Modulation of liver graft hemodynamics by partial ablation of the splenic circuit: a way to increase hepatic artery flow?

What Are Risk Factors for Graft Loss in Patients Who Underwent Simultaneous Splenectomy During Living-donor Liver Transplantation?

BACKGROUND

The consensus that portal venous pressure modulation, including splenectomy (Spx), prevents portal hypertension-related complications after living-donor liver transplantation (LDLT) has been established. However, little evidence about the risk factors for graft loss after simultaneous Spx during LDLT is available. This study aimed to identify the independent predictors of graft loss after simultaneous Spx during LDLT.

METHODS

Data of 655 recipients who underwent LDLT between 1997 and 2021 were collected and separated into the simultaneous Spx group (n = 461) and no-Spx group (n = 194).

RESULTS

The simultaneous Spx group had significantly lower serum total bilirubin levels, drained ascites volumes, and prothrombin time-international normalized ratios on postoperative day 14 than the no-Spx group (P < 0.001 for each). Incidences of small-for-size graft syndrome (P < 0.001), acute cellular rejection (P = 0.002), and sepsis (P = 0.007) were significantly lower in the Spx group. Graft survival of the Spx group was significantly better than that of the no-Spx group (P < 0.001; hazard ratio [HR], 1.788; 95% confidence interval, 1.214-2.431). A multivariate analysis revealed that 3 variables, platelet count ≤4.0 × 104/mm3 (P = 0.029; HR, 2.873), donor age ≥60 y old (P = 0.013; HR, 6.693), and portal venous pressure at closure ≥20 mm Hg (P = 0.010; HR, 3.891), were independent predictors of graft loss within 6 mo after simultaneous Spx during LDLT.

CONCLUSIONS

Spx is a safe inflow modulation procedure with a positive impact on both postoperative complications and prognosis for most patients. However, patients with the 3 aforementioned independent factors could experience graft loss after 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.

Technical challenges in LDLT - Overcoming small for size syndrome and venous outflow reconstruction

Living Donor Liver Transplantation (LDLT) emerged as an alternative treatment option for patients with end-stage liver disease waiting for an organ from a deceased donor. In addition to allowing for a faster access to transplantation, LDLT provides improved recipient outcomes when compared to deceased donor LT. However, it represents a more complex and demanding procedure for the transplant surgeon. In addition to a comprehensive preoperative donor assessment and stringent technical considerations during the donor hepatectomy to ensure upmost donor safety, the recipient procedure also comes with intrinsic challenges during LDLT. A proper approach during both procedures will result in favorable donor and recipient's outcomes. Hence, it is critical for the transplant surgeon to know how to overcome such technical challenges and avoid deleterious complications. One of the most feared complications following LDLT is small-for-size syndrome (SFSS). Although, surgical advances and deeper understanding of the pathophysiology behind SFSS has allowed for a safer implementation of LDLT, there is currently no consensus on the best strategy to prevent or manage this complication. Therefore, we aim to review current practices in technically challenging situations during LDLT, with a particular focus on management of small grafts and venous outflow reconstructions, as they possess one of the biggest technical challenges faced during LDLT.

Volume and flow modulation strategies to mitigate post-hepatectomy liver failure

INTRODUCTION

Post hepatectomy liver failure is the most common cause of death following major hepatic resections with a perioperative mortality rate between 40% to 60%. Various strategies have been devised to increase the volume and function of future liver remnant (FLR). This study aims to review the strategies used for volume and flow modulation to reduce the incidence of post hepatectomy liver failure.

METHOD

An electronic search was performed of the MEDLINE, EMBASE and PubMed databases from 2000 to 2022 using the following search strategy "Post hepatectomy liver failure", "flow modulation", "small for size flow syndrome", "portal vein embolization", "dual vein embolization", "ALPPS" and "staged hepatectomy" to identify all articles published relating to this topic.

RESULTS

Volume and flow modulation strategies have evolved over time to maximize the volume and function of FLR to mitigate the risk of PHLF. Portal vein with or without hepatic vein embolization/ligation, ALPPS, and staged hepatectomy have resulted in significant hypertrophy and kinetic growth of FLR. Similarly, techniques including portal flow diversion, splenic artery ligation, splenectomy and pharmacological agents like somatostatin and terlipressin are employed to reduce the risk of small for size flow syndrome SFSF syndrome by decreasing portal venous flow and increasing hepatic artery flow at the same time.

CONCLUSION

The current review outlines the various strategies of volume and flow modulation that can be used in isolation or combination in the management of patients at risk of PHLF.

Current evidence on posthepatectomy liver failure: comprehensive review

INTRODUCTION

Despite important advances in many areas of hepatobiliary surgical practice during the past decades, posthepatectomy liver failure (PHLF) still represents an important clinical challenge for the hepatobiliary surgeon. The aim of this review is to present the current body of evidence regarding different aspects of PHLF.

