Split-liver transplantation: an underused resource in liver transplantation

Encouraging Split Liver Transplantation for Two Adult Recipients to Mitigate the High Incidence of Wait-list Mortality in The Setting of Extreme Shortage of Deceased Donors

Background: Organ demand for liver transplantation (LT) is constantly increasing. Split liver transplantation (SPLT) is an ideal option for increasing the number of available liver grafts for transplantation and ameliorating organ shortage to a certain degree. However, SPLT for two adult recipients is still not broadly applied. Methods: We retrospectively analyzed the outcomes of SPLT for adult recipients at a single center. All donor, recipient, and transplantation factors were thoroughly investigated to clarify factors affecting patient outcomes after LT. Results: One hundred consecutive adult SPLTs were performed during the study period. Early mortality and 1-year mortality occurred in 21 and 31 recipients, respectively. On multivariate analysis, graft weight (p = 0.036, odds ratio = 0.99, 95% confidence interval = 0.98-0.99) was the independent risk factor associated with early mortality; however, no factor was significantly related to 1-year mortality. On receiver operating characteristic curve analysis, a graft weight of 580 g was identified the cutoff for stratifying outcomes. Recipients transplanted with a graft weighing ≥580 g had significantly better outcome as compared with other recipients (p = 0.001). Moreover, SPLT remarkably provided a better survival benefit for recipients than those on the LT wait-list (p < 0.0001). Conclusions: Given the considerable incidence of wait-list mortality, SPLT for two adult recipients should be encouraged whenever possible to increase the donor pool and benefit patients awaiting LT. Nonetheless, caution should be taken with a smaller graft weight owing to the risk of early graft loss.

Is there an ethical obligation to split every donor liver? Scarce resources, medical factors, and ethical reasoning

SLT has the potential to counter the worldwide shortage of donor organs. Although the preferred recipients of SLT are usually pediatric patients, a more stringent ethical argument than the fundamental prioritization of children is to demonstrate that SLT of deceased donor organs could increase access to this potentially lifesaving resource for all patients, including children. Several empirical studies show that SLT also makes it possible to achieve similar outcomes to WLT in adults if several factors are observed. In general, it can be regarded as ethically permissible to insist on splitting a donor liver if, in an individual case, SLT is expected to have a similar outcome to that of WLT. The question is therefore no longer whether, but under what conditions SLT is able to achieve similar results to WLT. One of the main challenges of the current debate is the restricted comparability of the available data. We therefore have an ethical obligation to improve the available empirical data by implementing prospective clinical studies, SLT programs, and national registries. The introduction of 2 modes of allocation-one for patients willing to accept both SLT and WLT, and a second for patients only willing to accept WLT-would help to resolve the issue of patient autonomy in the case of mandatory splitting policy.

Early and Late Factors Impacting Patient and Graft Outcome in Pediatric Liver Transplantation: Summary of an ESPGHAN Monothematic Conference

As pediatric liver transplantation comes of age, experts gathered to discuss current paradigms and define gaps in knowledge warranting research to further improve patient and graft outcomes. Identified areas ripe for collaborative research include understanding the molecular and cellular mechanisms of tolerance and the role of donor-specific antibodies, considering ways to expand donor pool, minimizing long-term side effects of immunosuppression, and fine-tuning surgical techniques to minimize biliary and vascular complications.

Changes in liver acceptance patterns after implementation of Share 35

The Share 35 policy was implemented June 2013. We sought to evaluate liver offer acceptance patterns of centers under this policy. We compared three 1-year eras (1, 2, and 3) before and 1 era (4) after the implementation date of the Share 35 policy (June 18, 2013). We evaluated all offers for liver-only recipients including only those offers for livers that were ultimately transplanted. Logistic regression was used to develop a liver acceptance model. In era 3, there were 4809 offers for Model for End-Stage Liver Disease (MELD) score ≥ 35 patients with 1071 acceptances (22.3%) and 10,141 offers and 1652 acceptances (16.3%) in era 4 (P < 0.001). In era 3, there were 42,954 offers for MELD score < 35 patients with 4181 acceptances (9.7%) and 44,137 offers and 3882 acceptances (8.8%) in era 4 (P < 0.001). The lower acceptance rate persisted across all United Network for Organ Sharing regions and was significantly less in regions 2, 3, 4, 5, and 7. Mean donor risk index was the same (1.3) for all eras for MELD scores ≥ 35 acceptances and the same (1.4) for MELD score < 35 acceptances. Refusal reasons did not vary throughout the eras. The adjusted odds ratio of accepting a liver for a MELD score of 35 + compared to a MELD score < 35 patient was 1.289 before the policy and 0.960 after policy implementation. In conclusion, the Share 35 policy has resulted in more offers to patients with MELD scores ≥ 35. Overall acceptance rates were significantly less compared to the same patient group before the policy implementation. Centers are less likely to accept a liver for a patient with a MELD score of 35 + after the policy change. Decreased donor acceptance rates could reflect more programmatic selectivity and ongoing donor and recipient matching.

