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Stanley Theodore H. MD; Lunn, Judd K. MD; Liu, Wen-Shin MD; Gentry, Scott BS; Olsen, Don DVM
Anesthesia & Analgesia: January 1980

Peripheral vascular and direct cardiac effects of intravenous digoxin (5, 10, and 15 μg/kg) were determined in a pharmacologic animal model, the unanesthetized calf before and after replacement of its natural heart (NH) with a pneumatically driven artificial heart (AH). All doses of digoxin significantly increased cardiac output and stroke volume 30 and 60 minutes after administration before and after AH replacement. Increases in output and stroke volume were greater before AH replacement than after. Increases in output were similar with all doses of digoxin in AH calves but greater with increasing doses in NH calves. Digoxin produced significant and similar increases in systemic vascular resistance within 5 minutes and significant and similar decreases 25 and 55 minutes later in NH and AH calves. While increases in systemic vascular resistance were greater with 10 and 15 μg/kg than with 5 μg/kg of digoxin, decreases in resistance were similar at all doses of digoxin in NH and AH animals. Mean aortic blood pressure transiently increased 5 minutes after all doses of digoxin in NH calves. Heart rate was reduced by all doses of digoxin 5 minutes after administration in NH calves but was unchanged from control in subsequent measurements. Heart rate was fixed in calves with an AH. Mean right a trial pressure was increased similarly by all doses of digoxin in NH and AH calves 30 and 60 minutes following administration. These data indicate that digoxin had significant peripheral vascular (arterial and venous) effects in the healthy calf and suggest that elevations in cardiac output and stroke volume after its use are partially due to both increases in pre-load and to decreases in systemic vascular resistance (after-load).

Supported in part by Contract 69–2181 and Grant HL 13738, National Heart Institute, National Institutes of Health, and the Lad L. and Mary Herick Fund, and Mr. Maurice Warshaw.

© 1980 International Anesthesia Research Society