Experimental Research Of Key Technologies Of Perioperative Myocardial Protection In Vivo

Research 1Objective: To investigate the feasibility of implementating the ischemic preconditioning(IPC) and hypoxic preconditioning(HPC) in vivo by using double bypass model; to explore myocardial protective effect, and the possibility of clinical application and conversion of implementing the IPC/HPC by using double bypass model. Method: 1)10 healthy beagles were used for establishing cardiopulmonary bypass(CPB), double bypass(Double-bypass) and implementing IPC/HPC under Double-bypass model, HR,MAP, CVP, blood gas analysis and successful weaned from CPB were observed. 2) 18 beagles were randomly divided into three groups: ① control group(Group C):establishing of double-bypass, without implementing any preconditioning; ②IPC Group:establishing double-bypass and implementing IPC; ③ HPC Group: establish double-bypass and implementing HPC, and all of animals then each group CPB bypass one hour, two hours reperfusion. And hemodynamic and cardiac dynamics indicators(HR,MAP, CVP, LVESP, LVEDP, + dp/dtmax,-dp/dtmax), c Tn I, myocardial ATP content were measured, and cardiac myocyte apoptosis and electron microscopy structure were detected. Results: 1) Double-bypass canine model success, Double-bypas can be used to implement IPC and HPC in vivo. 2) Compared with group C, Double-bypass canine model to implement IPC and HPC significantly reduced left ventricular systolic function caused by reperfusion decreased(P<0.05). HPC group and IPC group, serum c Tn I levels lower than that in group C(P<0.001), myocardial apoptosis ratio is also lower(13.69%,10.02% vs. 18.49%, respectively, P < 0.001). Myocardial cell structure can be better protected by HPC than IPC, and only HPC significantly reduced myocardial ATP consumption((ATP Reperfusion/Baseline<0.05). Conclusion: IPC/HPC by using double bypass model is feasible and effective, Both IPC and HPC attenuated the reperfusion-induced decrease in left ventricular end systolic pressure seen in the control group. Both the HPC and IPC groups had lower serum c Tn I levels, better myocardiocyte histology, and lowerrates of apoptosis compared to the control group without preconditioning. HPC reduced the abnormal cardiomyocyte histology and apoptosis to a greater extent than IPC, and only HPC signicantly restored the depletion of ATP.Research 2Objective: To assess whether increasing oxygen content and changing carrier fluid,the new adenosine lidocaine cardioplegia using the hyperoxic acetate Ringer as the carrier liquid(ALHA) can improve the myocardium and coronary endothial protective effect after ischemia-reperfusion injury. Method: 20 beagle dogs were randomly divided into five groups: ① High potassium cardioplegia(K) group; ② the SAL(0.9% Na Cl as carrier fluid); ③ the AAL(the Ringer’s acetate) group; ④ the HSAL(hyperoxic 0.9% Na Cl)group, and ⑤ the HAAL(hyperoxic Ringer’s acetate) group. All AL solution contained1.2mmol/L of adenosine and 0.7mmol/L of lidocaine. Coronary endothelial NO, ET, CEC and coronary vasodilation was observed ffects of CEC each group different cardioplegia perfusion with high potassium cardioplegia AAL cardioplegia; and different cardioplegia on hemodynamics and cardiac dynamics(HR, MAP, CVP, LVESP, LVEDP, +dp/dtmax,-dp/dtmax), myocardial injury indicators(c Tn I) and myocardial apoptosis,myocardial ATP content and the impact of electron microscopy structure. Results: 1)Compared with AAL group, the plasma NO levels significantly reduced, ET levels were significantly increased, CEC number increased significantly at T3(P < 0.05).Them Aximum percentage of coronary vasodilation was lower in group K than HAAL group(9.13 ± 8.24% VS 68.52 ± 11.32%, P<0.01). Coronary endothelial cells are more serious structural damage in K group comparing with HAAL group. 2) after resuscitation,THE incidence of arrhythmia was significantly lower in HAAL group than in SAL group(50.0% vs. 0%, P=0.021); myocardial ATP content was significantly higher in HAAL group than SAL group(29.48 ± 4.08 vs. 21.80 ± 3.63, P=0.019); and the concentration of lactate in coronary sinus was significantly lower in HAAL group than the SAL group at T2(2.74 ± 0.29 vs. 3.35 ± 0.31, P=0.006). Conclusion: Compared with high potassium cardioplegia, HAAL cardioplegia can better protect the structure and function of coronary endothelial cells; Change of carrier fluid and a simultaneous increase in oxygen content significantly reduced the incidence of arrhythmia after resuscitation and increased the ATP content in ischemic myocardial cells but did not significantly improve the systolic and diastolic function of the left ventricle.