Central and peripheral components of chronic heart failure: determinants of exercise tolerance.

This study sought to determine the relationship between myocardial dysfunction and peripheral haemodynamic disorders to exercise intolerance in patients with chronic heart failure (CHF). Seventeen patients with mild to moderate CHF (peak oxygen consumption (VO2) >16 ml/min/kg) and 13 with severe CHF (peak VO2 <16 ml/min/kg) underwent invasive (Swan-Ganz) cardiopulmonary exercise testing and forearm venous occlusion plethysmography at rest and during maximal dilatation in reactive hyperaemia. There was a shift from central to peripheral haemodynamic factors limiting exercise, suggesting an increasing importance of peripheral factors in parallel to the progression of CHF. In mild to moderate CHF peak VO2 was closely related to central haemodynamics (r = 0.57 for cardiac index at rest; r = 0.76 for cardiac index at maximal workload; r = -0.54 for right arterial pressure at maximal workload; all p<0.05) and poorly correlated with peripheral haemodynamics (blood flow, vascular resistance and venous tone). In contrast, in severe CHF peak VO2 was closely related to peripheral haemodynamic factors (r = 0.79 for forearm blood flow; r = -0.82 for vascular resistance; r = -0.77 for venous tone; all p<0.05) and less to central ones. Thus, exercise tolerance of patients with mild to moderate CHF is predominantly determined by central haemodynamic factors, notably by the cardiac index. In severe CHF peripheral factors assume ever greater importance in the determining of exercise capacity.