The Impact of Implantation Time During Liver Transplantation on Outcome: A Eurotransplant Cohort Study

Shortening the recipient warm ischemia time could be a strategy for expanding the liver donor pool

BACKGROUND

Shortening the recipient warm ischemia time (rWIT) has been proven to be effective for improving the short- and long-term outcomes after liver transplantation (LT) and offsets the negative impact of an extended cold ischemia time. However, few studies have been conducted to explore the prognostic effects of shortening the rWIT in transplantations using a liver graft from an extended-criteria donor (ECD).

AIM

To investigate whether shortening the rWIT could improve the outcomes of ECD LT.

METHODS

Rat ECD autologous orthotopic LT were performed with variable rWITs (0, 10, 20, and 30 minutes). Near-infrared fluorescence imaging (FI) was used for the real-time assessment of liver graft ischemia-reperfusion injury after the anhepatic phase. Survival was assessed, and liver function and histological analyses were performed on the third day after transplantation.

RESULTS

The FI curve growth rate and postoperative three-day survival rate significantly increased, and the liver function and Suzuki score of the liver grafts significantly improved when the rWIT was ≤ 10 minutes (P < 0.05).

CONCLUSION

The post-transplant outcomes were significantly better with a shorter rWIT (10 minutes or less) than with a longer rWIT, which could be a strategy for expanding the liver donor pool.

The effect of rewarming ischemia on tissue transcriptome and metabolome signatures: A clinical observational study in lung transplantation

BACKGROUND

In lung transplantation (LuTx), various ischemic phases exist, yet the rewarming ischemia time (RIT) during implantation has often been overlooked. During RIT, lungs are deflated and exposed to the body temperature in the recipient's chest cavity. Our prior clinical findings demonstrated that prolonged RIT increases the risk of primary graft dysfunction. However, the molecular mechanisms of rewarming ischemic injury in this context remain unexplored. We aimed to characterize the rewarming ischemia phase during LuTx by measuring organ temperature and comparing transcriptome and metabolome profiles in tissue obtained at the end versus the start of implantation.

METHODS

In a clinical observational study, 34 double-LuTx with ice preservation were analyzed. Lung core and surface temperature (n = 65 and 55 lungs) were measured during implantation. Biopsies (n = 59 lungs) were wedged from right middle lobe and left lingula at start and end of implantation. Tissue transcriptomic and metabolomic profiling were performed.

RESULTS

Temperature increased rapidly during implantation, reaching core/surface temperatures of 21.5°C/25.4°C within 30 minutes. Transcriptomics showed increased proinflammatory signaling and oxidative stress at the end of implantation. Upregulation of NLRP3 and NFKB1 correlated with RIT. Metabolomics indicated elevated levels of amino acids, hypoxanthine, uric acid, and cysteineglutathione disulfide alongside decreased levels of glucose and carnitines. Arginine, tyrosine, and 1-carboxyethylleucine showed a correlation with incremental RIT.

CONCLUSIONS

The final rewarming ischemia phase in LuTx involves rapid organ rewarming, accompanied by transcriptomic and metabolomic changes indicating proinflammatory signaling and disturbed cell metabolism. Limiting implantation time and cooling of the lung represent potential interventions to alleviate rewarming ischemic injury.

Age Matters: What Affects the Cumulative Lifespan of a Transplanted Liver?

OBJECTIVE

To assess factors affecting the cumulative lifespan of a transplanted liver.

BACKGROUND

Liver aging is different from other solid organs. It is unknown how old a liver can actually get after liver transplantation.

METHODS

Deceased donor liver transplants from 1988 to 2021 were queried from the United States UNOS registry. Cumulative liver age was calculated as donor age + recipient graft survival.

RESULTS

In total, 184,515 livers were included. Most were donation after brain death donors (n = 175,343). The percentage of livers achieving >70, 80, 90, and 100 years cumulative age was 7.8% (n = 14,392), 1.9% (n = 3576), 0.3% (n = 528), and 0.01% (n = 21), respectively. The youngest donor age contributing to a cumulative liver age >90 years was 59 years, with posttransplant survival of 34 years. In pediatric recipients, 736 (4.4%) and 282 livers (1.7%) survived >50 and 60 years overall, respectively. Transplanted livers achieved cumulative age >90 years in 2.86 per 1000 and >100 years in 0.1 per 1000. The U.S. population at large has a cumulative "liver age" >90 years in 5.35 per 1000 persons, and >100 years in 0.2 per 1000. Livers aged >60 years at transplant experienced both improved cumulative survival ( P < 0.0001) and interestingly improved survival after transplantation ( P < 0.0001). Recipient warm ischemia time of >30 minutes was most predictive of reduced cumulative liver survival overall (n = 184,515, hazard ratio = 1.126, P < 0.001) and excluding patients with mortality in the first 6 months (n = 151,884, hazard ratio = 0.973, P < 0.001).

CONCLUSIONS

In summary, transplanted livers frequently get as old as those in the average population despite ischemic-reperfusion-injury and immunosuppression. The presented results justify using older donor livers regardless of donation type, even in sicker recipients with limited options.

Rapid liver graft implantation in canine: A preliminary study

Background

The current method for liver graft implantation during the anhepatic phase is complex. Therefore, this study aimed to introduce a modified orthotopic liver transplantation (OLT) technique with major vascular reconstruction using cuff technique to simplify the process of liver graft implantation during the anhepatic phase.

Methods

Twenty-four canines were randomly assigned to two groups: the modified orthotopic liver transplantation group (M-OLT, n = 12) and the control group (n = 12). All animals were randomly assigned to the donor or recipient groups. The recipients received orthotopic liver transplantation using a modified technique in the M-OLT group, and OLT using traditional implantation technique without venovenous bypass was performed in the control group. The donor and recipient characteristics were compared between the two groups. Vascular anastomotic patency was evaluated using angiography immediately and one week after surgery.

