Haemodynamic effects of dobutamine in patients with coronary artery disease

The haemodynamic effects of the infusion of dobutamine in dosages of 2-5, 5-0 and 10-0 mug/kg/min were studied in twelve patients with coronary artery disease. At the lowest dose, infusion of dobutamine caused a significant increase in cardiac output; greater increases occurred with doses of 5-0 and 10-0 mug/kg/min. The means by which the myocardium produced the increase in cardiac output differed according to the dose of the drug; 2-5 and 5-0 mug/kg/min produced an increase in stroke volume without any significant variation in the heart rate. At the highest dose rate, an increase in heart rate made a distinct contribution to the overall increase in output. The ventricular dp/dt max. increased at all three dosages. Blood pressure, pulmonary arterial and capillary pressure, and left ventricular and diastolic pressure did not show any significant change. The separation of the inotropic and the chronotropic effects of dobutamine according to the infused dose appears to have extremely interesting clinical implications.