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

Abstract

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 DCD, blood collection delays delivery of cardio-protective solution resulting in longer warm ischaemic times. Banked blood (BB) is a potential alternative to donor blood. We investigate 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 24 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 NO pre-treatment (n=5), and Sodium Nitroprusside (SNP) infusion (n=5). Results: BB demonstrates severe metabolic and electrolyte disturbances requiring correction before organ perfusion. Both group were successful in cardiac reanimation and demonstrated favourable lactate trend during perfusion. BB had higher perfusion pressure which continues to rise overtime with resultant deterioration in cardiac function. The introduction of NO and SNP only provided temporary relief to the observed hypertension. Conclusion: BB in the reperfusion of donor hearts on NMP results in significantly higher perfusion pressures leading to progressive deterioration of cardiac recovery. Treatment with vasodilators produced short-lived benefits.