METHODS

A literature review was conducted to identify relevant articles for each topic of PHLF covered in this review. The literature search was performed using Medical Subject Heading terms on PubMed for articles on PHLF in English until May 2022.

RESULTS

Uniform reporting on PHLF is lacking due to the use of various definitions in the literature. There is no consensus on optimal preoperative assessment before major hepatectomy to avoid PHLF, although many try to estimate future liver remnant function. Once PHLF occurs, there is still no effective treatment, except liver transplantation, where the reported experience is limited.

DISCUSSION

Strict adherence to one definition is advised when reporting data on PHLF. The use of the International Study Group of Liver Surgery criteria of PHLF is recommended. There is still no widespread established method for future liver remnant function assessment. Liver transplantation is currently the only effective way to treat severe, intractable PHLF, but for many indications, this treatment is not available in most countries.

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.

Portocaval shunt can optimize transhepatic flow following extended hepatectomy: a short-term study in a porcine model

The aim of this study was to evaluate whether the portocaval shunt (PCS) corrects these unwanted changes in transhepatic flow after extended hepatectomy (EH). Forty female Landrace pigs were divided into two main groups: (A) EH (75%) and (B) no EH. Group A was divided into 3 subgroups: (A1) EH without PCS; (A2) EH with side-to-side PCS; and (A3) EH with end-to-side PCS. Group B was divided into 2 subgroups: (B1) side-to-side PCS and (B2) end-to-side PCS. HAF, PVF, and PVP were measured in each animal before and after the surgical procedure. EH increased the PVF/100 g (173%, p < 0.001) and PVP (68%, p < 0.001) but reduced the HAF/100 g (22%, p = 0.819). Following EH, side-to-side PCS reduced the increased PVF (78%, p < 0.001) and PVP (38%, p = 0.001). Without EH, side-to-side PCS reduced the PVF/100 g (68%, p < 0.001) and PVP (12%, p = 0.237). PVP was reduced by end-to-side PCS following EH by 48% (p < 0.001) and without EH by 21% (p = 0.075). PCS can decrease and correct the elevated PVP and PVF/100 g after EH to close to the normal values prior to resection. The decreased HAF/100 g in the remnant liver following EH is increased and corrected through PCS.

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

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

Portal flow modulation in living donor liver transplantation: review with a focus on splenectomy

Small-for-size graft (SFSG) syndrome after living donor liver transplantation (LDLT) is the dysfunction of a small graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. It is a serious complication of LDLT and usually triggered by excessive portal flow transmitted to the allograft in the postperfusion setting, 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. These conditions may be attenuated with portal flow modulation. Attempts have been made to control excessive portal flow to the SFSG, including simultaneous splenectomy, splenic artery ligation, hemi-portocaval shunt, and pharmacological manipulation, with positive outcomes. Currently, a donor liver is considered a SFSG when the graft-to-recipient weight ratio is less than 0.8 or the ratio of the graft volume to the standard liver volume is less than 40%. A strategy for transplanting SFSG safely into recipients and avoiding extensive surgery in the living donor could effectively address the donor shortage. We review the literature and assess our current knowledge of and strategies for portal flow modulation in LDLT.

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.

Changes in peripheral lymphocyte subsets in patients after partial microwave ablation of the spleen for secondary splenomegaly and hypersplenism: a preliminary study

PURPOSE

Microwave ablation therapy for secondary splenomegaly and hypersplenism has been shown to be effective from pre-clinical animal models and clinical investigations. This study was performed to determine its effects on the status of peripheral lymphocyte subsets in patients receiving microwave ablation of the spleen.

MATERIALS AND METHODS

Ten patients with secondary splenomegaly and hypersplenism received microwave ablation of the spleen during laparoscopy or percutaneously under ultrasound guidance. The percentage peripheral blood T cells, B lymphocytes and NK cells were measured using flow cytometry before and on days 1, 3 and 7 after therapy, as well as 1 and 3 months afterwards.

RESULTS

Percentages of CD3(+) and CD4(+) cells increased rapidly 1 month after therapy. There was no significant change in CD8(+), CD4(+)/CD8(+) or NK cells of the pre- and post-therapy levels and B lymphocytes increased significantly after therapy. In patients with an ablation volume (AV) less than 20% (group A), T cells increased 1 month after ablation but decreased 3 months after ablation. B lymphocytes increased significantly after surgery. Levels of NK cells were lower than that before therapy on each testing. In patients with 20-40% AV (group B), levels of T cells, B lymphocytes and NK cells showed an increase. Levels of CD4(+) cells were significantly higher in group B than in group A, 3 months after therapy.

