Small graft for living donor liver transplantation

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.

Estimation of right lobe graft weight for living donor liver transplantation using deep learning-based fully automatic computed tomographic volumetry

This study aimed at developing a fully automatic technique for right lobe graft weight estimation using deep learning algorithms. The proposed method consists of segmentation of the full liver region from computed tomography (CT) images, classification of the entire liver region into the right and left lobes, and estimation of the right lobe graft weight from the CT-measured right lobe graft volume using a volume-to-weight conversion formula. The first two steps were performed with a transformer-based deep learning model. To train and evaluate the model, a total of 248 CT datasets (188 for training, 40 for validation, and 20 for testing and clinical evaluation) were used. The Dice similarity coefficient (DSC), mean surface distance (MSD), and the 95th percentile Hausdorff distance (HD95) were used for evaluating the segmentation accuracy of the full liver region and the right liver lobe. The correlation coefficient (CC), percentage error (PE), and percentage absolute error (PAE) were used for the clinical evaluation of the estimated right lobe graft weight. The proposed method achieved high accuracy in segmentation for DSC, MSD, and HD95 (95.9% ± 1.0%, 1.2 ± 0.4 mm, and 5.2 ± 1.9 mm for the entire liver region; 92.4% ± 2.7%, 2.0 ± 0.7 mm, and 8.8 ± 2.9 mm for the right lobe) and in clinical evaluation for CC, PE, and PAE (0.859, - 1.8% ± 9.6%, and 8.6% ± 4.7%). For the right lobe graft weight estimation, the present study underestimated the graft weight by - 1.8% on average. A mean difference of - 21.3 g (95% confidence interval: - 55.7 to 13.1, p = 0.211) between the estimated graft weight and the actual graft weight was achieved in this study. The proposed method is effective for clinical application.

The role of graft to recipient weight ratio on enhanced recovery of the recipient after living donor liver transplantation - A systematic review of the literature and expert panel recommendations

BACKGROUND

There continues to be debate about the lower limit of graft-to-recipient weight ratio (GRWR) for living donor liver transplant (LDLT).

OBJECTIVES

To identify the lower limit of GRWR compatible with enhanced recovery after living donor liver transplant and to provide international expert panel recommendations.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. Studies assessing how GRWR affects recipient outcomes such as small for size syndrome, other complications, patient and graft survival, and length of stay were included.

PROTOCOL REGISTRATION

CRD42021260794.

RESULTS

Twenty articles were included in the qualitative synthesis, and all were retrospective observational studies. There was heterogeneity in the definition of study cohorts and key outcome measures such as small-for-size syndrome. Most studies lacked risk adjustment given limited single-center sample size. GRWR of ≥ .8% is associated with enhanced recovery. Recipients of grafts with GRWR < .8%, however, were found to have similar outcomes as those with ≥ .8% when appropriate consideration is made for portal flow modulation and recipient illness severity.

CONCLUSIONS

GRWR ≥ .8% is often compatible with enhanced recovery, but grafts < .8% can be used in selected LDLT recipients with optimal donor-recipient selection, surgical technique, and perioperative management (Quality of Evidence; Low | Grade of Recommendation; Strong).

Anatomical limits in living donor liver transplantation

We review the anatomical limits of living donor liver transplantation. Graft size is the fundamental challenge in partial liver transplantation. Insufficient graft size leads to small-for-size syndrome, graft failure, and graft loss. However, smaller grafts can be used safely with surgical techniques to optimize outflow and modulate inflow, thereby minimizing portal hyperperfusion. Meanwhile, anatomical variations are common in the vascular and biliary systems. These variants pose additional challenges for vascular and biliary reconstruction. Recognition and appropriate management of these variants ensure donor safety and reduce recipient morbidity. The ultimate principle of partial liver transplantation is to ensure a sufficient graft volume with unimpeded outflow and reconstructable vascular and biliary systems. On this basis, the anatomical limits of living donor liver transplantation can be safely expanded.

The Effects of Growth Factors and Cytokines on Hepatic Regeneration: A Systematic Review

The incidence of liver disease increases throughout the years due to many lifestyle factors; thus, the only definite treatment available for chronic liver disease is a liver transplant. However, the liver has a natural ability to repair itself and regenerate its hepatic tissue from stem cells. It is hypothesized that by inducing the liver with specific growth factors and cytokines such as interleukin 6 (IL-6) compared to general growth factors like growth differentiation factor 15 (GDF-15), it can regenerate, decreasing the need for liver transplant procedures. MEDLINE, the Journal of Hepatology, and Google Scholar were used to find articles. Various studies, including epidemiological studies dated from the year 2000 and greater, were used for the introduction. The results used only randomized control trials, experimental studies, and primary articles published since 2000. This compared the results of manipulating variables to determine the effects of hepatic regeneration by either specific hepatocyte growth factors or general growth factors like GDF-15. A total of 10 collected studies showed increased levels of gene expression and function, improved gross morphology, and histological appearance of the liver when induced by cytokines and specific growth factors versus general growth factors. Overall, the hypothesis was proven. The effects of GDF-15 were not significant compared to the effects of hepatocyte-specific growth factors and cytokines like IL-6 because they have two different effects on the liver after liver injury. Future studies should investigate this topic on the human hepatic regenerative ability, plus compare the effects of general growth factors like GDF-15 and specific hepatocyte growth factors and cytokines such as IL-6 in human liver tissue.

Liver resection versus liver transplantation for hepatocellular carcinoma within Milan criteria: a meta-analysis of 18,421 patients

Background

Outcomes after liver resection (LR) and liver transplantation (LT) for hepatocellular carcinoma (HCC) are heterogenous and may vary by region, over time periods and disease burden. We aimed to compare overall survival (OS) and disease-free survival (DFS) between LT versus LR for HCC within the Milan criteria.

Methods

Two authors independently searched Medline and Embase databases for studies comparing survival after LT and LR for patients with HCC meeting the Milan criteria. Meta-analyses and metaregression were conducted using random-effects models.

Results

We screened 2,278 studies and included 35 studies with 18,421 patients. LR was associated with poorer OS [hazard ratio (HR) =1.44; 95% confidence interval (CI): 1.14-1.81; P<0.01] and DFS (HR =2.71; 95% CI: 2.23-3.28; P<0.01) compared to LT, with similar findings among intention-to-treat (ITT) studies. In uninodular disease, OS in LR was comparable to LT (P=0.13) but DFS remained poorer (HR =2.95; 95% CI: 2.30-3.79; P<0.01). By region, LR had poorer OS versus LT in North America and Europe (P≤0.01), but not Asia (P=0.25). LR had inferior survival versus LT in studies completed before 2010 (P=0.01), but not after 2010 (P=0.12). Cohorts that underwent enhanced surveillance had comparable OS after LT and LR (P=0.33), but cohorts undergoing usual surveillance had worse OS after LR (HR =1.95; 95% CI: 1.24-3.07; P<0.01).

Conclusions

Mortality after LR for HCC is nearly 50% higher compared to LT. Survival between LR and LT were similar in uninodular disease. The risk of recurrence after LR is threefold that of LT.

A new formula for estimation of standard liver volume using liver height and thoracic width

Purpose

Precise estimation of the standard liver volume (SLV) is crucial in decision making regarding major hepatectomy and living donor liver transplantation. This study aimed to propose an accurate and efficient formula for estimating the SLV in the Korean population.

