Novel technique for pediatric living donor liver transplantation in patients with portal vein obstruction: The "pullout technique"

Retro-pancreatic pull-through reconstruction of the hypoplastic portal vein using the autologous mesosystemic shunt vessel in adult living donor liver transplantation: a case report

BACKGROUND

In liver transplant patients with hypoplastic portal vein (PV), when the narrowed segment is extended too deep into the dorsal side of the pancreas, it is difficult and dangerous to reconstruct the interposition graft from the upper part of the pancreas. Herein, we present a case of PV reconstruction with the autologous mesosystemic shunt vessel from the caudal side of the pancreas in a situation where the narrowed PV was deep, and we discuss the technical details.

CASE PRESENTATION

A 25-year-old woman presented with cholestatic liver cirrhosis due to biliary atresia after Kasai procedure. Since her jaundice progressed, she was referred to our hospital for liver transplantation. Laboratory tests showed that her total bilirubin was elevated to 7.6 mg/dL. The Model for End-Stage Liver Disease score was 18, and the Child-Pugh score was 9 (Grade B). She underwent living donor liver transplantation (LDLT) using a right hemi-liver graft procured from her 54-year-old mother. The conventional approach from the cephalad side to the superior mesenteric vein (SMV) and splenic vein (SpV) confluence behind the pancreas was extremely difficult in this case because the confluence of SMV and SpV was close to the lower edge of the pancreas. Therefore, we decided to perform PV reconstruction from the caudal side. The main trunk of PV was documented as narrow (5 mm in diameter), for which retro-pancreatic pull-through PV reconstruction was successfully performed using her own mesosystemic shunt vessel. A contrast computed tomography (CT) scan was performed on postoperative day 5 because of an elevation of D-dimer and found a partial thrombus in the left pulmonary artery, as well as in the PV and left renal vein. Thereafter, thrombolytic therapy with low-molecular-weight heparin was started immediately and switched to a direct oral anticoagulant. The follow-up CT taken 3 months after liver transplantation revealed a patent PV without thrombus; therefore, anticoagulant therapy was discontinued. Currently, the patient has been well and active with a patent PV without anticoagulant therapy for 3 years after LDLT.

CONCLUSIONS

Retro-pancreatic pull-through reconstruction of the hypoplastic PV is a feasible and effective method when conventional reconstruction is not indicated.

Portal vein pressure and flow modulation in pediatric liver transplantation

Liver transplantation (LT) has been indicated for smaller and more clinically severe patients in recent years. Small biliary atresia (BA) patients often show portal hypoplasia and sclerotic portal vein (PV), which may make PV reconstruction more difficult during the operation. Among PV complications, intraoperative PV thrombosis can be considered a disaster, and it is important to prevent this catastrophic event by the precise assessment of the PV structure and PVF using radiological imaging before and during LT. However, there are no objective parameters to indicate whether sufficient PVF can be obtained. PV pressure (PVP) and PV flow (PVF) have mainly been studied in adult living donor LT, for the purpose of preventing small-for-size syndrome, and PVP has been considered an objective parameter of graft inflow modulation (GIM). In the setting of pediatric LT, GIM is mainly performed to prevent hypoperfusion, and it must be performed before graft implantation. GIM to maximize the PVF of pediatric patients with potentially low PVF in LT consists of the interruption of collateral vessels, the assessment of the usability of the native PV, and technical modifications in PV reconstruction. Reliable objective parameters that represent sufficient PVF before graft implantation are desired. Our recent study proposed that a PVP of ≥25 mmHg before graft implantation can be considered an objective parameter to obtain sufficient PVF (cutoff value: 50 mL/min/100 g of graft weight). Further investigation is needed to determine the best strategy for successful PV reconstruction in pediatric LT.

