Metabolic assessment of exercise in chronic heart failure patients treated with short-term vasodilators.

Abstract

Short-term vasodilators increase exercise cardiac output without an increase an exercise tolerance when administered to chronic heart failure patients. Cardiac output CO, O2 consumption [OC], and lactate metabolism during exercise in chronic heart failure. Patients (13) participated in 17 studies during control exercise (C) and during vasodilator exercise after short-term treatment with either hydralazine (H) or prazosin (P). CO increased during exercise both with hydralazine (C = 5.8 .+-. 2.31/min, H = 6.9 .+-. 2.31/min) and with prazosin (C = 5.9 .+-. 2.31/min, P = 7.6 .+-. 2.71/min). OC did not change during exercise either with hydralazine (C = 663 .+-. 249 ml/min, H - 651 .+-. 200 ml/min) or with prazosin (C = 696 .+-. 246 ml/min, P = 734 .+-. 245 ml/min). Peak blood lactate did not change either with hydralazine (C = 49.7 .+-. 24.2 mg/dl, H = 44.0 .+-. 21.4 mg/dl) or with prazosin (C = 33.8 .+-. 16.5 mg/dl, P = 32.1 .+-. 12.2 mg/dl). Vasodilators did not change the rate of lactate disappearance during recovery from exercise. Short-term administration of vasodilators apparently increased CO during exercise but did not improve nutritional flow to exercising muscle. Chronic administration of vasodilators with sustained improvement in CO may allow the readjustment of peripheral mechanisms that control the nutritional flow of muscle to take advantage of improved cardiac performance caused by vasodilators.