Background: An increasing number of experimental and clinical studies reports hemodynamic instability in the donor organism after brain death. However, the relative importance of brain death-related cardiac dysfunction on posttransplantation cardiac function and the reversibility of the observed changes remain controversial. In this study a load-independent analysis of cardiac function after brain death was performed. Special interest was focused on a possible interactive influence of brain death and cardiac preservation on postischemic cardiac function.
Methods: In 12 anesthetized dogs, brain death was induced by inflation of a subdural balloon; 12 sham-operated animals served as control subjects. After a 2-hour observation in situ, the hearts were explanted and perfused parabiotically either immediately or after hypothermic ischemic preservation (4 hours, 4 degrees C). Heart rate, cardiac output, left ventricular pressure, the maximum of left ventricular pressure development and aortic pressure were measured in situ. In addition, the slope of the end-systolic pressure-volume relationship, coronary blood flow, and myocardial oxygen consumption were estimated in the cross-circulated hearts.
Results: In spite of a brain death-associated hemodynamic deterioration in situ (expressed as low mean aortic pressure and significant decrease of maximal dP/dt), myocardial function was similar to control after explantation, if assessed ex vivo. Furthermore, after hypothermic ischemic preservation and reperfusion, complete functional recovery of control and brain-dead hearts could be observed.
Conclusions: These data indicate that hemodynamic instability after brain death may rather reflect altered loading conditions than irreversible myocardial damage or primary cardiac dysfunction. Furthermore, there is no evidence for a brain death-related impairment of ischemic tolerance.