Results

All recipients underwent successful liver transplantation. There were no significant differences between the two groups in terms of sex, body weight, or cold ischemia time of the donor liver. However, recipients in the M-OLT group had a shorter operation time, less intraoperative blood loss, shorter anhepatic phase, shorter vascular occlusion time, and shorter warm ischemia time than that in the control group (all p < 0.05). No anastomotic leakage or stenosis was detected in either group after liver transplantation. One recipient in the M-OLT group and three in the control group died within one week of transplantation.

Conclusions

This modified technique is safe and feasible for canine liver transplantation and can significantly simplify liver graft implantation procedures during the anhepatic period.

Does Time to Asystole in Donors After Circulatory Death Impact Recipient Outcome in Liver Transplantation?

BACKGROUND

The agonal phase can vary following treatment withdrawal in donor after circulatory death (DCD). There is little evidence to support when procurement teams should stand down in relation to donor time to death (TTD). We assessed what impact TTD had on outcomes following DCD liver transplantation.

METHODS

Data were extracted from the UK Transplant Registry on DCD liver transplant recipients from 2006 to 2021. TTD was the time from withdrawal of life-sustaining treatment to asystole, and functional warm ischemia time was the time from donor systolic blood pressure and/or oxygen saturation falling below 50 mm Hg and 70%, respectively, to aortic perfusion. The primary endpoint was 1-y graft survival. Potential predictors were fitted into Cox proportional hazards models. Adjusted restricted cubic spline models were generated to further delineate the relationship between TTD and outcome.

RESULTS

One thousand five hundred fifty-eight recipients of a DCD liver graft were included. Median TTD in the entire cohort was 13 min (interquartile range, 9-17 min). Restricted cubic splines revealed that the risk of graft loss was significantly greater when TTD ≤14 min. After 14 min, there was no impact on graft loss. Prolonged hepatectomy time was significantly associated with graft loss (hazard ratio, 1.87; 95% confidence interval, 1.23-2.83; P  = 0.003); however, functional warm ischemia time had no impact (hazard ratio, 1.00; 95% confidence interval, 0.44-2.27; P  > 0.9).

CONCLUSIONS

A very short TTD was associated with increased risk of graft loss, possibly because of such donors being more unstable and/or experiencing brain stem death as well as circulatory death. Expanding the stand down times may increase the utilization of donor livers without significantly impairing graft outcome.

A single center analysis of long-term outcomes and survival related risk factors in liver retransplantation

Background

Liver retransplant is the only option to save a patient with liver graft failure. However, it is controversial due to its poor survival outcome compared to primary transplantation. Insufficient deceased organ donation in Taiwan leads to high waitlist mortality. Hence, living-donor grafts offer a valuable alternative for retransplantation. This study aims to analyze the single center's outcome in living donor liver retransplantation (re-LDLT) and deceased donor liver retransplantation (re-DDLT) as well as the survival related confounding risk factors.

Methods

This is a single center retrospective study including 32 adults who underwent liver retransplantation (re-LT) from June 2002 to April 2020. The cohort was divided into a re-LDLT and a re-DDLT group and survival outcomes were analyzed. Patient outcomes over different periods, the effect of timing on survival, and multivariate analysis for risk factors were also demonstrated.

Results

Of the 32 retransplantations, the re-LDLT group (n=11) received grafts from younger donors (31.3 vs. 43.75 years, P=0.016), with lower graft weights (688 vs. 1,457.2 g, P<0.001) and shorter cold ischemia time (CIT) (45 vs. 313 min, P<0.001). The 5-year survival was significantly better in the re-LDLT group than in the re-DDLT group (100% vs. 70.8%, P=0.02). This difference was adjusted when only retransplantation after 2010 was analyzed. Further analysis showed that the timing of retransplantation (early vs. late) did not affect patient survival. Multivariate analysis revealed that prolonged warm ischemia time (WIT) and intraoperative blood transfusion were related to poor long-term survival.

Conclusions

Retransplantation with living donor graft demonstrated good long-term outcomes with acceptable complications to both recipient and donor. It may serve as a choice in areas lacking deceased donors. The timing of retransplantation did not affect the long-term survival. Further effort should be made to reduce WIT and massive blood transfusion as they contributed to poor survival after retransplantation.

Off-pump lung re-transplantation avoiding clamshell thoracotomy is feasible and safe: a single-center experience

Background

Lung re-transplantation (re-LTx) is the only therapeutic option for selected patients with advanced allograft dysfunction. This study aims to describe our center's experience to illustrate the feasibility and safety of off-pump re-LTx avoiding clamshell incision.

Methods

We performed a retrospective analysis of 42 patients who underwent bilateral re-LTx between 2007 and 2021. Patients were classified according to their surgical approach and extracorporeal life support (ECLS)-use. Demographics, surgical technique, and short- and long-term outcomes were compared between groups. Continuous data were examined with an independent-sample t-test or non-parametric test. Pearson's chi-squared and Fisher's exact were used to analyze categorical data.

Results

Twenty-six patients (61.9%) underwent re-LTx by anterior thoracotomy without ECLS. Compared to the more invasive approach (thoracotomy with ECLS and clamshell with/without ECLS, n=16, 38.1%), clamshell-avoiding off-pump re-LTx patients had a shorter operative time (471.6±111.2 vs. 704.0±273.4 min, P=0.010) and less frequent grade 3 primary graft dysfunction (PGD-3) at 72 h (7.7% vs. 37.5%, P=0.038). No significant difference was found in PGD-3 incidence within 72 h, mechanical ventilation, intensive care unit (ICU) and hospital stay, and the incidence of reoperation within 90 days between groups (P>0.05). In the long-term, the clamshell-avoiding and off-pump approach resulted in similar 1- and 5-year patient survival vs. the more invasive approach.

Conclusions

Our experience shows that clamshell-avoiding off-pump re-LTx is feasible and safe in selected patients on a case-by-case evaluation.

Biliary atresia and liver transplantation in the United States: A contemporary analysis

BACKGROUND

Biliary atresia (BA) remains the number one indication for paediatric liver transplantation (LT) worldwide but is an uncommon indication for older LT recipients. The impact of recent donor allocation changes, pervasive organ shortage and evolving LT practices on the BA LT population is unknown.

