Changes in portal venous pressure in the early phase after living donor liver transplantation: pathogenesis and clinical implications

Prediction and management of small-for-size syndrome in living donor liver transplantation

Small-for-size syndrome (SFSS) remains a critical challenge in living donor liver transplantation (LDLT), characterized by graft insufficiency due to inadequate liver volume, leading to significant postoperative morbidity and mortality. As the global adoption of LDLT increases, the ability to predict and manage SFSS has become paramount in optimizing recipient outcomes. This review provides a comprehensive examination of the pathophysiology, risk factors, and strategies for managing SFSS across the pre-, intra-, and postoperative phases. The pathophysiology of SFSS has evolved from being solely volume-based to incorporating portal hemodynamics, now recognized as small-for-flow syndrome. Key risk factors include donor-related parameters like age and graft volume, recipient-related factors such as MELD score and portal hypertension, and intraoperative factors related to venous outflow and portal inflow modulation. Current strategies to mitigate SFSS include careful graft selection based on graft-to-recipient weight ratio and liver volumetry, surgical techniques to optimize portal hemodynamics, and novel interventions such as splenic artery ligation and hemiportocaval shunts. Pharmacological agents like somatostatin and terlipressin have also shown promise in modulating portal pressure. Advances in 3D imaging and artificial intelligence-based volumetry further aid in preoperative planning. This review emphasizes the importance of a multifaceted approach to prevent and manage SFSS, advocating for standardized definitions and grading systems. Through an integrated approach to surgical techniques, hemodynamic monitoring, and perioperative management, significant strides can be made in improving the outcomes of LDLT recipients. Further research is necessary to refine these strategies and expand the application of LDLT, especially in challenging cases involving small-for-size grafts.

Graft inflow modulation in recipients with portal hypertension

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching, potentially leading to the "small-for-size syndrome" (SFSS). SFSS is a rare dysfunction that may affect a partial liver graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. A key role in the physiopathology of SFSS is played by portal hypertension (PHT) to which a small allograft is submitted after reperfusion, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. Thus, SFSS prevention relies not only on increasing graft volume (implementing the use of larger grafts or auxiliary/dual liver transplantation), but also on the control of the increased portal vein pressure (PVP) and portal vein flow (PVF). To this aim, surgical graft inflow modulation techniques (GIM) such as splenic artery ligation (SAL), splenectomy and hemiportocaval shunts, can be considered when an imbalance between the PVP and the hepatic arterial flow (HAF) is acknowledged. However, such strategies have their pros and cons, and a deep knowledge of the indications and complications is needed. Furthermore, pharmacological modulation has also been proposed. This review is aimed to update available literature on the current knowledge and strategies for modulating portal vein flow in LDLT.

Intraoperatively measured prehepatectomy portal vein pressure as a useful predictor of posthepatectomy liver failure

BACKGROUND

Predicting posthepatectomy liver failure (PHLF) may be a critical requirement for liver disease patients undergoing hepatectomy. This study retrospectively analyzed the impact of the intraoperatively measured portal vein pressure (PVP) prior to hepatectomy on the prediction of PHLF in hepatectomized patients.

METHODS

A total of 334 hepatectomized patients in whom the PVP was intraoperatively measured before resection at our institution were enrolled in the present study. Outcomes were assessed according to the International Study Group of Liver Surgery definition and the severity of PHLF grading.

RESULTS

Thirty-nine of the 334 patients (11.6%) developed grade B/C PHLF. The following factors were significantly associated with grade B/C PHLF in a univariate analysis: indocyanine green retention rate after 15 min, Child-Pugh score, prehepatectomy PVP, and transfusion (each P < 0.0001). A prehepatectomy PVP value of 19.5 cmH2O was the optimal cutoff value for predicting grade B/C PHLF. In a multivariate analysis, prehepatectomy PVP (≥ 19.5 cmH2O) was selected as the most relevant risk factor for grade B/C PHLF (P = 0.0003, hazard ratio: 5.96, 95% CI: 1.80-19.70).

CONCLUSIONS

Prehepatectomy PVP can serve as a useful predictor of the risk of PHLF in patients who have undergone hepatectomy. The results emphasize the possibility of reducing the planned extent of hepatic resection when the prehepatectomy PVP value measured intraoperatively exceeds 19.5 cmH2O, and the importance of predicting the PVP before the operation.

Development of a model to predict the risk of early graft failure after adult-to-adult living donor liver transplantation: An ELTR study

Graft survival is a critical end point in adult-to-adult living donor liver transplantation (ALDLT), where graft procurement endangers the lives of healthy individuals. Therefore, ALDLT must be responsibly performed in the perspective of a positive harm-to-benefit ratio. This study aimed to develop a risk prediction model for early (3 months) graft failure (EGF) following ALDLT. Donor and recipient factors associated with EGF in ALDLT were studied using data from the European Liver Transplant Registry. An artificial neural network classification algorithm was trained on a set of 2073 ALDLTs, validated using cross-validation, tested on an independent random-split sample (n=518), and externally validated on United Network for Organ Sharing Standard Transplant Analysis and Research data. Model performance was assessed using the AUC, calibration plots, and decision curve analysis. Graft type, graft weight, level of hospitalization, and the severity of liver disease were associated with EGF. The model ( http://ldlt.shinyapps.io/eltr_app ) presented AUC values at cross-validation, in the independent test set, and at external validation of 0.69, 0.70, and 0.68, respectively. Model calibration was fair. The decision curve analysis indicated a positive net benefit of the model, with an estimated net reduction of 5-15 EGF per 100 ALDLTs. Estimated risks>40% and<5% had a specificity of 0.96 and sensitivity of 0.99 in predicting and excluding EGF, respectively. The model also stratified long-term graft survival ( p <0.001), which ranged from 87% in the low-risk group to 60% in the high-risk group. In conclusion, based on a panel of donor and recipient variables, an artificial neural network can contribute to decision-making in ALDLT by predicting EGF risk.

Trends of liver transplantation in Asia

Liver transplantation (LT) in Asia started comparatively early in 1964, just 1 year after Starzl's trail-blazing first attempt. Despite the quick start, LT was slow to develop in this region. Limited access to universal healthcare, lack of public understanding and support as well as the absence of strong legislation, on a backdrop of a wide range of diverse social, religious, economic and cultural background are all contributory factors. Through strong administrative efforts, the number of DDLTs in selected Asian countries has been slowly rising in recent years. However, Asians are generally still less likely to donate organs than Caucasians after death. The strong demand for LT with limited access to deceased organs has, therefore, led to constant need for innovation in LT this region, with the pioneering of various LDLT techniques and safe expansion of donor pool being driven primarily by Asian centers. Familiarity and the development of technical expertise in donor surgery have also resulted in Asian centers repeatedly pushing the boundaries on minimally invasive donor and recipient surgery. In this article, we focus on the past and present states of LT in Asia and explore the future trends of LT in this region.