Methods

We created a regression model for SLV estimation using a data set of 230 Korean patients with healthy livers. The proposed model was cross validated using a different data set of 37 patients with healthy livers. The total liver volume (TLV), except for the volume of liver blood vessels, was measured through computed tomography volumetry as the dependent variable. Various anthropometric variables, liver height (LH), thoracic width (TW), age, and sex (0, female and 1, male) were considered as candidates for independent variables. We conducted stepwise regression analysis to identify variables to be included in the proposed model.

Results

A new formula was established; SLV = −1,275 + 9.85 × body weight (BW, kg) + 19.95 × TW (cm) + 7.401 × LH (mm). The proposed formula showed the best performance among existing formulas over the cross-validation data set.

Conclusion

The proposed formula derived using BW, TW, and LH estimated the TLV in the cross-validation data set more accurately than existing formulas.

The Risk of Going Small: Lowering GRWR and Overcoming Small-For-Size Syndrome in Adult Living Donor Liver Transplantation

OBJECTIVE

The aim of this study was to determine the outcomes of living donor liver transplantation (LDLT) according to various graft-to-recipient weight ratio (GRWR).

BACKGROUND

The standard GRWR in LDLT is >0.8%. Our center accepted predicted GRWR ≥0.6% in selected patients.

METHODS

Data from patients who underwent LDLT from 2001 to 2017 were included. Patients were stratified according to actual GRWR (Group 1:GRWR ≤0.6%; Group 2: 0.6%0.8%).

RESULTS

There were 545 LDLT (group 1 = 39; group 2 = 159; group 3 = 347) performed. Pretransplant predicted GRWR showed good correlation to actual GRWR (R2 = 0.834) and these figures differed within a ± 10%margin (P = 0.034) using an equivalence test. There were more left lobe grafts in group 1 (33.3%) than group 2 (10.7%) and 3 (2.9%). Median donor age was <35 years and steatosis >10% was rare.There was no difference in postoperative complication, vascular and biliary complication rate between groups. Over one-fifth (20.5%) of group 1 patients required portal flow modulation (PFM) and was higher than group 2 (3.1%) and group 3 (4%) (P = 0.001). Twenty-six patients developed small-for-size syndrome (SFSS): 5 of 39 (12.8%) in group 1 and 21 of 159 (13.2%) in group 2 and none in group 3 (P < 0.001). There were 2 hospital mortalities; otherwise, the remaining patients [24/26 (92.3%)] survive with a functional liver graft. The 5-year graft survival rates were 85.4% versus 87.8% versus 84.7% for group 1, 2, and 3, respectively (P = 0.718). GRWR did not predict worse survivals in multivariable analysis.

CONCLUSIONS

Graft size in LDLT can be lowered to 0.6% after careful recipient selection, with low incidence of SFSS and excellent outcomes. Accurate graft weight prediction, donor-recipient matching, meticulous surgical techniques, appropriate use of PFM, and vigilant perioperative care is important to the success of such approach.

Which is better to use "body weight" or "standard liver weight", for predicting small-for-size graft syndrome after living donor liver transplantation?

AIM

Little evidence about whether to apply graft-to-recipient body weight ratio (GRWR) or graft weight to standard liver weight (GW/SLW) for graft selection has been published. The aim of the present study was to clarify the importance of the correct use of GRWR and GW/SLW for selecting graft according to the recipients' physique in living donor liver transplantation (LDLT).

METHODS

Data were collected for 694 recipients who underwent LDLT between 1997 and 2020.

RESULTS

One of the marginal grafts meeting GW/SLW ≥ 35% but GRWR < 0.7% has been used in more recipients with men and higher body mass index (BMI), and the other meeting GRWR ≥ 0.7% but GW/SLW < 35% has been used in more recipients with women with lower BMI. In the cohort of BMI > 30 kg/m2, the recipients with GRWR < 0.7% had a significantly higher incidence of small-for-size graft syndrome (SFSS) compared to those with GRWR ≥ 0.7% (P = 0.008, 46.2% vs 5.9%), and using the cutoff of GW/SLW < 35% could not differentiate. In contrast, in the cohort of BMI ≤ 30 kg/m2, the recipients with GW/SLW < 35% also had a significantly higher incidence of SFSS (P = 0.013, 16.9% vs 9.4%). Multivariate analysis showed that GRWR < 0.7% [odds ratio (OR) 14.145, P = 0.048] was the independent risk factor for SFSS in obese recipients, and GW/SLW < 35% [OR 2.685, P = 0.002] was the independent risk factor in non-obese recipients.

CONCLUSION

Proper use of the formulas for calculating GRWR and GW/SLW in choosing graft according to recipient BMI is important, not only to meet metabolic demand for avoiding SFSS but also to ameliorate donor shortages.

Prediction of liver regeneration in recipients after living-donor liver transplantation in using preoperative CT texture analysis and clinical features

PURPOSE

The aim of the study is to predict the rate of liver regeneration in recipients after living-donor liver transplantation using preoperative CT texture and shape analysis of the future graft.

METHODS

102 donor-recipient pairs who underwent living-donor liver transplantation using right lobe grafts were retrospectively included. We semi-automatically segmented the future graft from preoperative CT. The volume of the future graft (LV_pre) was measured, and texture and shape analyses were performed. The graft liver was segmented from postoperative follow-up CT and the volume of the graft (LV_post) was measured. The regeneration index was defined by the following equation: [(LV_post-LV_pre)/LV_pre] × 100(%). We performed a stepwise, multivariate linear regression analysis to investigate the association between clinical, texture and shape parameters and the RI and to make the best-fit predictive model.

RESULTS

The mean regeneration index was 47.5 ± 38.6%. In univariate analysis, the volume of the future graft, energy, effective diameter, surface area, sphericity, roundness_m, compactness1, and grey-level co-occurrence matrix contrast as well as several clinical parameters were significantly associated with the regeneration index (p < 0.05). The best-fit predictive model for the regeneration index made by multivariate analysis was as follows: Regeneration index (%) = 127.020-0.367 × effective diameter - 1.827 × roundness_m + 47.371 × recipient body surface area (m²) + 12.041 × log(recipient white blood cell count) (× 10³/μL)+ 18.034 (if the donor was female).

CONCLUSION

The effective diameter and roundness_m of the future graft were associated with liver regeneration. Preoperative CT texture analysis of future grafts can be useful for predicting liver regeneration in recipients after living-donor liver transplantation.

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.

Association of Graft-to-Recipient Weight Ratio with the Prognosis Following Liver Transplantation: a Meta-analysis

BACKGROUND

Studies indicate that low graft-to-recipient weight ratio (GRWR) affect graft survival in adult-to-adult living donor liver transplantation. However, the potential role of GRWR in the prognosis of patients following living donor liver transplantation according to patient characteristics remains controversial. This study aimed to update the role of GRWR in patients following living donor liver transplantation.

METHODS

PubMed, Embase, and Cochrane Library were comprehensively searched for studies comparing low GRWR (< 0.8%) with normal GRWR (≥ 0.8%) in the prognosis following living donor liver transplantation from inception to March 2019. The 1-, 3-, and 5-year summary survival rates, small-for-size syndrome (SFSS), perioperative mortality, biliary complications, postoperative bleeding, and acute rejection were calculated using the random-effects model.

RESULTS

Eighteen studies comprising 4001 patients were included. Patients with low GRWR were associated with lower 1-year and 3-year survival rates compared to patients with normal GRWR, while no significant difference was found in the association of 5-year survival rate with low and normal GRWRs. Moreover, the risk of SFSS significantly increased in patients with low GRWR. Finally, no significant differences were observed in the association of low and normal GRWRs with the risk of perioperative mortality, biliary complications, postoperative bleeding, and acute rejection.

