Effects of dobutamine on atrioventricular conduction

Dobutamine, a new beta-stimulating catecholamine, has been investigated in terms of its effect upon atrioventricular conduction. Bundle of His recordings were obtained on six patients in basal conditions and with right atrial pacing at rates of 100, 120, and 140 per minute. Recordings were repeated following intravenous administration of Dobutamine in doses of 5, 10, and 15 mug per kilogram per minute. Dose-response curves were thus obtained for A-H and H-V intervals. Heart rate increased only moderately with progressive concentrations of the drug. Very significant facilitation of A-H conduction was demonstrated with doses of 10 and 15 mug per kilogram per minute, with no effect upon H-V times. Dobutamine may be a clinically useful inotropic agent in conditions associated with A-V conduction disturbances.