METHODS

We identified patients who underwent LT between January 2010 and December 2021 using the UNOS database. We compared clinical outcomes between patients with BA and those with non-BA cholestatic liver disease. Groups were stratified by age, <12 years (allocated via PELD system) and ≥12 years (allocated via MELD system). Waitlist outcomes were compared using competing-risk regression analysis, graft survival rates were compared using Kaplan-Meier time-to-event analysis and Cox proportional hazards modelling provided adjusted estimates.

RESULTS

There were 2754 BA LT waitlist additions and 2206 BA LTs (1937 <12 years [younger], 269 ≥12 years [older]). There were no differences in waitlist mortality between BA and non-BA cholestatic patients. Among BA LT recipients, there were 441 (20.0%) living-donor liver transplantations (LDLT) and 611 (27.7%) split deceased-donor LTs. Five-year graft survival was significantly higher among BA versus non-BA cholestatic patients in the older group (88.3% vs. 79.5%, p < .01) but not younger group (89.3% vs. 89.5%). Among BA LT recipients, improved graft outcomes were associated with LDLT (vs. split LT: HR: 2, 95% CI: 1.03-3.91) and higher transplant volume (volume >100 vs. <40 BA LTs: HR: 3.41, 95% CI: 1.87-6.2).

CONCLUSION

Liver transplant outcomes among BA patients are excellent, with LDLT and higher transplant centre volume associated with optimal graft outcomes.

Stapled Anastomosis for Side-to-Side Cavo-Cavostomy in Orthotopic Liver Transplantation

In liver transplantation, a side-to-side anastomosis is one of the commonly performed techniques of the inferior vena cava reconstruction. The authors report a case of an application of an endoscopic vascular linear stapler for a side-to-side caval anastomosis during deceased-donor liver transplantation. The back table procedure was performed in a standard fashion for a side-to-side anastomosis. The linear vascular stapler was introduced during the temporary clamping of the recipient's inferior vena cava and the anastomosis was created without problems. Suturing of the resulting defect completed the anastomosis. The use of the stapler resulted in a shortening of the anastomosis time. The staple line after the reperfusion of the graft was completely sealed. The patient's postoperative course was uncomplicated and post-operative ultrasound and computed tomography confirmed the patency of the anastomosis. This case demonstrates a novel approach to a side-to-side caval reconstruction during liver transplantation that enables a shortening of the implantation time and may improve the quality of anastomoses.

New therapeutic concepts against ischemia-reperfusion injury in organ transplantation

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a positive amplification feedback loop that stimulates innate immune-driven tissue damage associated with organ procurement from deceased donors and during transplantation surgery. As our appreciation of its basic immune mechanisms has improved in recent years, translating putative biomarkers into therapeutic interventions in clinical transplantation remains challenging.

AREAS COVERED

This review presents advances in translational/clinical studies targeting immune responses to reactive oxygen species in IRI-stressed solid organ transplants, especially livers. Here we focus on novel concepts to rejuvenate suboptimal donor organs and improve transplant function using pharmacologic and machine perfusion (MP) strategies. Cellular damage induced by cold ischemia/warm reperfusion and the latest mechanistic insights into the microenvironment's role that leads to reperfusion-induced sterile inflammation is critically discussed.

EXPERT OPINION

Efforts to improve clinical outcomes and increase the donor organ pool will depend on improving donor management and our better appreciation of the complex mechanisms encompassing organ IRI that govern the innate-adaptive immune interface triggered in the peritransplant period and subsequent allo-Ag challenge. Computational techniques and deep machine learning incorporating the vast cellular and molecular mechanisms will predict which peri-transplant signals and immune interactions are essential for improving access to the long-term function of life-saving transplants.

Liver transplantation with donation after medical assistance in dying: Case series and systematic review of the literature

Medical assistance in dying (MAiD) has been a legally approved practice in Canada since 2016. Only recently have patients undergoing MAiD also been considered as donors for liver transplantation (LT). This study aimed to evaluate a case series of LT outcomes for recipients with MAiD donors and was paired with a systematic literature review of studies assessing the efficacy of MAiD-associated liver donation. A retrospective chart review of patients registered within the LT Registry at London Health Sciences Centre (LHSC) in London, Ontario, Canada, that had received MAiD donor LT was conducted to develop a case series. Descriptive statistics were produced based on available patient outcomes information. The systematic review included euthanasia due to MAiD being a term exclusive to Canada. Case series had a 100% 1-year graft survival rate, with 50% of patients experiencing early allograft dysfunction but having no significant clinical outcome. A single case of postoperative biliary complication was reported. Median warm ischemic time ranged from 7.8-13 minutes among case series and literature reviews. Utilization of donation after circulatory death allografts procured after MAiD appears to be promising. Mechanisms associated with potential impact in postoperative outcomes include relatively lower warm ischemic time relative to donation after circulatory death Maastricht III graft recipients.

Changing liver utilization and discard rates in clinical transplantation in the ex-vivo machine preservation era

Liver transplantation is a well-established treatment for many with end-stage liver disease. Unfortunately, the increasing organ demand has surpassed the donor supply, and approximately 30% of patients die while waiting for a suitable liver. Clinicians are often forced to consider livers of inferior quality to increase organ donation rates, but ultimately, many of those organs end up being discarded. Extensive testing in experimental animals and humans has shown that ex-vivo machine preservation allows for a more objective characterization of the graft outside the body, with particular benefit for suboptimal organs. This review focuses on the history of the implementation of ex-vivo liver machine preservation and how its enactment may modify our current concept of organ acceptability. We provide a brief overview of the major drivers of organ discard (age, ischemia time, steatosis, etc.) and how this technology may ultimately revert such a trend. We also discuss future directions for this technology, including the identification of new markers of injury and repair and the opportunity for other ex-vivo regenerative therapies. Finally, we discuss the value of this technology, considering current and future donor characteristics in the North American population that may result in a significant organ discard.

