Skeletal muscle function at low work level as a model for daily activities in patients with chronic heart failure.
OBJECTIVE
Metabolic exercise abnormalities have been reported in chronic heart failure patients. This study sought to evaluate whether these abnormalities affected daily activity.


RESULTS
In 16 patients with moderate-to-severe chronic heart failure and in eight controls we measured femoral flow (thermodilution) and metabolism (glucose, lactate, free fatty acids, blood gas values) at rest and during a constant load of 20 W, which may mimic a daily activity. At rest, chronic heart failure patients had a leg flow similar to controls, but showed a higher leg oxygen consumption (4.6 +/- 0.6 vs 2.6 +/- 0.4 ml.min-1; P < 0.05), a higher arteriovenous oxygen difference (7.2 +/- 0.5 vs 5.4 +/- 0.7 ml.dl-1; P < 0.05), and a lower femoral vein pH (7.37 +/- 5.03 vs 7.42 +/- 0.01; P = 0.01). At 20 W, chronic heart failure patients had a leg flow similar to controls, but showed increased lactate release (from resting 11.7 +/- 33 to 142 +/- 125 micrograms.min-1 P < 0.0001 vs controls, from resting 5.7 +/- 15.4 to 50 +/- 149 micrograms.min-1 ns), higher arterial concentration of free fatty acids (781 +/- 69 vs 481 +/- 85 mumol.l-1; P < 0.01), lower femoral vein HCO3 (24.1 +/- 2.6 vs 26.3 +/- 1.7 mmol.l-1; P < 0.05) and base excess (-2.3 +/- 2.3 vs -0.24 +/- 1.7 mmol.l-1; P = 0.01).


CONCLUSIONS
In chronic heart failure patients, the important cellular metabolic alterations already present at rest partially affect daily activities, owing to a further decrease in the efficiency of muscle metabolic processes, and may preclude tolerance of heavier activities. Such alterations appear, at least in part, independent of peripheral haemodynamic responses to exercise.
Opasich
C
C
Fondazione S. Maugeri, Institute of Care and Research, Montescano (PV), Italy.
Pasini
E
E
Aquilani
R
R
Cobelli
F
F
Solfrini
R
R
Ferrari
R
R
Tavazzi
L
L
D000203:Activities of Daily Living; D001783:Blood Flow Velocity; D001784:Blood Gas Analysis; D002908:Chronic Disease; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005268:Femoral Vein; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D007866:Leg / Q000098:blood supply / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D013318:Stroke Volume; D013815:Thermodilution
D005230:Fatty Acids, Nonesterified; D019344:Lactic Acid