Effects of hemi-portocaval shunts for inflow modulation on the outcome of small-for-size grafts in living donor liver transplantation

Porcine model for the study of liver regeneration enhanced by non-invasive 13C-methacetin breath test (LiMAx test) and permanent portal venous access

Introduction

Despite advances in perioperative management and surgical technique, postoperative liver failure remains a feared complication after hepatic resection. Various supportive treatment options are under current discussion, but lack of structured evaluation. We therefore established a porcine model of major liver resection to study regeneration after partial hepatectomy in a reliable and well-defined pre-clinical setting.

Methods

Major hepatectomy was performed on seven minipigs with the intention to set up a non-lethal but relevant transient impairment of liver function. For steady postoperative vascular access (e.g. for blood withdrawal, measurement of venous pressure), permanent catheters were implanted into the internal jugular and portal veins, respectively. Animals were followed up for 30 days; clinical and laboratory results were recorded in detail. Monitoring was enhanced by non-invasive determination of the maximum liver function capacity (LiMAx test).

Results and conclusions

The established porcine model appeared suitable for evaluation of postoperative liver regeneration. Clinical characteristics and progression of liver function impairment as well as subsequent recovery were comparable to courses known from surgery in humans. Laboratory parameters (e.g. liver enzymes, bilirubin, INR, coagulation factor II) showed relevant derangements during postoperative days (POD) 0 to 3 followed by normalization until POD 7. Application of the LiMAx test was feasible in minipigs, again showing values comparable to humans and kinetics in line with obtained laboratory parameters. The exteriorized portal vein catheters enabled intra- and postoperative monitoring of portal venous pressures as well as easy access for blood withdrawal without relevant risk of postoperative complications.

Somatostatin and the "Small-For-Size" Liver

“Small-for-size” livers arising in the context of liver resection and transplantation are vulnerable to the effects of increased portal flow in the immediate postoperative period. Increased portal flow is an essential stimulus for liver regeneration. If the rise in flow and stimulus for regeneration are excessive; however, liver failure and patient death may result. Somatostatin is an endogenous peptide hormone that may be administered exogenously to not only reduce portal blood flow but also offer direct protection to different cells in the liver. In this review article, we describe key changes that transpire in the liver following a relative size reduction occurring in the context of resection and transplantation and the largely beneficial effects that peri-operative somatostatin therapy may help achieve in this setting.

The Impact of a Nitric Oxide Synthase Inhibitor (L-NAME) on Ischemia⁻Reperfusion Injury of Cholestatic Livers by Pringle Maneuver and Liver Resection after Bile Duct Ligation in Rats

The Pringle maneuver (PM) has been widely used to control blood loss during liver resection. However, hepatic inflow occlusion can also result in hepatic ischemia–reperfusion injury (IRI), especially in patients with a cholestatic, fibrotic, or cirrhotic liver. Here we investigate a nitric oxide synthase (NOS) inhibitor N-Nitroarginine methyl ester (L-NAME) on IRI after the PM and partial hepatectomy of cholestatic livers induced by bile duct ligation (BDL) in rats. Control group (non-BDL/no treatment), BDL + T group (BDL/L-NAME treatment) and BDL group (BDL/no treatment) were analyzed. Cholestasis was induced by BDL in the L-NAME and BDL group and a 50% partial hepatectomy with PM was performed. L-NAME was injected before PM in the BDL + T group. Hepatocellular damage, portal venous flow, microcirculation, endothelial lining, and eNOS, iNOS, interleukin (IL)-6, and transforming growth factor-β (TGF-β) were evaluated. Microcirculation of the liver in the BDL + T group tended to be higher. Liver damage and apoptotic index were significantly lower and Ki-67 labeling index was higher in the BDL + T group while iNOS and TGF-β expression was decreased. This was corroborated by a better preserved endothelial lining. L-NAME attenuated IRI following PM and improved proliferation/regeneration of cholestatic livers. These positive effects were considered as the result of improved hepatic microcirculation, prevention of iNOS formation, and TGF-β mRNA upregulation.

Is Portal Venous Pressure Modulation Still Indicated for All Recipients in Living Donor Liver Transplantation?

There is a consensus that portal venous pressure (PVP) modulation prevents portal hypertension (PHT) and consequent complications after adult-to-adult living donor liver transplantation (ALDLT). However, PVP-modulation strategies need to be updated based on the most recent findings. We examined our 10-year experience of PVP modulation and reevaluated whether it was necessary for all recipients or for selected recipients in ALDLT. In this retrospective study, 319 patients who underwent ALDLT from 2007 to 2016 were divided into 3 groups according to the necessity and results of PVP modulation: not indicated (n = 189), indicated and succeeded (n = 92), and indicated but failed (n = 38). Graft survival and associations with various clinical factors were investigated. PVP modulation was performed mainly by splenectomy to lower final PVP to ≤15 mm Hg. Successful PVP modulation improved prognosis to be equivalent to that of patients who did not need modulation, whereas failed modulation was associated with increased incidence of small-for-size syndrome (SFSS; P = 0.003) and early graft loss (EGL; P = 0.006). Among patients with failed modulation, donor age ≥ 45 years (hazard ratio [HR], 3.67; P = 0.02) and ABO incompatibility (HR, 3.90; P = 0.01) were independent risk factors for graft loss. Survival analysis showed that PVP > 15 mm Hg was related to poor prognosis in grafts from either ABO-incompatible or older donor age ≥ 45 years (P < 0.001), but it did not negatively affect grafts from ABO-compatible/identical and young donor age < 45 years (P = 0.27). In conclusion, intentional PVP modulation is not necessarily required in all recipients. Although grafts from both ABO-compatible/identical and young donors can tolerate PHT, lowering PVP to ≤15 mm Hg is a key to preventing SFSS and consequent EGL with grafts from either ABO-incompatible or older donors.