CONCLUSIONS

Microwave ablation therapy for splenomegaly and hypersplenism appears to have a favourable effect on peripheral lymphocyte subsets. A relationship may exist between the ablation volume and the level of peripheral lymphocyte subsets.

The 'small for size' liver syndrome

PURPOSE OF REVIEW

Small-for-size syndrome (SFSS) is a clinical syndrome described following liver transplantation (LT) and extended hepatectomy. New evidence has emerged documenting the importance of preoperative evaluation of functional liver mass, liver quality, influence of portal hypertension, and variations in surgical technique to improve outcome.

RECENT FINDINGS

SFSS is characterized by postoperative coagulopathy and liver dysfunction due to insufficient functional liver mass. Recent radiologic advances allow accurate preoperative estimation of total, graft, and remnant liver volume (RLV). In adult-to-adult living donor liver transplantation (LDLT), a graft-to-recipient body weight ratio > or = 0.8% or graft weight ratio > or = 30% are important to avoid SFSS. Minimal functional RLV following extended hepatectomy is > or = 25% in a normal liver, and > or = 40% with preoperative liver dysfunction. Preoperative portal vein or hepatic artery embolization to increase RLV and function after extended hepatectomy, and the increasing use of parenchymal-sparing segmental resections have improved outcome. In LT, the evolving use of split livers, LDLT and marginal grafts has resulted in increased recognition of SFSS. This has led to a renewed interest in defining the pathophysiology, and the development of new surgical techniques to reduce its incidence.

SUMMARY

Current radiologic imaging techniques can be used to evaluate liver volume and the risk of SFSS following LT and extended hepatectomy. Intraoperative techniques to predict postoperative dysfunction are emerging, and may be helpful in directing the use of pre-emptive surgical interventions. The future lies in the development of perioperative liver protection and support in predicted SFSS, and enhancement of healthy liver regeneration.

Radiofrequency ablation for hypersplenism in patients with liver cirrhosis: a pilot study

Radiofrequency ablation is a relatively new technique used for local ablation of unresectable tumors. We investigated the feasibility and efficacy of radiofrequency ablation for hypersplenism and its effect on liver function in patients with liver cirrhosis and portal hypertension. Nine consecutive patients with hypersplenism due to cirrhotic portal hypertension underwent radiofrequency ablation in enlarged spleens. The ablation was performed either intraoperatively or percutaneously. Patients are followed up for over 12 months. After treatment, between 20% and 43% of spleen volume was ablated, and spleen volume increased by 4%-10.2%. White blood cell count, platelet count, liver function, and hepatic artery blood flow showed significant improvement after 1-year follow-up. Splenic vein and portal vein blood flow were significantly reduced. Only minor complications including hydrothorax (three of nine patients) and mild abdominal pain (four of nine patients) were observed. No mortality or other morbidity occurred. Radiofrequency ablation is a safe, effective, and minimally invasive approach for the management of splenomegaly and hypersplenism in patients with liver cirrhosis and portal hypertension. Increased hepatic artery blood flow may be responsible for sustained improvement of liver condition. Radiofrequency ablation may be used as a bridging therapy for cirrhotic patients waiting for liver transplantation.

Clinical relevance of adapting portal vein flow in living donor liver transplantation in adult patients

Size mismatching is a major concern in adult living donor liver transplantation (ALDLT). Graft hyperperfusion in these grafts is considered the main factor leading to graft dysfunction and poor survival. We describe the clinical significance of graft inflow modification (GIM) by splenic artery ligation in a series of 24 consecutive ALDLT. Between September 1999 and December 2001, 24 patients underwent ALDLT at our institution. Patients were divided into two groups: G1, n = 11 without GIM, and G2, n = 13 with GIM. Both groups were equivalent in terms of preoperative clinical state, graft characteristics, and surgical technique. Graft hyperperfusion was noticed overall, especially in small grafts (graft-to-recipient body weight ratio <0.8), with mean recipient portal vein (rPVF) values at least three times greater than those recorded in the donors. GIM permitted in G2 a significant decrease in rPVF. Small-for-size syndrome (SFSS) occurred in three (27%) patients in G1 with small grafts showing graft hyperperfusion and necessitating a retransplantation. SFSS did not occur in G2. One-year overall survival was 62% and 93% respectively for G1 and G2. It is concluded that when small-for-size grafts are accompanied by graft hyperperfusion, the rPVF should be lowered to avoid the SFSS and to improve the outcome.

Changes in portal vein flow after adult living-donor liver transplantation: does it influence postoperative liver function?

