (VT2) thresholds have been used as reference points for exercise prescription in different populations. Objective: We aimed to test the hypothesis that exercise prescription, based on VTs determined by treadmill cardiopulmonary exercise testing (CPET), is influenced by the rate of increase in treadmill workload. Methods: Nine healthy individuals underwent two CPETs, followed by two sessions of submaximal exercise, both in randomized order. For the "speed" protocol, there was an increment of 0.1 to 0.3 km.h-1 every 15s. The "grade" incremental protocol increased 1% every 30s and 0.1 km.h-1 every 45s. This was followed by submaximal exercise sessions lasting 40min at an intensity corresponding to heart rate (HR) between the VT1 and VT2. Results: The "speed" protocol resulted in higher VT1 (p = 0.01) and VT2 (p = 0.02) when compared to the "grade" incremental protocol, but there was no effect on VO2max. The target HR for the submaximal exercise sessions was higher in the "speed" protocol compared to the "grade" incremental protocol (p < 0.01) and remained stable during the two steady-state exercise sessions. Blood lactate remained stable during the submaximal exercise sessions, with higher values observed during the "speed" protocol than those "grade" incremental protocol (p < 0.01). Conclusions: Compared to a grade-based protocol, a speed-based protocol resulted in higher VT1 and VT2, which significantly affected cardiorespiratory and metabolic responses to prescribed exercise intensity in healthy young adults

Syntax Score and Major Adverse Cardiac Events in Patients with Suspected Coronary Artery Disease: Results from a Cohort Study in a University-Affiliated Hospital in Southern Brazil / Syntax Escore e Eventos Cardíacos Adversos Maiores em Pacientes com Suspeita de Doença Arterial Coronariana: Resultados de um Estudo de Coorte em Hospital Universitário no Sul do Brasil

Abstract Background: The importance of coronary anatomy in predicting cardiovascular events is well known. The use of traditional anatomical scores in routine angiography, however, has not been incorporated to clinical practice. SYNTAX score (SXscore) is a scoring system that estimates the anatomical extent of coronary artery disease (CAD). Its ability to predict outcomes based on a baseline diagnostic angiography has not been tested to date. Objective: To evaluate the performance of the SXscore in predicting major adverse cardiac events (MACE) in patients referred for diagnostic angiography. Methods: Prospective cohort of 895 patients with suspected CAD referred for elective diagnostic coronary angiography from 2008 to 2011, at a university-affiliated hospital in Brazil. They had their SXscores calculated and were stratified in three categories: no significant CAD (n = 495), SXscoreLOW-INTERMEDIATE: < 23 (n = 346), and SXscoreHIGH: ≥ 23 (n = 54). Primary outcome was a composite of cardiac death, myocardial infarction, and late revascularization. Secondary endpoints were the components of MACE and death from any cause. Results: On average, patients were followed up for 1.8 ± 1.4 years. The primary outcome occurred in 2.2%, 15.3%, and 20.4% in groups with no significant CAD, SXscoreLOW-INTERMEDIATE, and SXscoreHIGH, respectively (p < 0.001). All-cause death was significantly higher in the SXscoreHIGH compared with the 'no significant CAD' group, 16.7% and 3.8% (p < 0.001), respectively. After adjustment for confounding factors, all outcomes remained associated with the SXscore. Conclusions: SXscore independently predicts MACE in patients submitted to diagnostic coronary angiography. Its routine use in this setting could identify patients with worse prognosis.

Resumo Fundamento: A importância da anatomia coronariana na predição de eventos cardiovasculares é bem conhecida. O uso de escores anatômicos tradicionais na cineangiocoronariografia de rotina, entretanto, não foi incorporado à prática clínica. O SYNTAX escore (SXescore) é um sistema de escore que estima a extensão anatômica da doença arterial coronariana (DAC). Sua capacidade para predizer desfechos com base na cineangiocoronariografia diagnóstica de base ainda não foi testada. Objetivo: Avaliar o desempenho do SXescore para predizer eventos cardíacos adversos maiores (MACE) em pacientes encaminhados para cineangiocoronariografia diagnóstica. Métodos: Coorte prospectiva de 895 pacientes com suspeita de DAC encaminhados para cineangiocoronariografia diagnóstica eletiva de 2008 a 2011, em hospital universitário no Brasil. Os pacientes tiveram seus SXescores calculados e foram estratificados em três categorias: 'sem DAC significativa' (n = 495); SXescoreBAIXO-INTERMEDIÁRIO: < 23 (n = 346); e SXescoreALTO: ≥ 23 (n = 54). O desfecho primário foi composto de morte cardíaca, infarto do miocárdio e revascularização tardia. Os desfechos secundários foram MACE e morte por todas as causas. Resultados: Em média, os pacientes foram acompanhados por 1,8 ± 1,4 anos. Desfecho primário ocorreu em 2,2%, 15,3% e 20,4% nos grupos 'sem DAC significativa', SXescoreBAIXO-INTERMEDIÁRIO e SXescoreALTO, respectivamente (p < 0,001). Morte por todas as causas foi significativamente mais frequente no grupo de SXescoreALTO comparado ao grupo 'sem DAC significativa', 16,7% e 3,8% (p < 0,001), respectivamente. Após ajuste para fatores de confusão, todos os desfechos permaneceram associados com o SXescore. Conclusão: O SXescore prediz independentemente MACE em pacientes submetidos a cineangiocoronariografia diagnóstica. Seu uso rotineiro nesse contexto poderia identificar pacientes de pior prognóstico.