Intraoperative Surgical Portosystemic Shunt in Liver Transplantation: Systematic Review and Meta-Analysis

Background

Expanded clinical and surgical techniques in liver transplantation can markedly improve patient and graft survival. The main purpose of this study was to evaluate the efficacy of intraoperative portocaval shunts in liver transplantation.

Material/Methods

Searches were conducted in Cochrane, MEDLINE, and EMBASE databases, and updated in January 2018. The following specific outcomes of interest were defined and evaluated separated using 2 different reviews and meta-analyses for 1) hemi-portocaval shunt (HPCS) and 2) temporary portocaval shunt (TPCS). Comparative studies were analyzed separately for both surgical portocaval shunt modalities.

Results

Only 1 well-designed randomized controlled trial was found. Most studies were retrospective or prospective. Initially, we found 1479 articles. Of those selected, 853 were from PubMed/MEDLINE, 32 were from Cochrane and 594 were from EMBASE. Our meta-analysis included a total of 3232 patients for all the included studies. Results found that 41 patients with HPCS experienced increased 1-year patient survival (OR 16.33; P=0.02) and increased 1-year graft survival (OR 17.67; P=0.01). The TPCS analysis with 1633 patients found patients had significantly shorter intensive care unit length of stay (days) (P=0.006) and hospital length of stay (P=0.02) and had decreased primary nonfunction (PNF) (OR 0.30, P=0.02) and mortality rates (OR 0.52, P=0.01).

Conclusions

Intraoperative surgical portosystemic shunt in relation to liver transplantation with TPCS was able to prevent PNF, decrease hospital length of stay and unit care length of stay. Furthermore, in analyzing data for patients with HPCS, we observed increases in the 1-year graft and patient survival rates. More prospective randomized trials are needed to arrive at a more precise conclusion.

Post hepatectomy liver failure - A comprehensive review of current concepts and controversies

Post hepatectomy liver failure (PHLF) comprises of a conundrum of symptoms and signs following major hepatic resections. The pathophysiology essentially revolves around disruption of the normal hepatocyte regeneration and disturbed liver homeostasis. Prompt identification of the pre-operative predictors of PHLF in the form of biochemical parameters and imaging features are of paramount importance for any hepatic surgeon and forms the cornerstone of its management. Treatment revolves around a goal-directed resuscitation of the systemic organ failure. Auxiliary support systems such as liver dialysis devices and stem cell therapy are still under investigational trials for treatment of the same. Orthotopic liver transplantation (OLT) is the last resort in most cases not responding to other measures.

Living Donor Liver Transplantation: Technical Innovations

Living donor liver transplantation (LDLT) has found a place to serve the end-stage liver disease community as the donor safety and recipient suitability has been elucidated. Donor safety is of paramount importance and transplant programs must continue endeavors to maintain the highest possible standards. At the same time, adequacy of grafts based on recipient clinical status via their model for end-stage liver disease (MELD) score and volumetric studies to achieve a GRBWR >0.8, along with special attention to anatomic tailoring and portal venous flow optimization are necessary for successful transplantation. Technical innovations have improved sequentially the utility and availability of LDLT.

Allograft Portacaval Shunt in Small-for-Size Liver in Deceased Donor Liver Transplant

Portal hyperperfusion is detrimental to small-for-size livers (SFSLs) in liver transplantation. Surgical techniques modulating portal inflow provide the most effective approach to protect the SFSL. In this report, we describe a technique creating an allograft portacaval shunt that effectively attenuates portal inflow without a requirement of extensive surgical dissection in the recipient during the transplantation.

Incidence and Outcome of Small-for-Size Liver Grafts Transplanted in Adult Recipients

Small-for-size liver transplantation (SFS-LT) carries high morbidity and mortality after transplantation. SFS-LT is usually associated with living-donor or deceased-donor split LT; however its incidence and outcome are poorly defined in adult LT recipients who receive whole grafts (WLT). In this study, we retrospectively reviewed our cohort of 3,106 deceased-donor LT in adult recipients. We found that among the 31 split LTs, 11 (35.5%) were SFS. In contrast, there only 1.08% of the whole-graft transplants (31 out of 2,868) were SFS. Although less common, SFS-WLT is associated with poorer long-term outcome of both graft and patient survivals.

Interventional radiology in the management of the liver transplant patient

Liver transplantation (LT) is commonly used to treat patients with end-stage liver disease. The evolution of surgical techniques, endovascular methods, and medical care has led to a progressive decrease in posttransplant morbidity and mortality. Despite these improvements, a multidisciplinary approach to each patient remains essential as the early diagnosis and treatment of the complications of transplantation influence graft and patient survival. The critical role of interventional radiology in the collaborative approach to the care of the LT patient will be reviewed. Liver Transplantation 23 1328-1341 2017 AASLD.