Split liver transplantation with extended right grafts on adult recipients: A propensity score matching analysis

INTRODUCTION

Split liver transplantation (SLT) emerged due to its potential to contribute to the organ pool and reduce organ shortage. However, SLT is technically challenging and has been associated with higher rates of postoperative complications leading to concerns about graft and patient survival. Moreover, there are few studies on matched-pair adult recipients of SLT and whole-liver transplant (WLT), with conflicting results.

METHODS

This retrospective study analyze outcomes among adults who underwent SLT at our institution from 2010 to 2019. A 1:1 propensity score matching analysis was performed based on important donor and recipient variables. Baseline characteristics and postoperative outcomes were analyzed and compared between groups. Actuarial graft and patient survival were analyzed by KM curves.

RESULTS

Out of 592 adults receiving a LT in our institution, 21 SLT adult recipients were identified and matched with 21 adults undergoing WLT. As expected donor age was significantly lower in SLT recipients (16 (15-22) vs. 32 (17-47), P = .012). Additional donor characteristics, including anthropometrics, and ischemic times were similar between groups. Baseline recipient characteristics and postoperative outcomes, including length of stay, vascular complications, biliary complications, and re-transplantation were comparable between SLT and WLT recipients. Graft (95/95/95 vs. 100/94/94, P = .98) and patient (100/100/100 vs. 100/94/94, P = .30) survival at 1-, 3-, 5-years, were similar between the SLT- and WLT group, respectively.

CONCLUSION

Split liver transplantation has the potential to increase the availability of organs for adult recipients without compromising individual outcomes.

Development of a preoperative score to predict surgical difficulty in liver transplantation

BACKGROUND

A difficulty score to predict intraoperative surgical complexity in liver transplantation has never been developed. The aim of this study was to assess factors associated with a difficult liver transplant and develop a score to predict difficult surgery.

METHODS

All patients undergoing deceased donor whole liver transplantation from 2012 to 2019 at a single center were included. Estimated intraoperative blood loss (mL/kg) and surgery duration (skin-to-arterial reperfusion time) were used as surrogates of difficulty. Based on these variables, the study population was divided into 2 groups: high risk and standard risk of difficulty. Univariate and multivariate analyses were performed to identify predictors associated with a demanding liver transplantation and develop a difficulty score.

RESULTS

A total of 515 patients were included in the study population, and 101 (20%) were considered difficult operations. Patients with a higher risk of difficulty showed a significantly higher rate of Clavien-Dindo ≥III complications (50.5% vs 24.4%, P = .001) and a longer hospital stay (19 vs 16 days, P = .001). Preoperative factors associated with difficulty were retransplantation (odds ratio 4.34, P = .001), preoperative portal vein thrombosis (odds ratio 3.419, P = .001), previous upper abdominal surgery (odds ratio 2.161, P = .003), spontaneous bacterial peritonitis (odds ratio 1.985, P < .02), and prior variceal bleeding (odds ratio 1.401, P = .051). A 10-point difficulty score was created, showing a negative predictive value of 84% at 4 points.

CONCLUSION

Difficult liver transplantation surgery, as assessed by skin-to-arterial reperfusion time and estimated blood loss, is associated with worse perioperative outcomes. We developed a simple score with clinical preoperative variables that predicts difficult surgery, and therefore, it may help to optimize allocation policies and perioperative logistics.

Impact of anastomosis time during lung transplantation on primary graft dysfunction

Primary graft dysfunction (PGD) is a major obstacle after lung transplantation (LTx), associated with increased early morbidity and mortality. Studies in liver and kidney transplantation revealed prolonged anastomosis time (AT) as an independent risk factor for impaired short- and long-term outcomes. We investigated if AT during LTx is a risk factor for PGD. In this retrospective single-center cohort study, we included all first double lung transplantations between 2008 and 2016. The association of AT with any PGD grade 3 (PGD3) within the first 72 h post-transplant was analyzed by univariable and multivariable logistic regression analysis. Data on AT and PGD was available for 427 patients of which 130 (30.2%) developed PGD3. AT was independently associated with the development of any PGD3 ≤72 h in uni- (odds ratio [OR] per 10 min 1.293, 95% confidence interval [CI 1.136-1.471], p < .0001) and multivariable (OR 1.205, 95% CI [1.022-1.421], p = .03) logistic regression analysis. There was no evidence that the relation between AT and PGD3 differed between lung recipients from donation after brain death versus donation after circulatory death donors. This study identified AT as an independent risk factor for the development of PGD3 post-LTx. We suggest that the implantation time should be kept short and the lung cooled to decrease PGD-related morbidity and mortality post-LTx.

Living Donor Liver Transplantation vs. Split Liver Transplantation Using Left Lateral Segment Grafts in Pediatric Recipients: An Analysis of the UNOS Database

Split and LDLT in pediatric patients have the potential to decrease wait times and waitlist mortality. Using UNOS-STAR data, we compared outcomes of pediatric patients undergoing LDLT and SLT using LLS grafts. The baseline characteristics and post-operative outcomes were compared between groups. Actuarial graft and patient survival were analyzed with Kaplan-Meier curves. Between 2010 and 2019, 911 pediatric LT were included in the analysis (LD graft group, n = 508, split graft group, n = 403). LD graft recipients spent more time on the waitlist vs. the split graft group (60 (22–138) days vs. 46 (16–108) days; p = 0.007). LD recipients had a lower rate of graft failure, found in 9.8% of patients compared with 14.6% in the split graft group (p = 0.02). HAT was the most common graft failure cause, with similar rates. Graft and patient survival at 1-, 3-, and 5-years was comparable between LDLT and SLT. In subgroup analyses, patients with biliary atresia, those ≤10 kg or ≤10 years old receiving an LD graft showed improved graft survival. In conclusion, LDLT is associated with a lower rate of graft failure in pediatric patients. The use of LLS regardless of the type of donor is a safe way to facilitate access to transplantation to pediatric patients with acceptable short and long-term outcomes.