CONCLUSION

The results of this study indicated that low GRWR was associated with poor prognosis for patients following living donor liver transplantation, especially in terms of 1- and 3-year survival rates and SFSS.

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.

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.

Outcomes of adult patients adopting small-for-size grafts in living donor liver transplantation: A systematic review and meta-analysis

BACKGROUND

Small-for-size graft (SFSG) has emerged as one of the very contentions in adult-to-adult living donor liver transplantation (LDLT) as a certain graft size is related to recipients' prognosis. Graft-to-recipient weight ratio (GRWR) ≥0.8% was considered as a threshold to conduct LDLT. However, this also has been challenged over decades as a result of technique refinements. For a better understanding of SFSG in practice, we conducted this meta-analysis to compare the perioperative outcomes and long-term outcomes between patients adopting the grafts with a lower volume (GRWR < 0.8%, SFSG group) and sufficient volume (GRWR ≥ 0.8%, non-SFSG group) in adult-to-adult LDLT.

DATA SOURCES

The studies comparing recipients adopting graft with a GRWR < 0.8% and ≥ 0.8% were searched by three authors independently in PubMed, Web of Science, Embase, the Cochrane Library, MEDLINE and Google Scholar databases until September 2018 and data were analyzed by RevMan 5.3.5.

RESULTS

Sixteen studies with a total of 3272 subjects were included in this meta-analysis. In terms of small-for-size syndrome (SFSS), no significant difference was found in subjects enrolled after year 2010 (before 2010, OR=3.00, 95% CI: 1.69-5.35, P = 0.0002; after 2010, OR=1.23, 95% CI: 0.79-1.90, P = 0.36; P for interaction: 0.02). There was no significant difference in operative duration, blood loss, cold ischemia time, biliary complications, acute rejection, postoperative bleeding, hospitalization time, perioperative mortality, and 1-, 3- and 5-year overall survival rates between two groups.

CONCLUSIONS

This meta-analysis suggested that adopting SFSG in adult LDLT has comparable outcomes to those with non-SFSG counterparts since 2010.

Graft Regeneration and Functional Recovery in Patients with Early Allograft Dysfunction After Living-Donor Liver Transplantation

Background

Successful graft regeneration is important in living-donor liver transplantation (LDLT) because partial liver grafts are used. Early allograft dysfunction (EAD) is an intermediate outcome that affects the long-term postoperative course in liver transplantation. The aim of the present study was to investigate liver graft regeneration under EAD development in LDLT.

Material/Methods

The data of 226 patients who underwent LDLT from September 2010 to July 2014 were retrospectively analyzed. The patients were classified into 2 groups: one with and one without EAD. Graft regeneration, functional recovery, and long-term patient survival were compared between the 2 groups.

Results

The grafts grew more vigorously in the EAD group than in the non-EAD group, as evidenced by the larger absolute (ALV) and relative liver volumes (RLV) of the former on postoperative days (POD) 7 and 21. The median (interquartile range) RLVs of the non-EAD group versus the EAD group were as follows: 55.2 (47.9–65.8) vs. 53.7 (46.6–64.5)% preoperatively, p>0.05; 76.1 (66.9–85.7) vs. 86.7 (73.9–96.8)% on POD 7, p<0.01; 79.6 (69.3–91.2) vs. 93.7 (79.6–101.6)%, p<0.01 on POD 21. In the early postoperative period, hepatic function, measured as total bilirubin and international normalized ratio, was higher in the EAD group; however, after EAD development, graft function recovered in these patients. In the follow-up period, overall patient survival was comparable between the 2 groups.

Conclusions

The liver grafts of EAD patients steadily regenerated, such that the development of EAD did not affect long-term patient survival after LDLT.

Estimation of Standard Liver Volume Using CT Volume, Body Composition, and Abdominal Geometry Measurements

PURPOSE

The present study developed formulas for estimation of standard liver volume (SLV) with high accuracy for the Korean population.

MATERIALS AND METHODS

SLV estimation formulas were established using gender-balanced and gender-unbalanced measurements of anthropometric variables, body composition variables, and abdominal geometry of healthy Koreans (n=790). Total liver volume excluding blood volume, was measured based on CT volumetry.

RESULTS

SLV estimation formulas as preferred in various conditions of data availability were suggested in the present study. The suggested SLV estimation formulas in the present study were found superior to existing formulas, with an increased accuracy of 4.0-217.5 mL for absolute error and 0.2-18.7% for percentage of absolute error.

CONCLUSION

SLV estimation formulas using gender-balanced measurements showed better performance than those using gender-unbalanced measurements. Inclusion of body composition and abdominal geometry variables contributed to improved performance of SLV estimation.

Dr. Liver: A preoperative planning system of liver graft volumetry for living donor liver transplantation

BACKGROUND AND OBJECTIVE

Manual tracing of the right and left liver lobes from computed tomography (CT) images for graft volumetry in preoperative surgery planning of living donor liver transplantation (LDLT) is common at most medical centers. This study aims to develop an automatic system with advanced image processing algorithms and user-friendly interfaces for liver graft volumetry and evaluate its accuracy and efficiency in comparison with a manual tracing method.

METHODS

The proposed system provides a sequential procedure consisting of (1) liver segmentation, (2) blood vessel segmentation, and (3) virtual liver resection for liver graft volumetry. Automatic segmentation algorithms using histogram analysis, hybrid level-set methods, and a customized region growing method were developed. User-friendly interfaces such as sequential and hierarchical user menus, context-sensitive on-screen hotkey menus, and real-time sound and visual feedback were implemented. Blood vessels were excluded from the liver for accurate liver graft volumetry. A large sphere-based interactive method was developed for dividing the liver into left and right lobes with a customized cutting plane. The proposed system was evaluated using 50 CT datasets in terms of graft weight estimation accuracy and task completion time through comparison to the manual tracing method. The accuracy of liver graft weight estimation was assessed by absolute difference (AD) and percentage of AD (%AD) between preoperatively estimated graft weight and intraoperatively measured graft weight. Intra- and inter-observer agreements of liver graft weight estimation were assessed by intraclass correlation coefficients (ICCs) using ten cases randomly selected.

RESULTS

The proposed system showed significantly higher accuracy and efficiency in liver graft weight estimation (AD = 21.0 ± 18.4 g; %AD = 3.1% ± 2.8%; percentage of %AD > 10% = none; task completion time = 7.3 ± 1.4 min) than the manual tracing method (AD = 70.5 ± 52.1 g; %AD = 10.2% ± 7.5%; percentage of %AD > 10% = 46%; task completion time = 37.9 ± 7.0 min). The proposed system showed slightly higher intra- and inter-observer agreements (ICC = 0.996 to 0.998) than the manual tracing method (ICC = 0.979 to 0.999).

CONCLUSIONS

The proposed system was proved accurate and efficient in liver graft volumetry for preoperative planning of LDLT.

Serum interleukin-6 and tumor necrosis factor-α are associated with early graft regeneration after living donor liver transplantation

Background

Liver graft regeneration is orchestrated by specific and sequential stimuli, including hepatocyte growth factors, cytokines, and catecholamines. We evaluated the association between preoperative serum cytokines and early liver graft regeneration in human living donor liver transplantation (LDLT).