The International Liver Transplantation Society Living Donor Liver Transplant Recipient Guideline

Living donor liver transplantation (LDLT) has been increasingly embraced around the world as an important strategy to address the shortage of deceased donor livers. The aim of this guideline, approved by the International Liver Transplantation Society (ILTS), is to provide a collection of expert opinions, consensus, and best practices surrounding LDLT. Recommendations were developed from an analysis of the National Library of Medicine living donor transplantation indexed literature using the Grading of Recommendations Assessment, Development and Evaluation methodology. Writing was guided by the ILTS Policy on the Development and Use of Practice Guidelines (www.ilts.org). Intended for use by physicians, these recommendations support specific approaches to the diagnostic, therapeutic, and preventive aspects of care of living donor liver transplant recipients.

Compared to cadaveric liver transplantation, live donor LT (LDLT) is challenged by ethical, medical and surgical considerations, many of which are still unresolved. The aim of this guideline is to provide a collection of expert opinions, consensus, and best practices surrounding LDLT.

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).

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).

Outcomes of right-lobe and left-lobe living-donor liver transplantations using small-for-size grafts

AIM

To analyze the outcomes of living-donor liver transplantation (LDLT) using left-lobe (LL) or right-lobe (RL) small-for-size (SFS) grafts.

METHODS

Prospectively collected data of adult patients who underwent LDLT at our hospital in the period from January 2003 to December 2013 were reviewed. The patients were divided into the RL-LDLT group and the LL-LDLT group. The two groups were compared in terms of short- and long-term outcomes, including incidence of postoperative complication, graft function, graft survival, and patient survival. A SFS graft was defined as a graft with a ratio of graft weight (GW) to recipient standard liver volume (RSLV) (GW/RSLV) of < 50%. The Urata formula was used to estimate RSLV.

RESULTS

Totally 218 patients were included for analysis, with 199 patients in the RL-LDLT group and 19 patients in the LL-LDLT group. The two groups were similar in terms of age (median, 53 years in the RL-LDLT group and 52 years in the LL-LDLT group, P = 0.997) but had significantly different ratios of men to women (165:34 in the RL-LDLT group and 8:11 in the LL-LDLT group, P < 0.0001). The two groups were also significantly different in GW (P < 0.0001), GW/RSLV (P < 0.0001), and graft cold ischemic time (P = 0.007). When it comes to postoperative complication, the groups were comparable (P = 0.105). Five patients died in hospital, 4 (2%) in the RL-LDLT group and 1 (5.3%) in the LL-LDLT group (P = 0.918). There were 38 graft losses, 33 (16.6%) in the RL-LDLT group and 5 (26.3%) in the LL-LDLT group (P = 0.452). The 5-year graft survival rate was significantly better in the RL-LDLT group (95.2% vs 89.5%, P = 0.049). The two groups had similar 5-year patient survival rates (RL-LDLT: 86.8%, LL-LDLT: 89.5%, P = 0.476).

CONCLUSION

The use of SFS graft in LDLT requires careful tailor-made surgical planning and meticulous operation. LL-LDLT can be a good alternative to RL-LDLT with similar recipient outcomes but a lower donor risk. Further research into different patient conditions is needed in order to validate the use of LL graft.

Impact of Portal Hemodynamic Changes in Partial Liver Grafts on Short-Term Graft Regeneration in Living Donor Liver Transplantation

BACKGROUND

Regeneration of partial liver grafts is critical for successful living donor liver transplantation (LDLT), especially in adult recipients. The purpose of this study was to investigate the intraoperative hemodynamic changes in partial liver grafts and characterize their potential impact on post-transplant liver regeneration in LDLT.

METHODS

We examined the portal venous flow (PVF) and hepatic arterial flow (HAF) to partial liver grafts by means of ultrasonic transit time flowmeter of donors immediately before graft retrieval and of the corresponding recipients after vascular reconstruction in 48 LDLT cases. We evaluated post-transplant liver regeneration according to the changes in graft liver volume between the time of transplantation and the 7th post-transplant day.

RESULTS

There was a significant increase in PVF to the partial liver grafts in recipients (rPVF) compared with that in donors. In contrast, graft HAF in recipients significantly decreased compared with that in donors. The rPVF inversely correlated with graft weight (GW)-recipient body weight ratio (GRWR), whereas HAF volume showed no significant correlation. The rPVF/GW positively correlated with the rate of liver regeneration (GRR), which inversely correlated with GRWR. The rPVF/GW was significantly higher, and GRR tended to be larger in the small graft group than in the non-small graft group.

CONCLUSIONS

Intraoperative portal hemodynamic changes in partial liver grafts strongly affect their post-transplant regeneration. In particular, in small liver grafts, an immediate and remarkable increase in graft PVF may contribute to rapid liver regeneration after LDLT if the increased PVF remains within a safe range.

Portosystemic collaterals in living donor liver transplantation: What is all the fuss about?

Portosystemic collaterals are a common finding in patients with cirrhosis undergoing liver transplantation. Recently, there has been a renewed interest regarding their significance in the setting of living donor liver transplantation (LDLT) due to concerns of graft hypoperfusion or hyperperfusion and its impact on early posttransplant outcomes. Presence of these collaterals has greater significance in the LDLT setting when compared with the deceased donor liver transplantation setting as dictated by the difference in the physiology of partial liver grafts. We discuss current thinking of portal flow dynamics and the techniques for dealing with this clinical problem. Liver Transplantation 23 537-544 2017 AASLD.