Portal vein reconstruction in pediatric liver transplantation using end-to-side jump graft: A case report

Attenuated portal vein (PV) flow is challenging in pediatric liver transplantation (LT) because it is unsuitable for classic end-to-end jump graft reconstruction from a small superior mesenteric vein (SMV). We thus introduce a novel technique of an end-to-side jump graft from SMV during pediatric LT using an adult partial liver graft. We successfully performed two cases of end-to-side retropancreatic jump graft using an iliac vein graft for PV reconstruction. One patient was a 2-year-old boy with hepatoblastoma and a Yerdel grade 3 PV thrombosis who underwent split LT. Another patient was an 8-month-old girl who had biliary atresia and PV hypoplasia with stenosis on the confluence level of the SMV; she underwent retransplantation because of graft failure related to PV thrombosis. After native PV was resected at the SMV confluence level, an end-to-side reconstruction was done from the proximal SMV to an interposition iliac vein. The interposition vein graft through posterior to the pancreas was obliquely anastomosed to the graft PV. There was no PV related complication during the follow-up period. Using a jump vascular graft in an end-to-side manner to connect the small native SMV and the large graft PV is a feasible treatment option in pediatric recipients with inadequate portal flow due to thrombosis or hypoplasia of the PV.

Global research on portal vein thrombosis and liver transplantation: A bibliometric and visualized study

In recent years, the association between portal vein thrombosis and liver transplantation has extensive attention from physicians worldwide. However, there is no available literature on bibliometric analysis in this research area. Herein, we aimed to conduct a bibliometric analysis to identify the hotspots and frontiers of research related to portal vein thrombosis and liver transplantation. Documents published between 2002 and 2022 were retrieved and downloaded from the Web of Science Core Collection database. VOSviewer was utilized to generate a visualization network map of authors, nations, institutions, journals, and keyword co-occurrence/clustering. Additionaly, CiteSpace was used to analyze the keywords with the strongest bursts. A total of 1272 articles and reviews were extracted from the database. The author Marco Senzolo published the largest number of papers. The United States was the most prolific country, and Hope-Bochon (France) was the top productive institution. Liver Transplantation was the most prolific journal in the field. The most commonly identified keywords in the study were cirrhosis, risk factors, portal vein thrombosis, and management, as revealed by the keyword co-occurrence analysis. It is suggested that patients with cirrhosis, portal vein thrombosis prevention, and management measures for portal vein thrombosis have been prominet topics in recent years. Furthermore, an analysis of keywords with the strongest citation bursts highlighted pediatric liver transplantation, direct oral anticoagulants, and nonalcoholic fatty liver disease as current research trends. Research in portal vein thrombosis and liver transplantation exhibits a general upward trend. The latest hot topics within this area of study involve pediatric patients and nonalcoholic fatty liver disease.

Reconstructing the portal vein through a posterior pancreatic tunnel: New choice for portal vein thrombosis during liver transplantation

BACKGROUND

Thrombectomy and anatomical anastomosis (TAA) has long been considered the optimal approach to portal vein thrombosis (PVT) in liver transplantation (LT). However, TAA and the current approach for non-physiological portal reconstructions are associated with a higher rate of complications and mortality in some cases.

AIM

To describe a new choice for reconstructing the portal vein through a posterior pancreatic tunnel (RPVPPT) to address cases of unresectable PVT.

METHODS

Between August 2019 and August 2021, 245 adult LTs were performed. Forty-five (18.4%) patients were confirmed to have PVT before surgery, among which seven underwent PV reconstruction via the RPVPPT approach. We retrospectively analyzed the surgical procedure and postoperative complications of these seven recipients that underwent PV reconstruction due to PVT.

RESULTS

During the procedure, PVT was found in all the seven cases with significant adhesion to the vascular wall and could not be dissected. The portal vein proximal to the superior mesenteric vein was damaged in one case when attempting thrombolectomy, resulting in massive bleeding. LT was successfully performed in all patients with a mean duration of 585 min (range 491-756 min) and mean intraoperative blood loss of 800 mL (range 500-3000 mL). Postoperative complications consisted of chylous leakage (n = 3), insufficient portal venous flow to the graft (n = 1), intra-abdominal hemorrhage (n = 1), pulmonary infection (n = 1), and perioperative death (n = 1). The remaining six patients survived at 12-17 mo follow-up.

CONCLUSION

The RPVPPT technique might be a safe and effective surgical procedure during LT for complex PVT. However, follow-up studies with large samples are still warranted due to the relatively small number of cases.

Portal vein reconstruction with cryopreserved vascular grafts: A two-edged sword

BACKGROUND

Portal vein anastomotic complications related to size discrepancy are important causes of morbidity and mortality in pediatric liver transplantation. Interposed vascular grafts in portal vein anastomosis can solve this problem. The aim of this study is to evaluate the results of pediatric liver transplantations performed using cryopreserved interposed vascular grafts between graft portal vein and superior mesenteric vein (SMV)-splenic vein (SpV) confluence.

