Origin of symptoms in chronic heart failure.

Skeletal muscle abnormalities are highly prevalent in chronic heart failure and are associated with an increase in the ergoreflex, a muscle reflex stimulated by work done. Stimulation of the ergoreflex results in increased ventilation and contributes to the increased sympathetic activation of the heart failure syndrome. The origin of the skeletal myopathy is related to a chronic imbalance between catabolic and anabolic processes, presumably as a consequence of chronic haemodynamic stress. Symptoms arise from the skeletal myopathy, causing the sensation of fatigue and contributing to the sensation of breathlessness as the myopathy affects respiratory muscle. Ergoreflex activation causes a greater ventilatory response to exercise than normal, contributing to the sensation of breathlessness.