Liver resection with two-step vascular exclusion, in situ hypothermic portal perfusion for the treatment of end-stage hepatic alveolar echinococcosis

PURPOSE

To evaluate the safety and efficacy of two-step vascular exclusion and in situ hypothermic portal perfusion in patients with end-stage hepatic hydatidosis.

METHODS

This study involved patients with advanced hepatic hydatid disease undergoing surgical treatment between 2022 and 2023, which included resection and reconstruction of the hepatic veins, inferior vena cava (IVC), and portal vein (PV). We described the technical details of liver resection and vascular reconstruction, as well as the use of two-step vascular exclusion and in situ hypothermic portal perfusion techniques during the vascular reconstruction process.

RESULT

We included 7 patients with advanced hepatic hydatid disease who underwent surgical resection using two-step vascular exclusion and in situ hypothermic portal perfusion. The mean duration of surgery was 12.5 h (range, 7.5-15.0 h). The average hepatic ischemia time was 45 min (range, 25-77 min), while the occlusion time of the IVC was 87 min (range, 72-105 min). The total blood loss was 1000 milliliters (range, 500-1250 milliliters). Postoperatively, patients exhibited good recovery of liver and renal function. The mean ICU stay was 2 days (range, 1-3 days), and the mean postoperative hospital stay was 13 days (range, 9-16 days), with no Grade III or above complications observed during a mean follow-up period of 15 months (range, 9-24 months), CONCLUSION: two-step vascular exclusion and in situ hypothermic portal perfusion for surgical resection of end-stage hepatic hydatid disease is safe and effective. This significantly reduces the anhepatic time.

Indications and results of right-lobe living donor liver transplantation

The shortage of deceased liver donor organs over the years has always posed the need to expand the donor pool. A viable alternative to deceased donors is that of the living donor. Indeed, the living donor in liver transplantation, initially in pediatric transplantation, but for several years now also in adult transplantation, is a more than viable alternative to deceased liver donation. In fact, right liver lobe donation has proven to be a surgical procedure with low impact on the donor's life in terms of morbidity and mortality, with excellent results in recipients of such organs. In recent years, an increasing number of studies have been published that show excellent results in right-lobe living donor liver transplantation, encouraging this practice not only in countries that have historically had a shortage of deceased donor organs, such as Asian countries, but making it a practice of increasing use in Western countries as well. In addition, thanks to improvements in surgical technique and the experience of high-volume centers, this surgery has also begun to be performed using minimally invasive surgical techniques, allowing us to envision ever better outcomes for both donor and recipient in the coming years.

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.

Outcomes of Living Donor Liver Transplantation Compared with Deceased Donor Liver Transplantation

Improved surgical techniques and revolutionary immunosuppressive agents have enhanced the long-term outcomes for liver transplantation, with more patients seeking the benefits of liver transplantation, and demand is high. In this review, we hope to delineate where the current data supporting favorable outcomes in using live donation to expand the donor pool compared with the outcomes seen in deceased donor liver transplants. Advances in surgery, transplant and center comfort has made live donor transplantation an asset with favorable patient outcomes in comparison to decease donor data.

Portal Vein Pressure Estimation and Portal Hypertension Discrimination Based on Subharmonic Scattering of Ultrasound Contrast Agent Microbubbles

OBJECTIVE

The acquisition of real-time portal vein pressure (PVP) is important for portal hypertension (PH) discrimination to monitor disease progress and select treatment options. To date, the PVP evaluation approaches are either invasive or noninvasive but with less stability and sensitivity.

METHODS

We customized an open ultrasound scanner to explore in vitro and in vivo the ultrasound contrast agent SonoVue microbubbles' subharmonic characteristics with acoustic pressure and local ambient pressure, and obtained promising results of PVP measurements in canine models with induced PH by ligation or embolization of portal vein.

RESULTS

In in vitro experiments, the highest correlations between the subharmonic amplitude of SonoVue microbubbles and ambient pressure were observed at acoustic pressures of 523 kPa and 563 kPa (r = -0.993, -0.993, P<0.05, respectively). The correlation coefficients between absolute subharmonic amplitudes and PVP (10.7-35.4 mmHg) were the highest among existing studies using microbubbles as pressure sensors (r values ranged from -0.819 to -0.918). The PH (>16 mmHg) diagnostic capacity also achieved a high level (563 kPa, sensitivity = 93.3%, specificity = 91.7%, accuracy = 92.6%).

CONCLUSION

This study proposes a promising measurement for PVP with the highest accuracy, sensitivity, and specificity in an in vivo model compared to existing studies. Future investigations are planned to assess the feasibility of this technique in clinical practice.

SIGNIFICANCE

This is the first study that comprehensively investigates the role of the subharmonic scattering signals from SonoVue microbubbles in evaluating PVP in vivo. It represents a promising alternative to invasive measurements for portal pressure.

e-GLR Score Predicts Early Graft Loss in Adult Live-Donor Liver Transplantation

Objective

This study aimed to analyze risk factors and develop a predictive model for early allograft loss due to early graft dysfunction (EGD) in adult live-donor liver transplantation (LDLT).

Methods

Data of patients who underwent LDLT from 2011 to 2019 were reviewed for EGD, associated factors, and outcomes. A homogeneous group of 387 patients was analyzed: random cohort A (n = 274) for primary analysis and random cohort B (n = 113) for validation.

Results

Of 274 recipients, 92 (33.6%) developed EGD. The risk of graft loss within 90 days was 29.3% and 7.1% in those with and without EGD, respectively (P < 0.001). Multivariate logistic regression analysis determined donor age (P = 0.045), estimated (e) graft weight (P = 0.001), and the model for end-stage liver disease (MELD) score (0.001) as independent predictors of early graft loss due to EGD. Regression coefficients of these factors were employed to formulate the risk model: Predicted (P) early graft loss risk (e-GLR) score = 10 × [(donor age × 0.052) + (e-Graft weight × 1.681) + (MELD × 0.145)] - 8.606 (e-Graft weight = 0, if e-Graft weight ≥640 g and e-Graft weight = 1, and if e-Graft weight < 640 g). Internal cross-validation revealed a high predictive value (C-statistic = 0.858).

Conclusions

Our novel risk score can efficiently predict early allograft loss following graft dysfunction, which enables donor-recipient matching, evaluation, and prognostication simply and reliably in adult LDLT.

