Optimizing Resuscitation of the Donation after Circulatory Death Heart by Mitochondrial Protection in a Female Porcine Model.

Background: Due to the shortage of donor organs, an increasing number of transplant organs are harvested after circulatory arrest (donation after circulatory death [DCD]). Using a translational porcine model of DCD, this study developed and evaluated a protocol based on cardioprotection by multidrug postconditioning to optimize resuscitation of DCD hearts during ex situ heart perfusion (ESHP).

Methods: Hearts of female pigs (45.0 ± 4.5 kg) were procured following a clinically identical DCD protocol, consisting of the termination of ventilator support and confirmation of circulatory arrest, followed by a 15-min standoff period. DCD hearts were randomly allocated to ESHP (38.4°C) in the absence (untreated, N = 5) or presence (treated, N = 5) of a postconditioning treatment added to the perfusate, consisting of Intralipid (1%), sevoflurane (2% v/v), and remifentanil (3 nM). All hearts were perfused with blood and Krebs-Henseleit solution (1:1) for 60 min in Langendorff mode and for an additional 300 min in working mode for a total perfusion time of 6 h. Oxidative capacity and detailed left ventricular mechanical function under an increasing workload (left atrial pressure, 6 to 12 mmHg) were assessed hourly. Left ventricular tissue was snap-frozen at the end of ESHP and used for molecular analyses.

Results: Left ventricular inotropy (LVdP/dtmax) did not decline over time in treated DCD hearts and was significantly higher at the end of the protocol as compared with untreated DCD hearts (ΔLVdP/dtmax = 440 mmHg/s; P = 0.009). Treated DCD hearts exhibited persistently higher left ventricular stroke work index during the 6-h period of ESHP, whereas untreated DCD hearts displayed a significant decline (change in left ventricular stroke work index = -3.10 ml · mmHg/g; P(time within untreated group) < 0.001). Treated DCD hearts displayed higher metabolic activity as measured by oxygen consumption (ΔO2 = 3.11 ml O2 · min-1 · 100 g-1; P = 0.004) and released lower amounts of cell-free mitochondrial DNA into the perfusate, a marker of potential graft dysfunction. Treated hearts also used fatty acids from Intralipid as an energy source, whereas untreated DCD hearts showed glyceroneogenesis with triglyceride accumulation and depletion of tricarboxylic acid cycle intermediates; reduced mitochondrial complex I, II, and III activities with accumulation of mitochondrial NADH, and signs of ultrastructural damage.

Conclusions: A translationally relevant protective ESHP protocol consisting of treatment with Intralipid, sevoflurane, and remifentanil markedly accelerated functional recovery and improved viability of DCD hearts.