A portal pressure cut-off of 15 versus a cut-off of 20 for prevention of small-for-size syndrome in liver transplantation: A comparative study

AIM

Portal hypertension has recently been implicated in the pathogenesis of small-for-size syndrome (SFSS) in adult-to-adult living-donor liver transplantation (A-LDLT). The aim of our study is to compare the portal venous pressure (PVP) cut-off values of 15 mmHg and 20 mmHg in terms of prevention of SFSS in A-LDLT.

METHODS

Seventy-six patients underwent A-LDLT. A PVP <20 mmHg at the end of the operation was targeted using graft inflow modulation. Patients were divided into two groups: group A, final PVP <15 mmHg; and group B, final PVP 15-19 mmHg. Peak serum bilirubin and peak international normalized ratio in the first month after A-LDLT, as well as hepatic encephalopathy, SFSS, 90-day morbidity, and mortality were observed in both groups.

RESULTS

Final PVP was well controlled below 20 mmHg in all patients (group A, n = 39; group B, n = 37). Six patients suffered SFSS in group B (16.2%) compared to one patient (2.6%) in group A (P = 0.04). Nine patients died in group B (24.3%), four of whom died of SFSS, compared to three patients in group A (7.7%) (P = 0.047).

CONCLUSION

A PVP cut-off of 15 mmHg seems to be a more appropriate target level than a cut-off of 20 mmHg for prevention of postoperative SFSS in A-LDLT.

Risk Factors for Intractable Ascites After Adult-to-Adult Living Donor Liver Transplantation Using Left Lobe

Background

Intractable ascites is one of the causes of graft loss after adult-to-adult living donor liver transplantation (LDLT) using a small graft. Identification of factors associated with increasing posttransplant ascites has important implications for prevention and treatment.

Methods

All 59 consecutive adult patients who underwent left lobe LDLT without portal inflow modulation between October 2002 and February 2016 were prospectively enrolled. Factors associated with the average daily amount of ascites for 2 weeks after LDLT were assessed.

Results

The median daily amount of ascites during the 2 weeks was 1052 mL (range, 52-3480 mL). Although 16 of the 59 patients developed intractable ascites, exceeding 1500 mL daily (massive ascites group), the remaining 43 patients produced less than 1500 mL of ascites daily (nonmassive ascites group). The presence of pretransplant ascites (P = 0.001), albumin (P = 0.011), albumin/globulin ratio (P = 0.026), cold ischemia time (P = 0.004), operation time (P = 0.022), and pretransplant portal vein pressure (PVP) (P = 0.047) differed significantly between the 2 groups. Neither posttransplant PVP nor portal vein flow differed between the 2 groups. The variables associated with intractable ascites that remained significant after logistic regression analysis were pretransplant PVP (P = 0.047) and cold ischemia time (P = 0.049). After appropriate fluid resuscitation for intractable ascites, 58 (98%) of the 59 recipients were discharged from hospital after removal of the indwelling drains.

Conclusions

It is important to shorten the scold ischemia time to reduce massive ascites after LDLT. Pretransplant portal hypertension is more closely associated with ascites production than posttransplant hemodynamic status.

Graft inflow modulation in adult-to-adult living donor liver transplantation: A systematic review

INTRODUCTION

Small-for-size syndrome (SFSS) has an incidence between 0 and 43% in small-for-size graft (SFSG) adult living donor liver transplantation (LDLT). Portal hypertension following reperfusion and the hyperdynamic splanchnic state are reported as the major triggering factors of SFSS. Intra- and postoperative strategies to prevent or to reduce its onset are still under debate. We analyzed graft inflow modulation (GIM) during adult LDLT considering the indications, efficacy of the available techniques, changes in hemodynamics and outcomes.

MATERIALS AND METHODS

A systematic literature search was performed using PubMed, EMBASE, Scopus and the Cochrane Library Central. Treatment outcomes including in-hospital mortality and morbidity, re-transplantation rate, 1-, 3-, and 5-year patient overall survival and 1-, 3-, and 5-year graft survival rates, hepatic artery and portal vein flows and pressures before and after inflow modulation were analyzed.

RESULTS

From 563 articles, 12 studies dated between 2003 and 2014 fulfilled the selection criteria and were therefore included in the study. These comprised a total of 449 adult patients who underwent inflow modulation during adult-to-adult LDLT. Types of GIM described were splenic artery ligation, splenectomy, meso-caval shunt, spleno-renal shunt, portocaval shunt, and splenic artery embolization. Mortality and morbidity ranged between 0 and 33% and 17% and 70%, respectively. Re-transplantation rates ranged between 0% and 25%. GIM was associated with good survival for both graft and recipients, reaching an 84% actuarial rate at 5 years. Through the use of GIM, irrespective of the technique, a statistically significant reduction of PVF and PVP was obtained.

CONCLUSIONS

GIM is a safe and efficient technique to avoid or limit portal hyperperfusion, especially in cases of SFSG, decreasing overall morbidity and improving outcomes.

