Comparison of dobutamine and dopamine in acute myocardial infarction. Effects of systemic hemodynamics, plasma catecholamines, blood flows and infarct size.
Year: 1983
Type: article
Abstract: To compare cardiovascular effects of dobutamine and dopamine, we administered the two agents at a dose of 10 gpg/kg/min i.v. to two groups of chronically instrumented conscious dogs, beginning 40 minutes after coronary artery occlusion and continuing for 24 hours thereafter.A control group that was given an infusion of 5% dextrose was also studied.During the first 30 minutes of infusion, both dobutamine and dopamine produced similar increases in cardiac output, left ventricular dP/dt and dP/dt/P, without significant changes in heart rate, mean arterial blood pressure or regional myocardial blood flow.At 24 hours, cardiac output and left ventricular dP/dt and dP/dt/P continued to be greater in the dobutamine group than in the control group.The acute positive inotropic effects of dopamine were no longer apparent at 24 hours.Epicardial blood flow in the dobutamine-treated group also was higher than that in the control group.There were, however, no differences between groups in the ischemic-to-nonischemic myocardial blood flow ratio.In addition, infarct size, measured by nitroblue tetrazolium staining, was smaller in the dobutamine group (55 ± 4% of risk zone) than in the dopamine group (76 ± 6%) or the control group (76 + 5%).The dobutamine group also differed from the dopamine group in their plasma catecholamine levels.Arterial plasma concentrations of norepinephrine and epinephrine increased above the postocclusion baseline values only during dopamine infusion by 1.50 ± 0.34 and 0.87 0.32 ng/ml, respectively.Dopamine also caused myocardial release of norepinephrine, as evidenced by a significant transmyocardial gradient (coronary sinus minus arterial difference) of 1.48 + 0.27 ng/mI.The results show that dobutamine increases collateral flow to the ischemic myocardium, enhances left ventricular performance, and reduces infarct size.None of these effects were produced by dopamine under these experimental conditions.The difference between the effects of the two drugs probably is related, at least in part, to the detrimental effects of local myocardial release of norepinephrine by dopamine.DOBUTAMINE is a cardioselective adrenergic agent that augments myocardial contractility, cardiac output and myocardial blood flow with only minimal changes in heart rate or arterial blood pressure.'-5It may be used clinically to improve depressed cardiac function with- out further impairment of oxygen balance or metabo- lism of the ischemic heart.6`Dobutaminenot only improves the global performance of the heart, but also reduces infarct size during acute experimental myocardial infarction.9These salutary effects probably are causally related to the increase in ischemic myocardial blood flow produced by dobutamine.However, Tut- tle'0 showed that a reduction of myocardial necrosis by dobutamine was accompanied not only by an increase in myocardial blood flow, but also by a reduction in the amount of norepinephrine released from cardiac sympathetic fibers that was facilitated after myocardial ischemia.Local release of excessive endogenous norepinephrine is generally thought to be injurious to is-
Source: Circulation
Authors: K Maekawa, C S Liang, W B Hood
Institution: Boston University
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Funder: Eli Lilly and Company
OpenAlex ID: W2015000308