Animal Model Simulation for Training With Split-Liver Transplants.

Abstract

Potential conflict of interest: Nothing to report. SEE ARTICLE ON PAGE 510 Split‐liver transplantation is a strategy that enhances the availability of organ transplants1 by potentially providing liver transplants for 2 patients from a single deceased donor.2 However, because of its complexity, most programs have not embraced this strategy. The process of teaching and learning operative procedures has typically involved repetitive exposure to the surgeon’s performance of the procedure by the trainee in order to learn the steps and techniques required and how to avoid the potential complications. The number of procedures necessary for a trainee to become independent is highly variable3 and depends on a number of factors, including the skill of the trainee, the philosophy of the trainer, and the difficulty of the procedure.4 Not all surgical trainees achieve significant autonomy by the end of their training with even the most commonly performed procedures.3 Many complex procedures are performed with low frequency, thus making it difficult to provide trainees with the experience they need to achieve competence.6 Simulation strategies have helped to prepare trainees especially with basic skills, such as suturing, central line placement, and laparoscopy.7 Surgical procedures have been simulated using artificial bench models, virtual reality, and animal models. Virtual reality has the potential to mimic human anatomy and, therefore, to more realistically prepare trainees. However, it does not capture the tactile aspects of performing surgical procedures. Conversely, animal models typically are associated with anatomy that is different from human anatomy, and large animal models have most frequently used pigs, dogs, and primates.8 In this issue of Liver Transplantation, Sanada et al.9 describe the use of an ex vivo porcine liver model to train surgeons to split a cadaveric liver. They describe some general variations in the lobar anatomy of the porcine liver compared with the human liver, which must, of course, be taken into consideration in the training process. Although they indicate that 10 porcine liver transplant splits were performed to develop their technique, they do not comment on the anatomic variability encountered, particularly in the vascular and biliary anatomy, between the individual porcine livers. In human split‐liver transplantation, variability in these structures is a major issue. Because split‐liver transplants come from deceased human multiorgan donors, it is not always possible to perform angiography and cholangiography to delineate the vascular and biliary anatomy prior to the split given the limited time for multiorgan donor procurements. Living donor liver transplantations also provide valuable experience for surgeons learning to perform split‐liver transplantations. With living donors’ angiography, cholangiography and other imaging studies are performed prior to the living donor hepatectomy so that a safe and effective resection line can be clearly defined, resulting in 2 functional liver segments, 1 of which remains in the donor. Despite this, early studies have shown that a program’s complication rate with living donor liver transplantations is not significantly reduced until they have performed at least 20 living donor transplantations.10 Experience with both living donor liver transplantation and deceased donor split‐liver transplantation has revealed that technically the easiest “split” is to separate the left lateral segment from the rest of the liver because this is associated with minimal anatomic variability. Separating the right lobe from the left lobe is feasible but is associated with greater anatomic variability, which makes it challenging to salvage both sides of the “split,” especially when imaging studies defining the anatomy are not available. Overall, because splitting a liver for transplantation is a procedure that is both complex and infrequently performed, strategies that provide trainees with the opportunity to practice performing the procedure in a simulated scenario are likely to be beneficial. Although evolving technologies such as virtual reality may prove to be helpful in the training of surgeons with complex procedures such as liver splits, animal models provide a more realistic experience particularly with the tactile aspects of tissue handling, the recognition of aberrant anatomy, and the decision making subsequently required. Clearly, there are many essential aspects of split‐liver transplantation that are not addressed with the porcine model, including recipient selection, assessment of donor graft quality, graft‐to‐recipient size matching, ischemia time, and vascular and biliary anastomoses. Furthermore, the costs, time commitments, and ethical controversies associated with large animal models further complicate its use.7 Overall, although additional studies will be required to prove its effectiveness, simulation using a porcine model is beneficial in the training of surgeons in performing split‐liver transplantations. Surgeons who master splitting livers in a pig model will still need to actively participate in multiple human deceased donor split‐liver transplantations and/or living donor liver transplantations before they become competent with performing split‐liver transplantations in humans.