Patients and methods

We retrospectively reviewed the data of adult patients who underwent LDLT from January 2010 to December 2014. Serum cytokines, including interleukin (IL)-2, 6, 10, 12, 17, interferon (IFN)-γ and tumor necrosis factor (TNF)-α were measured in the recipients 1 day before surgery and on postoperative day (POD) 7. Liver graft volume was estimated using abdominal computed tomography images of the donors and recipients.

Results

In total, 226 patients were analyzed in this study. Median preoperative levels of serum cytokines were as follows: IL-2, 0.1 (0.1–1.6) pg/mL; IL-6, 7.3 (0.1–30.2) pg/mL; IL-10, 0.5 (0.1–11.0) pg/mL; IL-12, 0.1 (0.1–0.1) pg/mL; IL-17, 2.0 (0.1–16.4) pg/mL; IFN-γ, 3.2 (0.1–16.0) pg/mL; and TNF-α, 9.8 (5.4–17.9) pg/mL. Higher preoperative serum levels of IL-6, IL-10, and TNF-α, dichotomized at the median, were associated with increased relative liver volumes by POD 7. Multivariate analysis revealed that higher levels of serum IL-6 and TNF-α were independently associated with increased graft volume during the first 1 week after LDLT, based on the lower levels of those cytokines.

Conclusions

IL-6 and TNF-α were important mediators of the success of early graft regeneration in patients who underwent LDLT.

Hepatic Hemodynamics and Portal Flow Modulation: The A2ALL Experience

OBJECTIVE

A principal aim of the Adult-to-Adult Living Donor Liver Transplantation Cohort Study was to study hepatic blood flow and effect of portal flow modulation on graft outcomes in the setting of increasing use of smaller and left lobe grafts.

METHODS

Recipients of 274 living donor liver transplant were enrolled in the Adult-to-Adult Living Donor Liver Transplantation Cohort Study, including 233 (85.0%) right lobes, 40 (14.6%) left lobes, and 1 (0.5%) left lateral section. Hepatic hemodynamics were recorded after reperfusion. A total of 57 portal flow modulations were performed on 52 subjects.

RESULTS

Modulation lowered portal pressure in 68% of subjects with inconsistent effects on hepatic arterial and portal flow. A higher rate of graft dysfunction was observed in modulated vs. unmodulated subjects (31% vs. 18%; P = 0.03); however, graft survival in modulated subjects was not different from unmodulated subjects at 3 years.

CONCLUSIONS

These results suggest the need for a study using a prespecified portal flow modulation protocol with defined indications to better define the effects of these interventions.

Small for size syndrome difficult dilemma: Lessons from 10 years single centre experience in living donor liver transplantation

AIM

To analyze the incidence, risk factors, prevention, treatment and outcome of small for size syndrome (SFSS) after living donor liver transplantation (LDLT).

METHODS

Through-out more than 10 years: During the period from April 2003 to the end of 2013, 174 adult-to-adults LDLT (A-ALDLT) had been performed at National Liver Institute, Menoufiya University, Shibin Elkoom, Egypt. We collected the data of those patients to do this cohort study that is a single-institution retrospective analysis of a prospectively collected database analyzing the incidence, risk factors, prevention, treatment and outcome of SFSS in a period started from the end of 2013 to the end of 2015. The median period of follow-up reached 40.50 m, range (0-144 m).

RESULTS

SFSS was diagnosed in 20 (11.5%) of our recipients. While extra-small graft [small for size graft (SFSG)], portal hypertension, steatosis and left lobe graft were significant predictors of SFSS in univariate analysis (P = 0.00, 0.04, 0.03, and 0.00 respectively); graft size was the only independent predictor of SFSS on multivariate analysis (P = 0.03). On the other hand, there was lower incidence of SFSS in patients with SFSG who underwent splenectomy [4/10 (40%) SFSS vs 3/7 (42.9%) no SFSS] but without statistical significance, However, there was none significant lower incidence of the syndrome in patients with right lobe (RL) graft when drainage of the right anterior and/or posterior liver sectors by middle hepatic vein, V5, V8, and/or right inferior vein was done [4/10 (28.6%) SFSS vs 52/152 (34.2%) no SFSS]. The 6-mo, 1-, 3-, 5-, 7- and 10-year survival in patients with SFSS were 30%, 30%, 25%, 25%, 25% and 25% respectively, while, the 6-mo, 1-, 3-, 5-, 7- and 10-year survival in patients without SFSS were 70.1%, 65.6%, 61.7%, 61%, 59.7%, and 59.7% respectively, with statistical significant difference (P = 0.00).

CONCLUSION

SFSG is the independent and main factor for occurrence of SFSS after A-ALDLT leading to poor outcome. However, the management of this catastrophe depends upon its prevention (i.e., selecting graft with proper size, splenectomy to decrease portal venous inflow, and improving hepatic vein outflow by reconstructing large draining veins of the graft).

Living donor liver transplantation in patients weighing ≥100 kg: Low graft weight and obesity do not impact outcomes

Living donor liver transplantation (LDLT) in obese patients raises concerns with regards to obtaining grafts of "adequate" graft-to-recipient weight ratio (GRWR) and the impact of obesity on the outcomes of LDLT. LDLT outcomes in patients weighing ≥100 kg were compared with those weighing <100 kg. Patients weighing ≥100 kg were divided into 3 categories based on the GRWR of the grafts they received. Groups 1, 2, and 3 included patients with GRWR ≥0.8%, between 0.65% and 0.8%, and <0.65%, respectively. The 56 (6.5%) adult liver transplants were performed in patients weighing 100 kg or more. Except for higher mean body mass index (35.8 versus 25.2 kg/m² ; P value < 0.01) and grafts of lower GRWR in obese patients (0.74% versus 1.02%; P value < 0.01), all other parameters were similar between the 2 groups. Despite obesity and smaller grafts, the posttransplant outcomes such as day to normal bilirubin and international normalized ratio; infective, respiratory, and biliary complications; and hospital mortality were similar between the 2 groups. On comparing obese patients in the 3 GRWR categories, except for graft weight (985 versus 769 versus 646 g; P value < 0.01), all the pretransplant parameters were comparable. There was no significant difference in terms of graft function, postoperative morbidity, and hospital mortality between patients with grafts of normal GRWR and those with grafts of low and very low GRWR. Grafts of low GRWR give satisfactory results in obese patients undergoing LDLT and obesity does not adversely impact the outcome of LDLT. Liver Transplantation 23:35-42 2017 AASLD.

Graft-to-recipient weight ratio threshold adjusted to the model for end-stage liver disease score for living donor liver transplantation

The graft-to-recipient weight ratio (GRWR) is an important selection criterion for living donor liver transplantation (LDLT). The generally accepted threshold is known to be 0.8%. We believe that this threshold can be reduced under certain conditions. The aim of this study was to evaluate the results of these patients with GRWR < 0.8%. Between 2004 and 2015, 649 patients underwent right lobe LDLT for end-stage liver disease in adult patients. All recipients who had GRWR < 0.8% were identified. The data of these patients were retrospectively analyzed and compared to patients with GRWR ≥ 0.8%. There were 43 patients with GRWR < 0.8%. Out of these patients, 7 (16%) had GRWR of 0.6%. The median Model for End-Stage Liver Disease (MELD) score was 15, and the median donor age was 30 years. Anterior segment drainage was ensured. Portal inflow modulation was performed by splenic artery ligation according to the portal flow. Postoperative complications were seen in 6 (14%) patients. Of all 43 patients, 3 (7%) died perioperatively within 1 month, and 1 (2%) patient underwent retransplantation due to graft failure. The mean hospital stay was 18 days. The 1-year survival rate was 93%. None of the patients had a laboratory MELD score above 20. The comparison of the results with the patients who had GRWR ≥ 0.8% has shown no significant difference, except MELD score, body mass index (BMI), and rate of anterior segment drainage. The GRWR can be decreased even to 0.6% if the MELD score is below 20, donor age is below 45 years, and there are no signs for any hepatosteatosis of the donor graft. In these patients, it is essential that the anterior segment drainage is secured and the portal inflow modulation is performed according to the portal flow. Liver Transplantation 22 1643-1648 2016 AASLD.

