Milrinone administered before ischemia or just after reperfusion, attenuates myocardial stunning in anesthetized swine.

Purpose: We assessed the dose or timing effect of milrinone administered against myocardial stunning in 37 anesthetized open-chest swine.

Methods: All swine were subjected to 12-min ischemia followed by reperfusion to produce myocardial stunning. Group A (n = 12) received saline in place of milrinone both before and after ischemia. Group B (n = 9) and C (n = 9) received intravenous milrinone at a rate of 5 microg/kg/min for 10 min followed by 0.5 microg/kg/min for 10 min and 10 microg/kg/min for 10 min followed by 1 microg/kg/min for 10 min, respectively, until 30 min before coronary occlusion. Group D (n = 7) received the same dose of milrinone as group B starting 1 min after reperfusion. Myocardial contractility was assessed by percentage segment shortening (%SS).

Results: Five swine in group A and two swine in groups B and C each had ventricular fibrillation or tachycardia after reperfusion, and were thus excluded from further analysis. The percentage changes of %SS from the baseline 90 min after reperfusion in groups B, C, and D were 78 +/- 9%, 82 +/- 13%, and 79 +/- 7%, respectively, which were significantly higher than those in group A (43 +/- 13%).

Conclusion: We conclude that milrinone administered before ischemia or just after reperfusion attenuates myocardial stunning.