Cardio-respiratory responses of the 6-minute walk test in patients with refractory heart failure during the preoperative period for heart transplant surgery.

BACKGROUND: The six-minute walk test (6MWT) has been used to assess functional capacity, clinical status and prognosis. There are a very few descriptions in the literature on the safety and metabolic impact of the test, especially in patients with severe heart failure, awaiting cardiac transplantation. OBJECTIVE: The aim of the present study was to assess the cardiovascular responses and correlate the performance on the 6MWT with clinical status. METHOD: From 15 initial candidates, twelve patients (10 males) aged 52 +/- 8 years were submitted to a comprehensive clinical evaluation. The patients performed the 6MWT with electrocardiographic and perceived exertion monitoring in addition to determination of blood lactate concentration. Patients were followed up for 12 months. RESULTS: The patients walked 399.4 +/- 122.5 meters, reaching a perceived exertion (PE) of 14.3 +/- 1.5 and an increase of 34% in resting heart rate. Two patients exhibited a greater severity of arrhythmia prior to the 6MWT, which did not increase during exertion. Four patients exhibited a significant increase in blood lactate levels (>5 mmol/dL) and three interrupted the test prematurely. The distance walked (D) revealed a correlation with the ejection fraction (%) and functional classification (NYHA). After 12 months of follow up, three patients died and seven were re-hospitalized due to heart failure decompensation. CONCLUSION: Clinical and electrocardiographic behavior suggests that the 6MWT is safe, but may be considered of high intensity for some patients with severe heart failure. Variables related to the performance on the 6MWT may be associated to worsening clinical status in this population.

Short-duration transcutaneous electrical nerve stimulation in the postoperative period of cardiac surgery.

BACKGROUND: Respiratory muscle strength has been related to the postoperative outcome of cardiac surgeries. The main documented therapeutic purpose of transcutaneous electrical nerve stimulation (TENS) is the reduction of pain, which could bring secondary benefits to the respiratory muscles and, consequently, to lung capacities and volumes. OBJECTIVES: The objective of the present study was to evaluate the effectiveness of short-duration transcutaneous electrical nerve stimulation (TENS) in the reduction of pain and its possible influence on respiratory muscle strength and lung capacity and volumes of patients in the postoperative period of cardiac surgery. METHODS: Twenty five patients with mean age of 59.9 +/- 10.3 years, of whom 72% were men, and homogeneous as regards weight and height, were randomly assigned to two groups. One group received therapeutic TENS (n = 13) and the other, placebo TENS (n = 12), for four hours on the third postoperative day of cardiac surgery. Pain was analyzed by means of a visual analogue scale, and of respiratory muscle strength as measured by maximum respiratory pressures and lung capacity and volumes before and after application of TENS. RESULTS: Short-duration TENS significantly reduced pain of patients in the postoperative period (p < 0.001). Respiratory muscle strength (p < 0.001), tidal volume (p < 0.001) and vital capacity (p < 0.05) significantly improved after therapeutic TENS, unlike in the placebo group. CONCLUSION: Short-duration TENS proved effective for the reduction of pain and improvement of respiratory muscle strength, as well as of lung volumes and capacity.

Analysis of 6-minute walk test safety in pre-heart transplantation patients.

BACKGROUND: The 6-minute walk test (6WT) has been used as a means of assessment of the functional capacity, clinical staging and cardiovascular prognosis. Its safety and metabolic impact have not been frequently described in the literature, especially in patients with severe heart failure with clinical indication for cardiovascular transplantation. OBJECTIVE: To evaluate the occurrence of arrhythmias and cardiovascular changes during 6WT. To correlate 6WT performance with clinical staging and cardiovascular prognosis. METHODS: Twelve patients, 10 of whom males, aged 52 +/- 8 years were evaluated at baseline. 6WT was performed with telemetry electrocardiography, vital signs and lactate monitoring. The patients were followed-up for 12 months. RESULTS: The patients walked 399.4+/-122.5 (D, m), reaching a perceived exertion (PE) of 14.3+/-1.5 and a 34% baseline heart rate variation. Two patients presented more severe pre-6WT arrhythmia which did not worsen with the exercise, four patients presented a significant increase of blood lactate levels (>5 mmol/dl), and three interrupted the test. The distance walked correlated with the ejection fraction (%) and functional class (NYHA). After 12-month follow-up, three patients died and seven were rehospitalized for cardiac decompensation. The D/PE ratio and 2-minute heart rate recovery (HRR2, bpm) were lower in the death group. CONCLUSION: The clinical and electrocardiographic behaviors suggest that the method is safe, but it may be considered too strenuous for some patients with severe heart failure. Variables related to 6WT performance may be associated with the one-year follow-up mortality.

Short-term transcutaneous electrical nerve stimulation after cardiac surgery: effect on pain, pulmonary function and electrical muscle activity.

