The Protection Of Myocardial And Renal Function By Heart Ischemic Postconditioning And Lower Limb Remote Ischemic Preconditioning In Surgical Management Of Tetralogy Of Fallot

Objective:The remote ischemic preconditioning (RIPC) and ischemic postconditioning(IPO) had been proved in preventing the myocardial I/R injury in a large amount of animal experiments and a few clinical trials.There are few clinical reports pertaining to protective effect of RIPC or IPO on acute kidney injury in cardac surgery and there is no comparison of RIPC and IPO in myocardial protection and renal protection in complex congential heart disease. In this study, lower limb ischemic preconditioning and cardiac ischemic postconditioning were conducted in patients with surgical repair of tetralogy of fallot, and the protective effects of RIPC and IPO were compared on myocardial and kidney I/R injury.Methods:Eighty patients with tetralogy of fallot undergoing surgical repair were selected in our department from March 2008 to January 2010. The patients aged 7 months to 27 years old were divided randomly into four groups:control group(n=20),RIPC group(n=20), IPO group(n=20),RIPC+IPO group(n=20). Patients' guardian signed a informed consent before surgery. The cuff in the right thigh was used in RIPC group after tracheal intubation, and inflatable cuff and the pressure was maintained at 200-600mmHg for 5min. Then deflate the cuff for 5min. The cycle was repeated for 3 times. The IPO started after aortic de-clamping for 30 seconds. Then, aortic was re-clamped for 30 seconds again resulting in heart ischemia. After that, the aortic clamp was released for 30 seconds in order to achieve complete myocardial reperfusion. This cycle was repeated 3 times. The RIPC+IPO group used the above two kinds of treatment. The control group was not preconditioned or postconditioned. The bypass time, aortic cross-clamping time, The cardiac auto-defebrillation, electron microscopy examination of myocardium at 5 minutes after aortic declamping. The CK-MB and cTnâ… were measured before surgery,4,8 and 20 hours after aortic de-clamping.The Kim-1 was measured before surgery,4,24 hours after aortic de-clamping. The blood urea nitrogen, Serum creatinine and Creatinine clearance rate were also measured before surgery,4 and 24 hours after aortic de-clampingResults:The age, body weight, cardiopulmonary bypass time, aortic cross-clamp time, preoperative CK-MB, cTnâ… Kim-1 and Creatinine clearance were not significantly different (all P> 0.05) among the four groups. The CK-MB and cTnâ… in four groups were increased significantly than the baseline at 4 hours,8 hours and 20 hours after aortic de-clamping. The CK-MB in RIPC,IPO and RIPC+IPO group were significantly lower than in controls(all P<0.05) at 4 and 8 hours after aortic de-clamping. There were no significant differences with regard to CK-MB release among the three treatment groups (all P>0.05). The cTnâ…  in RIPC, IPO and RIPC+IPO group were significantly lower than control group at 4,8 and 20 hours after aortic de-clamping (p=0.001, p=0.000, p=0.009). There were no significant differences between among three treatment groups after aortic de-clamping(p=0.067, p=0.060, p=0.937).The electron microscopy examination 5 minutes after aortic de-clamping showed significant myocardial interstitial edema, muscle fiber lytic necrosis, markeble mitochondrial swelling, cristae swelling and vacuolization in control group. The myocardial cells in three treatment groups showed less mitochondrial swelling, vacuolization than in controls.The Kim-1 in four groups were increased significantly respectively than the baseline at 4 and 24 hours after aortic de-clamping. The Kim-1 in RIPC, IPO and RIPC+IPO group were significantly lower than control group(all p<0.05) at 4 and 24 hours after aortic de-clamping. The Kim-1 was not significantly different among three treatment groups (all p>0.05)There were no diffrences among the four groups with respect to creatinine, creatinine clearance and urea nitrogen postoperatively (all p>0.05).Conclusion:The present study suggested that RIPC, IPO and RIPC+IPO can reduce the myocardial and renal ischemia-reperfusion injury in surgical repair of tetralogy of fallot. The RIPC, IPO provide the equal protective effect on myocardium and kidney injury The combination of RIPC and IPO provide no additive effect on myocardium and kidney injury in the setting of surgery for tetralogy of fallot.