Evaluation Of Acute Cardiac Transplant Rejection With Targeted Myocardial Contrast Echocardiography

Objective: To study the value of leukocyte-targeted myocardial contrast echocardiography as a tool in observing the degree of acute rejection after heart transplantation.Methods: Abdominal heterotopic cardiac transplantation was performed in 36 rats successfully,among which 8 isografts were as A group,B,C groups involved 8 allografts respectively,D0 group involved 12 allografts. B,C groups were treated with cyclosporin A (CsA) at a high dose (10mg·kg-1·d-1),a low dose (3 mg·kg-1·d-1) from 3 days before transplantation respectively.A,D0 groups were untreated with CsA. Myocardial contrast echocardiography(MCE) was performed during continuous intravenous SonoVue injection postoperatively on the third day after operation. We performed 2 types of MCE: perfusion imaging and leukocyte-targeted imaging.The images were obtained at 20 seconds and 5 minutes after injection of contrast agent. Measure the value of the contrast image grayscale (GS) by image analyzer(GS20s,GS5m). GStarget was calculated as the GS5m minus the GS20s in the same rat. Postmortem histology was performed after observation. The degree of myocardial rejection was determined by HE-stained graft myocardium. Immunohistochemistry was performed to quantify the CD3-positive cell,and correlation analysis was performed between CD3-positive cell count and GS20s,GS5m,GStarget.Result:1.Evaluation of Acute Rejection aftert Cardiac Transplantation with Leukocyte-Targeted Myocardial Contrast Echocardiography the results of imaging and Postmortem histology in A group (control group) and D0 group(rejection group) showed that:Perfusion imaging showed Myocardial GS20s slightly decreased in rejecting versus control rats (43.9±3.2 vs 46.1±3.3,P>0.05).Leukocyte-Targeted imaging showed Myocardial GS5m significantly higher in rejecting versus control rats (64.1±3.1 vs 49.2±3.6,P<0.001). GStarget was significantly higher in rejecting versus control rats (20.2±4.0 vs 3.1±1.5,P<0.001).Postmortem histology showed normal myocardium in control rats, whereas allograft myocardium demonstrated gradeⅢtoⅣrejection. Immunohistochemistry showed the CD3-positive cell infiltration was significantly higher in rejecting versus control(30±5 vs 2±1,P<0.001). There was a significant positive correlation between the CD3-positive cell and GStarget(r=0.79,P<0.001).2. The degree of Acute Cardiac Transplant Rejection was evaluated with Leukocyte-Targeted Myocardial Contrast Echocardiography8 allografts was selected from D0 group as D group randomly, A,B,C,D groups were studied. Perfusion imaging showed no significant difference in myocardial GS20s of each group. Leukocyte-Targeted imaging exhibited a clear gradient in these groups(P<0.05).there was significant difference in GStarget of each group(P<0.001). Postmortem histology showed 0～Ⅰgrade rejection in A group,Ⅰ～Ⅱgrade rejection in B group,Ⅱ～Ⅲgrade rejection in C group,Ⅲ～Ⅳgrade rejection in D group. Immunohistochemistry showed the CD3-positive cell infiltration was gradually increased from the A group to the D group. There was a significant positive correlation between the CD3-positive cell and GStarget(r=0.86,P<0.001).Conclusion: Leukocyte-Targeted contrast echocardiography may thus offer a noninvasive and effective ultrasound imaging technique for the detecting the degree of acute cardiac transplant rejection.