This study aimed to evaluate the effectiveness of transcutaneous electrical nerve stimulation (TENS) for treatment of postoperative pain in patients who underwent cardiac surgery. In addition, we sought to determine whether TENS would be related to improved pulmonary function and muscle electrical activity in this patient population. Forty-five patients, 32 males and 13 females, aged 41-74 years were randomly allocated to receive TENS (n=23) or sham treatment (n=22) during 4 h on the third postoperative day. A 0-10 visual analogic scale was used to assess pain; lung function was evaluated by spirometry and surface electromyography (n=10 in each group) was used to quantify electrically-induced muscle activity (trapezius and pectoralis major). TENS was associated with significant reductions on spontaneous and cough-induced postoperative pain as compared to sham (P<0.05). There was also improvement in chest wall-pulmonary mechanics after TENS with proportional increases in tidal volume and vital capacity (P<0.05). In addition, electrical activity of both muscle groups was enhanced after TENS, but not post sham (P<0.05). TENS is a valuable strategy to alleviate postoperative pain following cardiac surgery with positive effects on pulmonary ventilatory function and electrical activity of thoracic and girdle muscles.

Estimulação elétrica nervosa transcutânea de curta duração no pós-operatório de cirurgia cardíaca / Short-duration transcutaneous electrical nerve stimulation in the postoperative period of cardiac surgery

FUNDAMENTO: A força muscular respiratória tem sido relacionada com a evolução no pós-operatório de cirurgia cardíaca. A estimulação elétrica nervosa transcutânea (TENS) tem como principal finalidade terapêutica documentada a redução da dor; beneficio esse que poderia produzir benefícios secundários na força muscular respiratória e, consequentemente, nos volumes e capacidades pulmonares. OBJETIVOS: O presente trabalho procurou avaliar a efetividade da estimulação elétrica nervosa transcutânea (TENS) de curta duração para redução da dor e possíveis interferências e na força muscular respiratória, volumes e capacidade pulmonar em pacientes no pós-operatório de cirurgia cardíaca. MÉTODOS: Vinte e cinco pacientes com idade média de 59,9±10,3 anos, sendo 72 por cento homens, homogêneos quanto a peso e altura, foram aleatoriamente alocados em dois grupos. Um grupo recebeu a TENS tratamento (n=13) e outro, a TENS placebo (n=12), por período de quatro horas, no terceiro dia do pós-operatório de cirurgia cardíaca, avaliando a dor a partir da escala visual analógica, força muscular respiratória pelas pressões respiratórias máximas, volumes e capacidade pulmonar antes e após a aplicação da TENS. RESULTADOS: A TENS de curta duração reduziu a dor de pacientes no período pós-operatório de forma significativa (p<0,001). A força muscular respiratória (p<0,001), o volume corrente (p<0,001) e a capacidade vital (p<0,05) após a TENS tratamento demonstraram melhora significativa, alterações que não ocorreram no grupo placebo. CONCLUSÃO: A TENS de curta duração mostrou-se efetiva para redução da dor, melhora da força muscular respiratória, volumes e capacidade pulmonar.

BACKGROUND: Respiratory muscle strength has been related to the postoperative outcome of cardiac surgeries. The main documented therapeutic purpose of transcutaneous electrical nerve stimulation (TENS) is the reduction of pain, which could bring secondary benefits to the respiratory muscles and, consequently, to lung capacities and volumes. OBJECTIVES: The objective of the present study was to evaluate the effectiveness of short-duration transcutaneous electrical nerve stimulation (TENS) in the reduction of pain and its possible influence on respiratory muscle strength and lung capacity and volumes of patients in the postoperative period of cardiac surgery. METHODS: Twenty five patients with mean age of 59.9 ± 10.3 years, of whom 72 percent were men, and homogeneous as regards weight and height, were randomly assigned to two groups. One group received therapeutic TENS (n = 13) and the other, placebo TENS (n = 12), for four hours on the third postoperative day of cardiac surgery. Pain was analyzed by means of a visual analogue scale, and of respiratory muscle strength as measured by maximum respiratory pressures and lung capacity and volumes before and after application of TENS. RESULTS: Short-duration TENS significantly reduced pain of patients in the postoperative period (p < 0.001). Respiratory muscle strength (p < 0.001), tidal volume (p < 0.001) and vital capacity (p < 0.05) significantly improved after therapeutic TENS, unlike in the placebo group. CONCLUSION: Short-duration TENS proved effective for the reduction of pain and improvement of respiratory muscle strength, as well as of lung volumes and capacity. (Arq Bras Cardiol 2010; 94(3):325-331)

Avaliação da segurança do teste de caminhada dos 6 minutos em pacientes no pré-transplante cardíaco / Evaluación de la seguridad de la test de marcha de 6 minutos en pacientes en el pre-transplante cardiaco / Analysis of 6-minute walk test safety in pre-heart transplantation patients

