Dobutamine increases cardiac output of the total artificial heart. Implications for vascular contribution of inotropic agents to augmented ventricular function.

BACKGROUNDThe synthetic catecholamine dobutamine increases stroke volume in normal subjects and in patients with congestive heart failure. In addition to its direct influence on myocardial contractility, dobutamine may significantly modulate vascular tone because of its alpha- and beta-adrenergic agonist activity.METHODS AND RESULTSTo test the hypothesis that such vasoactive properties significantly contribute to the improved ventricular performance noted with this agent, hemodynamic parameters were measured during stepped ascension infusion of dobutamine in a model that is insensitive to positive inotropic stimulation. Administration of dobutamine in nine calves that underwent replacement of the native right and left ventricles with pneumatically driven total artificial hearts resulted in a significant (p = 0.0001) increase in cardiac output from 7.0 +/- 1.8 to 8.2 +/- 1.8 l/min and a significant (p = 0.0001) decrease in total peripheral vascular resistance from 1,224 +/- 559 to 745 +/- 317 dyne.sec/cm5....