Objectives and Methods: Brain death related hemodynamic instability and/or cardiac dysfunction is frequently described in the potential organ donor which may lead to exclusion of the heart from transplantation. The underlying mechanisms are controversely discussed. Therefore, in the present study, potential brain death associated cardiodepressant factors were evaluated separately in cross-circulated canine heart models. Brain death was induced by inflation of a subdural balloon catheter. Loading conditions and coronary perfusion pressure were kept identical in all cross-circulated hearts throughout the experiment. Results:Inductionof brain death led to a significanthyperdynamic responsein allgroups, with a maximal effect by the combination of neural and humoral pathways. After the initial reaction all hemodynamic parameters returned to baseline and remained stable until the end of experiments. Even if the hearts were explanted from brain dead donors with typical hemodynamic deterioration in vivo, they showed no significant differences in comparison to the other groups including healthy controls ex vivo. Condusions: Therefore we conclude, that hemodynamic instability in the potential donor may rather reflect altered loading conditions and impaired coronary perfusion than neuro-humorally mediated direct myocardial injury.

Keywords: Brain Death, myocardial function, isolated heart, Transplantation