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

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

Management of Established Small-for-size Syndrome in Post Living Donor Liver Transplantation: Medical, Radiological, and Surgical Interventions: Guidelines From the ILTS-iLDLT-LTSI Consensus Conference

Small-for-size syndrome (SFSS) following living donor liver transplantation is a complication that can lead to devastating outcomes such as prolonged poor graft function and possibly graft loss. Because of the concern about the syndrome, some transplants of mismatched grafts may not be performed. Portal hyperperfusion of a small graft and hyperdynamic splanchnic circulation are recognized as main pathogenic factors for the syndrome. Management of established SFSS is guided by the severity of the presentation with the initial focus on pharmacological therapy to modulate portal flow and provide supportive care to the patient with the goal of facilitating graft regeneration and recovery. When medical management fails or condition progresses with impending dysfunction or even liver failure, interventional radiology (IR) and/or surgical interventions to reduce portal overperfusion should be considered. Although most patients have good outcomes with medical, IR, and/or surgical management that allow graft regeneration, the risk of graft loss increases dramatically in the setting of bilirubin >10 mg/dL and INR>1.6 on postoperative day 7 or isolated bilirubin >20 mg/dL on postoperative day 14. Retransplantation should be considered based on the overall clinical situation and the above postoperative laboratory parameters. The following recommendations focus on medical and IR/surgical management of SFSS as well as considerations and timing of retransplantation when other therapies fail.

Zero Mortality in Living-Donor Liver Transplantation for Primary Biliary Cholangitis in Patients With a Meld Score of <20

BACKGROUND

Although primary biliary cholangitis (PBC) is considered a good indication for living-donor liver transplantation (LDLT), the postoperative results are not well known.

METHODS

At Jikei University Hospital, 14 patients with PBC underwent LDLT from February 2007 to June 2022. We consider PBC with a Model for End-Stage Liver Disease (MELD) score of <20 to indicate LDLT. We performed a retrospective analysis of the patients' clinical records.

RESULTS

The patients' median age was 53 years, and 12 of the 14 patients were female. A right graft was used in 5 patients, and 3 ABO-incompatible transplants were performed. The living donors were children in 6 cases, partners in 4 cases, and siblings in 4 cases. The preoperative MELD scores ranged from 11 to 19 (median, 15). The graft-to-recipient weight ratio ranged from 0.8 to 1.1 (median, 1.0). The median operative time for donors and recipients was 481 and 712 minutes, respectively. The median operative blood loss of donors and recipients was 173 and 1,800 mL, respectively. The median postoperative hospital stay of donors and recipients was 10 and 28 days, respectively. All recipients recovered satisfactorily and remained well during a median follow-up of 7.3 years. Three patients underwent a liver biopsy after LDLT because of acute cellular rejection without histologic findings of PBC recurrence.

CONCLUSIONS

Living-donor liver transplantation provides satisfactory long-term survival for patients with PBC with a graft-to-recipient weight ratio of >0.7 and MELD score of <20 without hepatocellular damage and only portal vein hypertension.

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

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

Postreperfusion Syndrome Presenting as Posttransplant Portal Hypertension due to Prolonged Elevation of Pulmonary Vascular Resistance and the Role of Nitroglycerin in Diagnosis and Treatment: A Case Report of Budd-Chiari Syndrome

Postreperfusion syndrome is one of the responsible mechanisms of portal hypertension in patients undergoing liver transplantation. And post-transplant portal hypertension causes graft dysfunction. Postreperfusion syndrome is characterized by a decrease in arterial pressure and cardiac output, and an increase in central venous pressure, pulmonary artery pressure, and pulmonary vascular resistance that occurs after the release of the portal vein clamp. Although early recovery from postreperfusion syndrome is desired, there is a little medication therapy such as the administration of calcium chloride, sodium bicarbonate, and beta-agonist for postreperfusion syndrome. We present a case of postreperfusion syndrome manifested as post-transplant portal hypertension and reversed after nitroglycerin administration. A 49-year-old Asian woman was scheduled for liver transplantation because of Budd-Chiari syndrome. After portal vein reperfusion, she experienced severe postreperfusion syndrome. Administration of ephedrine and calcium restored arterial pressure; however, pulmonary artery pressure, pulmonary vascular resistance, and central venous pressure elevations were sustained, causing right ventricular overload. This condition did not improve after hepatic artery reperfusion, and caused post-transplant portal hypertension. After nitroglycerin administration, pulmonary vascular resistance and central venous pressure decreased, mean arterial pressure increased, right heart contractility recovered, and portal hypertension disappeared. Hemodynamic improvement by nitroglycerin administration helped in diagnosing postreperfusion syndrome and avoiding unnecessary splenectomy. If portal vein pressure increases after liver transplantation, the change in hemodynamic parameters by nitroglycerin administration should be assessed, which will lead to accurate diagnosis and appropriate treatment. Furthermore, postreperfusion syndrome should be listed as a differential diagnosis of post-transplant portal hypertension.

Does modification of portal pressure and flow enhance recovery of the recipient after living donor liver transplantation? A systematic review of literature and expert panel recommendations

BACKGROUND

Portal inflow modulation (PIM) aimed at reducing portal hyperperfusion is commonly used in living donor liver transplantation (LDLT) to reduce the risk of small-for-size syndrome (SFSS). Many different techniques, both pharmacological and surgical have been used for this purpose. There is, however, little consensus on the best method of PIM, its exact role in preventing SFSS and on early post-LDLT recovery.

OBJECTIVES

To identify whether modifications of portal pressures and flows enhance recovery after LDLT 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.

PROSPERO ID

CRD42021260997.

RESULTS

Five hundred and ninety four articles were identified through databases' search. Of the 24 included for a final review by the working group (WG), there were five randomized control trials, four prospective studies and 15 retrospective series. Six outcome measures which were likely to influence early recovery after LDLT, especially in small-for-size grafts (SFSG) were shortlisted. These included acute kidney injury, SFSS, morbidity including sepsis, length of ICU and hospital stay, morbidity of the PIM technique and overall mortality. The WG noted that PIM in this subset of LDLT recipients had a beneficial effect on all the outcomes measures.

CONCLUSIONS

Considering all decision domains, the panel recommends pre- and intraoperative actual graft weight validation, portal pressure/flow measurements, and a comprehensive donor evaluation for the determination of potentially small-for-size/ small-for-flow grafts as mandatory. (Quality of Evidence: Moderate | Grade of Recommendation: Strong) Pharmacological PIM helps improve early renal function in LDLT recipients. (Quality of Evidence: High | Grade of Recommendation: Strong) In selected patients with SFSG, PIM helps reduce SFSS/EAD and sepsis. (Quality of Evidence: Moderate | Grade of Recommendation: Strong) PIM in the form of splenectomy has increased morbidity compared to splenic artery ligation (SAL). (Quality of Evidence: Low | Grade of Recommendation: Strong) In LDLT recipients with SFSG, PIM may help reduce morbidity/mortality. (Quality of Evidence: Low | Grade of Recommendation: Strong) In LDLT recipients with SFSG, modification of portal pressures and flows enhances recovery after LDLT. (Quality of Evidence: Moderate | Grade of Recommendation: Strong).