Graft selection strategy in adult-to-adult living donor liver transplantation: When both hemiliver grafts meet volumetric criteria

To ensure donor safety in living donor liver transplantation (LDLT), the left and caudate lobe (LL) is the preferred graft choice. However, patient prognosis may still be poor even if graft volume (GV) selection criteria are met. Our aim was to evaluate the effects of right lobe (RL) donation when the LL graft selection criteria are met. Consecutive donors (n = 135) with preoperative LL graft volumetric GV/standard liver volume (SLV) of ≥35% and RL remnant of ≥35% were retrospectively studied. Patients were divided into 2 groups: LL graft and RL graft. Recipient's body surface area (BSA), Model for End-Stage Liver Disease (MELD) score, and the donor's age were higher in the RL group. The donor's BSA and preoperative volumetric GV/SLV of the LL graft were smaller in the RL group. The predicted score (calculated using data for graft size, donor age, MELD score, and the presence of portosystemic shunt, which correlated well with graft function and with 6-month graft survival) of the RL group, was significantly lower if the LL graft were used, but using the actual RL graft improved the score equal to that of the LL group. Six-month and 12-month graft survival rates did not differ between the 2 groups. In patients with a poor prognosis, a larger RL graft improved the predicted score and survival was equal to that of patients who received LL grafts. In conclusion, graft selection by GV, donor age, and recipient MELD score improves outcomes in LDLT. Liver Transplantation 22 914-922 2016 AASLD.

Small for Size and Flow (SFSF) syndrome: An alternative description for posthepatectomy liver failure

Small for Size Syndrome (SFSS) syndrome is a recognizable clinical syndrome occurring in the presence of a reduced mass of liver, which is insufficient to maintain normal liver function. A definition has yet to be fully clarified, but it is a common clinical syndrome following partial liver transplantation and extended hepatectomy, which is characterized by postoperative liver dysfunction with prolonged cholestasis and coagulopathy, portal hypertension, and ascites. So far, this syndrome has been discussed with focus on the remnant size of the liver after partial liver transplantation or extended hepatectomy. However, the current viewpoints believe that the excessive flow of portal vein for the volume of the liver parenchyma leads to over-pressure, sinusoidal endothelial damages and haemorrhage. The new hypothesis declares that in both extended hepatectomy and partial liver transplantation, progression of Small for Size Syndrome is not determined only by the "size" of the liver graft or remnant, but by the hemodynamic parameters of the hepatic circulation, especially portal vein flow. Therefore, we suggest the term "Small for Size and Flow (SFSF)" for this syndrome. We believe that it is important for liver surgeons to know the pathogenesis and manifestation of this syndrome to react early enough preventing non-reversible tissue damages.

Right lobe living-donor hepatectomy-the Toronto approach, tips and tricks

Living-donor liver transplantation (LDLT) is a well-established treatment for end-stage liver disease. Nevertheless, it has not been extensively accepted in North America or Europe as it has been in Asia. At the University of Toronto we initiated our LDLT program in 2000 and since then our program has grown each year, representing today the largest LDLT program in North America. Our right-lobe LDLT experience from 2000-2014 includes 474 right lobes. Only 30% of our grafts have included the middle hepatic vein. We present excellent outcomes in terms of graft and patient survival which is not different to that achieved with deceased donor liver transplantation. In the present study we will discuss the evolution, challenges and current practices of our LDLT program. We will discuss what is and has been the program philosophy. We will also discuss how we evaluate our donors and the extensive workup we do before a donor is accepted for live donation. Furthermore we will discuss some tips and tricks of how we perform the right hepatectomy for live donation.

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.

Hepatic Hemodynamic Changes Following Stepwise Liver Resection

AIM

Extended liver resection has increased during the last decades. However, hepatic hemodynamic changes after resection and the consequent complications like post hepatectomy liver failure are still a challenging issue. The aim of this study was to systematically evaluate the role of stepwise liver resection on hepatic hemodynamic changes.

METHODS

To evaluate this effect we performed 25, 50, and 75 % sequential liver resections in 10 pigs. Before and after each resection, the hepatic artery flow and portal vein flow in relation to the remnant liver volume (RLV) as well as hepatic vascular pressures were measured and compared between the groups.

RESULTS

Following sequential liver resection, the hepatic artery flow /100 g decreases and the portal vein flow increases up to 17 and 167 % following extended liver resection (75 %), respectively. Also, during stepwise liver resection, the portal vein pressure increases gradually up to 33 % following extended hepatectomy (75 %).

CONCLUSION

Sequential decrease in the RLV decreases the hepatic artery flow /100 g and increases the portal vein flow /100 g and portal vein pressure. As the consequence, the liver goes under more poor-oxygenated blood supply and higher pressure. This may be one of the most important mechanisms of the post hepatectomy liver failure in case of extended liver resection.

Outcomes of adult-to-adult living donor liver transplantation in 321 recipients

We conducted a retrospective investigation in order to clarify whether selecting the type of liver graft had an impact on outcomes of adult-to-adult living donor liver transplantation (AALDLT). Data from the medical records of the donors and the recipients of 321 consecutive cases of AALDLT performed between April 2004 and March 2014 were retrospectively analyzed. Our general criteria for selecting the type of liver graft was that a left graft was preferentially selected when the estimated volume of the left graft was ≥35% of the standard liver volume of the recipient, and that a right graft was selected only when the estimated remnant liver volume of the donor was ≥35% of the total liver volume. In this series, 177 left grafts, 136 right grafts, and 8 posterior grafts were used. The left grafts tended to have 2 or more arteries, whereas the right grafts tended to have 2 or more bile duct orifices. The graft survival curves and the incidences of severe complications were comparable between the AALDLT using right grafts and the AALDLT using left grafts. The preoperative estimation of graft size hardly enabled us to predict severe posttransplant complication. Moreover, small-for-size graft syndrome occurred regardless of the estimated graft volumes. Instead, donor age was a significant risk factor for small-for-size graft syndrome. In conclusion, left grafts should be more aggressively used for the sake of donors' safety. The use of hepatic grafts from older donors should be avoided if possible in order to circumvent troublesome posttransplant complications.