Cold Ischemia Time and Graft Fibrosis Are Associated with Autoantibodies after Pediatric Liver Transplantation: A Retrospective Cohort Study of the European Reference Network TransplantChild

The reported prevalence of autoantibodies (AAB) (ANA, SMA, LKM, SLA) after pediatric liver transplantation (pLTX) varies considerably from 26-75%, but their clinical impact on outcome is uncertain. We aimed to study the prevalence of AAB after pLTX, their association with donor-, transplant-, and recipient-characteristics, and their relation to outcome. In our multicenter retrospective study, we aimed to clarify conflicting results from earlier studies. Six ERN TransplantChild centers reported data on 242 patients, of whom 61% were AAB positive. Prevalence varied across these centers. Independent of the interval between pLTX and AAB analysis, a one-hour increase in CIT resulted in an odds ratio (OR) of 1.37 (95% CI 1.11-1.69) for SMA positivity and an OR of 1.42 (95%CI 1.18-1.72) for ANA positivity. Steroid-free immunosuppression (IS) versus steroid-including IS (OR 5.28; 95% CI 1.45-19.28) was a risk factor for SMA positivity. Liver enzymes were not associated with ANA or SMA positivity. We did not observe an association of rejection activity index with ANA or SMA. However, the liver fibrosis score in follow-up biopsies was associated with ANA titer and donor age. In conclusion, this first multicenter study on AAB after pLTX showed high AAB prevalence and varied widely between centers. Longer CIT and prednisolone-free-IS were associated with AAB positivity, whereas AAB were not indicative of rejection, but instead were associated with graft fibrosis. The detection of AAB may be a marker of liver fibrosis and may be taken into consideration when indications for liver biopsy and immunosuppressive regimes, or reduction of immunosuppression in long-term follow-up, are being discussed. Prospective immunological profiling of pLTX patients, including AAB, is important to further improve our understanding of transplant immunology and silent graft fibrosis.

Over 30 Years of Pediatric Liver Transplantation at the Charité-Universitätsmedizin Berlin

Background: Pediatric liver transplantation (LT) is the treatment of choice for children with end-stage liver disease and in certain cases of hepatic malignancies. Due to low case numbers, a technically demanding procedure, the need for highly specialized perioperative intensive care, and immunological, as well as infectious, challenges, the highest level of interdisciplinary cooperation is required. The aim of our study was to analyze short- and long-term outcomes of pediatric LT in our center. Methods: We conducted a retrospective single-center analysis of all liver transplantations in pediatric patients (≤16 years) performed at the Department of Surgery, Charité – Universitätsmedizin Berlin between 1991 and 2021. Three historic cohorts (1991–2004, 2005–2014 and 2015–2021) were defined. Graft- and patient survival, as well as perioperative parameters were analyzed. The study was approved by the institutional ethics board. Results: Over the course of the 30-year study period, 212 pediatric LTs were performed at our center. The median patient age was 2 years (IQR 11 years). Gender was equally distributed (52% female patients). The main indications for liver transplantation were biliary atresia (34%), acute hepatic necrosis (27%) and metabolic diseases (13%). The rate of living donor LT was 25%. The median cold ischemia time for donation after brain death (DBD) LT was 9 h and 33 min (IQR 3 h and 46 min). The overall donor age was 15 years for DBD donors and 32 years for living donors. Overall, respective 1, 5, 10 and 30-year patient and graft survivals were 86%, 82%, 78% and 65%, and 78%, 74%, 69% and 55%. One-year patient survival was 85%, 84% and 93% in the first, second and third cohort, respectively (p = 0.14). The overall re-transplantation rate was 12% (n = 26), with 5 patients (2%) requiring re-transplantation within the first 30 days. Conclusion: The excellent long-term survival over 30 years showcases the effectiveness of liver transplantation in pediatric patients. Despite a decrease in DBD organ donation, patient survival improved, attributed, besides refinements in surgical technique, mainly to improved interdisciplinary collaboration and management of perioperative complications.

Impact of the Kasai Procedure and the Length of Native Liver Survival Time on Outcomes of Liver Transplantation for Biliary Atresia

The aim is to explore the impact of the Kasai procedure (KP) and the length of native liver survival time (NLST) on outcomes of liver transplantation (LT). Patients with biliary atresia (BA), who underwent LT in Beijing Friendship Hospital from January 2017 to December 2019, were enrolled and divided into non-KP (N-KP) and post-KP (P-KP) groups. The patients in the P-KP group were further divided into early failure (KP-EF) defined by NLST <1 year, medium failure (KP-MF, NLST 1-5 years), and late failure (KP-LF, NLST >5 years) subgroups. Clinical data at baseline and during follow-up were collected. The inverse probability of treatment weighting method was used to evaluate the independent effect of KP and the length of NLST on clinical outcomes. Among 197 patients with BA, the N-KP group accounted for 43 (21.8%), KP-EF 71 (46.1%), KP-MF 59 (38.3%), and KP-LF 24 (15.6%) cases, respectively. The N-KP and KP-EF groups had significantly longer hospitalization and intensive care unit stays after LT. Graft and overall survival rates were 93.0% in the N-KP group and 97.4% in P-KP group, respectively. The mortality rate in the P-KP group were significantly lower compared with that of the N-KP group with a hazard ratio (HR) of 0.2 (P = 0.02). The risks of biliary and vascular complications and cytomegalovirus (CMV) infection after LT were significantly higher in KP-EF group than those in the KP-MF and KP-LF groups (HRs = 0.09, 0.2, and 0.3, respectively; all P < 0.001). The KP significantly improved after LT overall survival. Patients with early native liver failure after KP have significantly higher risks for biliary and vascular complications and CMV infection.