Approach to persistent ascites after liver transplantation

Persistent ascites (PA) after liver transplantation (LT), commonly defined as ascites lasting more than 4 wk after LT, can be expected in up to 7% of patients. Despite being relatively rare, it is associated with worse clinical outcomes, including higher 1-year mortality. The cause of PA can be divided into vascular, hepatic, or extrahepatic. Vascular causes of PA include hepatic outflow and inflow obstructions, which are usually successfully treated. Regarding modifiable hepatic causes, recurrent hepatitis C and acute cellular rejection are the leading ones. Considering predictors for PA, the presence of ascites, refractory ascites, hepato-renal syndrome type 1, spontaneous bacterial peritonitis, hepatic encephalopathy, and prolonged ischemic time significantly influence the development of PA after LT. The initial approach to patients with PA should be to diagnose the treatable cause of PA. The stepwise approach in evaluating PA includes diagnostic paracentesis, ultrasound with Doppler, and an echocardiogram when a cardiac cause is suspected. Finally, a percutaneous or transjugular liver biopsy should be performed in cases where the diagnosis is unclear. PA of unknown cause should be treated with diuretics and paracentesis, while transjugular intrahepatic portosystemic shunt and splenic artery embolization are treatment methods in patients with refractory ascites after LT.

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

BACKGROUND

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

SUMMARY

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

KEY MESSAGES

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

Preservation of the round ligament to accommodate transient portal hypertension after major hepatectomy

Purpose

Posthepatectomy liver failure (PHLF) remains a leading cause of death after extensive liver resection. Apart from the size and function of the remaining liver remnant, the development of postresection portal hypertension (pHT) plays a crucial role in the development of PHLF. We hypothesize that the umbilical vein in the preserved round ligament (RL) may recanalize in response to new-onset pHT after extended hepatectomy, thus providing a natural portosystemic shunt.

Methods

In this exploratory study, RL was preserved in 10 consecutive patients undergoing major liver resection. Postoperative imaging was pursued to obtain evidence of reopened umbilical vein in the RL. The postoperative course, including the occurrence of PHLF, as well as the rate of procedure-specific complications were recorded.

Results

None of the 10 cases presented with an adverse event due to preservation of the RL. In 6 cases, postoperative imaging demonstrated reopening of the umbilical vein with hepatofugal flow in the RL. The rates of procedure-related surgical complications were lower than would be expected in this population; in particular, the rate of occurrence of PHLF as defined by the International Study Group of Liver Surgery (ISGLS) was low.

Conclusion

Our results support the theoretical concept of portosystemic pressure relief via a preserved umbilical vein after major liver surgery. As preservation of the RL is easily done, we suggest keeping it intact in extended hepatectomy cases and in patients with preexistent pHT.

Minimizing the risk of small-for-size syndrome after liver surgery

BACKGROUND

Primary and secondary liver tumors are not always amenable to resection due to location and size. Inadequate future liver remnant (FLR) may prevent patients from having a curative resection or may result in increased postoperative morbidity and mortality from complications related to small-for-size syndrome (SFSS).

DATA SOURCES

This comprehensive review analyzed the principles, mechanism and risk factors associated with SFSS and presented current available options in the evaluation of FLR when planning liver surgery. In addition, it provided a detailed description of specific modalities that can be used before, during or after surgery, in order to optimize the conditions for a safe resection and minimize the risk of SFSS.

RESULTS

Several methods which aim to reduce tumor burden, preserve healthy liver parenchyma, induce hypertrophy of FLR or prevent postoperative complications help minimize the risk of SFSS.

CONCLUSIONS

With those techniques the indications of radical treatment for patients with liver tumors have significantly expanded. The successful outcome depends on appropriate patient selection, the individualization and modification of interventions and the right timing of surgery.

Auxiliary Liver Transplantation for Cirrhosis: From APOLT to RAPID: A Scoping Review

OBJECTIVE

To survey the available literature regarding the use of auxiliary liver transplantation (ALT) in the setting of cirrhosis.

SUMMARY OF BACKGROUND

ALT is a type of liver transplantation (LT) procedure in which part of the cirrhotic liver is resected and part of the liver graft is transplanted. The cirrhotic liver left in situ acts as an auxiliary liver until the graft has reached sufficient volume. Recently, a 2-stage concept named RAPID (Resection and Partial Liver segment 2/3 transplantation with Delayed total hepatectomy) was developed, which combines hypertrophy of the small graft followed by delayed removal of the native liver.

METHODS

A scoping review of the literature on ALT for cirrhosis was performed, focusing on the historical background of RAPID and the status of RAPID for this indication. The new comprehensive nomenclature for hepatectomy ("New World" terminology) was used in this review.

RESULTS

A total of 72 cirrhotic patients underwent ALT [heterotopic (n = 34), orthotopic (Auxiliary partial orthotopic liver transplantation, n = 34 including 5 followed by resection of the native liver at the second stage) and RAPID (n = 4)]. Among the 9 2-stage LTs (APOLT, n = 5; RAPID, n = 4), portal blood flow modulation was performed in 6 patients by deportalization of the native liver (n = 4), portosystemic shunt creation (n = 1), splenic artery ligation (n = 3) or splenectomy (n = 1). The delay between the first and second stages ranged from 18 to 90 days. This procedure led to an increase in the graft-to-recipient weight ratio between 33% and 156%. Eight patients were alive at the last follow-up.

CONCLUSIONS

Two-stage LT and, more recently, the RAPID procedure are viable options for increasing the number of transplantations for cirrhotic patients by using small grafts.

Concomitant splenic artery ligation has no preventive effect on left‐sided portal hypertension following pancreaticoduodenectomy with the resection of the portal and superior mesenteric vein confluence for pancreatic ductal adenocarcinoma

Background

Left‐sided portal hypertension (LSPH) caused by splenic vein (SV) division in pancreaticoduodenectomy (PD) with portal vein (PV) resection remains challenging. The current study aimed to investigate the efficacy of splenic artery (SA) ligation in preventing LSPH.

Methods

One‐hundred thirty patients who underwent PD with PV resection for pancreatic ductal adenocarcinoma were classified into SV and SA preservation (SVP, n = 30), SV resection and SA preservation (SVR, n = 59), and SV resection and SA ligation (SAL, n = 41). The postoperative incidence of LSPH was assessed.