The outcomes of pediatric living donor liver transplantation using small-for-size grafts: experience of a single institute

PURPOSE

We aimed to evaluate patients who had undergone pediatric LDLT with small-for-size graft (SFSG) and identify risk factors of graft failure to establish a preoperative graft selection strategy.

METHODS

The data was collected retrospectively. SFSG was used in 14LDLTs (5.7%) of 245 LDLTs performed between May 2001 and March 2014. The mean patient age and body weight at LDLT were 12.6 ± 2.0 years and 40.5 ± 9.9 kg, respectively. The graft type was left lobe in six patients, left + caudate lobe in seven patients, and posterior segment in one patient.

RESULTS

The graft survival rates in SFSG and non-SFSG groups were 78.9 and 93.1%, respectively (p = 0.045). In the univariate analysis, bleeding volume during LDLT were an independent risk factors for graft failure (p = 0.011). Graft failure was caused by sepsis in all three patients and occurred at a median of 70 postoperative days 70 (range 14-88 days). Among them, two cases showed high preoperative PELD/MELD score (PELD; 19.4 and MELD; 22, respectively).

CONCLUSIONS

Pediatric LDLT using SFSG had poor outcome and prognosis, especially when it accompanies the surgical infectious complications with preoperative high PELD/MELD scores.

Transplantation of a 2-year-old deceased-donor liver to a 61-year-old male recipient

The suitable size of a graft is a key element in the success of liver transplantation. A small-for-size liver graft is very likely to sustain a significant degree of injury as a result of ischemia, preservation, reperfusion, and rejection. Usually, small-for-size grafts are a concern in living-donor liver transplantation rather than in deceased-donor liver transplantation. Here, we describe the successful transplantation of a liver from a 2-year-old deceased donor to a 61-year-old male recipient who suffered from liver failure related to hepatitis B. No report of successful deceased-donor liver transplantation with discrepancies between donor and recipient age and size to such an extent has been found in the literature. Despite unusually large discrepancies, with effort in minimizing the ischemic time, revised surgical techniques, and strong regenerative power of the "young" graft, the old patient's liver function gradually returned to normal. This again proves that the definition of a "suitable graft" evolves with time and experience.

Effects of Kupffer cell inactivation on graft survival and liver regeneration after partial liver transplantation in rats

BACKGROUND

Gadolinium chloride (GdCl3) selectively inactivates Kupffer cells and protects against ischemia/reperfusion and endotoxin injury. However, the effect of Kupffer cell inactivation on liver regeneration after partial liver transplantation (PLTx) is not clear. This study was to investigate the role of GdCl3 pretreatment in graft function after PLTx, and to explore the potential mechanism involved in this process.

METHODS

PLTx (30% partial liver transplantation) was performed using Kamada's cuff technique, without hepatic artery reconstruction. Rats were randomly divided into the control low-dose (5 mg/kg) and high-dose (10 mg/kg) GdCl3 groups. Liver injury was determined by the plasma levels of alanine aminotransferase and aspartate aminotransferase, liver regeneration by PCNA staining and BrdU uptake, apoptosis by TUNEL assay. IL-6 and p-STAT3 levels were measured by ELISA and Western blotting.

RESULTS

GdCl3 depleted Kupffer cells and decreased animal survival rates, but did not significantly affect alanine aminotransferase and aspartate aminotransferase (P>0.05). GdCl3 pretreatment induced apoptosis and inhibited IL-6 overexpression and STAT3 phosphorylation after PLTx in graft tissues.

CONCLUSION

Kupffer cells may contribute to the liver regeneration after PLTx through inhibition of apoptosis and activation of the IL-6/p-STAT3 signal pathway.

Which is the best route of administration for cell therapy in experimental model of small-for size syndrome in rats?

PURPOSE

To evaluate which is the best route of administration for cell therapy in experimental rat model of small-for size syndrome.

METHODS

A total of 40 rats underwent partial hepatectomy (70%) that induces the small-for-size syndrome and were divided into four groups of route administration: intravenous, intraperitoneal, enteral and tracheal. The small-for-size syndrome model was designed with extended partial hepatectomy (70%). The animals were divided into four groups of routes administration: intravenous (n=10) - intravenously through the dorsal vein of the penis; intraperitoneal (n=10) - intraperitoneally in the abdominal cavity; enteral (n=10) - oroenteral with the placement of a number 4 urethral probe and maintained at third duodenal portion; tracheal (n=10) - after tracheal intubation. We track the animals and monitor them for 21 days; during this follow-up we evaluated the result of cell therapy application tracking animals using ultrasound, radiography and PET-scan. Statistical analysis was performed using GraphPad Prism Software(r). Differences were considered significant with the p<0.05. Data are presented as the median and variation for continuous variables. Comparisons between groups were made using analysis of the imaging test by the researchers.

RESULTS

All four groups underwent partial hepatectomy of 70% liver tissue targeting the same weight of resected liver. Initially the PET-scan tests showed similarity in administered cells by different routes. However, in few days the route of intravenous administration showed to be the most appropriated to lead cells to the liver followed by enteral. The tracheal and peritoneal routes were not as much successful for this goal.

CONCLUSION

The intravenous route is the best one to cell therapy in experimental rat model of small-for size-syndrome.

Outcome of duct-to-duct vs. Roux-en-Y hepaticojejunostomy biliary anastomoses in below 15-kg pediatric liver transplant recipients

The best type of biliary anastomosis to use in lower weight pediatric liver transplant recipients is debatable. In this study, we share a single center's experience comparing the rate of anastomotic biliary complications based on the type of biliary anastomosis performed in this population of patients. A retrospective review of pediatric liver transplants for recipients weighing <15 kg from 11/2003 till 12/2011 was performed. Patients were grouped based on the type of biliary anastomosis into two groups: duct-to-duct (d-d) and Roux-en-Y hepaticojejunostomy (h-j) anastomoses. A total of 24 patients (12 males, 12 females) with a mean age of 26 ± 20 months and a mean weight of 9.27 ± 2.63 kg (range = 5.3-13.9 kg) were studied. All anastomotic complications occurred in patients who received left lateral segments. No statistical differences were found in the post-operative biliary (p = 0.86) or vascular (p = 0.99) complications between the two groups. Acknowledging the limited sample size, our data suggest that duct-to-duct anastomosis can be performed safely in pediatric liver transplantation recipients weighing below 15 kg.

Liver regeneration after liver resection: Clinical aspects and correlation with infective complications

AIM: To investigate whether early liver regeneration after resection in patients with hepatic tumors might be influenced by post-operative infective complications.

METHODS: A retrospective analysis of 27 liver resections for tumors performed in a single referral center from November 2004 to January 2010. Regeneration was evaluated by multidetector computed tomography at a mean follow-up of 43.85 d. The Clavien-Dindo classification was used to evaluate postoperative events in the first 6 mo after transplantation, and Centers for Disease Control and Prevention definitions were used for healthcare associated infections data. Generalized linear regression models with Gaussian family distribution and log link function were used to reveal the principal promoters of early liver regeneration.