Feasibility of split liver transplantation for 2 adults in the model of end-stage liver disease era

OBJECTIVE

To examine the results of split liver transplantation for 2 adults in the model of end-stage liver disease (MELD) era.

BACKGROUND

In the MELD era, liver allografts are first allocated to recipients with the highest MELD scores. However, the application of split liver transplantation for 2 adults in urgent condition has doubled and has become a matter of concern.

METHODS

Twenty-one deceased liver grafts were split into full right and full left lobes for 42 adult recipients. One of the hemiliver grafts was allocated to the recipient with the highest MELD score in the waiting list. The results of split liver transplantation were examined and compared with those of living donor liver transplantation.

RESULTS

Among 42 recipients, 24 (57.1%) had MELD scores higher than 20. The median (interquartile) MELD score for the recipients with split liver transplantation was 22 (15-30), which was higher than that for the recipients with living donor liver transplantation (P < 0.001). The 1-, 3-, and 5-year survival rates for split liver transplantation were comparable with those of living donor transplantation (P = 0.489). Nevertheless, 10 of 42 split liver recipients died within 3 months after transplantation. By receiver operating characteristic curve analysis, the safe graft-recipient weight ratio was better more than 1% to avoid early patient death for split liver transplantation.

CONCLUSIONS

Although most of the recipients with split liver transplantation had high MELD scores, the results were comparable with those of living donor liver transplantation. Split liver transplantation for 2 adults is still feasible in the MELD era.

Donor-recipient matching: myths and realities

Liver transplant outcomes keep improving, with refinements of surgical technique, immunosuppression and post-transplant care. However, these excellent results and the limited number of organs available have led to an increasing number of potential recipients with end-stage liver disease worldwide. Deaths on waiting lists have led liver transplant teams maximize every organ offered and used in terms of pre and post-transplant benefit. Donor-recipient (D-R) matching could be defined as the technique to check D-R pairs adequately associated by the presence of the constituents of some patterns from donor and patient variables. D-R matching has been strongly analysed and policies in donor allocation have tried to maximize organ utilization whilst still protecting individual interests. However, D-R matching has been written through trial and error and the development of each new score has been followed by strong discrepancies and controversies. Current allocation systems are based on isolated or combined donor or recipient characteristics. This review intends to analyze current knowledge about D-R matching methods, focusing on three main categories: patient-based policies, donor-based policies and combined donor-recipient systems. All of them lay on three mainstays that support three different concepts of D-R matching: prioritarianism (favouring the worst-off), utilitarianism (maximising total benefit) and social benefit (cost-effectiveness). All of them, with their pros and cons, offer an exciting controversial topic to be discussed. All of them together define D-R matching today, turning into myth what we considered a reality in the past.

Prediction models of donor arrest and graft utilization in liver transplantation from maastricht-3 donors after circulatory death

Shortage of organs for transplantation has led to the renewed interest in donation after circulatory-determination of death (DCDD). We conducted a retrospective analysis (2001-2009) and a subsequent prospective validation (2010) of liver Maastricht-Category-3-DCDD and donation-after-brain-death (DBD) offers to our program. Accepted and declined offers were compared. Accepted DCDD offers were divided into donors who went on to cardiac arrest and those who did not. Donors who arrested were divided into those producing grafts that were transplanted or remained unused. Descriptive comparisons and regression analyses were performed to assess predictor models of donor cardiac arrest and graft utilization. Variables from the multivariate analysis were prospectively validated. Of 1579 DCDD offers, 621 were accepted, and of these, 400 experienced cardiac arrest after withdrawal of support. Of these, 173 livers were transplanted. In the DCDD group, donor age < 40 years, use of inotropes and absence of gag/cough reflexes were predictors of cardiac arrest. Donor age >50 years, BMI >30, warm ischemia time >25 minutes, ITU stay >7 days and ALT ≥ 4× normal rates were risk factors for not using the graft. These variables had excellent sensitivity and specificity for the prediction of cardiac arrest (AUROC = 0.835) and graft use (AUROC = 0.748) in the 2010 prospective validation. These models can feasibly predict cardiac arrest in potential DCDDs and graft usability, helping to avoid unnecessary recoveries and healthcare expenditure.

Regulation of hepatic blood flow: The hepatic arterial buffer response revisited

The interest in the liver dates back to ancient times when it was considered to be the seat of life processes. The liver is indeed essential to life, not only due to its complex functions in biosynthesis, metabolism and clearance, but also its dramatic role as the blood volume reservoir. Among parenchymal organs, blood flow to the liver is unique due to the dual supply from the portal vein and the hepatic artery. Knowledge of the mutual communication of both the hepatic artery and the portal vein is essential to understand hepatic physiology and pathophysiology. To distinguish the individual importance of each of these inflows in normal and abnormal states is still a challenging task and the subject of ongoing research. A central mechanism that controls and allows constancy of hepatic blood flow is the hepatic arterial buffer response. The current paper reviews the relevance of this intimate hepatic blood flow regulatory system in health and disease. We exclusively focus on the endogenous interrelationship between the hepatic arterial and portal venous inflow circuits in liver resection and transplantation, as well as inflammatory and chronic liver diseases. We do not consider the hepatic microvascular anatomy, as this has been the subject of another recent review.

