Sustained improvement in flow-mediated vasodilation after short-term administration of dobutamine in patients with severe congestive heart failure

Background - In patients with severe congestive heart failure (CHF), short-term administration of dobutamine exerts sustained clinical benefits that are partially mediated by a training-like effect on skeletal muscle. Recently, physical training has been shown to enhance endothelial function in the skeletal muscle vasculature by improving endothelial function. Whether the dobutamine-induced training effect is also associated with an improvement in endothelial function in the skeletal muscle vasculature is currently unknown. Methods and Results - Flow-mediated vasodilation in response to peak reactive hyperemia was evaluated in the forearms of 9 patients with severe CHF who were treated with dobutamine for 72 hours. Resting and peak hyperemic brachial artery blood flow and diameter (BABF [mL/min] and BAD [mm], respectively) were measured by 2-dimensional and Doppler ultrasonography at baseline, at 3 and 72 hours during dobutamine infusion, and at 2 and 4 weeks after discontinuation of dobutamine therapy. In addition, the brachial artery response to sublingual (SL) administration of nitroglycerin (NTG) was evaluated at baseline and at 2 and 4 weeks after discontinuation of dobutamine therapy. Ten patients with severe CHF who did not receive dobutamine served as control subjects. Resting BABF was significantly increased at 13 and 72 hours (391.2±31.8 and 366.8±31.0 mL/min, respectively, compared with 289.8±18.6 mL/min at baseline; P<0.05). Peak hyperemic BABF was not altered by dobutamine infusion compared with baseline values The increase in BAD during peak hyperemic response was greater after infusion of dobutamine for 72 hours (15.2±2.7% versus 9.1±1.8%, P<0.05) and remained significantly greater for ≥2 weeks after discontinuation of dobutamine (12.3±2.2% versus 9.1±1.8%, P<0.05). In contrast to the peak hyperemic response, the increase in BAD (%) induced by SL NTG was unchanged by administration of dobutamine for 72 hours. Two and 4 weeks after discontinuation of dobutamine, NTG-induced increases in BAD were similar to the BAD noted at baseline. Conclusions - In patients with severe CHF, short- term administration of dobutamine for 72 hours selectively improves vascular endothelial function for ≥2 weeks.