RESULTS: Ten of the 27 patients (37%) underwent chemotherapy prior to surgery, with a statistically significant prevalence of patients with metastasis (P = 0.007). Eight patients (30%) underwent embolization, 3 with primary tumors, and 5 with secondary tumors. Twenty patients (74%) experienced complications, with 12 (60%) experiencing Clavien-Dindo Grade 3a to 5 complications. Regeneration ≥ 100% occurred in 10 (37%) patients. The predictors were smaller future remnant liver volume (-0.002; P < 0.001), and a greater spleen volume/future remnant liver volume ratio (0.499; P = 0.01). Patients with a resection of ≥ 5 Couinaud segments experienced greater early regeneration (P = 0.04). Nine patients experienced surgical site infections, and in 7 cases Clavien-Dindo Grade 3a to 4 complications were detected (P = 0.016). There were no significant differences between patients with primary or secondary tumors, and either onset or infections or severity of surgical complications.

CONCLUSION: Regardless of the onset of infective complications, future remnant liver and spleen volumes may be reliable predictors of early liver regeneration after hepatic resection on an otherwise healthy liver.

Impact of future remnant liver volume on post-hepatectomy regeneration in non-cirrhotic livers

Objective: The purpose of the study is to detect if some parameters can be considered as predictors of liver regeneration in two different patient populations composed of in living donors for adult to adult living donor liver transplant and patients with hepatic malignancies within a single institution.

Summary Background Data: Preoperative multi-detector computed tomography volumetry is an essential tool to assess the volume of the remnant liver.

Methods: A retrospective analysis from an ongoing clinical study on 100 liver resections, between 2004 and 2010. Seventy patients were right lobe living donors for liver transplantation and 30 patients were resected for treatment of tumors. Pre-surgical factors such as age, weight, height, body mass index (BMI), original liver volume, future remnant liver volume (FRLV), spleen volume, liver function tests, creatinine, platelet count, steatosis, portal vein embolization, and number of resected segments were analyzed to evidence potential markers for liver regeneration.

Results: Follow-up period did not influence the amount of liver regenerated: the linear regression evidenced that there is no correlation between percentage of liver regeneration and time of follow-up (p = 0.88). The pre-surgical variables that resulted markers of liver regeneration include higher preoperative values of BMI (p = 0.01), bilirubin (p = 0.04), glucose (p = 0.05), and gamma-glutamyl transpeptidase (p = 0.014); the most important association was revealed regarding the lower FRLV (p < 0.0001) and percentage of liver regeneration. The stepwise regression revealed a strong impact of FRLV (p < 0.0001) on the other predictor variables.

Conclusion: Liver regeneration follows similar pathway in living donor and in patients resected for cancer. Small FRLV tends to regenerate more and faster, confirming that a larger resections may lead to a greater promotion of liver regeneration in patients with optimal conditions in terms of body habitus, preoperative liver function tests, and glucose level.

Comparison of remnant to total functional liver volume ratio and remnant to standard liver volume ratio as a predictor of postoperative liver function after liver resection

BACKGROUNDS/AIMS

The future liver remnant (FLR) is usually calculated as a ratio of the remnant liver volume (RLV) to the total functional liver volume (RLV/TFLV). In liver transplantation, it is generally accepted that the ratio of the graft volume to standard liver volume (SLV) needs to be at least 30% to 40% to fit the hepatic metabolic demands of the recipient. The aim of this study was to compare RLV/TFLV versus RLV/SLV as a predictor of postoperative liver function and liver failure.

METHODS

CT volumetric measurements of RLV were obtained retrospectively in 74 patients who underwent right hemihepatectomy for a malignant tumor from January 2010 to May 2013. RLV and TFLV were obtained using CT volumetry, and SLV was calculated using Yu's formula: SLV (ml)=21.585×body weight (kg)(0.732)×height (cm)(0.225). The RLV/SLV ratio was compared with the RLV/TFLV as a predictor of postoperative hepatic function.

RESULTS

Postheptectomy liver failure (PHLF), morbidity, and serum total bilirubin level at postoperative day 5 (POD 5) were increased significantly in the group with the RLV/SLV ≤30% compared with the group with the RLV/SLV >30% (p=0.002, p=0.004, and p<0.001, respectively). But RLV/TFLV was not correlated with PHLF and morbidity (p=1.000 and 0.798, respectively). RLV/SLV showed a stronger correlation with serum total bilirubin level than RLV/TFLV (RLV/SLV vs. RLV/TFLV, R=0.706 vs. 0.499, R(2)=0.499 vs. 0.239).

CONCLUSIONS

RLV/SLV was more specific than RLV/TFLV in predicting the postoperative course after right hemihepatectomy. To determine the safe limit of hepatic resection, a larger-scaled prospective study is needed.

A formula to calculate the standard liver volume in children and its application in pediatric liver transplantation

Due to a lack of available size-matched liver grafts from children, most pediatric recipients are transplanted with technical variant grafts from adult donors. Size requirements for these grafts are not well defined, and consequences of mismatched graft sizes in pediatric liver transplantation are not known. Existing formulas for calculation of a standard liver volume are mostly derived from adults disregarding the age-related percentual liver weight changes in children. In this study, we aimed to establish a formula for general use in children to calculate the standard liver volume. In a second step, the formula was applied in pediatric patients undergoing liver transplantation at our institution between 2000 and 2010 (n = 377). Analysis of a large number (n = 388) of autopsy data from children by regression analysis revealed a best fit for two formulas: "Formula 1," children 0 to ≤1 year (n = 246): standard liver volume [ml] = -143.062973 +4.274603051 * body length [cm] + 14.78817631 * body weight [kg]; "Formula 2," children >1 to <16 years (n = 142): standard liver volume [ml] = -20.2472281 + 3.339056437 * body length [cm] + 13.11312561 * body weight [kg]. In comparison with children receiving size-matched organs, we found an elevated risk of liver graft failure in children transplanted with a small-for-size graft, whereas large-for-size organs seem to have no negative impact.

Strategies for successful left-lobe living donor liver transplantation in 250 consecutive adult cases in a single center

BACKGROUND

Living donor liver transplantation (LDLT) using left-lobe grafts was not generally recognized as feasible due to the problem of graft size.

STUDY DESIGN

We retrospectively evaluated strategies for successful left-lobe LDLT in 250 consecutive cases stratified into 2 eras: Era 1 (n = 121), in which surgical procedures were continually refined, and Era 2 (n = 129), in which established procedures were used.

RESULTS

Graft volume (GV) did not affect the incidence of graft function or survival. Era 2 patients had decreased portal vein (PV) pressure at closure (16.0 ± 3.5 mmHg vs 19.1 ± 4.6 mmHg, p < 0.01), increased PV flow/GV (301 ± 125 mL/min/100g vs 391 ± 142 mL/min/100g, p < 0.01), and improved graft survival rate (1-year: 90.6% vs 81.8%. p < 0.01) despite the smaller GV/standard volume (SLV) ratio (36.2% ± 5.2% vs 41.2% ± 8.8%, p < 0.01) compared with Era 1. Patients in Era 2 had lower PV pressure and greater PV flow (y = 598-5.7 x, p = 0.02) at any GV/SLV compared with cases in Era 1 (y = 480-4.3 x, p < 0.01), representing greater graft compliance. Univariate analysis for graft survival showed that Era 1, Model for End-Stage Liver Disease (MELD) score ≥ 20, inpatient status, closing portal venous pressure ≥ 20 mmHg, no splenectomy, and operative blood loss ≥ 10 L were the risk factors for graft loss, and multivariate analysis showed that Era 1 was the only significant factor (p < 0.01). During Era 2, development of primary graft dysfunction was associated with inpatient recipient status (p = 0.02) and donor age ≥ 45 years (p < 0.01).

