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

This study sought to determine the relationship between myocardial dysfunct ion and peripheral haemodynamic disorders to exercise intolerance in patien ts with chronic heart failure (CHF). Seventeen patients with mild to modera te 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 exe rcise testing and forearm venous occlusion plethysmography at rest and duri ng maximal dilatation in reactive hyperaemia. There was a shift from centra l to peripheral haemodynamic factors limiting exercise, suggesting an incre asing importance of peripheral factors in parallel to the progression of CH F. In mild to moderate CHF peak VO2 was closely related to central haemodyn amics (r=0.57 for cardiac index at rest; r=0.76 for cardiac index at maxima l workload; r=-0.54 for right arterial pressure at maximal workload; all p< 0.05) and poorly correlated with peripheral haemodynamics (blood flow, vasc ular resistance and venous tone). In contrast, in severe CHF peak VO2 was c losely 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 eve r greater importance in the determining of exercise capacity. (C) 1999 Else vier Science Ireland Ltd. All rights reserved.