Conventional split liver transplantation for two adult recipients: a recent experience in a single European center

BACKGROUND

Split liver transplantation (SLT) for two adult recipients is still considered a challenging procedure, especially when subjected to model for end-stage liver disease (MELD)-based allocation criteria.

METHODS

Twenty-two SLTs were performed in adult recipients in a European center operating within a MELD-oriented system. Thirteen right-sided grafts and nine left-sided grafts were used. Right-sided grafts included 11 extended right grafts and two full right grafts. Left-sided grafts included six left lateral segment grafts and three full left grafts. Ninety-three percent of donors were allocated based on MELD score. Median graft-to-recipient body weight ratio was 1.53 (range 1.07-2.11) with right-sided grafts and 0.81 (range 0.67-1.11) with left-sided grafts. Liver cirrhosis (46%) and metabolic/genetic disorders (56%) were the main indications for transplant in recipients of right and left grafts, respectively.

RESULTS

Overall patient and graft survival were 90% and 86%. Patient survival was 84% in recipients of right grafts and 100% in recipients of left grafts. Graft survival was 84% and 89%, respectively. Vascular and biliary complications occurred in 14% and 4% of cases. Postoperative serum levels of total bilirubin were significantly higher in recipients of left-sided grafts versus right-sided grafts on postoperative days 7 and 14. Prothrombin activity was significantly lower in recipients of left-sided grafts versus right-sided grafts on postoperative days 3 and 7.

CONCLUSIONS

SLT for two adult recipients can be successfully performed even using left lateral segments by assigning one graft according to MELD score, and with a more liberal allocation of the second graft.

Liver transplantation: Issues for the next 20 years

The growing numbers of potential transplant recipients on waiting lists is increasingly disproportionate to the supply of cadaveric donor organs. The hope for the next 20 years is that supply will satisfy demand. This requires both a reduction in indications for the procedure and an increase in the transplants performed. A multi-pronged approach is needed to increase cadaveric organ donation, generating enthusiasm for donation among both the general public and hospital staff. Accurate assessment of marginal grafts with stringent criteria known to predict graft function will diminish wastage of organs. Methods of rehabilitating marginal grafts during extracorporeal perfusion will increase organ availability. Supply of non-heart beating donors can be greatly expanded and protocols developed with ethical consent to optimize their initial function despite warm ischemia. Splitting livers that fulfill selection criteria, thus providing for two recipients, should be universally applied with acceptable incentives to those units who do not directly benefit. A proportion of recipients, though not those transplanted for autoimmune disease, will be spared the side-effects of immunosuppression thanks to immune tolerance. Protocols for close monitoring of those patients for rejection during treatment withdrawal must be carefully observed. In addition to gene therapy, it is highly likely that hepatocyte transplantation will replace orthotopic grafting in patients without cirrhosis, especially for inherited metabolic diseases. It is much more difficult to envisage that heterologous stem cell transplantation or xenotransplantation will have clinical impact in the next 20 years, although research in those areas has obvious long-term potential.

[How can the number of liver transplantations be increased?]

The number of patients suitable for liver transplantation is progressively increasing due to the excellent results achieved with this procedure, giving rise to a growing imbalance in the number of candidates on the waiting list and the number of donors. This situation has prompted transplant teams to search for alternatives to increase the number of liver grafts. On the one hand, the criteria for donation have been broadened to include donors with advanced age, liver steatosis, hepatitis B and C viruses, neoplasms, and benign underlying diseases. On the other hand, new transplant techniques have been used with grafts from split livers, living donors, sequential or domino transplants and non-heart-beating donors. Other options such as xenotransplantation and hepatocyte transplants currently lack clinical applicability.

Percutaneous Transhepatic Bile Duct Ablation with n-Butyl Cyanoacrylate in the Treatment of a Biliary Complication after Split Liver Transplantation

Biliary complications continue to be a major cause of morbidity after split-liver transplantation (SLT). In this report we describe an uncommon late biliary complication. One year after SLT the patient showed an intrahepatic bile dicy dilatation with severe cholangitis episodes. The segmentary bile duct of hepatic segment VI-VII draining in the left duct was unidentified and tied at the time of the in situ split-liver procedure. We perform a permanent obliteration of the dilated intrahepatic ducts by a percutaneous embolization using an n-butyl cyanoacrylate (NABC). The management of biliary complications after SLT requires a multidisciplinary approach. The use of NBCA in obliteration of a dilated bile duct seems to be a safe procedure with good results providing a less invasive option than hepatic resection and decreasing the morbidity associated with chronic external biliary drainage. Further studies are needed to determine whether this approach is effective and safe and whether it could reduce hospital stay and cost.