Ex-Vivo Perfusion of Donor Hearts: the Feasibility of Banked Blood for Normothermic Machine Perfusion

Background: Normothermic machine perfusion (NMP) utilises 1.2-1.5L of donor blood (DB) with a target perfusate haematocrit of 25% to reanimate the donor heart.Limitations to current practise include small donor size and donor anaemia which can impact on the recovery of these hearts.Furthermore, in donation after circulatory death (DCD), blood collection may delay delivery of preservation solutions resulting in longer warm ischaemic times for the heart and other organs.Banked blood (BB) is a potential alternative to donor blood.We investigated the effect of banked blood for the reanimation and perfusion of donor hearts in a DCD porcine model.Methods: Series 1: Landrace pigs (n=12) underwent DCD withdrawal with subsequent procurement of the heart; 6 were reperfused with autologous blood; 6 were reperfused with BB (collected 48 hours prior).Hearts were maintained on NMP for 5 hours with continuous pressure and flow measurement.Serial venous and arterial lactate measurements were performed as a marker of organ health.Series 2: Ten further studies in the BB group with nitric oxide (NO) pre-treatment (n=5), or sodium nitroprusside (SNP) infusion (n=5).Results: BB demonstrated severe metabolic and electrolyte disturbances requiring correction before organ perfusion.Both groups were successful in cardiac reanimation and demonstrated favourable lactate trends during perfusion.Perfusion with BB resulted in higher coronary perfusion pressure (CPP) which continued to rise overtime with resultant deterioration in cardiac function.The administration of NO delayed but did not prevent the rise in CPP.SNP infusion prevented the rise in CPP but resulted in severe hyperkalaemia.Conclusions: Reperfusion of DCD hearts with BB during NMP results in significantly higher perfusion pressures leading to progressive deterioration of cardiac recovery.Treatment with nitro vasodilators produced short-lived benefits.