Lobato EB. Urdaneta F. Martin TD. Gravenstein N. Effects of milrinone versus epinephrine on grafted internal mammary artery flow after cardiopulmonary bypass. Journal of Cardiothoracic & Vascular Anesthesia. 14(1):9-11, 2000.
The authors compared changes on grafted internal mammary artery (IMA) flow after cardiopulmonary bypass in response to the administration of milrinone or epinephrine in a prospective and randomized study. Twenty consenting, adult patients undergoing CABG were randomized to receive either milrinone, 50 mcg/kg, or epinephrine, 0.03 mcg/kg/min, immediately after cardiopulmonary bypass. IMA flow was measured with a laser Doppler flow probe before and after the administration of either drug. Baseline grafted IMA flow was similar for both groups (milrinone, 38+/-14 mL/min; epinephrine, 33+/-10 mL/min). In patients who received milrinone, flow increased by 24% to 50+/-17 mL/min, p<0.05; whereas with epinephrine, it remained essentially unchanged (33+/-10 v. 31+/-11 mL/min). The authors conclude their data from this study confirms that the vasodilatory effect of milrinone on the IMA is also present after its anastomosis, whereas low-dose epinephrine exhibits neither beneficial nor adverse effects. It is suggested that in the absence of excessive vasodilation, milrinone should be considered as a first-line inotrope after coronary artery bypass graft surgery, to achieve an increase in contractility and IMA artery flow.