Effect of intensive therapy for heart failure on the vasodilator response to exercise

OBJECTIVES The purpose of the study was to evaluate the lower extremity Vas cular responsiveness to metabolic stimuli in patients with heart failure an d to determine whether these responses improve acutely after intensive medi cal therapy. BACKGROUND Metabolic regulation of vascular tone is an important determinan t of blood flow, and may be abnormal in heart failure. METHODS The leg blood flow responses were measured in II patients with none dematous class III-IV heart failure before and after inpatient medical ther apy and in 10 normal subjects. Venous occlusion plethysmography was used to measure peak blood flow and total hyperemia in the calf after arterial occ lusion and also after isotonic ankle exercise. Measurements were repeated f ollowing short-term inpatient treatment with vasodilators and diuretics adm inistered to decrease right atrial pressure (18 +/- 2 to 7 +/- I mm Hg), pu lmonary wedge pressure (32 +/-3 to 15 +/- 2 mm Hg), and systemic Vascular r esistance (1581 +/- 200 to 938 +/- 63 dynes s cm(-5), all p < 0.02). RESULTS Leg blood flow at rest, after exercise, and during reactive hyperem ia was less in heart failure patients than in control subjects. Resting leg blood flow did not increase significantly after medical therapy, but peak flow after the high level of exercise increased by 59% (p = 0.009). Total h yperemic volume in the recovery period increased by 73% (p = 0.03). Similar ly the peak leg blood flow response to ischemia increased by 88% (p = 0.04) , whereas hyperemic volume rose by 98% (p = 0.1). CONCLUSIONS The calf blood flow responses to metabolic stimuli are blunted in patients with severe heart failure, and improve rapidly with intensive m edical therapy. (C) 1999 by the American College of Cardiology.