Hypothermic continuous machine perfusion enables preservation of energy charge and functional recovery of heart grafts in an ex vivo model of donation following circulatory death

OBJECTIVES: Cardiac transplantation using hearts from donors after circulatory death (DCD) is critically limited by the unavoidable warm ischaemia and its related unpredictable graft function. Inasmuch as hypothermic machine perfusion (MP) has been shown to improve heart preservation, we hypothesized that MP could enable the use of DCD hearts for transplantation. METHODS: We recovered 16 pig hearts following anoxia-induced cardiac arrest and cardioplegia. Grafts were randomly assigned to two different groups of 4-h preservation using either static cold storage (CS) or MP (Modified LifePort (c) System, Organ Recovery Systems (c), Itasca, Il). After preservation, the grafts were reperfused ex vivo using the Langendorff method for 60 min. Energetic charge was quantified at baseline, post-preservation and post-reperfusion by measuring lactate and high-energy phosphate levels. Left ventricular contractility parameters were assessed both in vivo prior to ischaemia and ex vivo during reperfusion. RESULTS: Following preservation, the hearts that were preserved using CS exhibited higher lactate levels (57.1 +/- 23.7 vs 21.4 +/- 12.2 mu mol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate ratio (0.53 +/- 0.25 vs 0.11 +/- 0.11; P < 0.001) and lower phosphocreatine/ creatine ratio (9.7 +/- 5.3 vs 25.2 +/- 11; P < 0.001) in comparison with the MP hearts. Coronary flow was similar in both groups during reperfusion (107 +/- 9 vs 125 v 9 ml/100 g/min heart; P = ns). Contractility decreased in the CS group, yet remained well preserved in the MP group. CONCLUSION: MP preservation of DCD hearts results in improved preservation of the energy and improved functional recovery of heart grafts compared with CS.