Results

The incidence of variceal formation in SVP, SVR, and SAL were 4.8%, 53.2%, and 46.4% at 3 mo, 13.0%, 71.2%, and 62.5% at 6 mo, and 25.0%, 87.5%, and 87.1% at 12 mo, respectively. The rate was significantly higher in SVR at 3 and 6 mo (P = .001 and P < .001, respectively) and in SVR and SAL (P < .001) at 12 mo. Variceal hemorrhage occurred only in SVR (n = 4). The platelet count ratio at 3, 6, and 12 mo began to significantly decrease from 3 mo in SVR (0.77, 0.67, and 0.60, respectively; P < .001) and 6 mo in SAL (0.91, 0.73, and 0.69, respectively; P < .001). The spleen volume ratio also showed significant increase from 3 mo in SVR (1.24, 1.34, and 1.42, respectively; P < .001) and 6 mo in SAL (1.31, 1.32, and 1.34, respectively; P < .001). SVR and SAL were significant risk factors for variceal formation at 12 mo (odds ratio, 21.0 and 20.3, respectively).

Conclusion

In PD with PV resection, SAL delayed LSPH but could not prevent its occurrence.

Outcomes in Living Donor Compared With Deceased Donor Primary Liver Transplantation in Lower Acuity Patients With Model for End-Stage Liver Disease Scores <30

Although recent studies have reported favorable outcomes in living donor liver transplantation (LDLT), it remains unclear which populations benefit most from LDLT. This study aims to evaluate LDLT outcomes compared with deceased donor LT (DDLT) according to Model for End-Stage Liver Disease (MELD) score categories. Using data from the United Network for Organ Sharing registry, outcomes were compared between 1486 LDLTs; 13,568 donation after brain death (DBD)-DDLTs; and 1171 donation after circulatory death (DCD)-DDLTs between 2009 and 2018. Because LDLT for patients with MELD scores >30 was rare, all patients with scores >30 were excluded to equalize LDLT and DDLT cohorts. Risk factors for 1-year graft loss (GL) were determined separately for LDLT and DDLT. Compared with LDLT, DBD-DDLT had a lower risk of 30-day (adjusted hazard ratio [aHR], 0.60; P < 0.001) and 1-year GL (aHR, 0.57; P < 0.001). The lower risk of GL was more prominent in the mid-MELD score category (score 15-29). Compared with LDLT, DCD-DDLT had a lower risk of 30-day GL but a comparable risk of 1-year GL, regardless of MELD score category. In LDLT, significant ascites was an independent risk for GL in patients with mid-MELD scores (aHR, 1.68; P = 0.02), but not in the lower-MELD score group. The risk of 1-year GL in LDLT patients with ascites who received a left liver was higher than either those who received a right liver or those without ascites who received a left liver. In LDLT, combinations of MELD scores of 15 to 29, moderate/severe ascites, and the use of a left liver are associated with worse outcomes. These findings help calibrate appropriate patient and graft selection in LDLT.

Intraoperative Increase of Portal Venous Pressure is an Immediate Predictor of Posthepatectomy Liver Failure After Major Hepatectomy: A Prospective Study

OBJECTIVES

The aim of this study was to assess intraoperative changes of hepatic macrohemodynamics and their association with ascites and posthepatectomy liver failure (PHLF) after major hepatectomy.

SUMMARY OF BACKGROUND DATA

Large-scale ascites and PHLF remain clinical challenges after major hepatectomy. No study has concomitantly evaluated arterial and venous liver macrohemodynamics in patients undergoing liver resection.

METHODS

Portal venous pressure (PVP), portal venous flow (PVF), and hepatic arterial flow (HAF) were measured intraoperatively pre- and postresection in 67 consecutive patients with major hepatectomy (ie, resection of ≥3 liver segments). A group of 30 patients with minor hepatectomy served as controls. Liver macrohemodynamics and their intraoperative changes (ie, Δ) were analyzed as predictive biomarkers of ascites and PHLF using Fisher exact, t test, or Wilcoxon rank sum test for univariate and logistic regression for multivariate analyses.

RESULTS

Major hepatectomy increased PVP by 26.9% (P = 0.001), markedly decreased HAF by 40.7% (P < 0.001), and slightly decreased PVF by 13.4% (P = 0.011). Minor resections had little effects on hepatic macrohemodynamics. There was no significant association of liver macrohemodynamics with ascites. While middle hepatic vein resection caused higher postresection PVP after right hepatectomy (P = 0.04), the Pringle maneuver was associated with a significant PVF (P = 0.03) and HAF reduction (P = 0.03). Uni- and multivariate analysis revealed an intraoperative PVP increase as an independent predictor of PHLF (P = 0.025).

CONCLUSION

Intraoperative PVP kinetics serve as independent predictive biomarker of PHLF after major hepatectomy. These data highlight the importance to assess intraoperative dynamics rather than the pre- and postresection PVP values.

Sequential Organ Failure Assessment (SOFA) Score-Based Factors Predict Early Mortality in High-Risk Patients with Living Donor Liver Transplant

Background

Patients with a Sequential Organ Failure Assessment (SOFA) score >7 on post-transplant day (POD) 7 have been reported to have a higher risk of short-term mortality after living donor liver transplant (LDLT). We sought to identify factors that were associated with early mortality in this high-risk population.

Material/Methods

A total of 102 patients with a high SOFA score (>7) on POD 7 were enrolled, of which 72 (70.6%) were assigned to the survivor group, and the other 30 (29.4%) patients were assigned to the non-survivor group according to post-transplant 3-month results. Demographics, clinical data, operative parameters, and individual SOFA component scores were collected. Independent risk factors for 3-month mortality were identified by multivariate logistic regression analysis using backward elimination procedures.

Results

Of 102 high SOFA score patients, the 3-month mortality rate after LDLT in our study was 29.4%. Four independent risk factors were indicative for early death: graft-to-recipient weight ratio (GRWR) <0.8 (hazard ratio [HR]=3.00; 95% CI=1.05–8.09; P=0.041), longer warm ischemia time (HR=37.84; 95% CI=1.63–880.77; P=0.024), high liver component of the SOFA score, and cardiovascular component of the SOFA score (liver component: HR=10.39; 95% CI=1.77–60.89; P=0.009 and cardiovascular component: HR=13.34; 95% CI=2.22–80.12; P=0.005).

Conclusions

In conclusion, 3-month mortality among patients with high SOFA score on POD 7 is associated with multiple independent risk factors, including smaller GRWR, longer warm ischemia time, and higher category of liver and cardiovascular component of SOFA score. By recognizing high-risk patients earlier, the LDLT outcomes may be improved by timely intensive therapies.