Nucleic acid biomarkers to assess graft injury after liver transplantation

Many risk factors and complications impact the success of liver transplantation, such as ischaemia-reperfusion injury, acute rejection, and primary graft dysfunction. Molecular biomarkers have the potential to accurately diagnose, predict, and monitor injury progression or organ failure. There is a critical opportunity for reliable and non-invasive biomarkers to reduce the organ shortage by enabling i) the assessment of donor organ quality, ii) the monitoring of short- and long-term graft function, and iii) the prediction of acute and chronic disease development. To date, no established molecular biomarkers have been used to guide clinical decision-making in transplantation. In this review, we outline the recent advances in cell-free nucleic acid biomarkers for monitoring graft injury in liver transplant recipients. Prior work in this area can be divided into two categories: biomarker discovery and validation studies. Circulating nucleic acids (CNAs) can be found in the extracellular environment pertaining to different biological fluids such as bile, blood, urine, and perfusate. CNAs that are packaged into extracellular vesicles may facilitate intercellular and interorgan communication. Thus, decoding their biological function, cellular origins and molecular composition is imperative for diagnosing causes of graft injury, guiding immunosuppression and improving overall patient survival. Herein, we discuss the most promising molecular biomarkers, their state of development, and the critical aspects of study design in biomarker research for early detection of post-transplant liver injury. Future advances in biomarker studies are expected to personalise post-transplant therapy, leading to improved patient care and outcomes.

Combination of arterial lactate levels and Cv-aCO2/Da-vO2 ratio to predict early allograft dysfunction after liver transplantation

PURPOSE

We examined the ability of the P(v-a)CO2/Da-vO2 ratio combined with elevated lactate levels to predict early allograft dysfunction (EAD).

MATERIALS AND METHODS

Patients were classified into four groups according to lactate levels and P(v-a)CO2/Da-vO2 ratio: Group 1; lactate >2.0 mmol/L and P(v-a)CO2/Da-vO2 ratio >1.0; Group 2; lactate >2.0 mmol/L and P(v-a)CO2/Da-vO2 ratio <1.0; group 3; lactate<2.0 mmol/L and P(v-a)CO2/Da-vO2 ratio >1.0; group 4; lactate<2.0 mmol/L and P(v-a)CO2/Da-vO2 ratio <1.0. We defined EAD according to Olthoff criteria.

RESULTS

One-hundred and fifty patients were included. EAD occurred in 41 patients (27.3%), and was associated with worse graft survival at 1 year (92% vs. 73%; P = ,003) as well as a higher re-transplantation rate (4,6% vs. 17,1%; P = ,019). The multivariate analysis revealed that P(v-a)CO2/Da-vO2 ratio at T6 [OR 7.05(CI95% 2.77-19.01, P<.001)] was an independent predictor for EAD. Belonging to group 1 at 6 h was associated with worse clinical outcomes but no association was found with 1-year graft survival or 1-year patient survival.

CONCLUSIONS

In this single center, prospective, observational study in patients who received an OLT, we found that elevated lactate levels combined with a high Cv-aCO2/Da-vO2 after 6 h was associated with the development of EAD and worse clinical outcomes in the early postoperative period.

"Time is tissue"-A minireview on the importance of donor nephrectomy, donor hepatectomy, and implantation times in kidney and liver transplantation

Donor organs are exposed to sequential temperature changes during the transplantation process. The role of donor warm ischemia and cold ischemia times on post-transplant outcomes has been extensively studied. Much less attention has been paid to the transient ischemia occurring during donor organ removal and implantation. Recently, it has become clear that prolonged donor nephrectomy and implantation time are independently associated with delayed graft function after kidney transplantation. In addition, implantation time correlates with post-transplant kidney graft function, histology, and survival. Similar detrimental associations of donor hepatectomy and implantation time with early allograft dysfunction, ischemic cholangiopathy, and graft and patient survival after liver transplantation have been demonstrated. This review details kidney and liver temperature changes occurring during procurement and transplantation. It summarizes the effects of the ischemia the kidney and liver sustain during these phases on short- and long-term post-transplant outcomes, advocating the standardized reporting of donor hepatectomy, donor nephrectomy, and implantation times in (inter)national registries. The review also explores strategies to protect the graft from this ischemic injury.

Short recipient warm ischemia time improves outcomes in deceased donor liver transplantation

While adverse effects of prolonged recipient warm ischemia time (rWIT) in liver transplantation (LT) have been well investigated, few studies have focused on possible positive prognostic effects of short rWIT. We aim to investigate if shortening rWIT can further improve outcomes in donation after brain death liver transplant (DBD-LT). Primary DBD-LT between 2000 and 2019 were retrospectively reviewed. Patients were divided according to rWIT (≤30, 31-40, 41-50, and >50 min). The requirement of intraoperative transfusion, early allograft dysfunction (EAD), and graft survival were compared between the rWIT groups. A total of 1,256 patients of DBD-LTs were eligible. rWIT was ≤30min in 203 patients (15.7%), 31-40min in 465 patients (37.3%), 41-50min in 353 patients (28.1%), and >50min in 240 patients (19.1%). There were significant increasing trends of transfusion requirement (P < 0.001) and increased estimated blood loss (EBL, P < 0.001), and higher lactate level (P < 0.001) with prolongation of rWIT. Multivariable logistic regression demonstrated the lowest risk of EAD in the WIT ≤30min group. After risk adjustment, patients with rWIT ≤30 min showed a significantly lower risk of graft loss at 1 and 5-years, compared to other groups. The positive prognostic impact of rWIT ≤30min was more prominent when cold ischemia time exceeded 6 h. In conclusion, shorter rWIT in DBD-LT provided significantly better post-transplant outcomes.

Donor Warm Ischemia Time in DCD Liver Transplantation-Working Group Report From the ILTS DCD, Liver Preservation, and Machine Perfusion Consensus Conference

Donation after circulatory death (DCD) grafts are commonly used in liver transplantation. Attributable to the additional ischemic event during the donor warm ischemia time (DWIT), DCD grafts carry an increased risk for severe ischemia/reperfusion injury and postoperative complications, such as ischemic cholangiopathy. The actual ischemia during DWIT depends on the course of vital parameters after withdrawal of life support and varies widely between donors. The ischemic period (functional DWIT) starts when either Spo2 or blood pressure drop below a certain point and lasts until the start of cold perfusion during organ retrieval. Over the years, multiple definitions and thresholds of functional DWIT duration have been used. The International Liver Transplantation Society organized a Consensus Conference on DCD, Liver Preservation, and Machine Perfusion on January 31, 2020 in Venice, Italy. The aim of this conference was to reach consensus about various aspects of DCD liver transplantation in context of currently available evidence. Here we present the recommendations with regards to the definitions used for DWIT and functional DWIT, the importance of vital parameters after withdrawal of life support, and acceptable thresholds of duration of functional DWIT to proceed with liver transplantation.

