Renal Vasodilatory Action of Dopamine in Patients With Heart Failure Magnitude of Effect and Site of Action

Background— A “renal dose” of dopamine is often used to increase renal blood flow; however, data on the magnitude of effect and site of action in patients with heart failure are scarce. Methods and Results— Renal effects of intravenous dopamine (1, 2, 3, 5, and 10 μg · kg−1 · min−1) were evaluated in 13 patients with chronic heart failure. Renal blood flow was calculated from renal artery cross-sectional area measured with intravascular ultrasound and renal blood flow velocity-time integral measured by the intravascular Doppler technique. Cross-sectional area increased and was significantly higher than baseline (0.30±0.04 cm2) at 5 μg · kg−1 · min−1 (0.36±0.05 cm2) and 10 μg · kg−1 · min−1 (0.38±0.06 cm2). The velocity-time integral was significantly higher than baseline (22±3 cm) at doses of 3 and 5 μg · kg−1 · min−1 (both 31±4 cm). Renal blood flow increased, whereas renal vascular resistance decreased, reaching statistical significance at 2 μg · kg−1 · min−1 through 10 μg · kg−1 · min−1. Cardiac output...