The effects of dobutamine on cardiac sympathetic activity in patients with congestive heart failure

Abstract

ObjectivesThe goal of this work was to study the effects of short-term infusion of dobutamine on efferent cardiac sympathetic activity. BackgroundIncreased efferent cardiac sympathetic activity is associated with poor outcomes in the setting of congestive heart failure (CHF). Dobutamine is commonly used in the therapy of decompensated CHF. Dobutamine, through its effects on excitatory beta-receptors, may increase cardiac sympathetic activity. MethodsSeven patients with normal left ventricular (LV) function and 13 patients with CHF were studied. A radiotracer technique was used to measure cardiac norepinephrine spillover (CANESP) before and during an intravenous infusion of dobutamine titrated to increase the rate of rise in LV peak positive pressure (+dP/dt) by 40%. ResultsSystemic arterial pulse pressure increased significantly in response to dobutamine in the normal LV function group (74 ± 3 mm Hg to 85 ± 3 mm Hg, p = 0.005) but remained unchanged in the CHF group. Dobutamine caused a significant decrease in LV end-diastolic pressure in the CHF group (14 ± 2 mm Hg to 11 ± 2 mm Hg, p = 0.02), an effect not observed in the normal LV group. In the normal LV function group, CANESP did not change in response to dobutamine (75 ± 22 pmol/min vs. 72 ± 22 pmol/min, p = NS). In contrast, dobutamine infusion was associated with a significant reduction in CANESP in patients with CHF (199 ± 43 pmol/min to 128 ± 30 pmol/min, p < 0.0009). ConclusionsDobutamine infusion caused a significant sympatholytic response in patients with CHF. This sympathetic withdrawal response is probably related to reduction of LV filling pressures and/or activation of ventricular mechanoreceptors with dobutamine infusion.