Study on the relationship between electrophysiological change in heterotopic heart transplants and acute heart graft rejection in rats

Objective To evaluate the correlation between effective refractory period of atrioventricular conduction system (ERP AVCS) and histopathological changes, to assess if ERP AVCS could be a noninvasive procedure for frequently monitoring of acute heart graft rejection (GR). Methods Three kinds of heterotopic neck heart transplants were performed. Group A: WKA rats received WKA rat isografts ( n =32), group B: WKA rats received Fisher 344 allografts ( n =30), and group C: WKA rats received Fisher 344 allografts treated with immunosuppressants ( n =32, 15 deoxyspergualin 5 mg/kg and prednisolone 5 mg/kg per day after transplantation). The correlation between ERP AVCS changes and the morphological changes in the grafts was observed during acute heart GR. Results The ERP AVCS in the groups A and C was not prolonged, while in the group B it was significantly prolonged from the day 3 to 7 after transplantation (96.88±6.77 ms at the day 3, P 0.05; 114.62±7.46 ms at the day 5, P 0.01; 121.67±9.73 ms at the day 7, P 0.01). Histopathologically, no abnormalities occurred in the groups A and C, but in the group B, progressive moderate to severe GR occurred from the day 3 to 7 after transplantation. The correlation between the ERP AVCS and histopathologic grade was particularly notable in the group B ( r =0.926, Y =9.00 X +90.43, P 0.01). Conclusion Determination of ERP AVCS is a promising simple noninvasive procedure for detecting acute heart GR.