Electrophysiologic changes during acute rejection of heterotopically transplanted rat hearts.

Noninvasive monitoring of heart allograft rejection was performed by electrophysiologic techniques using an implanted electrode located on the epicardial surface of the heterotopic transplanted heart of rats. R wave and slew rate determinations were performed daily in 30 syngeneic and 66 allogeneic transplants. These determinations were later compared with histopathologic studies of the transplanted hearts. R wave and slew rate values of allogeneic or rejecting hearts were found to decrease significantly compared with syngeneic or nonrejecting hearts on the days studied. This noninvasive electrophysiologic method may be a promising method for monitoring heart allograft rejection.