Cardiovascular effects of dopamine and dobutamine in conscious pigs with chronic heart failure.

OBJECTIVE

To test the hypothesis that the cardiovascular responses of dopamine and dobutamine might be affected by the cardiovascular conditions.

DESIGN

Prospective, controlled dose-response comparison of dopamine and dobutamine.

SETTING

Laboratory for Experimental Cardiology at a university.

SUBJECTS

Normal conscious pigs and conscious pigs with chronic left ventricular dysfunction induced by occlusion of a coronary artery 3 to 4 wks before measurements were obtained.

INTERVENTIONS

Intravenous infusions of dopamine and dobutamine at rates of 1 to 25 micrograms/kg/min.

MEASUREMENTS AND MAIN RESULTS

Left ventricular function was characterized by a lower cardiac output in the pigs with left ventricular dysfunction (23%), stroke volume (34%), and left ventricular pressure (15%), and a higher heart rate (16%), peripheral resistance (41%), and left ventricular end-diastolic pressure (96%) than the normal pigs. Dopamine increased cardiac output to the same extent in the animals with failure as in the normal animals; stroke volume increased only in the animals that had left ventricular dysfunction. The vasodilatory response to dopamine was also similar, but the increase in left ventricular pressure was attenuated similar, in the animals with left ventricular dysfunction, compared with normal animals. Dobutamine showed cardiovascular effects equivalent to dopamine. Left ventricular work, depressed at baseline, increased more rapidly during infusion of dopamine (or dobutamine) in the animals with heart failure than in normal animals.

CONCLUSIONS

Both dopamine and dobutamine increased cardiac output in conscious pigs with chronic heart failure. Unlike the response in normal conscious pigs, in which only heart rate increased, in animals with heart failure, these agents enhanced both stroke volume and heart rate.