METHODS

Twenty-nine pediatric patients received liver transplantation using cryopreserved venous grafts in our Liver Transplant Institute between 2013 and 2020 were included in this study. Demographic, clinical, and operative characteristics and postoperative follow-up were analyzed.

RESULTS

Sixteen patients (55.2%) had portal hypoplasia and five patients (17.2%) had portal vein thrombosis. In total, six patients (20.6%) suffered portal vein thrombosis in the early postoperative period. Three patients (10.3%) experienced portal vein thrombosis in the late postoperative period. Late portal vein thrombosis rate was significantly higher in patients with early portal vein thrombosis (3/6 patients [50%] versus 0/23 patients [0%]; p = .034). Lack of portal flow was significantly higher in patients with both early (50% versus 0%; p = .002) and late portal vein thrombosis (66.7% versus 6.7%; p = .03).

CONCLUSION

Preoperative portal vein thrombosis and insufficient flow are important factors affecting success of liver transplant in children. The use of interposed vein grafts in problematic portal anastomoses can overcome portal flow problems.

The extracorporeal circulation with transdiaphragmatic approach in living-donor liver transplantation for HB with atrial extension of tumor thrombus: A case report

Surgical intervention for HB with tumor thrombi extending into the IVC and the RA might requires careful planning of the surgical procedures, including vascular reconstruction and extracorporeal circulation. We herein report a successful case of LDLT for HB with atrial extension of a tumor thrombus by extracorporeal circulation with a transdiaphragmatic approach. The patient was a 5-year-old boy with PRETEXT IV HB with a tumor thrombus that extended into the IVC and the RA. After 4 cycles of chemotherapy and resection of bilateral lung metastases, the size of the primary HB tumor decreased. As the tumor extension from the LHV to the RA had decreased but was still present, we performed LDLT with tumor thrombectomy. The central part of the diaphragm was sagittally incised to expose the suprahepatic IVC and the RA. Venovenous bypass was achieved from the right femoral vein and IMV to the RA En bloc resection of the native liver with the tumor thrombus was then performed. HV anastomosis was made between the newly created orifice on the IVC and the graft LHV. The duration of LDLT was 10 hours and 44 minutes (extracorporeal circulation time: 78 minutes). Pediatric LT for HB with the extension of tumor thrombi into the RA under extracorporeal circulation is a feasible option and allows for the expansion of the indications for transplantation for children with unresectable liver tumors.

Efficacy of intraoperative cine-portogram for complicated portal vein reconstruction in pediatric living donor liver transplantation

Sufficient PV flow is necessary to achieve successful PV reconstruction in pediatric LDLT. IOCP can be used to assess the severity of PV stenosis and to identify potential portosystemic collateral pathways. The present study reviewed the utility of IOCP and the outcomes of patients who underwent assessment with an IOCP. Consecutive primary LDLTs were performed in 488 pediatric recipients between November 2005 and October 2019. IOCP was used in patients who were unable to achieve sufficient PV flow after the ligation of collaterals. In total, 11 patients underwent IOCP to assess potential portosystemic collateral pathways. The median age and body weight was 8 months (IQR, 6-11 months) and 6.6 kg (IQR, 5.7-8.9 kg), respectively. The reasons for using the IOCP were recurrent PV thrombus in seven patients and insufficient PV flow in four patients. IOCP revealed remaining collaterals in six patients and residual hypoplastic PV in eight patients. Two patients required additional interruption of the potential collaterals under IOCP, which were unable to be recognized as a dominant portosystemic collateral pathway on preoperative imaging. All eight patients with residual hypoplastic PV required vein graft interposition for the complete removal of the hypoplastic PV. All the patients are currently doing well with a median follow-up period of 4.9 years (IQR, 2.2-5.6 years). IOCP can be an effective tool for precisely detecting occult portosystemic collateral pathways and for assessing the patency of the PV anastomosis in pediatric LDLT.

Impact of prolonged clamping of the portal vein during liver transplantation in infants with biliary atresia: renewed interest in a long-standing issue

PURPOSE

Various approaches to portal vein (PV) reconstruction have been described; however, there is still scope to improve the safety and efficiency of how PV anastomosis is performed in infants.