In adult living donor liver transplantation, using small grafts in cirrhotic patients with severe portal hypertension may have unpredictable consequences. The so-called small-for-size syndrome is present in most series worldwide. The goal of this study was to prospectively evaluate the influence of hemodynamic changes on postoperative liver function and on the percentage of liver volume increase, in the setting of living donor liver transplantation. Twenty-two consecutive adult living donor liver transplantations were performed at our institution in a 2-year period. We measured right portal flow and right hepatic arterial flow with an ultrasonic flow meter in the donor, and then in the recipient 1 hour after reperfusion. Postoperative liver function was measured by daily laboratory work. We also performed duplex ultrasounds on postoperative days 1, 2, and 7. Liver volume increase was estimated by magnetic resonance imaging graft volumetry at 2 months posttransplantation. We compared the blood flow results with the immediate liver function and its liver volume increase rate at 2 months. There was a significant increase in portal flow in the recipients compared with the donors (up to fourfold in some cases). Higher portal flow increase rates significantly correlated with faster prothrombin time normalization and faster liver volume increases. Median graft volume increase at 2 months was 44.9%. The increase in blood flow to the graft is well tolerated by the liver mass not affecting hepatocellular function as long as the graft-to body weight ratio is maintained (>0.8) and adequate outflow is provided.

Modulation of portal graft inflow: a necessity in adult living-donor liver transplantation?

OBJECTIVE

To evaluate the clinical significance of modulating the recipient portal inflow (rPVF) through perioperative ligation of the splenic artery in adult living-donor liver transplantation (ALDLTx) by focusing on vascular complications, intractable ascites production, and the prevention of small-for-size syndrome (SFSS).

SUMMARY BACKGROUND DATA

In ALDLTx, portal graft flow is enhanced to at least twice the donor value, raising the total liver inflow. Recipient hepatic arterial flow (rHAF) is lower than expected. Portal hyperperfusion of small grafts in larger recipients is thought to be one of the main causes of posttransplant graft dysfunction/SFSS.

METHODS

Seventeen ALDLTx were reviewed for a minimum of 2 months. Patients were divided retrospectively into two groups: G1 (n = 7), without modulation of rPVF, and G2 (n = 10), with splenic artery ligation to decrease rPVF perioperatively. Donor and recipient hepatic hemodynamics were evaluated against graft function and outcome, including correlations between rPVF, graft weight, graft:recipient body weight ratio, and recipient weight.

RESULTS

Following portal and arterial reperfusion, mean rPVF and rPVF/graft weight were much higher than in the donors, whereas mean rHAF and rHAF/graft weight were much lower. No differences were found between groups, except for rPVF and rHAF, which were much more higher and lower, respectively, before splenic artery ligation. In G1 patients, SFSS was seen in two patients and vascular complications occurred in two others. In G2 patients, splenic artery ligation permitted a significant decrease in rPVF, an improvement in rHAF, and the resolution of refractory ascites. Neither SFSS nor vascular complications were seen in G2 patients.

CONCLUSIONS

When a suboptimal graft:recipient body weight ratio is accompanied by high rPVF in ALDLTx, the portal flow should be modulated perioperatively; splenic artery ligation is a simple and safe method that is sufficient to allow this modulation in most patients.

Modulation of portal graft inflow: a necessity in adult living-donor liver transplantation?

OBJECTIVE

To evaluate the clinical significance of modulating the recipient portal inflow (rPVF) through perioperative ligation of the splenic artery in adult living-donor liver transplantation (ALDLTx) by focusing on vascular complications, intractable ascites production, and the prevention of small-for-size syndrome (SFSS).

SUMMARY BACKGROUND DATA

In ALDLTx, portal graft flow is enhanced to at least twice the donor value, raising the total liver inflow. Recipient hepatic arterial flow (rHAF) is lower than expected. Portal hyperperfusion of small grafts in larger recipients is thought to be one of the main causes of posttransplant graft dysfunction/SFSS.

METHODS

Seventeen ALDLTx were reviewed for a minimum of 2 months. Patients were divided retrospectively into two groups: G1 (n = 7), without modulation of rPVF, and G2 (n = 10), with splenic artery ligation to decrease rPVF perioperatively. Donor and recipient hepatic hemodynamics were evaluated against graft function and outcome, including correlations between rPVF, graft weight, graft:recipient body weight ratio, and recipient weight.

RESULTS

Following portal and arterial reperfusion, mean rPVF and rPVF/graft weight were much higher than in the donors, whereas mean rHAF and rHAF/graft weight were much lower. No differences were found between groups, except for rPVF and rHAF, which were much more higher and lower, respectively, before splenic artery ligation. In G1 patients, SFSS was seen in two patients and vascular complications occurred in two others. In G2 patients, splenic artery ligation permitted a significant decrease in rPVF, an improvement in rHAF, and the resolution of refractory ascites. Neither SFSS nor vascular complications were seen in G2 patients.

CONCLUSIONS

When a suboptimal graft:recipient body weight ratio is accompanied by high rPVF in ALDLTx, the portal flow should be modulated perioperatively; splenic artery ligation is a simple and safe method that is sufficient to allow this modulation in most patients.