Older Donor Age Is a Risk Factor for Negative Outcomes After Adult Living Donor Liver Transplantation Using Small-for-Size Grafts

Optimizing pediatric liver transplantation: Evaluating the impact of donor age and graft type on patient survival outcome

BACKGROUND

We examined the combined effects of donor age and graft type on pediatric liver transplantation outcomes with an aim to offer insights into the strategic utilization of these donor and graft options.

METHODS

A retrospective analysis was conducted using a national database on 0-2-year-old (N = 2714) and 3-17-year-old (N = 2263) pediatric recipients. These recipients were categorized based on donor age (≥40 vs <40 years) and graft type. Survival outcomes were analyzed using the Kaplan-Meier and Cox proportional hazards models, followed by an intention-to-treat (ITT) analysis to examine overall patient survival.

RESULTS

Living and younger donors generally resulted in better outcomes compared to deceased and older donors, respectively. This difference was more significant among younger recipients (0-2 years compared to 3-17 years). Despite this finding, ITT survival analysis showed that donor age and graft type did not impact survival with the exception of 0-2-year-old recipients who had an improved survival with a younger living donor graft.

CONCLUSIONS

Timely transplantation has the largest impact on survival in pediatric recipients. Improving waitlist mortality requires uniform surgical expertise at many transplant centers to provide technical variant graft (TVG) options and shed the conservative mindset of seeking only the "best" graft for pediatric recipients.

Outcomes of living donor liver transplant recipients receiving grafts with the graft-to-recipient weight ratio less than 0.6%: A matched pair analysis

We sometimes experience living donor liver transplantation (LDLT) involving very small grafts with graft-to-recipient weight ratio (GRWR) < 0.6% when the actual graft size is smaller than predicted. The outcomes in this situation have not been fully investigated. The present study aimed to determine the graft outcomes of LDLT with GRWR < 0.6%. We retrospectively reviewed 280 cases of adult LDLT performed at our institution between January 2000 and March 2021. In our institution, the lower limit for graft volume/standard liver volume ratio was 30%. The patients were divided into 2 groups according to the cutoff value of 0.6% for actual GRWR. Graft survival and surgical outcomes, including small-for-size syndrome (SFSS), were compared between the groups using propensity score matching analysis. Risk factors associated with SFSS in recipients with GRWR < 0.6% were also evaluated. Fifty-nine patients received grafts with GRWR < 0.6%. After propensity score matching, similar graft survival rates were observed for GRWR < 0.6% (n = 53) and GRWR ≥ 0.6% (n = 53) ( p = 0.98). However, patients with GRWR < 0.6% had a significantly worse 3-month graft survival rate (86.8% vs. 98.1%, p = 0.03) and higher incidence of SFSS ( p < 0.001) than patients with GRWR ≥0.6%. On multivariate analysis, Model for End-Stage Liver Disease score and donor age were associated with SFSS in patients with GRWR < 0.6%. The same factors were also associated with graft survival. In conclusion, although similar overall graft survival rates were observed for LDLT with GRWR < 0.6% and GRWR ≥ 0.6%, GRWR < 0.6% was associated with an increased risk of SFSS. Appropriate donor and recipient selection is important for successful LDLT with very small grafts.

Post Living Donor Liver Transplantation Small-for-size Syndrome: Definitions, Timelines, Biochemical, and Clinical Factors for Diagnosis: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

BACKGROUND

When a partial liver graft is unable to meet the demands of the recipient, a clinical phenomenon, small-for-size syndrome (SFSS), may ensue. Clear definition, diagnosis, and management are needed to optimize transplant outcomes.

METHODS

A Consensus Scientific committee (106 members from 21 countries) performed an extensive literature review on specific aspects of SFSS, recommendations underwent blinded review by an independent panel, and discussion/voting on the recommendations occurred at the Consensus Conference.

RESULTS

The ideal graft-to-recipient weight ratio of ≥0.8% (or graft volume standard liver volume ratio of ≥40%) is recommended. It is also recommended to measure portal pressure or portal blood flow during living donor liver transplantation and maintain a postreperfusion portal pressure of <15 mm Hg and/or portal blood flow of <250 mL/min/100 g graft weight to optimize outcomes. The typical time point to diagnose SFSS is the postoperative day 7 to facilitate treatment and intervention. An objective 3-grade stratification of severity for protocolized management of SFSS is proposed.

CONCLUSIONS

The proposed grading system based on clinical and biochemical factors will help clinicians in the early identification of patients at risk of developing SFSS and institute timely therapeutic measures. The validity of this newly created grading system should be evaluated in future prospective studies.