Octreotide prevents liver failure through upregulating 5'-methylthioadenosine in extended hepatectomized rats

BACKGROUND & AIMS

Insufficient liver regeneration and hepatocyte injury caused by excessive portal perfusion are considered to be responsible for post-hepatectomy liver failure (PLF) or small-for-size syndrome in living-donor liver transplantation. Somatostatin can decrease portal vein pressure (PVP) but simultaneously inhibits liver regeneration. This interesting paradox motivated us to investigate the outcome of PLF in response to somatostatin treatment.

METHODS

Rats receiving extended partial hepatectomy (90% PH) were treated with octreotide, a somatostatin analogue, or placebo. Animal survival, serum parameters and hepatic histology were evaluated. Metabolomic analysis was performed to investigate the effect of octreotide on hepatocyte metabolism.

RESULTS

Despite significantly inhibiting early regeneration, octreotide application noticeably improved the hepatic histology, liver function and survival after PH but did not decrease the PVP level. Metabolomic analysis exhibited that octreotide profoundly and exclusively altered the levels of five metabolites that participate in or closely associate with the methionine cycle, a biochemical reaction that uniquely produces S-adenosylmethionine (SAMe), an active methyl residual donor for methyltransferase reactions. Among these metabolites, 5'-methylthioadenosine (MTA), a derivate of SAMe, increased three-fold and was found independently improve the hepatic histology and reduce inflammatory cytokines in hepatectomized rats.

CONCLUSIONS

Octreotide exclusively regulates the methionine cycle reaction and augments the MTA level in hepatocytes. MTA prominently protects hepatocytes against shear stress injury and reduces the secondary inflammation, thereby protecting rats from PLF.

Modulation of splanchnic circulation: Role in perioperative management of liver transplant patients

Splanchnic circulation is the primary mechanism that regulates volumes of circulating blood and systemic blood pressure in patients with cirrhosis accompanied by portal hypertension. Recently, interest has been expressed in modulating splanchnic circulation in patients with liver cirrhosis, because this capability might produce beneficial effects in cirrhotic patients undergoing a liver transplant. Pharmacologic modulation of splanchnic circulation by use of vasoconstrictors might minimize venous congestion, replenish central blood flow, and thus optimize management of blood volume during a liver transplant operation. Moreover, splanchnic modulation minimizes any high portal blood flow that may occur following liver resection and the subsequent liver transplant. This effect is significant, because high portal flow impairs liver regeneration, and thus adversely affects the postoperative recovery of a transplant patient. An increase in portal blood flow can be minimized by either surgical methods (e.g., splenic artery ligation, splenectomy or portocaval shunting) or administration of splanchnic vasoconstrictor drugs such as Vasopressin or terlipressin. Finally, modulation of splanchnic circulation can help maintain perioperative renal function. Splanchnic vasoconstrictors such as terlipressin may help protect against acute kidney injury in patients undergoing liver transplantation by reducing portal pressure and the severity of a hyperdynamic state. These effects are especially important in patients who receive a too small for size graft. Terlipressin selectively stimulates V1 receptors, and thus causes arteriolar vasoconstriction in the splanchnic region, with a consequent shift of blood from splanchnic to systemic circulation. As a result, terlipressin enhances renal perfusion by increasing both effective blood volume and mean arterial pressure.

Living donor liver transplantation using dual grafts: Experience and lessons learned from cases worldwide

In living donor liver transplantation (LDLT), insufficient graft volume could result in small-for-size syndrome in recipients, whereas major liver donation predisposes the donor to a high risk of posthepatectomy liver failure. Dual graft LDLT is therefore introduced to obtain combined graft sufficiency. To date, 367 patients have been reported worldwide. We reviewed all the relevant literature, with a special focus on 43 case reports containing enough data to extract and analyze. A simple decision-making algorithm was developed. Dual graft LDLT is indicated when (1) a single donation is unacceptable due to graft-to-recipient size mismatch; (2) the future liver remnant is insufficient in the single donor after major resection; or (3) there is a significant underlying disorder or anatomical variation within the donor liver. The outcome of dual graft LDLT is reported to be comparable with that of single donor LDLT. Unilateral graft atrophy was found in 7 of the 43 patients, predominantly in the right-sided, heterotopic and initially smaller grafts. Technically, the heterotopic implantation and complex vascular reconstruction are the most demanding. Elaborate surgical planning and modification are needed. Ethical concerns about involving a second living donor need to be addressed. In conclusion, dual graft LDLT should be prudently performed in select cases by surgeons of proven expertise when single donation is unacceptable and a second living donor is available. The decision-making criteria need to be standardized. More surgical modification and clinical research are needed.

