Abstract 2315: Reversal of Myocardial Injury After Cardioplegic Arrest By The Ischemic Post-conditioning At The Early Phase Of Reperfusion
This study tests the hypothesis that the ischemia/reperfusion-induced myocardial damage can be reduced by “ischemic post-conditioning” at the early phase of reperfusion.
METHODS: Eighteen piglets, weighing 10.3+/− 1.5 kg underwent 90 minutes of ischemia with single dose crystalloid cardioplegia followed by 60 minutes of reperfusion on CPB. In 12 of them, the two types of ischemic post-conditioning strategies: 6 cycles of 10 second -Ischemia/Reperfusion (PC-I) or 3 cycles of 30 second I/R (PC-II) were applied prior to aortic unclamping, whereas the other 6 were not treated (Control). LV function (sysolic/diastolic) was evaluated by Ees & Tau. Myocardial and blood lipidperoxide (LPO), TroponinT, CK were measured.
RESULTS: LV systolic and diastolic dysfunction (depressed Ees: 54+/− 14% of preischemic value and increased Tau:240+− 38%), associated with oxidants induced biochemical injury (increased CK, Trop and lipid peroxidates) were noted after 90 minutes of cradioplegic ischemia followed by untreated reperfusion in Control group. In contrast, post-conditioning especially by the protocol II allowed significant better LV functional recovery (%Ees: PC-I 67+/− 23%; PC-II 130+/− 43%*, *p < 0.01 vs control group 54+/− 14%), LV diastolic time constant in isovolumic relaxation (%Tau: PC-I 140+/− 60%*; PC-II 123+/− 43%*, p < 0.01 vs control group 240+− 38%), and less myocardial biochemical injury (myocardial lipid peroxide: 123+/− 21*; and 134+/− 12%* p < 0.05 vs 180+/− 34). Also serum CK, Troponine and LPO were reduced in the both post-con groups.
CONCLUSION: “Ischemic post-conditioning” at the early phase of reperfusion produced prompt myocardial functional recovery with improved biochemical injury in in vivo piglet CPB model. The interval and duration of repeated brief I/R during PC might be crucial to determine the beneficial effects of IC.