Preventing Small-for-size Syndrome in Living Donor Liver Transplantation: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

Small-for-size syndrome (SFSS) is a well-recognized complication following liver transplantation (LT), with up to 20% developing this following living donor LT (LDLT). Preventing SFSS involves consideration of factors before the surgical procedure, including donor and recipient selection, and factors during the surgical procedure, including adequate outflow reconstruction, graft portal inflow modulation, and management of portosystemic shunts. International Liver Transplantation Society, International Living Donor Liver Transplantation Group, and Liver Transplant Society of India Consensus Conference was convened in January 2023 to develop recommendations for the prediction and management of SFSS in LDLT. The format of the conference was based on the Grading of Recommendations, Assessment, Development, and Evaluation system. International experts in this field were allocated to 4 working groups (diagnosis, prevention, anesthesia, and critical care considerations, and management of established SFSS). The working groups prepared evidence-based recommendations to answer-specific questions considering the currently available literature. The working group members, independent panel, and conference attendees served as jury to edit and confirm the final recommendations presented at the end of the conference by each working group separately. This report presents the final statements and evidence-based recommendations provided by working group 2 that can be implemented to prevent SFSS in LDLT patients.

Machine learning improves the accuracy of graft weight prediction in living donor liver transplantation

Precise graft weight (GW) estimation is essential for planning living donor liver transplantation to select grafts of adequate size for the recipient. This study aimed to investigate whether a machine-learning model can improve the accuracy of GW estimation. Data from 872 consecutive living donors of a left lateral sector, left lobe, or right lobe to adults or children for living-related liver transplantation were collected from January 2011 to December 2019. Supervised machine-learning models were trained (80% of observations) to predict GW using the following information: donor's age, sex, height, weight, and body mass index; graft type (left, right, or left lateral lobe); computed tomography estimated graft volume and total liver volume. Model performance was measured in a random independent set (20% of observations) and in an external validation cohort using the mean absolute error (MAE) and the mean absolute percentage error and compared with methods currently available for GW estimation. The best-performing machine-learning model showed an MAE value of 50 ± 62 g in predicting GW, with a mean error of 10.3%. These errors were significantly lower than those observed with alternative methods. In addition, 62% of predictions had errors <10%, whereas errors >15% were observed in only 18.4% of the cases compared with the 34.6% of the predictions obtained with the best alternative method ( p  < 0.001). The machine-learning model is made available as a web application ( http://graftweight.shinyapps.io/prediction ). Machine learning can improve the precision of GW estimation compared with currently available methods by reducing the frequency of significant errors. The coupling of anthropometric variables to the preoperatively estimated graft volume seems necessary to improve the accuracy of GW estimation.

Impact of donor age on recipient morbidity and mortality after living donor liver transplantation

BACKGROUND

Evidence for use of graft from older donors in living donor liver transplantation (LDLT) has been conflicting. This study aims to clarify the impact of donor age on recipient morbidity and mortality after adult LDLT.

METHODS

A total of 90 live liver donors and recipients who underwent primary adult-to-adult LDLT were divided into three groups according to donor age: donors in 20s (D-20s) group, donors in 30s and 40s (D-30s and 40s) group and donors in 50s & 60s (D-50s and 60s) group. Multivariate analyses were conducted to look for independent risk/prognostic factors. Donor age was analysed as a continuous variable to determine an optimal cut off.

RESULTS

Overall donor morbidity was 4/90 (4.44%), major donor morbidity was 1/90 (1.11%) and there was no donor mortality. Recipients in the D-20s group had better 1-, 3- and 5-year recipient survival than recipients in the D-50s and 60s group (96%, 91%, 91% versus 73%, 58%, 58%, respectively) (P = 0.020). Donor age was identified to be an independently significant risk factor for increased major complications (P = 0.007) and prognostic factor for reduced overall survival (P = 0.014). The optimal donor age cut off was determined to be 46.5 years old.

CONCLUSION

Older donors are associated with poorer recipient outcomes after adult-to-adult LDLT. Usage of liver grafts from older donors should be carefully considered when choosing liver grafts for patients undergoing LDLT.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.

