Introduction: Increasing the usage of hearts from marginal donors and from donors after circulatory death (DCD) has the potential to expand the donor pool. Such hearts may be resuscitated when subjected to ex vivo perfusion. In addition, this may provide an opportunity for viability testing prior to transplant. We describe a novel ex vivo perfusion system designed to reanimate porcine DCD hearts. The same system was subsequently tested using a human heart from a marginal brainstem-dead donor.
Method: In the first phase of the study 23 porcine hearts were procured following circulatory death. All hearts were subjected to a period of primary warm ischemia followed by 120 minutes of hypothermic preservation. The period of hypothermic preservation was initially static cold storage (SCS); then oxygenated machine perfusion and finally a combination of static cold storage and oxygen persufflation via the coronary sinus. Ex vivo perfusion of the hearts was performed with a normothermic, oxygenated blood-based solution in our Langendorff system. In the second phase of the study the same system was used to perfuse a human heart from a marginal brainstem-dead donor. This donor had not met criteria for consideration of heart donation.
Results: 15 of the 23 (65.2%) DCD porcine hearts reanimated following reperfusion on the ex vivo system. Reanimation was achieved with 63.6% (7/11) in the SCS group; 33.3% (2/6) in the machine perfusion group and 100% (6/6) in the persuffl ation group. The human heart was placed in the system after a cold ischemic period of 7 hours 4 minutes and perfused with a mid-thermic temperature solution for a further 2 hours 40 minutes to allow for correction of hyperkalemia before warming. The heart started to work after a further hour and then maintained until the experiment was terminated after a further two hours.
Conclusion: The ex vivo perfusion system described can potentially resuscitate marginal hearts including those from DCD. The system devised in this study could also be used as a platform to functionally assess marginal human hearts. This mode of viability testing would be an essential step to determine suitability for transplant.