CONCLUSIONS

The outcomes of left-lobe LDLT were improved by accumulated experience and technical developments.

Inhalation of hydrogen gas reduces liver injury during major hepatotectomy in swine

AIM: To study the effect of H₂ gas on liver injury in massive hepatectomy using the Intermittent Pringle maneuver in swine.

METHODS: Male Bama pigs (n = 14) treated with ketamine hydrochloride and Sumianxin II as induction drugs followed by inhalation anesthesia with 2% isoflurane, underwent 70% hepatotectomy with loss of bleeding less than 50 mL, and with hepatic pedicle occlusion for 20 min, were divided into two groups: Hydrogen-group (n = 7), the pigs with inhalation of 2% hydrogen by the tracheal intubation during major hepatotectomy; Contrast-group (n = 7), underwent 70% hepatotectomy without inhalation of hydrogen. Hemodynamic changes and plasma concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and malondialdehyde (MDA) in liver tissue were measured at pre-operation, post-hepatotectomy (PH) 1 h and 3 h. The apoptosis and proliferating cell nuclear antigen (PCNA) expression in liver remnant were evaluated at PH 3 h. Then we compared the two groups by these marks to evaluate the effect of the hydrogen in the liver injury during major hepatotectomy with the Pringle Maneuver in the swine.

RESULTS: There were no significant differences in body weight, blood loss and removal liver weight between the two groups. There was no significant difference in changes of portal vein pressure between two groups at pre-operation, PH 30 min, but in hydrogen gas treated-group it slightly decrease and lower than its in Contrast-group at PH 3 h, although there were no significant difference (P = 0.655). ALT and AST in Hydrogen-group was significantly lower comparing to Contrast-group (P = 0.036, P = 0.011, vs P = 0.032, P = 0.013) at PH 1 h and 3 h, although the two groups all increased. The MDA level increased between the two group at PH 1 h and 3 h. In the hydrogen gas treated-group, the MDA level was not significantly significant at pre-operation and significantly low at PH 1 h and 3 h comparing to Contrast-group (P = 0.0005, P = 0.0004). In Hydrogen-group, the HA level was also significantly low to Contrast-group (P = 0.0005, P = 0.0005) although the two groups all increased at PH 1 h and 3 h. The expression of cluster of differentiation molecule 31 molecules Hydrogen-group was low to Contrast-group. However, PCNA index (%) was not statistically significant between the two groups (P = 0.802). Microphotometric evaluation of apoptotic index (AI) in terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-stained tissue after hepatotectomy for 3h, the AI% level in the hydrogen was significantly low to Contrast-group (P = 0.012). There were no significant difference between Hydrogen-group and Contrast-group at pre-operation (P = 0.653, P = 0.423), but after massive hepatotectomy, the TNF-α and IL-6 levels increase, and its in Hydrogen-group was significantly low compared with Contrast-group (P = 0.022, P = 0.013, vs P = 0.016, P = 0.012), respectively. Hydrogen-gas inhalation reduce levels of these markers and relieved morphological liver injury and apoptosis.

CONCLUSION: H₂ gas attenuates markedly ischemia and portal hyperperfusion injury in pigs with massive hepatotectomy, possibly by the reduction of inflammation and oxidative stress, maybe a potential agent for treatment in clinic.

Increasing the recipient benefit/donor risk ratio by lowering the graft size requirement for living donor liver transplantation

In living donor liver transplantation (LDLT), a right liver graft is larger than a left liver graft and hence leads to better recipient survival. However, in comparison with donor left hepatectomy, donor right hepatectomy carries a higher donor risk. We estimated the expansion of the applicability of left liver living donor liver transplantation (LLDLT) by lowering the graft weight (GW)/standard liver volume (SLV) ratio in increments of 5%. Consecutive LDLT cases were included in this study. The results of computed tomography volumetry provided the graft volume measurements, and the GW was derived from the graft volume with the conversion factor of 1.19 mL/g. We tried to estimate how many more times LLDLT would have been feasible if the GW/SLV requirement had been lowered to 40%, 35%, 30%, or 25%. In all, 361 consecutive donor-recipient pairs underwent LDLT. Right liver living donor liver transplantation (RLDLT) accounted for 95% of the LDLT cases. Most recipients were male (74.2%), and most donors were female (60.4%). The median GW/SLV ratio was 46% (47% for RLDLT and 37% for LLDLT, P < 0.001). Two of the 218 female donors donated the left liver, and 12 of the 93 female recipients received a left liver. In 147 of the 173 cases (85%) when the donor was female and the recipient was male, the GW/SLV ratio did not reach 30%. LLDLT could have been performed more often than 5% of the time if a lower GW/SLV requirement had been adopted. With GW/SLV ratios ≥ 40%, ≥ 35%, ≥ 30%, and ≥ 25%, the proportion of LLDLT cases would have risen from 5% to 5.8%, 12.5%, 29.1%, and 62.3%, respectively. LLDLT could have been performed approximately twice as often with every 5% reduction of the GW/SLV requirement. In conclusion, lowering the graft size requirement could improve the applicability of LLDLT and hence reduce donor risk.

[Small-for-size: experimental findings for liver surgery]

The characteristics of the hepatic macrocirculation, i.e., the parallel portal-venous and arterial blood supply, is of utmost relevance for liver surgery. With extended hepatectomy or transplantation of a reduced-size liver the remaining or transplanted liver tissue is overperfused because the liver fails to regulate the portal-venous inflow. This portal hyperperfusion is responsible for the initiation of liver cell proliferation but represents at the same time one of the substantial events in the pathogenesis of the small-for-size syndrome. Portal-venous hyperperfusion, the so-called hepatic arterial buffer response, which describes the semi-reciprocal relationship between the portal-venous and hepatic arterial blood flows, leads to an arterial hypoperfusion of the small-for-size liver. In this article experimental and clinical data are discussed which underline the high but so far overseen relevance of this arterial underperfusion in the development of a small-for-size syndrome.

Primary graft dysfunction after living donor liver transplantation is characterized by delayed functional hyperbilirubinemia

The purpose of this study is to propose a new concept of primary graft dysfunction (PGD) after living donor liver transplantation (LDLT), characterized by delayed functional hyperbilirubinemia (DFH) and a high early graft mortality rate. A total of 210 adult-to-adult LDLT grafts without anatomical, immunological or hepatitis-related issues were included. All of the grafts with early mortality (n = 13) caused by PGD in LDLT had maximum total bilirubin levels >20 mg/dL after postoperative day 7 (p < 0.001). No other factors, including prothrombin time, ammonia level or ascites output after surgery were associated with early mortality. Thus, DFH of >20 mg/dL for >seven consecutive days occurring after postoperative day 7 (DFH-20) was used to characterize PGD. DFH-20 showed high sensitivity (100%) and specificity (95.4%) for PGD with early mortality. Among the grafts with DFH-20 (n = 22), those with early mortality (n = 13) showed coagulopathy (PT-INR > 2), compared with those without mortality (p = 0.002). Pathological findings in the grafts with DFH-20 included hepatocyte ballooning and cholestasis, which were particularly prominent in the centrilobular zone. PGD after LDLT is associated with DFH-20 caused by graft, recipient and surgical factors, and increases the risk of early graft mortality.