Successful Simultaneous Subtotal Splenectomy During Left Lobe Auxiliary Liver Transplantation for Portal Inflow Modulation and Severe Hypersplenism Correction: A Case Report

Adult-to-adult living donor liver transplantation with small partial liver grafts often requires intraoperative portal inflow modulation to prevent portal hyperperfusion and subsequent small-for-size syndrome (SFSS). However, there are concerns about the specific morbidity of these modulation techniques. This study aims to lower post-perfusion portal venous pressure and correct severe hypersplenism in a patient with end-stage liver cirrhosis by simultaneous subtotal splenectomy during auxiliary partial orthotopic liver transplantation (APOLT). A 29-year-old man was diagnosed with cryptogenic cirrhosis and severe portal hypertension suffered recurrent acute variceal bleeding, severe thrombocytopenia, and massive ascites before admission to our hospital. After the recipient's left liver was resected, we performed APOLT using his 51-year-old father's left lobe graft with a graft-to-recipient weight ratio of 0.55%. Intraoperatively, simultaneous subtotal splenectomy was performed to lower graft post-perfusion portal vein pressure below 15 mmHg and correct severe hypersplenism-related pancytopenia. The recipient's postoperative hospital course was uneventful with no occurrence of SFSS and procedure-related complications. Platelet and leukocyte counts remained in the normal ranges postoperatively. The living donor was discharged 6 days after the operation and recovered well-with no complications. After a follow-up period of 35.3 months, both the recipient and donor live with good liver function and overall condition. This is the first case report of simultaneous subtotal splenectomy during APOLT using small-for-size living-donated left liver lobes, which is demonstrated to be a viable procedure for modulating portal inflow and correcting severe hypersplenism in selected adult patients with end-stage liver cirrhosis. APOLT using a small-for-size liver graft may be a safe and feasible treatment option for selected adult patients with end-stage liver cirrhosis.

Post-transplant hepatic fibrosis in pediatric liver-small bowel transplant recipients: A single-center, retrospective, observational study

BACKGROUND

Little is known about the prevalence of hepatic graft fibrosis in combined LSBT children. We aimed to determine the prevalence of and identify potential predictors for hepatic graft fibrosis in LSBT children and to compare them with those in LT children.

METHODS

We retrospectively included children younger than 19 years who had received a primary LT/LSBT between 2000 and 2018 and had a liver biopsy performed at least 6 months post-transplant. A Cox proportional hazards regression model was used to determine predictors associated with significant hepatic graft fibrosis (≥F2) in LSBT vs LT children.

RESULTS

Ninety-six children (47 LSBT, 54 females) were included. The median post-transplant follow-up (years) was 12.8 in LT vs 10.5 in LSBT patients (P = .06). Hepatic graft fibrosis was found in 81.6% of LT vs 70.2% of LSBT children (P = .19), after a median time of 2.5 years and 2.6 years, respectively. On multivariate analyses, having post-transplant biliary complications was found to be associated with significant graft fibrosis in LT children, whereas AST/ALT ratio was found to predict significant hepatic graft fibrosis in LSBT children. The use of parenteral nutrition after transplant was not associated with significant hepatic graft fibrosis.

CONCLUSIONS

The prevalence of hepatic graft fibrosis in LSBT children did not significantly differ from that in LT children, but the predictors may differ. Future studies should investigate the role of post-transplant autoimmune antibodies and donor-specific antibodies in the development and progression of hepatic graft fibrosis in LSBT children.

Inflammatory processes in the liver: divergent roles in homeostasis and pathology

The hepatic immune system is designed to tolerate diverse harmless foreign moieties to maintain homeostasis in the healthy liver. Constant priming and regulation ensure that appropriate immune activation occurs when challenged by pathogens and tissue damage. Failure to accurately discriminate, regulate, or effectively resolve inflammation offsets this balance, jeopardizing overall tissue health resulting from an either  overly tolerant or an overactive inflammatory response. Compelling scientific and clinical evidence links dysregulated hepatic immune and inflammatory responses upon sterile injury to several pathological conditions in the liver, particularly nonalcoholic steatohepatitis and ischemia-reperfusion injury. Murine and human studies have described interactions between diverse immune repertoires and nonhematopoietic cell populations in both physiological and pathological activities in the liver, although the molecular mechanisms driving these associations are not clearly understood. Here, we review the dynamic roles of inflammatory mediators in responses to sterile injury in the context of homeostasis and disease, the clinical implications of dysregulated hepatic immune activity and therapeutic developments to regulate liver-specific immunity.

Small-for-size graft, small-for-size syndrome and inflow modulation in living donor liver transplantation

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching called "small-for-size syndrome (SFSS)." The initial trials to resolve this problem involved increasing the procured graft size, from left to right, and even extending to include a right lobe graft. Clinical cases of living right lobe donations have been reported since then, drawing attention to the risks of increasing the liver volume procured from a living donor. However, not only other modes of increasing graft volume (GV) such as auxiliary or dual liver transplantation, but also control of the increased portal pressure caused by a small-for-size graft (SFSG), such as a porto-systemic shunt or splenectomy and optimal outflow reconstruction, have been trialed with some positive results. To establish an effective strategy for transplanting SFSG and preventing SFSS, it is essential to have precise knowledge and tactics to evaluate graft quality and GV, when performing these LDLTs with portal pressure control and good venous outflow. Thus, we reviewed the updated literature on the pathogenesis of and strategies for using SFSG.

