Alterations of skeletal muscle metabolism in humans studied by phosphorus 31 magnetic resonance spectroscopy in congestive heart failure.

Muscle metabolism of the finger flexor muscle of the dominant arm was examined in patients with congestive heart failure and age-related controls. Phosphocreatine utilization and decrease in pH during exercise was significantly greater in patients than in controls. Recovery rates were slow in some of these patients. Measurements of forearm blood flow at rest or during exercise were not significantly reduced in patients compared with controls. The inorganic phosphate peak was split during exercise in some of the patients, suggesting the presence of more glycolytic fibers in their muscles. These observations suggest that metabolic abnormalities may be present in the skeletal muscles of patients with heart failure that are not due to reduced nutritive blood flow. This may, in part, explain the lack of correlation between measurements of cardiac function and exercise tolerance in these patients.