Durability of small-for-size living donor allografts

Our aim was to study the long-term outcomes of living donor liver transplantation using small-for-size (SFS) grafts. From July 2002 to July 2009, 233 patients received a right liver graft with a middle hepatic vein from a living donor in our center. Recipients were stratified according to the graft weight to recipient standard liver volume (GW/SLV) ratio into 4 groups: >50% (n = 89), >40% to 50% (n = 85), >35% to 40% (n = 38), and ≤ 35% (n = 21). They were compared in terms of graft survivals, biliary stricture rates, renal function in terms of estimated glomerular filtration rate (eGFR), platelet counts, and graft function in terms of serum bilirubin and international normalized ratio (INR). The 5-year graft survivals for patients with GW/SLV of >50%, >40% to 50%, >35% to 40% and ≤ 35% were 88.8%, 88.2%, 81.5%, and 81.0%, respectively. Transplantation for hepatocellular carcinoma affected graft survivals (P = 0.02), but graft size did not (P = 0.66). There were no differences in frequency of biliary stricture (21.3% versus 17.1% versus 21.1% versus 28.6%; P = 0.75). At each year after transplant, their platelet counts (P = 0.12-0.65), eGFR (P = 0.49-0.91), bilirubin (P = 0.14-0.51), and INR (P = 0.20-0.98) remained comparable. SFS grafts with GW/SLV ≤ 35% and >35% to 40% had comparable long-term outcomes with larger liver grafts. Graft size did not affect long-term graft survivals.

Improved liver function after portal vein embolization and an elective right hepatectomy

BACKGROUND

Portal vein embolization (PVE) is used before extensive hepatic resections to increase the volume of the future remnant liver within acceptable safety margins (conventionally >0.6% of the patient's weight). The objective was to determine whether pre-operative PVE impacts on post-operative liver function independently from the increase in liver volume.

METHODS

The post-operative liver function of patients who underwent an anatomical right liver resection with (n = 28) and without (n = 53) PVE were retrospectively analysed. Donors of the right liver were also analysed (LD) (n = 17).

RESULTS

Patient characteristics were similar, except for age, weight and American Society of Anesthesiologists (ASA) score that were lower in LD. Post-operative factor V and bilirubin levels were, respectively, higher and lower in patients with PVE compared with patients without PVE or LD (P < 0.05). Patients with PVE had an increased blood loss, blood transfusions and sinusoidal obstruction syndrome. The day-3 bilirubin level was 40% lower in the PVE group compared with the no-PVE group after adjustment for body weight, chemotherapy, operating time, Pringle time, blood transfusions, remnant liver volume, pre-operative bilirubin level and pre-operative prothrombin ratio (P = 0.001).

CONCLUSIONS

For equivalent volumes, the immediate post-operative hepatic function appears to be better in livers prepared with PVE than in unprepared livers. Future studies should analyse whether the conventional inferior volume limit that allows a safe liver resection may be lowered when a PVE is performed.

The role of adult living donor liver transplantation and recent advances

Twenty years since the first cases were described, adult living donor liver transplantation (ALDLT) is now considered a valid option to expand the donor pool in view of the ongoing shortage of organs and the high waiting list mortality rate. Despite the rapid evolution and acceptance of this complex process of donation and transplantation in clinical practice, the indications, outcome, ethical considerations and quality and safety aspects continue to evolve based on new data from large cohort studies. This article reviews the surgical and clinical advances in the field of liver transplantation, focusing on technical refinements and discussing the issues that may lead to a further expansion of this complex surgical procedure and the role of ALDLT.

Should temporary extracorporeal continuous portal diversion replace meso/porta-caval shunts in “small-for-size” syndrome in porcine hepatectomy?

AIM: To investigate the feasibility of temporary extracorporeal continuous porta-caval diversion (ECPD) to relieve portal hyperperfusion in “small-for-size” syndrome following massive hepatectomy in pigs.

METHODS: Fourteen pigs underwent 85%-90% liver resection and were then randomly divided into the control group (n = 7) and diversion group (n = 7). In the diversion group, portal venous blood was aspirated through the portal catheter and into a tube connected to a centrifugal pump. After filtration, the blood was returned to the pig through a double-lumen catheter inserted into the internal jugular or subclavian vein. With the conversion pump, portal venous inflow was partially diverted to the inferior vena cava through a catheter inserted via the gastroduodenal vein at 100-130 mL/min. Portal hemodynamics, injury, and regeneration in the liver remnant were compared between the two groups.

RESULTS: Compared to the control group, porta-caval diversion via ECPD significantly mitigated excessive portal venous flow and portal vein pressure (PVP); the portal vein flow (PVF), hepatic artery flow (HAF), and PVP in the two groups were not significantly different at baseline; however, the PVF (431.8 ± 36.6 vs 238.8 ± 29.3, P < 0.01; 210.3 ± 23.4 vs 122.3 ± 20.6, P < 0.01) and PVP (13.8 ± 2.6 vs 8.7 ± 1.4, P < 0.01; 15.6 ± 2.1 vs 10.1 ± 1.3, P < 0.05) in the control group were significantly higher than those in the diversion group, respectively. The HAF in the control group was significantly lower than that in the diversion group at 2 h and 48 h post hepatectomy, and ECPD significantly attenuated injury to the sinusoidal lining and hepatocytes, increased the regeneration index of the liver remnant, and relieved damage that the liver remnant suffered due to endotoxin and bacterial translocation.

CONCLUSION: ECPD, which can dynamically modulate portal inflow, can reduce injury to the liver remnant and facilitate liver regeneration, and therefore should replace permanent meso/porta-caval shunts in “small-for-size” syndrome.