Liver transplantation in patients with portal vein thrombosis: A strategic road map throughout management

BACKGROUND

Liver transplantation in the setting of portal vein thrombosis is an intricate issue that occasionally necessitates extraordinary procedures for portal flow restoration. However, to date, there is no consensus on a persistent management strategy, particularly with extensive forms. This work aims to introduce our experience-based surgical management algorithm for portal vein thrombosis during liver transplantation and to clarify some of the debatable circumstances associated with this problematic issue.

METHODS

Between 2006 and 2019, 494 adults underwent liver transplantation at our institute. Ninety patients had preoperative portal vein thrombosis, and 79 patients underwent living donor liver transplantation. Our algorithm trichotomized the management plan into 3 pathways based on portal vein thrombosis grade. The surgical procedures implemented included thrombectomy, interposition vein grafts, jump grafts from the superior mesenteric vein, jump grafts from a collateral and renoportal anastomosis in 56, 13, 11, 4, and 2 patients, respectively. Four patients with mural thrombi did not require any special intervention.

RESULTS

Thirteen patients experienced posttransplant portal vein complications. They all proved to have a patent portal vein by the end of follow-up regardless of the management modality. No significant survival difference was observed between cohorts with versus without portal vein thrombosis. The early graft loss rate was significantly higher with advanced grades (P = .048) as well as technically demanding procedures (P = .032).

CONCLUSION

A stepwise broad-minded strategy should always be adopted when approaching advanced portal vein thrombosis during liver transplantation. An industrious preoperative evaluation should always be carried out to locate the ideal reliable source for portal flow restoration.

Proceedings of the 25th Annual Congress of the International Liver Transplantation Society

The 25th Annual Congress of the International Liver Transplantation Society was held in Toronto, Canada, from May 15 to 18, 2019. Surgeons, hepatologists, anesthesiologists, critical care intensivists, radiologists, pathologists, and research scientists from all over the world came together with the common aim of improving care and outcomes for liver transplant recipients and living donors. Some of the featured topics at this year's conference included multidisciplinary perioperative care in liver transplantation, worldwide approaches to organ allocation, donor steatosis, and updates in pediatrics, immunology, and radiology. This report presents excerpts and highlights from invited lectures and select abstracts, reviewed and compiled by the Vanguard Committee of International Liver Transplantation Society. This will hopefully contribute to further advances in clinical practice and research in liver transplantation.

Recent evolution of living donor liver transplantation at Kyoto University: How to achieve a one-year overall survival rate of 99%?

Previously, living donor liver transplantation was considered as a "high-risk, high-return" medical treatment due to the relatively high short-term mortality. It is our task to change "high-risk, high-return" into a "low-risk, high-return" situation. In this review article, the recent evolutions in living donor liver transplantation for both donors and recipients at Kyoto University such as portal vein pressure modulation, hybrid donor operation, and perioperative management considering sarcopenia, focusing on improvement of short-term outcomes are described. Under a paradigm of "marketing and innovation", various innovations and efforts have been made over the last decade aiming at improving the short-term outcomes of both donors and recipients. By doing so, excellent short-term results after living donor liver transplantation have been achieved, along with a potentially epoch-making discoveries.

Small-for-size syndrome in liver transplantation: Definition, pathophysiology and management

BACKGROUND

Since the first success in an adult patient, living donor liver transplantation (LDLT) has become an universally used procedure. Small-for-size syndrome (SFSS) is a well-known complication after partial LT, especially in cases of adult-to-adult LDLT. The definition of SFSS slightly varies among transplant physicians. The use of a partial liver graft has risks of SFSS development. Persistent portal vein (PV) hypertension and PV hyper-perfusion after LT were identified as the main factors. Hence, various approaches were explored to modulate PV flow and decrease PV pressure in order to alleviate this syndrome. Herein, the definition, clinical symptoms, pathophysiology, basic research, as well as preventive and treatment strategies for SFSS are reviewed based on an extensive review of the literature and on our own experiences.

DATA SOURCES

The articles were collected through PubMed using search terms "liver transplantation", "living donor liver transplantation", "living liver donation", "partial graft", "small-for-size graft", "small-for-size syndrome", "graft volume", "remnant liver", "standard liver volume", "graft to recipient body weight ratio", "sarcopenia", "porcine", "swine", and "rat". English publications published before March 31, 2020 were included in this review.

