No-Invasive Imaging Technique For Detection Of Allograft Cardiac Acute Rejection

ObjectiveTo establish a new volume-loaded heterotopic abdominal heart transplantationmodel in rabbits. A standard operating procedure was created for decrease morbidityand mortality. The hemodynamic feature of the new model compared to thetraditional model by using echocardiography.MethodsThirty male allogeneic New Zealand white rabbit, weighing from3.5to4kg, wasdivided into donors and recipients randomly. No-Working model was createdaccording to the traditional method established by Abbott. After anesthesia, donorswere undergone tracheotomy and endotracheal intubation. Middle sternotomy wasperformed and great vessels were isolated. A heparin needle was inserted intoinnominate artery for infusing cardioplegia after systemic heparinization. Donor heartwas harvested and protected in ice water. Part of left and right atrial wall was resectedand the two incisions were anastomosed. Inferior vena cave, pulmonary vein andpulmonary artery was ligated. The abdominal cavity of recipients was entered, andinfrarenal aorta and inferior vena cava were isolated. The superior vena cava andascending aorta of donor heart was anastomosed to the infrarenal aorta and inferior vena cava of recipients. The palpation score, survival time of donor hearts, theincidence of thrombosis, survival rate and morbidity of recipients were recorded.Echocardiography was applied to monitor the hemodynamic alternation.ResultsOne animal in Group NW died from anesthetic accident. One animal in GroupVL suffered from digestive complication. No pulmonary and nervous complicationsoccurred. Most of allografts developed to complete cessation of ventricularcontractility at day7after transplantation. Thrombus was observed in left heart inGroup NW, but not in heart cavity of Group VL. The aortic valve of Group VLopened following each ventricular contraction, but that in Group NW maintainedclose during cardiac cycle. The value of maximal aortic velocity and late diastolicmitral inflow velocity in Group VL was approximately equivalent to half that ofnative heart. The atrial anastomosis showed a right-to-left shunt. The anastomosis ofvena cava showed a bi-directional shunt.ConclusionsWe firstly created a new volume-loaded heterotopic heart transplantation model inrabbits. The model imitate the hemodynamic feature of native heart. We alsoestablished a series of modificated techniques and standard operating procedure,which significantly improved survival rate. However, the model still can notcompletely imitate the hemodynamic feature of native heart. ObjectiveA specific tracer, Synaptotagmin I combined with18F was applied to detect theallograft cardiac acute rejection in rabbit model by PET-CT.MethodsTwenty-four New Zealand white rabbits were divided into three groups. Animals ingroup3, group5and group7were underwent experiments on the postoperative3,5,7days respectively. The heterotopic model was established according to Part I. Theanimals in the three groups were performed PET-CT by injecting18F-SynaptotagminI. The standard uptake value (SUV) native heart and donor heart was recorded. Theanimals were sacrificed for histological and immunohistochemical examination.ResultsThe standard uptake value in native heart, group3, group5and group7were0.91±0.04?0.94±0.05?1.09±0.09?2.40±0.38respectively. There were no differenceamong native heart, group3and group5for standard uptake value. The SUV ingroup7was higher than that in group5. Hematoxylin and eosin stain showedrejection grade in native heart was0grade. Rejection grade in group3, group5andgroup7was1A,2and4grade respectively. TUNEL results showed the apoptosis ratein native heart and group3was not different, but lower than that in group5and group7significantly. The value in group3was lower than that in group5and group7. But there was no difference between group5and group7.ConclusionsPET-CT can supply clear images on different parts of the heart. No-specific uptakeis relatively low. The apoptosis rate of donor heart will increase as the survival timeprolong. High grade rejection was characterized by apoptosis of inflammatory cell. Itshowed a trend that the apoptosis rate and SUV will raise as the rejection gradeaggravate. The application of PET-CT to detect acute rejection showed superiority toSPECT. However, the method is required further clinical and experimentalresearches.