Protection of liver sinusoids by intravenous administration of human Muse cells in a rat extra-small partial liver transplantation model

Small-for-size syndrome (SFSS) has a poor prognosis due to excessive shear stress and sinusoidal microcirculatory disturbances in the acute phase after living-donor liver transplantation (LDLT). Multilineage-differentiating stress enduring (Muse) cells are reparative stem cells found in various tissues and currently under clinical trials. These cells selectively home to damaged sites via the sphingosine-1-phosphate (S1P)-S1P receptor 2 system and repair damaged tissue by pleiotropic effects, including tissue protection and damaged/apoptotic cell replacement by differentiating into tissue-constituent cells. The effects of intravenously administered human bone marrow-Muse cells and -mesenchymal stem cells (MSCs) (4 × 105 ) on liver sinusoidal endothelial cells (LSECs) were examined in a rat SFSS model without immunosuppression. Compared with MSCs, Muse cells intensively homed to the grafted liver, distributed to the sinusoids and vessels, and delivered improved blood chemistry and Ki-67(+) proliferative hepatocytes and -LSECs within 3 days. Tissue clearing and three-dimensional imaging by multiphoton laser confocal microscopy revealed maintenance of the sinusoid continuity, organization, and surface area, as well as decreased sinusoid interruption in the Muse group. Small-interfering RNA-induced knockdown of hepatocyte growth factor and vascular endothelial growth factor-A impaired the protective effect of Muse cells on LSECs. Intravenous injection of Muse cells might be a feasible approach for LDLT with less recipient burden.

Developing a Novel Scoring System for Risk Stratification in Living Donor Liver Transplantation

Background: We aimed to develop a novel scoring system for risk stratification specific to living donor liver transplantation (LDLT) recipients, to improve the accuracy of predicting short-term outcomes. Methods: The sequential organ failure assessment (SOFA) score at postoperative day 7 was collected and simplified by dichotomization, and these categories and other clinical factors were subjected to univariate and multivariate logistic regression analyses to select independent risks in constructing a “graft-to-recipient weight ratio (GRWR)-SOFA” scoring system. Results: We enrolled 519 patients who underwent LDLT. The GRWR-SOFA score comprises a sum of six factors: cardiovascular (mean arterial pressure < 70 mmHg, scored 3), coagulation (serum platelet < 50 × 10³/μL, scored 2), renal (creatinine > 1.2 mg/dL, scored 2), liver (serum total bilirubin > 5.9 mg/dL, scored 5), neurological (Glasgow coma scale < 15, scored 2), and GRWR < 0.8, scored 2. The GRWR-SOFA contained four classes: The early mortality rate at 3 months and 1 year after LDLT was 1.3% and 6.9% for class I (scores of 0–4), 9.1% and 16.7% for class II (scores of 5–8), 25.5% and 34% for class III (scores of 9–10), and 61.3% and 67.7% for class IV (scores ≥ 11), respectively. The area under the receiver operating characteristic curve of GRWR-SOFA in the 3-month mortality prediction was 0.881 (95% confidence interval (CI): 0.818–0.944). Conclusions: The GRWR-SOFA model demonstrates superior discriminatory power for predicting short-term mortality. It enables clinicians to identify the right level of care for distinct subgroups of patients receiving LDLT.

A systematic review of the impact of portal vein pressure changes on clinical outcomes following hepatic resection

BACKGROUND

There are evolving data correlating elevated post-hepatic resection portal vein pressure (PVP) with risk of developing post-resection liver failure (PLF) and other complications. As a consequence, modulation of PVP presents a potential strategy to improve outcomes following liver resection (LR). The primary aim of this study was to review the existing evidence regarding the impact of post-resection PVP on clinical outcomes in patients undergoing a LR.

METHODS

Systematic literature searches of electronic databases in accordance with PRISMA were conducted. Changes in PVP and clinical outcomes following liver resection were defined according to the existing literature.

RESULTS

Ten studies, consisting of 712 patients with a median age 61 (52-68) years, were identified that met the inclusion criteria. Of those, 77% (n = 550) underwent a major LR and 27% (n = 195) of patients had cirrhosis. Following LR, the median (range) PVP increased from 11.4 mmHg (median baseline, range 7.3-16.4) to 15.9 mmHg (7.9-19). The overall median incidence of PLF was 19%. Six of the ten studies found an elevated PVP after LR predicted PLF. One study found elevated PVP after LR predicted mortality after LR.

CONCLUSION

Elevated PVP following hepatic resection was associated with increased rates of PLF. It was not possible to define a specific threshold PVP for predicting PLF. Modulation of PVP therefore presents a potential strategy to mitigate the incidence of LR. Future studies should standardize on reporting liver remnant and haemodynamics to better characterize clinical outcomes following LR.

Pulse oximetry-based capillary refilling evaluation predicts postoperative outcomes in liver transplantation: a prospective observational cohort study

Background

Capillary refill time (CRT) is a non-invasive technique to evaluate tissue perfusion, and quantitative CRT (Q-CRT) adapted to pulse oximetry was developed with patients with sepsis and compared to blood lactate and sepsis scores. In post liver transplantation, large amounts of fluid administration are necessary for maintaining tissue perfusion to grafted liver against intravascular hypovolemia. This study aimed to evaluate whether Q-CRT can predict poor outcomes by detecting peripheral tissue perfusion abnormality in patients with liver transplantations who were treated with massive fluid administration.

Methods

In this single-center prospective cohort study, we enrolled adult patients with liver transplantations between June 2018 and July 2019. Measurement of Q-CRT was conducted at intensive care units (ICU) admission and postoperative day 1 (POD1).

Results

A total of 33 patients with liver transplantations were enrolled. Significant correlations of Q-CRT and ΔA_b, a tissue oxygen delivery parameter calculated by pulse oximetry data, at ICU admission with the postoperative outcomes such as length of ICU and hospital stay and total amount of ascitic fluid discharge were observed. Quantitative CRT and ΔA_b at ICU admission were significantly associated with these postoperative outcomes, even after adjusting preoperative and operative factors (MELD score and bleeding volume, respectively). However, quantitative CRT and ΔA_b at POD1 and changes from ICU admission to POD1 failed to show significant associations.

Conclusions

Q-CRT values were significantly associated with postoperative outcomes in liver transplantation. Although the mechanisms of this association need to be clarified further, Q-CRT may enable identification of high-risk patients that need intensive postoperative managements.

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.

RAPID procedure for colorectal cancer liver metastasis

Liver transplantation for colorectal cancer has regained renewed interest with reported good overall survival in selected patients. The scarcity of grafts is a major obstacle to wider implementation and exploration of this field of transplant oncology. The use of small segmental auxiliary grafts from deceased or living donors might be one way to expand the donor pool with minimal negative impact on the waiting list for deceased donor transplantation and minimal risk for the donor in case of living donor liver transplantation. This review provides an insight into the physiological background for this technique and summarizes technical and surgical considerations and the experiences with this novel concept. Although the international experience still is very limited, the short term outcome could suggest that this is technically feasible. There is not sufficient data to assess long term oncological outcome. The RAPID concept (i.e. resection and partial liver segment 2-3 transplantation with delayed total hepatectomy) is still an experimental surgical procedure and should be reserved for prospective clinical trials. Herein, we describe the main technical issues of RAPID procedure from deceased and from living donor as well and report preliminary results of the first cases performed worldwide.