Review of anesthesia in liver transplantation

Liver transplantation (LT) is a well-accepted treatment modality of many end-stage liver diseases. The main issue in LT is the shortage of deceased donors to accommodate the needs of patients waiting for such transplants. Live donors have tremendously increased the pool of available liver grafts, especially in countries where deceased donors are not common. The main ethical concern of this procedure is the safety of healthy donors, who undergo a major abdominal surgery not for their own health, but to help cure others. The first part of the review concentrates on live donor selection, preanesthetic evaluation, and intraoperative anesthetic care for living liver donors. The second part reviews patient evaluation, intraoperative anesthesia monitoring, and fluid management of the recipient. This review provides up-to-date information to help improve the quality of anesthesia, and contribute to the success of LT and increase the long-term survival of the recipients.

Small for size liver remnant following resection: prevention and management

In the latest decades an important change was registered in liver surgery, however the management of liver cirrhosis or small size hepatic remnant still remains a challenge. Currently post-hepatectomy liver failure (PLF) is the major cause of death after liver resection often associated with sepsis and ischemia-reperfusion injury (IRI). ''Small-for-size'' syndrome (SFSS) and PFL have similar mechanism presenting reduction of liver mass and portal hyper flow beyond a certain threshold. Few methods are described to prevent both syndromes, in the preoperative, perioperative and postoperative stages. Additionally to portal vein embolization (PVE), radiological examinations (mainly CT and/or MRI), and more recently 3D computed tomography are fundamental to quantify the liver volume (LV) at a preoperative stage. During surgery, in order to limit parenchymal damage and optimize regenerative capacity, some hepatoprotective measures may be employed, among them: intermittent portal clamping and hypothermic liver preservation. Regarding the treatment, since PLF is a quite complex disease, it is required a multi-disciplinary approach, where it management must be undertaken in conjunction with critical care, hepatology, microbiology and radiology services. The size of the liver cannot be considered the main variable in the development of liver dysfunction after extended hepatectomies. Additional characteristics should be taken into account, such as: the future liver remnant; the portal blood flow and pressure and the exploration of the potential effects of regeneration preconditioning are all promising strategies that could help to expand the indications and increase the safety of liver surgery.

Hepatic hemodynamic changes during liver transplantation: A review

Liver transplantation is performed in the recent decades with great improvements not only technically but also conceptually. However, there is still lack of consensus about the optimal hemodynamic characteristics during liver transplantation. The representative hemodynamic parameters include portal vein pressure, portal vein flow, and hepatic venous pressure gradient; however, there are still others potential valuable parameters, such as total liver inflow and hepatic artery flow. All the parameters are correlated closely and some internal modulating mechanisms, like hepatic arterial buffer response, occur to maintain stable hepatic inflow. To distinguish the unique importance of each hepatic and systemic parameter in different states during liver transplantation, we reviewed the published data and also conducted two transplant cases with different surgical strategies applied to achieve ideal portal inflow and pressure.

Optimal changes in portal hemodynamics induced by splenectomy during living donor liver transplantation

PURPOSES

The purpose of this study was to evaluate the impact of splenectomy in adult-to-adult living donor liver transplantation (LDLT).

METHODS

Adult-to-adult LDLTs (n = 276) were divided into those with simultaneous splenectomy during LDLT (Splenectomy group, n = 154) and those without (Non-Splenectomy group, n = 122).

RESULTS

In the Splenectomy group, splenectomy decreased the portal venous pressure from 24.0 to 19.1 mmHg (p < 0.001). At the end of surgery, the portal venous pressure was significantly lower and the graft compliance was significantly higher in the Splenectomy group compared with the Non-Splenectomy group. The graft portal venous flow was also better in the Splenectomy group (y = 625-5.1x; r (2) = 0.08, p < 0.01) than in the Non-Splenectomy group (y = 470-2.9x; r (2) = 0.04, p = 0.03). Fourteen days after LDLT, the total bilirubin and ascites output were lower in the Splenectomy group than in the Non-Splenectomy group. Among the patients with hepatitis C, splenectomy was associated with a significantly higher rate of a sustained viral response (59.4 vs. 35.9%, p = 0.020) than was noted in those without splenectomy (n = 39). There were no patients with post-splenectomy sepsis under vaccination.

CONCLUSIONS

By decreasing the portal pressure and increasing the graft vascular compliance, splenectomy conferred better graft outcomes in adult-to-adult LDLT.

Small-for-size syndrome in living-donor liver transplantation using a left lobe graft

In living-donor liver transplantation with a left lobe graft, which can reduce the burden on the donor compared to right lobe graft, the main problem is small-for-size (SFS) syndrome. SFS syndrome is a multifactorial disease that includes aspects related to the graft size, graft quality, recipient factors and even technical issues. The main pathophysiology of SFS syndrome is the sinusoidal microcirculatory disturbance induced by shear stress, which is caused by excessive portal inflow into the smaller graft. The donor age, the presence of steatosis of the graft and a poor recipient status are all risk factors for SFS syndrome. To resolve SFS syndrome, portal inflow modulation, splenectomy, splenic artery modulation and outflow modulation have been developed. It is important to establish strict criteria for managing SFS syndrome. Using pharmacological interventions and/or therapeutic approaches that promote liver regeneration could increase the adequate outcomes in SFS liver transplantation. Left lobe liver transplantation could be adopted in Western countries to help resolve the organ shortage.