Physiology of the abnormal response of heart failure patients to exercise.

Chronic heart failure is associated with reduced exercise capacity. Altered diastolic function and reduced chronotropic response play an important role. However, there is no clear correlation between any hemodynamic parameter and exercise capacity. Peripheral factors, long overlooked, seem to play a major role. Altered peripheral vasodilatation, involving endothelial abnormalities, alters the optimal distribution of blood flow. Muscular abnormalities are constant: aside from muscle atrophy, altered muscle metabolism results in an altered utilization of oxygen. A comprehensive understanding of all these determinants of exercise response is important to optimize the care of the patient. Sole improvement of cardiac function may be insufficient to correct their exercise intolerance; regular training may well have beneficial effects on exercise capacity, functional impairment, and quality of life.