Milrinone improved left ventricular pumping function and reduced stressed blood volume in heart failure canines, increasing the slope of the output curve from 18.3 to 30.2 mL·min −1 ·kg −1.
Does intravenous milrinone improve hemodynamic parameters and circulatory equilibrium in normal and heart failure canine models?
In a canine model of acute heart failure, milrinone improves circulatory equilibrium by enhancing left ventricular pumping function and reducing stressed blood volume.
Absolute Event Rate: 0% vs 0%
Milrinone, a phosphodiesterase III inhibitor, exerts positive inotropic and vasodilatory effects via cyclic adenosine monophosphate-mediated signaling pathways. However, its comprehensive hemodynamic impact, particularly on venous return, remains incompletely characterized. Using the generalized circulatory equilibrium framework, we investigated the cardiovascular effects of milrinone in normal and heart failure (HF) canine models. Ten beagle dogs (five normal, five with acute left HF induced by left coronary microembolization) were studied under general anesthesia and open-chest conditions. Milrinone was administered intravenously at 0.5 µg·kg −1 ·min −1 . From the circulatory equilibrium framework, we derived the effective stressed blood volume (SBV) and the logarithmic slope (SL) of left ventricular (LV) output curve, which indicates LV pumping capability. Milrinone infusion reduced SBV from 31.6 ± 1.3 to 26.5 ± 1.7 mL/kg in the normal model and from 35.7 ± 3.0 to 32.1 ± 3.6 mL/kg in the HF model, with a significant main effect of drug (P = 0.004) but no model × drug interaction in two-way ANOVA (P = 0.531). In the normal group, SL was unchanged 61.6 ± 1.6 to 62.2 ± 3.5 mL·min −1 ·kg −1 , resulting in decreases in aortic pressure (AP) and cardiac output (CO). In contrast, in the HF group, milrinone increased SL 18.3 ± 3.1 to 30.2 ± 4.3 mL·min −1 ·kg −1 , with a significant model × drug interaction (P = 0.044). As a result, AP and CO were preserved, while left atrial pressure was reduced. In conclusion, in the HF canine model, milrinone improves the circulatory equilibrium point by enhancing LV pumping function and reducing SBV.
Hiraki et al. (Sat,) reported a other. Milrinone improved left ventricular pumping function and reduced stressed blood volume in heart failure canines, increasing the slope of the output curve from 18.3 to 30.2 mL·min −1 ·kg −1.