Effect of dobutamine on cardiac function in man: reciprocal roles of heart rate and ventricular stroke volume.

The cardiovascular effects of dobutamine ( 7 micrograms/kg . min iv) and of additional N-allyl-clonidine (St 567, alinidine; 0.3 mg/kg iv), a compound which selectively inhibits the chronotropic effects of various stimulants, were studied in 9 patients scheduled for major abdominal surgery. Dobutamine increased cardiac index (CI), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), and heart rate, but failed to change the left ventricular stroke volume (LVSV) significantly. Alinidine decreased cardiac rate and increased LVSV index and left ventricular stroke work index (LVSWI), whereas CI, MAP, and MPAP remained virtually unaffected. Similar results were obtained when the combination of dobutamine and alinidine was given to 4 patients in neuroleptanesthesia. Thus, the decrease in preload which is associated wit tachycardia seems to modify the increase in LVSV in response to inotropic stimulation with dobutamine.