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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.

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