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. .

The contribution of inspiratory muscles function to exercise limitation in heart failure: pathophysiological mechanisms / Contribuição da musculatura inspiratória na limitação ao exercício na insuficiência cardíaca: mecanismos fisiopatológicos

BACKGROUND: Heart failure induces histological, metabolic and functional adaptations in the inspiratory muscles. This inspiratory muscle weakness, which occurs in 30% to 50% of the heart failure patients, is associated with reduction in the functional capacity, reduction in the quality of life and with a poor prognosis in these individuals. OBJECTIVES: The objective of this review was to discuss the pathophysiological mechanisms that may explain the role of the inspiratory muscles in the exercise limitation with focus in the reflexes that control the ventilation and the circulation during the exercise. METHOD: We performed searches in the PUBMED database using the terms "inspiratory muscles", "inspiratory muscle training", "metaboreflex" and chemoreflex" and including studies published since 1980. RESULTS: Inspiratory muscle weakness is associated with exercise intolerance and with an exaggerated inspiratory chemoreflex and metaboreflex in heart failure. The inspiratory metaboreflex may be attenuated by the inspiratory muscle training or by the aerobic exercise training improving the exercise performance. CONCLUSIONS: Patients with heart failure may present changes in the inspiratory muscle function associated with inspiratory chemoreflex and metaboreflex hyperactivity, which exacerbate the exercise intolerance.

CONTEXTUALIZAÇÃO: A insuficiência cardíaca (IC) acarreta alterações histológicas, metabólicas e funcionais dos músculos inspiratórios. A fraqueza dos músculos inspiratórios, que ocorre em 30% a 50% dos pacientes com IC, associa-se com a redução da capacidade funcional, prejuízos para a qualidade de vida e piora no prognóstico desses indivíduos. OBJETIVOS: Discutir os mecanismos fisiopatológicos que potencialmente explicam o papel da musculatura inspiratória na limitação ao exercício, abordando-se os reflexos que controlam a ventilação e a circulação durante o exercício. MÉTODO: Foram realizadas pesquisas na base de dados PUBMED, utilizando os termos inspiratory muscles, inspiratory muscle training, metaborreflex e chemoreflex e incluindo estudos publicados desde 1980. RESULTADOS: A fraqueza muscular inspiratória está relacionada com intolerância ao exercício e com exacerbação do quimiorreflexo e do metaborreflexo inspiratório na IC. O metaborreflexo inspiratório pode ser atenuado pelo treinamento muscular inspiratório ou pelo treinamento aeróbico, melhorando o desempenho ao exercício. CONCLUSÕES: Os pacientes com IC podem apresentar alterações da função muscular inspiratória associadas com hiperatividade quimiorreflexa e metaborreflexa inspiratória, as quais podem agravar a intolerância ao exercício.

High dose of nifedipine in severe pulmonary hypertension associated with systemic lupus erythematosus

Relatam-se dois casos de pacientes com lúpus eritematoso sistêmico que apresentavam hipertensão pulmonar grave e refratária. Após estudos hemodinâmicos, ambos os pacientes foram tratados com nifedipina em doses altas e apresentaram melhora funcional marcante, apesar de os estudos hemodinâmicos após administração aguda da droga terem demonstrado apenas melhora moderada. A hipertensão pulmonar no lúpus eritematoso sistêmico é uma doença heterogênea e a relação entre a resposta hemodinâmica a curto prazo e a melhora funcional a longo prazo não é bem compreendida

Hipertensäo arterial na infância e na adolescência: fatores determinates / High blood pressure in children and adolescents: Determinant factors

Objetivo: Revisar a prevalência mundial de hipertensäo arterial na infância e na adolescência e discutir a importância de sua prevençäo através do controle de seus fatores determinantes. Métodos: Onze fatores, possivelmente envolvidos, säo analisados através de revisäo criteriosa da literatura, levando em consideraçäo, em cada estudo, seu delineamento e sua validade interna e externa. Resultados e conclusöes: Disposiçäo central de gordura parece comportar-se como verdadeiro fator de risco, enquanto freqüência cardíaca elevada e níveis iniciais de pressäo arterial nos percentis mais elevados podem ser úteis como marcadores de futura hipertensäo. Os demais fatores estudados ainda carecem de validaçäo que comprove sua associaçäo com pressäo arterial nessa faixa etária: estado sócio-econômico, maturaçäo biológica, raça, ingestäo de sal e fatores genético-ambientais