Implanted adipose-derived stem cells attenuate small-for-size liver graft injury by secretion of VEGF in rats

Graft injury after small-for-size liver transplantation impairs graft function and threatens the survival of the recipients. The use of adipose-derived stem cells (ADSCs) for liver injury protection and repair is promising. Our aim was to investigate the role of vascular endothelial growth factor (VEGF) secreted by ADSCs in the treatment of small-for-size liver graft injury. Studies were performed using ADSCs with VEGF secretion blocked by RNA interference. In vitro, ADSCs prevented apoptosis of freshly isolated liver sinusoidal endothelial cells (LSECs) by secretion of VEGF. Syngeneic 35% orthotopic liver transplantation followed by implantation of syngeneic ADSCs through the portal vein system was performed using Wistar rats. We found VEGF secreted by implanted ADSCs improved graft microcirculatory disturbances, serum liver function parameters and survival. The improved microcirculatory status was also reflected by reduced hepatocellular damage, especially LSEC apoptosis and improved liver regeneration. These effects were accompanied by decreased expression of endothelin receptor type A, increased Bcl-2/Bax ratio, decreased expression of Bad and elevated proportion of phosphorylated Bad. In conclusion, implanted syngeneic ADSCs attenuated small-for-size liver graft injuries and subsequently enhanced liver regeneration in a rat 35% liver transplantation model. The VEGF secreted by implanted ADSCs played a crucial role in this process.

Left lobe adult-to-adult living donor liver transplantation: Should portal inflow modulation be added?

Recently, the successful application of portal inflow modulation has led to renewed interest in the use of left lobe grafts in adult-to-adult living donor liver transplantation (LDLT). However, data on the hepatic hemodynamics supporting portal inflow modulation are limited, and the optimal portal circulation for a liver graft is still unclear. We analyzed 42 consecutive adult-to-adult left lobe LDLT cases without splenectomy or a portocaval shunt. The mean actual graft volume (GV)/recipient standard liver volume (SLV) ratio was 39.8% ± 5.7% (median = 38.9%, range = 26.1%-54.0%). The actual GV/SLV ratio was less than 40% in 24 of the 42 cases, and the actual graft-to-recipient weight ratio was less than 0.8% in 17 of the 42 recipients. The mean portal vein pressure (PVP) was 23.9 ± 7.6 mm Hg (median = 23.5 mm Hg, range = 9-38 mm Hg) before transplantation and 21.5 ± 3.6 mm Hg (median = 22 mm Hg, range = 14-27 mm Hg) after graft implantation. The mean portal pressure gradient (PVP - central venous pressure) was 14.5 ± 6.8 mm Hg (median = 13.5 mm Hg, range = 3-26 mm Hg) before transplantation and 12.4 ± 4.4 mm Hg (median = 13 mm Hg, range = 1-21 mm Hg) after graft implantation. The mean posttransplant portal vein flow was 301 ± 167 mL/minute/100 g of liver in the 38 recipients for whom it was measured. None of the recipients developed small-for-size syndrome, and all were discharged from the hospital despite portal hyperperfusion. The overall 1-, 3-, and 5-year patient and graft survival rates were 100%, 97%, and 91%, respectively. In conclusion, LDLT with a left liver graft without splenectomy or a portocaval shunt yields good long-term results for adult patients with a minimal donor burden.

Validation of graft and standard liver size predictions in right liver living donor liver transplantation

PURPOSE

To assess the accuracy of a formula derived from 159 living liver donors to estimate the liver size of a normal subject: standard liver weight (g) = 218 + body weight (kg) × 12.3 + 51 (if male). Standard liver volume (SLV) is attained by a conversion factor of 1.19 mL/g.

METHODS

The total liver volume (TLV) of each of the subsequent consecutive 126 living liver donors was determined using the right liver graft weight (RGW) on the back table, right/left liver volume ratio on computed tomography, and the conversion factor. The estimated right liver graft weight (ERGW) was determined by the right liver volume on computed tomography (CT) and the conversion factor. SLV and ERGW were compared with TLV and RGW, respectively, by paired sample t test.

RESULTS

Donor characteristics of both series were similar. SLV and TLV were 1,099.6 ± 139.6 and 1,108.5 ± 175.2 mL, respectively, (R2 = 0.476) (p = 0.435). The difference between SLV and TLV was only -8.9 ± 128.2 mL (-1.0 ± 11.7%). ERGW and RGW were 601.5 ± 104.1 and 597.1 ± 102.2 g, respectively (R2 = 0.781) (p = 0.332). The conversion factor from liver weight to volume for this series was 1.20 mL/g. The difference between ERGW and RGW was 4.3 ± 49.8 g (0.3 ± 8.8%). ERGW was smaller than RGW for over 10% (range 0.21-40.66 g) in 18 of the 126 donors. None had the underestimation of RGW by over 20%.

CONCLUSION

SLV and graft weight estimations were accurate using the formula and conversion factor.

Role of hepatic stellate cells on graft injury after small-for-size liver transplantation

BACKGROUND AND AIM

Small-for-size grafts are prone to mechanical injury and a series of chemical injuries that are related to hemodynamic force. Hepatic stellate cells activate and trans-differentiate into contractile myofibroblast-like cells during liver injury. However, the role of hepatic stellate cells on sinusoidal microcirculation is unknown with small-for-size grafts.

METHODS

Thirty-five percent of small-for-size liver transplantation was performed with rats as donors and recipients. Endothelin-1 levels as well as hepatic stellate cells activation-related protein expression, endothelin-1 receptors, and ultrastructural changes were examined. The cellular localizations of two types of endothelin-1 receptors were detected. Furthermore, liver function and sinusoidal microcirculation were analyzed using two different selective antagonists of endothelin-1 receptor.

RESULTS

Intragraft expression of hepatic stellate cells activation-related protein such as desmin, crystallin-B and smooth muscle α-actin was upregulated as well as serum endothelin-1 levels and intragraft expression of the two endothelin receptors. The antagonist to endothelin-1 A receptor not to the endothelin-1 B receptor could attenuate microcirculatory disturbance and improve liver function.

CONCLUSIONS

Small-for-size liver transplantation displayed increased hepatic stellate cells activation and high level of endothelin-1 binding to upregulation of endothelin-1 A receptor on hepatic stellate cells, which contracted hepatic sinusoid inducing graft injury manifested as reduction of sinusoidal perfusion rate and elevation of sinusoidal blood flow.

End-stage liver cirrhosis with severe autoimmune hemolytic anemia, treated by blood type-incompatible living donor liver transplantation: a case report

We present a case of successful living donor liver transplantation (LDLT) for liver cirrhosis caused by hepatitis B virus with severe autoimmune hemolytic anemia (AIHA) using an ABO-incompatible (ABOi) graft. The patient was a 47-year-old woman who had a history of ruptured esophageal varices, accumulation of intractable ascites, frequent hepatic encephalopathy and severe anemia, with a hemoglobin value of approximately 3 g/dL due to AIHA. We treated the patient by LDLT using an ABOi liver graft. The treatment strategy included anti-CD20 antibody, plasma exchange and transfusion before LDLT. The patient's anemia improved after surgery; she required only 2 units of irradiated red blood cell concentrates-leukocytes reduced. The patient was discharged from the hospital on postoperative day 35. Two years after surgery, the patient still shows normal hepatic and hematological findings. The immunomodulation protocol for ABOi LDLT was effective not only to avoid humoral reactions associated with ABOi LDLT, but also those associated with AIHA.