RESULTS

Many transplant surgeons performed PV flow modulation, including portocaval shunt, splenic artery ligation and splenectomy. With these techniques, patient outcome has been improved even when using a "small" graft. Other factors, such as preoperative recipients' nutritional and skeletal muscle status, graft congestion, and donor factors, were also identified as risk factors which all have been addressed using various strategies.

CONCLUSIONS

The surgical approach controlling PV flow and pressure could help to prevent SFSS especially in severely ill recipients. In the absence of efficacious medications to resolve SFSS, conservative treatments, including aggressive fluid balance correction for massive ascites, anti-microbiological therapy to prevent or control sepsis and intensive nutritional therapy, are all required if SFSS could not be prevented.

Living donor liver transplantation in small-for-size setting

Small-for-Size Syndrome (SFSS) is one of the most feared complication of adult split liver and living donor liver transplantation. SFSS stems from a disproportionate/excessive portal vein flow relative to the volume of the implanted liver graft, and is currently one of the major practical limits to partial liver grafts' transplantation. In the last few decades many graft inflow modulation (GIM) techniques have been proposed to curtail the portal vein flow, allowing for successful transplantation of small partial liver grafts. Graft inflow modulation techniques span from Splenic Artery Ligation (SAL), to Splenectomy, Porto-Systemic Shunts and the lately proposed Splenic Devascularization. A patient tailored approach balancing the risk of SFSS with GIM specific morbidity, is more important than identifying the ideal GIM technique. Here we summarize the most recently published data to provide general indications in the challenging preoperative choice of a GIM techniques.

Post-transplant inflow modulation for early allograft dysfunction after living donor liver transplantation

Background

To treat small-for-size syndrome (SFSS) after living donor liver transplantation (LDLT), many procedures were described for portal flow modulation before, during, or after transplantation. The selection of the procedure as well as the best timing remains controversial.

Case presentation

A 43-year-old female with end-stage liver disease underwent LDLT with extended left with caudate lobe graft from her donor who was her 41-year-old brother (graft volume/standard liver volume (GV/SLV), 35.7%; graft to recipient weight ratio (GRWR), 0.67%). During the surgery, splenectomy could not be performed owing to severe peri-splenic adhesions to avoid the ruined bleedings. The splenic artery ligation was not also completely done because it was dorsal to the pancreas and difficult to be approached. Finally, adequate portal vein (PV) inflow was confirmed after portal venous thrombectomy. As having post-transplant optional procedures that are accessible for PV flow modulation, any other procedures for PV modulation during LDLT were not done until the postoperative assessment of the graft function and PV flow for possible postoperative modulation of the portal flow accordingly. Postoperative PV flow kept as high as 30 cm/s. By the end of the 1st week, there was a progressive deterioration of the total bilirubin profile (peak as 19.4 mg/dL) and ascitic fluid amount exceeded 1000 mL/day. Therefore, splenic artery embolization was done effectively and safely on the 10th postoperative day (POD) to reverse early allograft dysfunction as PV flow significantly decreased to keep within 20 cm/s and serum total bilirubin levels gradually declined with decreased amounts of ascites below 500 mL on POD 11 and thereafter. The patient was discharged on POD 28 with good condition.

Conclusions

SFSS can be prevented or reversed by the portal inflow modulation, even by post-transplant procedure. This case emphasizes that keeping accessible angiographic treatment options for PV modulation, such as splenic artery embolization, after LDLT is quite feasible.

Conceptual changes in small-for-size graft and small-for-size syndrome in living donor liver transplantation

Early series in living donor liver transplantation (LDLT) in adults demonstrated a lower safe limit of graft volume standard liver volume ratio 25%–45%. A subsequent worldwide large LDLT series proposed a 0.8 graft recipient weight ratio (GRWR) to define small-for-size graft (SFSG) in adult LDLT. Thereafter, researchers identified innate and inevitable factors including changes in liver volume during imaging studies and graft shrinkage due to perfusion solution. Although the definition of small-for-size syndrome (SFSS) advocated in the 2000s was mainly based on prolonged cholestasis and ascites output, the term SFSS was inadequate to describe clinical manifestations possibly caused by multiple factors. Thus, the term “early allograft dysfunction (EAD),” characterized by total bilirubin >10 mg/dL or coagulopathy with international normalized ratio >1.6 on day 7, has become prevalent to describe graft dysfunction including SFSS after LDLT. Although various efforts have been made to overcome EAD in LDLT, graft selection to maintain an expected GRWR >0.8 and full venous drainage, as well as inflow modulation using splenic artery ligation, have become standard in recent LDLT.