Donor shortage worldwide has led to the development of different strategies to increase the organ donor pool. Amongst these strategies, cDCD has emerged as one of the cornerstones for this growth. It is estimated, according to different data, that the utilization of hearts from cDCD donors would have the potential of increasing the heart transplant activity between 15 to 50% depending on the countries [17, 18]. In Spain, based on a raw analysis that includes cDCD donors under 45 years of age, and excludes those with a suspicion of cardiac injury, it is estimated that the inclusion of these donors would account for a 5–10% increase in the number of heart donors, which would increase the number of hearts transplanted by 15–30 hearts per year.
In order to optimize heart function, one of the inclusion criteria of our protocol was that cDCD heart donors had to be under 45 years of age, a fact that narrowed the number of potential donors. For this reason, it was necessary to build a collaborative approach with other donor hospitals. Given the complexity of the recovery procedure in the case of a cDCD heart, together with the relatively small size of the Autonomous Community of Madrid (8.022 km2), we considered that the best approach would be to transfer the potential cDCD heart donor to our own hospital. The previous implementation of an intensive care program to facilitate organ donation in our country has made this a routine practice, whereas small donor hospitals cannot take on sophisticated cDCD procedures [19].
In Spain, ante-mortem interventions aimed at organ preservation that do not interfere with the dying process are not forbidden before WLST as long as the family consents [20]. Ante-mortem cannulation helps to reduce the duration of WIT. The possibility of restoring circulation to the brain – which would retroactively negate the diagnosis of death based on circulatory criteria - is one concern associated to the use of NRP. In the case of A-NRP, it is necessary to inflate an aortic occlusion balloon or to surgically clamp the abdominal aorta before A-NRP starts. In TA-NRP, the ECMO flow cannot start before the supra-aortic trunks have been clamped in order to avoid cerebral perfusion. This maneuver may prolong WIT but, in our case, the sternotomy-to-clamping time was only 4 min, resulting in a WIT of 16 min, which is below the 30-min limit that had been previously stipulated.
The absence of anterior and posterior cerebral perfusion during the procurement, one of the key points of this novel approach, was demonstrated by transcranial doppler, and cerebral electrical activity was monitored with BIS™ which always remained in the 00 mark and showed a suppression rate of 100 indicating an isoelectric electroencephalogram [13, 16, 21, 22].
At present, the majority of hearts recovered from cDCD donors have undergone a period of ex-situ perfusion in an OCS™ [10,11,12]. However, two recent reports have revealed the feasibility of evaluating and successfully transplanting cDCD hearts without the need for ex-situ perfusion based on the use of TA-NRP [13, 14]. In our case, due to our previous experience with A-NRP, we favored this approach [15]. We also consider that one of the advantages of in-situ heart evaluation is that it allows for a more realistic assessment of the heart through well validated techniques like Swan-Ganz or echocardiography. Also, because this was a case of a multiorgan donor, it was essential to guarantee adequate liver and kidney perfusion during their evaluation and procurement. For this reason, liver function tests were monitored every 30 min. Lactate levels were also measured as both markers of organ perfusion and liver function. Although no cut-off values of lactate were established, a decreasing trend was used as a surrogate for appropriate organ perfusion and adequate liver function during AT-NRP [8]. In all, the recovery procedure took around 120 min. In our case, the lungs were not considered due to the donor’s previous history of severe asthma.
Because both the procurement and the transplant were done in the same center, the cold ischemia time was only 55 min. In the future, it will be necessary to address if hearts procured by this technique will tolerate longer cold ischemia times in order to be implanted at a center different from where they have been retrieved. For the time being, our protocol only contemplates procurement and implantation at the same center in order to minimize the duration of cold ischemia, which may lead to better results in the recipient.
Overall, this is one of the few cases in the world, and the first in Spain, of a cDCD heart retrieved using only TA-NRP and successfully implanted, and it opens up the way for multiorgan donation in cDCD. Given the high cost of ex-situ machine perfusion, unaffordable in many settings, TA-NRP may become an option to make heart transplantation from cDCD donors economically feasible for some countries.