In situ reconstruction of vascular inflow/outflow to left lateral liver section, ex-vivo liver resection and autologous liver transplantation of remaining liver remnant for hepatic alveolar echinococcosis

•

Advanced HAE treated with the modified technique of ex vivo liver resection and autologous liver transplantation.

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The in situ reconstruction of the vascular inflow/outflow of left lateral liver section maintained the PV circulation.

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The subsequent autologous right liver transplantation provided additional liver functional tissues, thus reduced the risk of liver failure.

•

This surgical procedure did not require any veno-venous bypass.

Objective

This is a case report on a patient with advanced hepatic alveolar echinococcosis (HAE) treated with autologous liver transplantation without any veno-venous bypass using the modified technique of ex vivo liver resection and autologous liver transplantation (the ERAT technique).

Method

A 27-year old male with advanced HAE underwent in situ reconstruction of vascular inflow/outflow to left lateral liver section, ex-vivo liver resection and autologous liver transplantation of remaining liver remnant (the modified ERAT technique). The operation consisted of hepatotomy along the right border of the falciform ligament, reconstruction of portal vein supplying the left lateral liver section, reconstruction of left hepatic vein, followed by removal of liver segments S1, S4 to S8, ex vivo resection of all involved tissues within these liver segments in the liver remnant, and autologous liver transplantation of the resected liver remnant. The whole surgical procedure lasted for 12 h, and the blood lost was 800 mL. The patient recovered uneventfully in the post-operation period.

Conclusion

The in situ reconstruction of the vascular inflow/outflow of left lateral liver section maintained the PV circulation and provided liver functional support during the operation. The subsequent autologous liver transplantation provided additional liver functional tissues, thus reduced the risk of post-hepatectomy liver failure. This surgical procedure did not require any veno-venous bypass.

Liver Transplantation

The field of liver transplantation has changed since the MELD scoring system became the most widely used donor allocation tool. Due to the MELD-based allocation system, sicker patients with higher MELD scores are being transplanted. Persistent organ donor shortages remain a challenging issue, and as a result, the wait-list mortality is a persistent problem for most of the regions. This chapter focuses on deceased donor and live donor liver transplantation in patients with complications of portal hypertension. Special attention will also be placed on donor-recipient matching, perioperative management of transplant patients, and the impact of hepatic hemodynamics on transplantation.

Is Portal Inflow Modulation Always Necessary for Successful Utilization of Small Volume Living Donor Liver Grafts?

Although the well-accepted lower limit of the graft-to-recipient weight ratio (GRWR) for successful living donor liver transplantation (LDLT) remains 0.80%, many believe grafts with lower GRWR may suffice with portal inflow modulation (PIM), resulting in equally good recipient outcomes. This study was done to evaluate the outcomes of LDLT with small-for-size grafts (GRWR <0.80%). Of 1321 consecutive adult LDLTs from January 2012 to December 2017, 287 (21.7%) had GRWR <0.80%. PIM was performed (hemiportocaval shunt [HPCS], n = 109; splenic artery ligation [SAL], n = 14) in 42.9% patients. No PIM was done if portal pressure (PP) in the dissection phase was <16 mm Hg. Mean age of the cohort was 49.3 ± 9.1 years. Median Model for End-Stage Liver Disease score was 14, and the lowest GRWR was 0.54%. A total of 72 recipients had a GRWR <0.70%, of whom 58 underwent HPCS (1 of whom underwent HPCS + SAL) and 14 underwent no PIM, whereas 215 had GRWR between 0.70% and 0.79%, of whom 51 and 14 underwent HPCS and SAL, respectively. During the same period, 1034 had GRWR ≥0.80% and did not undergo PIM. Small-for-size syndrome developed in 2.8% patients. Three patients needed shunt closure at 1 and 4 weeks and 60 months. The 1-year patient survival rates were comparable. In conclusion, with PIM protocol that optimizes postperfusion PP, low-GRWR grafts can be used for appropriately selected LDLT recipients with acceptable outcomes.

Portal Inflow Modulation by Somatostatin After Major Liver Resection: A Pilot Study

: Major hepatectomy (MH) can lead to an increasing portal vein pressure (PVP) and to lesions of the hepatic parenchyma. Several reports have assessed the deleterious effect of a high posthepatectomy PVP on the postoperative course of MH. Thus, several surgical modalities of portal inflow modulation (PIM) have been described. As for pharmacological modalities, experimental studies showed a potential efficiency of Somatostatin to reduce PVP and flow. To our knowledge, no previous clinical reports of PIM using somatostatin are available. Herein, we report the results of PIM using somatostatin in 10 patients who underwent MH with post-hepatectomy PVP > 20 mmHg. Our results suggest Somatostatin could be considered as an efficient reversible PIM when PVP decrease is above 2.5 mmHg.

Splenectomy in living donor liver transplantation and risk factors of portal vein thrombosis

BACKGROUND

Graft inflow modulation (GIM) during adult-to-adult living donor liver transplantation (LDLT) is a common strategy to avoid small-for-size syndrome, and some transplant surgeons attempt small size graft strategy with frequent GIM procedures, which are mostly performed by splenectomy, in LDLT. However, splenectomy can cause serious complications such as portal vein thrombosis and overwhelming postsplenectomy infection.

METHODS

Forty-eight adult-to-adult LDLT recipients were enrolled in this study and retrospectively reviewed. We applied the graft selection criteria, which routinely fulfill graft-to-recipient weight ratio ≥ 0.8%, and consider GIM as a backup strategy for high portal venous pressure (PVP).

RESULTS

In our current strategy of LDLT, splenectomy was performed mostly due to hepatitis C and splenic arterial aneurysms, but splenectomy for GIM was intended to only one patient (2.1%). The final PVP values ≤ 20 mmHg were achieved in all recipients, and no significant difference was observed in patient survival or postoperative clinical course based on whether splenectomy was performed or not. However, 6 of 18 patients with splenectomy (33.3%) developed postsplenectomy portal vein thrombosis (PVT), while none of the 30 patients without splenectomy developed PVT after LDLT. Splenectomy was identified as a risk factor of PVT in this study (P < 0.001). Our study revealed that a lower final PVP could be risk factor of postsplenectomy PVT.

CONCLUSIONS

Using sufficient size grafts was one of the direct solutions to control PVP, and allowed GIM to be reserved as a backup procedure. Splenectomy should be avoided as much as possible during LDLT because splenectomy was found to be a definite risk factor of PVT. In splenectomy cases with a lower final PVP, a close follow-up is required for early detection and treatment of PVT.