FUNDAMENTO: O teste de caminhada dos 6 minutos (TC6) tem sido utilizado como forma de avaliação da capacidade funcional, estadiamento clínico e prognóstico cardiovascular. A segurança e o impacto metabólico são pouco descritos na literatura, principalmente em pacientes com insuficiência cardíaca grave, com indicação clínica para transplante cardiovascular. OBJETIVO: Avaliar a ocorrência de arritmias e alterações cardiovasculares durante o TC6. Correlacionar o desempenho no TC6 com o estadiamento clínico e prognóstico cardiovascular. MÉTODOS: Doze pacientes, sendo 10 masculinos, com idade de 52 ± 8 anos, foram submetidos à avaliação inicial. Realizaram o TC6 com monitoramento eletrocardiográfico por telemetria, sinais vitais e lactato. Foram acompanhados por 12 meses. RESULTADOS: Os pacientes percorreram 399,4 ± 122,5 (D, m), atingindo um esforço percebido (EP) de 14,3 ± 1,5 e variação de 34 por cento na freqüência cardíaca basal. Dois pacientes apresentaram arritmia de maior gravidade pré-TC6 e não pioraram ante o esforço, quatro tiveram elevação significativa nos níveis de lactato sangüíneo (>5 mmol/dl), e três interromperam o exame. A distância percorrida evidenciou correlação com a fração de ejeção ( por cento) e classificação funcional (NYHA). Após 12 meses de seguimento, três pacientes foram a óbito, e reinternaram-se sete por descompensação cardíaca. A relação (D/EP) e freqüência cardíaca de recuperação no segundo minuto (FCR2, bpm) foram inferiores no grupo-óbito. CONCLUSÃO: O comportamento clínico e eletrocardiográfico sugere que o método é seguro, mas pode ser considerado de alta intensidade para alguns pacientes com insuficiência cardíaca grave. Variáveis relacionadas ao desempenho no TC6 podem estar associadas com a mortalidade no seguimento de um ano.

BACKGROUND: The 6-minute walk test (6WT) has been used as a means of assessment of the functional capacity, clinical staging and cardiovascular prognosis. Its safety and metabolic impact have not been frequently described in the literature, especially in patients with severe heart failure with clinical indication for cardiovascular transplantation. OBJECTIVE: To evaluate the occurrence of arrhythmias and cardiovascular changes during 6WT. To correlate 6WT performance with clinical staging and cardiovascular prognosis. METHODS: Twelve patients, 10 of whom males, aged 52 ± 8 years were evaluated at baseline. 6WT was performed with telemetry electrocardiography, vital signs and lactate monitoring. The patients were followed-up for 12 months. RESULTS: The patients walked 399.4±122.5 (D, m), reaching a perceived exertion (PE) of 14.3±1.5 and a 34 percent baseline heart rate variation. Two patients presented more severe pre-6WT arrhythmia which did not worsen with the exercice, four patients presented a significant increase of blood lactate levels (>5 mmol/dl), and three interrupted the test. The distance walked correlated with the ejection fraction ( percent) and functional class (NYHA). After 12-month follow-up, three patients died and seven were rehospitalized for cardiac decompensation. The D/PE ratio and 2-minute heart rate recovery (HRR2, bpm) were lower in the death group. CONCLUSION: The clinical and electrocardiographic behaviors suggest that the method is safe, but it may be considered too strenuous for some patients with severe heart failure. Variables related to 6WT performance may be associated with the one-year follow-up mortality.

FUNDAMENTO: El test de marcha de 6 minutos (TM6m) ha sido utilizado como forma de evaluación de la capacidad funcional, del estadiamiento clínico y el pronóstico cardiovascular. La seguridad y el impacto metabólico son poco descritos en la literatura, principalmente en pacientes con insuficiencia cardiaca severa e indicación clínica para transplante cardiovascular Objetivo: Evaluar la ocurrencia de arritmias y alteraciones cardiovasculares durante el TM6m. Correlacionar el desempeño en el TM6m con el estadiamiento clínico y el pronóstico cardiovascular. MÉTODOS: Un total de 12 pacientes, 10 varones, con edad de 52 ± 8 años, fueron sometidos a evaluación inicial. Realizaron el TM6m con monitoreo electrocardiográfico por telemetría, señales vitales y lactato. Se siguieron a los individuos por 12 meses. RESULTADOS: Los pacientes recorrieron 399,4 ± 122,5 (D, m), alcanzando un esfuerzo percibido (EP) de 14,3 ± 1,5 y variación del 34 por ciento en la frecuencia cardiaca basal. Dos pacientes presentaron arritmia de mayor severidad pre-TM6m y no mostraron empeoramiento ante el esfuerzo; cuatro tuvieron elevación significativa en los niveles de lactato sanguíneo (>5 mmol/dl), y tres interrumpieron el examen. La distancia recorrida evidenció correlación con la fracción de eyección ( por ciento) y la clasificación funcional (NYHA). Tras 12 meses de seguimiento, tres pacientes murieron, y siete se reinternaron por descompensación cardiaca. La relación (D/EP) y frecuencia cardiaca de recuperación en el segundo minuto (FCR2, lpm) fueron inferiores en el grupo óbito. CONCLUSIÓN: El comportamiento clínico y electrocardiográfico sugiere que el método es seguro, pero se puede considerarlo de alta intensidad para algunos pacientes con insuficiencia cardiaca severa. Variables relacionadas al desempeño en el TM6m pueden estar asociadas con la mortalidad en el seguimiento de un año.