[A comparison of cardiovascular effects of dobutamine and dopamine (author's transl)]

The influences of dobutamine and dopamine 5-40 microgram/kg-min intravenously on hemodynamics and myocardial oxygen consumption were investigated in closed chest dogs (n=9). Heart rate (HR), cardiac index (CI), stroke volume (SVI), mean aortic pressure (MAP), pulmonary artery pressure (PAP), central venous pressure (CVP), left ventricular enddiastolic pressure (LVEDP), myocardial blood flow (MBF) and maximum dp/dt (dp/dtmax) were measured. Total peripheral resistance (TPR), coronary vascular resistance (CVR), myocardial oxygen consumption (MVO2), efficiency of heart work (EME), the ventricular volumes (EDV, ESV) and the ejection fraction (EF) were calculated. When dopamine was infused, the cardiac output rose mainly by an increase of heart rate. During dobutamine an increase of stroke volume and ejection fraction was involved in the improvement of cardiac output. Heart rate and mean aortic pressure increased to a greater extent by dopamine. Dobutamine and dopamine increase myocardial blood flow and oxygen consumption. The comparatively slight effects of dobutamine on afterload and heart rate resulted in smaller increases in myocardial oxygen consumption. The efficiency of external heart work was increased by dobutamine at the doses of 5 microgram and 10 microgram/kg-min. In the higher dose range external myocardial efficiency decreased under dopamine and dobutamine. Load data and heart rate indicate that a greater inotropic effect of dobutamine compared with equal doses of dopamine is involved in the increase of dp/dtmax. The results are discussed in relation to a clinical use of dobutamine and dopamine.