Abnormalities of skeletal muscle metabolism in patients with chronic heart failure: evidence that they are present at rest.

Abstract

Objective-To investigate abnormalities of skeletal muscle metabolism in patients with congestive heart failure. Setting-A university teaching hospital. Methods-43 patients (22 New York Heart Association (NYHA) grade II, 21 grade III) and 10 controls were studied. A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction (MVC) was measured using handgrip dynamometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of MVC or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg, and 21 kg. Results-MVC (kg, mean (SEM)) was lower in patients than in controls (control 42-45 (2.3); NYHA II 34413 (1.3), P = 0 003; NYHA Ill 33-13 (1-94), P = 0.008). Resting lactate (mmol/1) was higher in patients than controls (control 0 65 (0.06); NYHA II 0-84 (0.08), P = 0-13; NYHA Ill 1'18 (0.1), P = 0.002). Resting ammonia (umol/l) was higher in NYHA III (65.7 (6.0)) than in NYHA II (48.0 (3.7), P = 0-016); no difference was found between controls (48.0 (7.1)) and patients. The overall lactate and ammonia response to exercise was greater in NYHA HI than in NYHA II and controls (P < 0.05). At Conclusions-Skeletal muscle metabolism is abnormal at rest in congestive heart failure. During exercise, the degree of metabolic abnormality is related to the symptomatic status of the patient.

The role of exercise training in chronic heart failure

“…Structural and functional changes observed in skeletal muscle are considered major factors that reduce strength, limit endurance exercise capacity, and lead to the early onset of fatigue 28. Among the morphological changes observed are a reduction in muscle mass, a shift in muscle fibre type with predominantly oxidative potential (types I and IIA) to fibres with anaerobic capacity (type IIB), and a reduction in mitochondrial size and number 29…”

The effect of dietary creatine supplementation on skeletal muscle metabolism in congestive heart failure

“…However, relatively small increases in skeletal muscle metabolites at rest and on exercise in chronic heart failure are associated with important changes in symptomatic status [18] . It is possible that a small improvement in abnormalities of skeletal muscle metabolism may result in substantial symptomatic improvement.…”

“…It is possible that a small improvement in abnormalities of skeletal muscle metabolism may result in substantial symptomatic improvement. There is an increasing body of evidence suggesting a pivotal role for abnormalities of skeletal muscle metabolism in the pathogenesis of symptoms in chronic heart failure and any intervention which can favourably affect these mechanisms is potentially important [7,18,24] . However, it is arguable if the majority of patients with chronic heart failure in their customary activity ever exercise to a truly maximal level where creatine supplementation is most likely to be effective [25] .…”

“…One study has suggested that creatine supplementation in chronic heart failure produces an increase in skeletal muscle total creatine and phosphocreatine with an improvement in skeletal muscle performance [17] . We have previously shown resting and exercising abnormalities of skeletal muscle metabolism and their relationship to symptoms in chronic heart failure using a forearm model of muscle metabolism [18] . The purpose of this study was to investigate the effects of dietary creatine supplementation on the metabolic response of the forearm to exercise in patients with chronic heart failure.…”

Exercício resistido na avaliação da disfunção endotelial na insuficiência cardíaca

“…The physiopathological basis of this fact consists in the presence of histological and metabolic modifi cations in the skeletal muscle fi bers 5,6 , as well as alterations in the capacity of the vessels to distribute fl ow to muscles.…”