Remote Ischemic Postconditioning Protects Myocardium From Acute Ischemia-Reperfusion Injury In Pigs

Background and objectiveThe myocardial ischemia-reperfusion injury is very common in daily clinical work, Therefore, how to alleviate the reperfusion injury and protect the ischemic myocardium have been paid more and more attention. Although the ischemic preconditioning(IPC) is the most powerful cardioprotective methord, the patients' ischemia is impossibly predicted, so its clinical application has been hampered. Ischemic postconditioning(IPOC) will have better clinical manipulation and application, but it's also an invasive protocol and hardly accepted by our patients. Therefore, to search a non-traumatic myocardial protection behind the myocardial ischemia events will have very important practical value and clinical sense. Recently, some scholars proposed the remote ischemie postconditioning(RIPOC) and has been confirmed by different animal models. It is also reported that the limb ischcmic postconditioning can protect the ischemia-reperfusion myocardium. Limb RIPOC procedure is a simple, safe and non-invasive cardioprotective technique, therefore, it may have a promising future in clinical work.At present, we studied little about RIPOC, especially the remote limb RIPOC in pig model. The objective of this experiment was to investigate the cardioprotective effects of hindlimb ischaemic postconditioning in a pig model of acute myocardial ischaemic and reperfusion injury.MethodsAll pigs were randomly divided into two equal groups:Control and Remote group. All the ten pigs were subjected to a total of 30min of left anterior descending coronary artery(LAD) occlusion and 6h of reperfusion. Remote group underwent ischaemic postconditioning was induced by four 5 min cycles of double femoral artery occlusion and release immediately after the coronary artery reperfusion. Throughout the experiment, HR, MAP, CO, LAD blood flow(LADF) and ECG were continuously monitored. Plasma activity of cardiac troponin T(cTnT), Myoglobin(MYO) and creatine kinase MB(CK-MB) were measured at baseline, the end of ischaemia, and after 3h,6h of reperfusion respectively. Infarct size(IS%) was assessed by area under the curve for total cTnT release.ResultsThe results showed no significant differences between two groups in parameters of haemodynamics(FHR=1.777, P=0.219; FMAP=1.118, P=0.321; FLADF=0.838, P=0.38, Fco=0.320, P=0.587) and incidences of ventricular arrhythmias in ischemia and reperfusion period (t1=-0.187, P=0.856;tR=0.535, P=0.608). As compared with Control group, plasma cTnT activity decreased significantly((F=6.213, P=0.037)) and IS% was reduced by 29.5% in Remote group; The activity levels of plasma CK-MB and MYO decreased significantly during the period of reperfusion in Remote group(P<0.05).Conclusion Hindlimb remote ischaemic postconditioning is a simple, safe and valuable technique to reduce myocardial ischemia-reperfusion injury. It may have a promising future in clinical work.