METHODS

We analyzed, retrospectively, the predictive factors for PV reanastomosis during living donor liver transplantation (LDLT) in 117 infants (< 1 year old) with biliary atresia (BA).

RESULTS

Twenty-six infants required PV reanastomosis because of intraoperative PV thrombosis in 21 and insufficient PV flow in 5. Univariate analysis identified multiple previous laparotomies and a prolonged anhepatic phase (AHP) as significant risk factors for repeated PV anastomosis. The AHP cutoff value for identifying patients requiring PV reanastomosis was 134 min. Multivariate analysis revealed prolonged AHP > 134 min (odds ratio, 15.98; 95% confidence interval, 5.05-50.6; P < 0.001) as an independent risk factor for repeated PV anastomosis. The plasma D-dimer and fibrinogen degradation product concentration just after reperfusion were significantly higher in patients requiring PV reanastomosis (P < 0.001). Patients requiring reanastomosis of the PV had a higher incidence of PV complications after LDLT than those who did not need PV reanastomosis (P = 0.01).

CONCLUSION

Attempting to minimize the AHP is indispensable for successful LDLT in infants with BA.

Tailored classification of portal vein thrombosis for liver transplantation: Focus on strategies for portal vein inflow reconstruction

Portal vein thrombosis (PVT) is currently not considered a contraindication for liver transplantation (LT), but diffuse or complicated PVT remains a major surgical challenge. Here, we review the prevalence, natural course and current grading systems of PVT and propose a tailored classification of PVT in the setting of LT. PVT in liver transplant recipients is classified into three types, corresponding to three portal reconstruction strategies: Anatomical, physiological and non-physiological. Type I PVT can be removed via low dissection of the portal vein (PV) or thrombectomy; porto-portal anastomosis is then performed with or without an interposed vascular graft. Physiological reconstruction used for type II PVT includes vascular interposition between mesenteric veins and PV, collateral-PV and splenic vein-PV anastomosis. Non-physiological reconstruction used for type III PVT includes cavoportal hemitransposition, renoportal anastomosis, portal vein arterialization and multivisceral transplantation. All portal reconstruction techniques were reviewed. This tailored classification system stratifies PVT patients by surgical complexity, risk of postoperative complications and long-term survival. We advocate using the tailored classification for PVT grading before LT, which will urge transplant surgeons to make a better preoperative planning and pay more attention to all potential strategies for portal reconstruction. Further verification in a large-sample cohort study is needed.

Extensive Thrombectomy as a Legitimate Strategy in Living Donor Liver Transplantation With Advanced Portal Vein Thrombosis

Management of portal vein thrombosis (PVT), especially advanced PVT involving the superior mesenteric vein (SMV), in living donor liver transplantation (LDLT) is challenging. There were 514 adults who underwent LDLT between 2005 and 2018 included in this retrospective study, and PVT was observed in 67 (13.0%) patients. The LDLT recipients with PVT were characterized by increased portal pressure at laparotomy (26.1 ± 6.0 versus 24.3 ± 5.9 mm Hg; P = 0.03) and at closure (16.8 ± 3.9 versus 15.6 ± 3.6 mm Hg; P = 0.02), increased operative blood loss (14.6 ± 29.7 versus 5.7 ± 6.3 L; P < 0.01), and decreased 1-year graft survival (83.5% versus 92.8%; P = 0.04). Among the 18 patients with atrophic or vanished portal vein on pre-LDLT computed tomography, significant portal atrophy was actually observed only in 1 (5.6%) patient during LDLT surgery. For advanced PVT (n = 7) involving SMV in era 1, we performed nonanatomical inflow reconstruction using interposition grafts, resulting in significant inflow problems in 4 (57.1%) patients. Thus, for the patients with advanced PVT (n = 4) in era 2, we abandoned nonanatomical reconstruction and applied extensive thrombectomy under ultrasound guidance with secure shunt ligation, resulting in no inflow problems and no graft loss. In conclusion, even for advanced PVT involving SMV, extensive thrombectomy under sonogram guidance followed by anatomical inflow reconstruction and shunt ligation is a legitimate strategy in adult LDLT with PVT.