Embolization Of Portal Branches Research Articles

Liver Regeneration and Recanalization Time Course following Repeated Reversible Portal Vein Embolization in Swine

Introduction: Portal vein embolization (PVE) is an accepted technique to preoperatively increase the volume of the future remnant liver before major hepatectomy. A permanent material is usually preferred since its superiority to induce liver hypertrophy over absorbable material has been demonstrated. Nevertheless, the use of an absorbable material generates a reversible PVE (RPVE) capable of inducing significant liver hypertrophy. In small animal models, the possibility to proceed to a repeated RPVE (RRPVE) has shown to boost liver hypertrophy further. The aim of this preliminary study was to assess the feasibility and the tolerance of RRPVE in a large animal model, in comparison with permanent PVE (PPVE) and single RPVE. Methods: Six swine (2 per group) were assigned either to single RPVE group (using powdered gelatin sponge), RRPVE group (2 RPVEs separated by 14 days) or PPVE group (using N-butyl-cyanoacrylate). The feasibility and tolerance of the procedures were evaluated using portography, liver function tests and histological analysis. Evolution of liver volumes was assessed with volumetric imaging by computed tomography. Results: Embolization of portal branches corresponding to 75% of total liver volume was performed successfully in all animals. Procedures were well tolerated, inducing moderate changes in portal pressure and transient aminotransferase increase. None of the animals developed portal vein thrombosis. After RPVE, complete recanalization occurred at day 11. RRPVE showed a trend for higher hypertrophy, the non-embolized liver to total liver ratio reaching 5.2 ± 1.0% in the RPVE group, 6.8 ± 0.1% in the RRPVE group and 5.0 ± 0.3% in the PPVE group. Discussion/Conclusion: In this preliminary comparative study, RRPVE was as feasible and as well tolerated as the other procedures, and resulted in higher liver hypertrophy.

Single photon emission computed tomography (SPECT) for planning of surgical tactics in advanced liver resections

Aim. To determine the indications for staged treatment in planning of advanced liver resections using SPECT. Material and methods. There were 26 patients for the period 2007–2016 who required advanced liver resections at the surgical clinic of the Botkin Hospital. Anatomic FLR (aFLR) was less than 30% in all cases that is an indication for right portal branch embolization. Two-stage treatment has been applied in 15 patients (group 1) for the period 2007–2014. Preoperative examination has included SPECT since 2015. Indication for two-stage treatment was functioning FLR (fFLR) less than 30% (group 2). The second group included 11 patients. Results. In the first group (n = 15), all patients underwent right portal branch embolization. Nine of them underwent surgery including advanced right-sided hemihepatectomy in 5 cases and right-sided hemihepatectomy in 4 cases.Acute postoperative liver failure occurred in 1 (11.1%) patient (ISGLS class A). In the second group (n = 11) need for portal embolization was determined after SPECT. In 5 patients fFLR was over 30%. Thus, advanced right-sided hemihepatectomy and conventional right-sided hemihepatectomy were carried out in 2 and 3 cases, respectively. Six patients had fFLR less than 30% and two-stage approach was indicated. Five patients underwent radical surgery: advanced right-sided hemihepatectomy and conventional right-sided hemihepatectomy were carried out in 2 and 3 cases, respectively. There were no cases of acute postoperative liver failure and mortality in this group. Conclusion. Preoperative SPECT is able to predict high risk of acute postoperative liver failure after advanced liver resection. Therefore, certain measures for prevention of this complication may be considered.

Portal vein embolization using an adapted hysterosalpingography catheter.

BackgroundPortal vein embolization is an accepted procedure that provides hypertrophy of the future remnant liver in order to reduce post-hepatectomy complications.AimTo present a series submitted to portal vein embolization using an adapted hysterosalpingography catheter via transileocolic route.MethodsWere performed right portal branch embolization in 19 patients using hysterosalpingography catheter. For embolizing the vessel, was used Gelfoam® powder with absolute alcohol solution. Indications for hepatectomy were colorectal liver metastases in all cases.ResultsAn adequate growth of the future remnant liver was achieved in 15 patients (78.9%) and second time hepatectomy could be done in 14 (73.7%). In one patient (5.2%), tumor progression prevented surgery. One patient presented acute renal failure after portal embolization.ConclusionsThe hysterosalpingography catheter is easy to handle and can be introduced into the portal vein with a wire guide. There were no major post-embolization complication. Its use is safe, cheap and effective.

Abstract No. 325: Portal vein embolization: spectrum of embolic agents with illustrated examples

Review the different embolic agents that are commonly used for PVE and discuss their follow up, potential complications and controversies. Portal vein embolization (PVE) is a technique of embolization used in the preoperative management of patients selected for major hepatic resection. PVE involves the occlusion of portal branches of liver parenchyma that will be resected while preserving portal branches of the intended liver remnant. Hypertrophy of the future liver remnant is expected to occur within four to six weeks thus reducing the complication rate after liver resection. Almost all embolic materials, alone and in combination, have been described for PVE. They can be divided into: 1. Coils and vascular plugs, characterized by proximal portal branch occlusion; 2. Particles and gelforam, characterized by distal portal branch embolization; 3. Liquid agents (NBCA glue, onyx or alcohol) characterized by inflammatory reaction around the portal vein. Illustrative cases of each embolic agent will be discussed as well as their result. 1PVE is an effective treatment in the management of patients selected for major hepatic resection.2Knowledge of the different embolic materials and their behavior is important for procedural success and safety.3There is no clear evidence on which embolic agent is safest.

