Liver Transplantation in the 21st Century: Expanding the Donor Options

Liver transplantation has evolved since Dr. Thomas Starzl performed the first orthotopic liver transplant (OLT) over 4 decades ago. Advances in immunosuppressive therapy, medical management, surgical technique, and identification of appropriate indications for OLT have resulted in significant improvements in patients’ survival and universal recognition of the procedure as preferred therapy for those suffering from hepatic failure. The number of patients awaiting primary or repeat OLT in the United States has tripled to 18,000 in the last 2 decades. Over the same period, organ availability increased from 1700 to 6200 grafts annually ; however, the concurrent increase in organ availability has not significantly impacted the rate of wait-list mortality; deaths on the waiting list have increased 5-fold over the same period. The discrepancy between supply and demand and the increasing organ scarcity has motivated select transplant centers to relax customary restrictions to donation, creating the term “extended-criteria” donors (ECD) or “marginal” donors. The precise definitions of these terms remain elusive. There is no consensus as to what makes a graft “marginal” in one center and acceptable in another. The use of these ECD grafts often depends on the judgement of the transplant surgeon and the needs of the recipient.

Definitions

An ECD implies higher risk in comparison with a reference donor. Conceptually, this added risk may manifest as an increased incidence of early failure, namely, delayed allograft function or primary nonfunction (PNF), transmission of a donor-derived disease, or, in the case of adult-to-adult living-donor liver transplantation (LDLT), living-donor morbidity. To appreciate the components that define an ECD, it is important to recognize the criteria that define a reference (or ideal) donor: These include age below 40 years, death caused by trauma, donation after brain death (DBD), hemodynamic stability at the time of organ procurement, no steatosis or any other underlying chronic liver disease, and no transmissible disease (infectious or neoplastic).

Durand and colleagues, in a Report of the Paris Consensus Meeting on Expanded Criteria Donors in Liver Transplantation, draw a distinction between an “ideal allograft” and an “ideal donor.” They mention that the ideal allograft category may be influenced by variables that are introduced after procurement, such as prolonged cold ischemia time (CIT) or technical variants, such as those occurring with allograft reduction (split-liver allograft). These variables should ideally not be included in the definition of ECD, because the aim is to assess risk at procurement.

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