Shift in Sympathovagal Balance Toward Parasympathetic Predominance Is Associated With Attenuation of Portal Hyperperfusion in Cirrhotic Recipients Undergoing Living Donor Liver Transplant

BACKGROUND

The autonomic innervation to a liver graft remains lost up to 1 year after liver transplant. Therefore, we investigated the effects of recipients' autonomic nervous activity on the extent of portal hyperperfusion of a partial liver graft in the absence of the autonomic innervation.

METHODS

A total of 31 cirrhotic recipients undergoing right lobe living donor liver transplant were analyzed. Following a 10-minute absence of surgical stimulation after hepatic artery and bile duct reconstruction, the electrocardiogram and blood pressure waveforms were recorded for 5 minutes. Low-frequency (LF) and high-frequency (HF) powers and their ratio (LF/HF) were calculated using fast Fourier transform from the electrocardiogram waveform. A decrease in LF/HF represents a shift in sympathovagal balance toward parasympathetic predominance. Then, portal venous (PVF) and hepatic arterial (HAF) blood flows were measured in mL/min per 100 g of liver weight using spectral Doppler ultrasonography. A decrease in their ratio (PVF/HAF) represents attenuation of portal hyperperfusion.

RESULTS

The medians of the PVF and HAF were 349 and 27 mL/min/100 g liver weight with interquartile ranges of 272 to 617 mL/min/100 g liver weight and 22 to 41 mL/min/100 g liver weight, respectively, yielding a median of the PVF/HAF of 13.7 (interquartile range, 8.5-21.3). The median of LF/HF was 0.67 (interquartile range, 0.16-1.45). With a reduction in LF/HF, PVF/HAF decreased according to an S-curve regression model between them (PVF/HAF=e^{2.743+-0.031LF/HF},adjustedR²=0.129,P=0.027).

CONCLUSION

A shift in sympathovagal balance toward parasympathetic predominance is associated with attenuation of portal hyperperfusion in a partial liver graft.

A High Portal Venous Pressure Gradient Increases Gut-Related Bacteremia and Consequent Early Mortality After Living Donor Liver Transplantation

BACKGROUND

Portal hypertension (PHT) is defined as a portal venous pressure gradient (PVPG) exceeding 5 mm Hg, which results in severe clinical manifestations. However, the validity of intraoperative PVPG monitoring and the association between PHT and bacterial translocation after liver transplantation remain unclear.

METHODS

In this retrospective study, 223 patients who underwent primary adult-to-adult living donor liver transplantation from 2008 to 2015 were divided into 2 groups based on the PVPG at the end of the operation: high PVPG (>5 mm Hg, n = 69) and low PVPG (≤5 mm Hg, n = 154). The clinical factors were compared between the groups, and the association between a high PVPG and posttransplant bacteremia/bacterial infections was investigated.

RESULTS

The high PVPG group had a significantly higher incidence of bacteremia (46% vs 24%, P < 0.001), higher 90-day mortality rate (20% vs 7%, P = 0.002), and poorer 1-year survival (71% vs 86%, P = 0.006). The high PVPG group had a particularly higher incidence of bacteremia caused by "gut bacteria" including Enterobacteriaceae, Bacteroides spp., and Enterococcus spp. (29% vs 12%, P = 0.003). Multivariate analysis showed that a PVPG greater than 5 mm Hg (odds ratio, 2.55; 95% confidence interval, 1.18-5.55; P = 0.017) was an independent predictor of bacteremia due to gut bacteria.

CONCLUSIONS

Monitoring of the PVPG is clinically meaningful for predicting patients' prognosis. In particular, a high PVPG with a threshold of 5 mm Hg at the end of adult-to-adult living donor liver transplantation may increase gut-related bacteremia through the mechanism of bacterial translocation, resulting in early mortality.

Predictive Value of Intraoperative Pulmonary Vascular Resistance in Liver Transplantation

We aimed to evaluate the association between intraoperative pulmonary vascular resistance (PVR) and clinical outcome of liver transplantation (LT). Cardiovascular involvement of end-stage liver disease is relatively common, and hemodynamic instability during LT can be fatal to recipients. However, the clinical impact of intraoperative PVR in LT remains undetermined. A total of 363 adult recipients with intraoperative right heart catheterization from January 2011 to May 2016 were analyzed. Patients were divided into 2 groups according to PVR. Two separate analyses were performed according to the time point of measurement: at the beginning and at the end of LT. The primary outcome was all-cause death or graft failure during the follow-up period. Increased PVR was observed in 11.8% (43/363) of recipients at the beginning and 12.7% (46/363) of recipients at the end of LT. PVR at the beginning of LT had no significant effect on the rate of death or graft failure in the multivariate analysis (hazard ratio [HR], 1.24; 95% confidence interval [CI], 0.64-2.38; P = 0.52). In contrast, PVR at the end of LT was significantly associated with death or graft failure during the overall follow-up period (HR, 2.00; 95% CI, 1.13-3.54; P = 0.02). In conclusion, PVR at the end of LT, rather than the beginning, is associated with clinical outcome. Larger trials are needed to support this finding.

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.

Readdressing the Middle Hepatic Vein in Right Lobe Liver Donation: Triangle of Safety

For equipoising donor safety and optimal recipient outcomes, we adopted an algorithmic "triangle of safety" approach to retrieve 3 types of right lobe liver grafts (RLGs), namely, the modified extended right lobe graft (MERLG), the partial right lobe graft (PRLG), and the modified right lobe graft (MRLG). Reconstruction to achieve a single wide anterior sector outflow was ensured in all patients. We present donor and recipient outcomes based on our approach in 665 right lobe (RL) living donor liver transplantations (LDLTs) performed from January 2013 to August 2015. There were 347 patients who received a MERLG, 117 who received a PRLG, and 201 who received a MRLG. A right lobe graft (RLG) with a middle hepatic vein was retrieved only in 3 out of 18 donors with steatosis >10%. Cold ischemia time was significantly more and remnant volume was less in the MRLG group. Of the donors, 29.3% had complications (26% Clavien-Dindo grade I, II) with no statistically significant difference among the groups. The Model for End-Stage Liver Disease score was higher in the MERLG group. There were 34 out of 39 with a graft-to-recipient weight ratio (GRWR) of <0.7% who received a MERLG with inflow modulation. Out of 4 patients who developed small-for-size syndrome in this group, 2 died. The 90-day patient survival rate was similar among different GRWRs and types of RLG. In conclusion, a selective and tailored approach for RL donor hepatectomy based on optimal functional volume and metabolic demands not only addresses the key issue of double equipoise in LDLT but also creates a safe path for extending the limits.