Myocardial Protective Effect Of Low Flow Perfusion On Isolated Rat Hearts

Objective: Simple cold static storage is a proven preservation method for heart transplantation, yet early post-operative graft dysfunction remains prevalent. And what's more, preservation time less than 4-6h is another disadvantage of this method. Low flow perfusion is another new preservation technique. So the purpose of this study is to compare the myocardial protective effect of low flow perfusion with simple cold static storage on isolated rat hearts. HTK solution and FWM solution are the two kinds of preservation solutions that used in our experiments, so the other aim of our study is to evaluate the efficacy of the two solutions.Methods: Thirty-two male SD rats were randomly divided into four groups (n=8, each) according to different preservation solutions and preservation techniques: F1 group, F2 group, H1 group, H2 group. The hearts were harvested and immediately mounted on the modified Langendorff apparatus perfusing K-H solution for 30 min, then the isolated hearts were arrested. F1and F2 group used FWM solution, the other two groups used HTK solution. The isolated hearts in H1 group or F1group then were immersed in 4℃HTK or FWM solution for 8 hours, respectively. In F2 group and H2 group, the hearts were infused continuously by 4℃HTK or FWM solution for 8 hours at a pressure of 10cm H2O. At the end of storage, the hearts were perfused K-H solution in the Langendorff apparatus for 60 min. During reperfusion, the values homodynamic values, the myocardial water content, and the leakage of myocardial enzymes (CK-MB and LDH) were measured. Sequentially the specimen of the hearts were taken to be observed the changes of myocardial structure through light microscope.Results: After reperfusion, all hearts in F1 group failed to beat. The recovery rate of cardiac function was 0.During reperfusion we found that the hearts were pale and touched hard, just like"stone heart". The myocardial water content and the leakage of myocardial enzyme were remarkably higher than those in other three groups (P<0.01). In H2 group, the recovery rates of left ventricular development pressure, heart rate, coronary flow and the myocardial water content were (77.7±3.4)%, (80.2±5.3)%, (54.6±6)% and (79.5±0.7)%, respectively. Comparing with other three groups, their differences were considered to be statistically significant (P<0.05). Pathological images of H2 group showed that myocardial cells ranged regularly and part of them occurred lysis and rupture myocardium mesenchyme had mild edema, myocardial tissue was better than other three groups in acidophilia. After analyzing data of every group, we found that myocardial protective effect of HTK solution was better than FWM solution under the same conditions of preservation technique and time.Conclusion: Our results suggest that the myocardial protective effect of low flow perfusion is better than simple cold static storage. It can improve myocardial function and prolong preservation time. The myocardial protective effect of HTK solution is superior to FWM solution.