Brain death-related energetic failure of the donor heart becomes apparent only during storage and reperfusion: An ex vivo phosphorus-31 magnetic resonance spectroscopy study on the feline heart

Background and Objective: Recently, we have shown, by using localized in vi vo phosphorus-31 magnetic resonance spectroscopy (P-31 MRS) of the anterior left ventricular wall, that brain death (BD) is not associated with reduce d myocardial energy status. In this study, we applied ex vivo P-31 MRS of t he entire heart to study the effects of BD on the energy status of the feli ne donor heart following explantation. Methods: We used cats (6 BD and 6 controls [C]) in a 26-hour protocol. Afte r 2 hours of preparation, we induced BD by filling an intracranial balloon at t = 0 hour. At t = 6 hours, the hearts were arrested with St. Thomas' Ho spital cardioplegic solution, explanted, and stored in the same solution at 4 degreesC in a 4.7 Tesla magnet for 17 hours. Subsequently, the hearts we re reperfused in the Langendorff mode at 38 degreesC for 1 hour. The first 5-minute P-31 MRS spectrum was obtained 1 hour after crossclamping the aort a; we obtained subsequent spectra every hour during storage and every 5 min utes during reperfusion. At the end, the hearts were dried and weighed. Pho sphocreatine (PCr), gamma -adenosine triphosphate (gamma -ATP), inorganic p hosphate (Pi), and phosphomonoesters (PME), were expressed per g dry heart weight. The intracellular pH (pH(i)) and the PCr/ATP ratio were calculated. Results: During storage, we identified a significant but similar decrease o f pH(i), PCr/ATP ratio, and PCr in both groups. During reperfusion, pHi and PCr/ATP ratio recovered similarly in both groups, whereas the recovery of PCr in the BD group was significantly lower (p < 0.05). The Pi and PME incr eased in both groups during storage but to a lesser extent in the BD group (p < 0.05). This difference disappeared during reperfusion. The gamma -ATP was already significantly lower in the BD group at the onset of storage, an d this remained so throughout storage and reperfusion (P < 0.05 vs C). Cont ractile capacity was lost in all hearts, except for I heart in the BD group . Conclusion: Brain death-related failure of the energetic integrity of the f eline donor heart becomes apparent only when using P-31 MRS during ischemic preservation and subsequent reperfusion.