Donor Hepatectomy and Implantation Time Are Associated With Early Complications After Liver Transplantation: A Single-center Retrospective Study

BACKGROUND

Donor hepatectomy and liver implantation time reduce long-term graft and patient survival after liver transplantation. It is not known whether these surgical times influence early outcomes after liver transplantation.

METHODS

This single-center study evaluated the effect of donor hepatectomy and implantation time on the risk of nonanastomotic biliary strictures (NAS) occurring within 1 year and of early allograft dysfunction (EAD) after deceased-donor solitary liver transplantation, adjusting for other donors, recipient, and surgical factors.

RESULTS

Of 917 transplants performed between January 2000 and December 2016, 106 (11.56%) developed NAS and 247 (27%) developed EAD. Donor hepatectomy time (median 35 min, IQR: 26-46) was an independent risk factor of NAS [adjusted hazard ratio, 1.19; 95% CI, 1.04-1.35; P = 0.01]. Implantation time (median 80 min, IQR: 69-95) was independently associated with EAD [adjusted odds ratio (OR), 1.15; 95% CI,1.07-1.23; P < 0.0001). The risk of EAD was increased by anastomosis time of both portal vein (adjusted OR, 1.26; 95% CI, 1.12-14.42; P = 0.0001) and hepatic artery (adjusted OR, 1.13; 95% CI, 1.04-1.22; P = 0.005). The magnitude of these effects was similar in donation after circulatory death liver grafts.

CONCLUSIONS

Donor hepatectomy and implantation time negatively affect short-term outcomes.

Novel Method of Evaluating Liver Transplant Surgery Fellows Using Objective Measures of Operative Efficiency and Surgical Outcomes

BACKGROUND

The majority of liver transplantations (LTs) in North America are performed by transplant surgery fellows with attending surgeon supervision. Although a strict case volume requirement is mandatory for graduating fellows, no guidelines exist on providing constructive feedback to trainees during fellowship.

STUDY DESIGN

A retrospective review of all adult LTs performed by abdominal transplant surgery fellows at a single American Society of Transplant Surgeons-accredited academic institution from 2005 to 2019 was conducted. Data from the most recent 5 fellows were averaged to generate reference learning curves for 8 variables representing operative efficiency (ie total operative time, warm ischemia time, and cold ischemia time) and surgical outcomes (ie intraoperative blood loss, unplanned return to the operating room, biliary complication, vascular complication, and patient/graft loss). Data for newer fellows were plotted against the reference curves at 3-month intervals to provide an objective assessment measure.

RESULTS

Three hundred and fifty-two adult LTs were performed by 5 fellows during the study period. Mean patient age was 56 years; 67% were male; and mean Model for End-Stage Liver Disease score at transplantation was 22. For the 8 primary variables, mean values included the following: total operative time 330 minutes, warm ischemia time 28 minutes, cold ischemia time 288 minutes, intraoperative blood loss 1.59 L, biliary complication 19.6%, unplanned return to operating room 19.3%, and vascular complication 2.3%. A structure for feedback to fellows was developed using a printed report card and through in-person meetings with faculty at 3-month intervals.

CONCLUSIONS

Comparative feedback using institution-specific reference curves can provide valuable objective data on progression of individual fellows. It can aid in the timely identification of areas in need of improvement, which enhances the quality of training and has the potential to improve patient care and transplantation outcomes.

Factors Associated with Prolonged Recipient Hepatectomy Time During Liver Transplantation: A Single-Centre Experience

BACKGROUND

Recipient hepatectomy during liver transplantation can be a challenging operation and can increase cold ischaemic time. The aim of this study is to assess factors associated with prolonged recipient hepatectomy.

METHODS

From 2005 to 2015, 930 patients were submitted to liver transplantation in our hospital. Prolonged hepatectomy time was defined as operative time >180 min (from knife on skin to total hepatectomy). Patients undergoing early liver retransplantation and living donation were excluded.

RESULTS

A total of 715 patients were included in our study. Median age at transplantation was 53 (18-70) years, and median BMI was 26.2 (16-40). Median hepatectomy time was 131 min. Prolonged hepatectomy time occurred in 89 (12.4%) patients. At univariate analysis, previous decompensated cirrhosis with variceal bleeding and/or ascites, higher BMI and previous abdominal surgery were associated with prolonged operating time. Higher surgeon experience and acute liver failure were associated with shorter hepatectomy time. At multivariate analysis, previous episodes of variceal bleeding (p = 0.027, OR 1.78), BMI > 27 (p = 0.01, OR 1.75), previous abdominal surgery (p = 0.04, OR 1.68) and surgeon experience (p = 0.007, OR 2.04) were independently associated with operating time. Prolonged hepatectomy time was significantly associated with cold and total ischaemic time and intraoperative bleeding (p < 0.001, p = 0.002 and p = 0.002, respectively).

CONCLUSIONS

Recipient BMI, previous episodes of variceal bleeding, previous abdominal surgery and surgeon experience are independently associated with hepatectomy duration. These factors can be helpful to identify those patients with potentially prolonged hepatectomy time, and therefore, strategies can be put in place to optimize outcomes in this group of patients.

Treatment of Anti-HLA Donor-Specific Antibodies Results in Increased Infectious Complications and Impairs Survival after Liver Transplantation

Donor-specific anti-human leukocyte antigen antibodies (DSA) are controversially discussed in the context of liver transplantation (LT). We investigated the relationship between the presence of DSA and the outcome after LT. All the LTs performed at our center between 1 January 2008 and 31 December 2015 were examined. Recipients < 18 years, living donor-, combined, high-urgency-, and re-transplantations were excluded. Out of 510 LTs, 113 DSA-positive cases were propensity score-matched with DSA-negative cases based on the components of the Balance of Risk score. One-, three-, and five-year survival after LT were 74.3% in DSA-positive vs. 84.8% (p = 0.053) in DSA-negative recipients, 71.8% vs. 71.5% (p = 0.821), and 69.3% vs. 64.9% (p = 0.818), respectively. Rejection therapy was more often applied to DSA-positive recipients (n = 77 (68.1%) vs. 37 (32.7%) in the control group, p < 0.001). At one year after LT, 9.7% of DSA-positive patients died due to sepsis compared to 1.8% in the DSA-negative group (p = 0.046). The remaining causes of death were comparable in both groups (cardiovascular 6.2% vs. 8.0%; p = 0.692; hepatic 3.5% vs. 2.7%, p = 0.788; malignancy 3.5% vs. 2.7%, p = 0.788). DSA seem to have an indirect effect on the outcome of adult LTs, impacting decision-making in post-transplant immunosuppression and rejection therapies and ultimately increasing mortality due to infectious complications.

The learning curve for piggyback liver transplantation: identifying factors challenging surgery

BACKGROUND

This study aimed to quantify the learning curve of piggyback liver transplantation and to identify factors that impact the operative time and blood transfusion during the learning curve.

METHODS

A retrospective review was performed on consecutive cases of patients' first piggyback liver transplantations that were performed by a single surgeon. The learning curve for the operative time was evaluated using the cumulative sum method.

RESULTS

There were 181, consecutive, first-time piggyback liver transplantations. The median operative time was 345 minutes (range: 180-745 minutes) with a median transfusion rate of 4 packed red blood cell units (range: 0-23 units). The cumulative sum learning curve identified 3 phases: an initial phase (1-70 piggyback liver transplantations), a plateau phase (71-101 piggyback liver transplantations), and a stable phase (102-181 piggyback liver transplantations). Over the 3 phases, there were significant decreases in the median duration of the surgery (388.8 vs 344.8 vs 326.9 minutes; P = .004, P = .0004, P ≤ .0001) and the number of red blood cell units transfused (6.00 vs 3.90 vs 3.71; P = .02, P = .79, P = .0006). Multivariable analysis identified that the following factors impacted the operative time: surgeon experience (P = .00006), previous upper abdominal surgery (P = .01), portocaval shunt fashioning (P = .0003), early portal section (P = .00001), multiple arterial graft reconstruction (P = .03), and the length of the retrohepatic inferior vena covered by segment 1 (P = .0006). Independent risk factors for increased blood loss were surgeon experience (P = .0001), previous upper abdominal surgery (P = .002), the retrohepatic inferior vena cava encirclement by segment 1 (P = .0001), severe portal hypertension (P = .01), early portal section (P = .001), and low prothrombin time (P = .00001).

CONCLUSION

Easily identifiable factors related to recipients (segment 1 morphology, previous upper abdominal surgery, severe portal hypertension) and to surgeon (operative experience, portocaval shunt fashioning, early portal section, and multiple arterial reconstructions) impact operative time and blood loss during the learning curve of piggyback liver transplantation. These factors can be used for grading the difficulties of liver transplantation to tailor the surgical strategy.

Ex Situ Arterial Reconstruction During Normothermic Perfusion of the Liver

Background.

Aberrant hepatic arterial anatomy may be seen in up to 30% of liver grafts, and reconstruction prolongs the cold ischemic time or the arterialization times. If normothermic machine preservation (NMP) is used to preserve liver grafts, the presence of aberrant arterial anatomy poses a challenge. Dual arterial cannulation is a temporary solution to enable effective perfusion, until optimal circumstances are met for arterial reconstruction, without compromising ischemia time. To date the technical and logistical feasibility of arterial reconstruction ex situ and during NMP has not been reported.

Methods.

Series of 5 cases from the Consortium for Organ Preservation in Europe randomized controlled trial in which grafts with arterial anatomic variations were reconstructed while organs were perfused on NMP.

Results.

One donor after cardiac death and 4 donor after brain death livers with arterial anatomical variations reconstructed while on NMP were included. All patients survived transplantation, spending 1–7 d in intensive care unit and discharged home after 5–15 d. None of the cases developed early allograft dysfunction or any early technical complications. At follow-up, there were no late hepatic artery thrombosis, stenosis, or any other vascular–related complication. Four of 5 patients underwent magnetic resonance cholangiopancreatography at 6 mo with no evidence of ischemic cholangiopathy.

Conclusions.

The case series described above suggests that ex vivo arterial reconstruction surgery on liver grafts while on board the NMP device is feasible, safe, and effective.

Post Liver Transplantation Survival and Related Prognostic Factors among Adult Recipients in Tehran Liver Transplant Center; 2002-2019

BACKGROUND

Liver transplantation is a standard treatment for patients with end-stage liver disease (ESLD). However, with increasing demand for this treatment and limited resources, it is available only to patients who are more likely to survive. The primary aim was to determine prognostic factors for survival.

METHODS

We collected data from 597 adult patients with ESLD, who received a single organ and initial orthotopic liver transplantation (OLT) in our center between 20 March 2008 and 20 March 2018. In this historical cohort study, univariate and multiple Cox model were used to determine prognostic factors of survival after transplantation.

RESULTS

After a median follow-up of 825 (0-3889) days, 111 (19%) patients died. Survival rates were 88%, 85%, 82% and 79% at 90 days, 1 year, 3 years, and 5 years, respectively. Older patients (HR = 1.27; 95% CI: 1.01-1.59), presence of pre-OLT ascites (HR = 2.03; 95% CI: 1.16-3.57), pre-OLT hospitalization (HR = 1.88; 95% CI:1.02-3.46), longer operative time (HR = 1.006; 95% CI: 1.004-1.008), post-OLT dialysis (HR = 3.51; 95% CI: 2.07-5.94), cancer (HR = 2.69; 95% CI: 1.23-5.89) and AID (HR = 2.04; 95% CI: 1.17-3.56) as underlying disease versus hepatitis, and higher pre-OLT creatinine (HR = 1.67; 95% CI: 1.10-2.52) were associated with decreased survival.

CONCLUSION

In this center, not only are survival outcomes excellent, but also younger patients, cases with better pre-operative health conditions, and those without complications after OLT have superior survival.