Mechanism of liver regeneration after liver resection and portal vein embolization (ligation) is different?

Whether or not liver regeneration after portal branch embolization (PE) (ligation, PVL) in the non-embolized (ligated) lobe is by the same mechanism as regeneration in the remnant lobe after liver resection has been reviewed. Portal vein branch embolization and heat shock protein are then discussed. Tumor growth accelerated in the remnant liver after hepatectomy. In contrast, PE or PVL resulted in marked contralateral hepatic hypertrophy and significant reduction of tumor growth in the non-embolized (non-ligated) lobes. Follistatin administration significantly increased liver regeneration after hepatectomy in rats. In contrast, regeneration of non-ligated lobes after PVL was not accelerated by exogenous follistatin. Tumor growth also was not accelerated. The liver regeneration rate peaked at 48-72 h in the nonligated lobe after PVL, a delay of 24 h compared with the remnant liver after hepatectomy. In the postoperative early stage, the expression of activin betaA, betaC, and betaE mRNAs was stronger in PVL than in hepatectomy. At 72 h the expression of activin receptor type IIA mRNA reached a peak in hepatectomy, but was significantly lower in PVL. Thus, regulation of activin signaling through receptors is one of the factors determining liver regeneration after hepatectomy and PVL. These serial experimental results imply that the mechanism of liver regeneration after portal branch ligation (embolization) is different from that after hepatectomy. Heat shock protein was induced in the liver experimentally by intermittent ischemic preconditioning and could play some beneficial role in the recovery of liver function after hepatectomy, even in cirrhotic patients. When heat shock protein following right portal vein embolization in both the embolized and non-embolized hepatic lobes was investigated in clinical cases, a two to fourfold increase in HSP70 was induced in the non-embolized lobe compared with the embolized lobe. Oral administration of geranylgeranylacetone (a non-toxic HSP inducer) suppressed inflammatory responses and improved survival after 95% hepatectomy by induction of HSP70 in rats.

PAI-1 GENE EXPRESSION IS INDUCED BY FLUID SHEAR STRESS IN RAT HEPATOCYTE

A186 Aims: Liver sinusoidal cells are always exposed to mechanical stress arising from sinusoidal blood flow. In the remnant liver after hepatectomy or non occluded lobe in the portal branch embolization or graft liver in liver transplantation, it is possible that increasing shear stress effects hepatocyte directory and modulate liver regeneration or liver damage. Some investigators have shown its possibility but there are few reports about shear stress and gene expression of hepatocyte. Plasminogen activator inhibitor-1 (PAI-1) is known to be induced transiently in the early phase of liver regeneration but its mechanism and function are still unclear. We loaded shear stress to the cultured hepatocyte and studied PAI-1 gene expression. Methods: 1. Rat hepatocyte were cultured on glass plate and set in the parallel chamber. Fluid shear stress was loaded to the hepatocyte. PAI-1 mRNA expression was analyzed by the real time PCR and compared with static control. Luciferase assay and nuclear run-on asasy were performed to study their transcriptional activity. 2. Wistar rat weighed 450g was used to confirm hemodynamic change. Portal vein branch responsible for about 70% of liver was ligated and portal vein pressure was measured by direct cannulation and sinusoidal blood velocity, flow rate and vascular area were analyzed in non ligated lobe by use of laser doppler flow meter. Then PAI-1 mRNA expression in the non ligated liver tissue was also studied. 3. Plasma PAI-1 level in the recipients of living donor liver transplantation were measured before and after reperfusion of the graft liver. Results: After loading shear stress (10dynes/cm2) for six hours PAI-1 mRNA expression was increased transiently to 6.7 fold of static control. Compared with normal medium and that added 5% dextran, PAI-1 mRNA expression was induced more in the latter at any flow rate. Transcriptional activity was also increased. Portal pressure was increased after portal branch ligation and sinusoidal blood velocity and flow rate were increased 40% significantly. PAI-1 mRNA level in non ligated liver tissue was risen up to 40 times at three hours after ligation. Plasma PAI-1 level after blood reperfusion was higher than before perfusion. Conclusions: PAI-1 mRNA expression was induced by fluid shear stress in rat hepatocyte. It is suggested that PAI-1 gene expression in the remnant liver after hepatectomy or graft liver in liver transplantation is induced by increased shear stress arisen from sinusoidal blood flow.

Changes in functional capacity after portal branch ligation in rats.

Preoperative portal branch embolization is performed to increase residual liver lobe volume so that posthepatectomy liver insufficiency associated with major hepatic resection can be prevented. Although it is essential to evaluate functional liver capacity after portal branch embolization. the timing of hepatectomy from this viewpoint remains unelucidated. The aim of this study was to clarify the optimal timing of hepatectomy after portal branch embolization. We evaluated the functional capacity of the liver after portal branch ligation (PBL) in rats, and studied the correlation between morphological and functional changes. Morphological changes were evaluated on the basis of the liver lobe weight ratio, and the proliferating cell nuclear antigen labeling index. Functional changes were evaluated by the indocyanine green disappearance rate and serum aminopyrine clearance as functional capacity. Although the total liver weight ratio remained unchanged after PBL, the unembolized lobe ratio increased significantly. Although functional capacity was minimal 2 days after PBL, it had recovered to the preoperative value by 8 days after PBL. The functional capacity of the liver after PBL was minimal around the cellular proliferative period but recovered thereafter. These findings suggest that major hepatectomy after portal branch embolization should be perfomed following the cellular proliferative period of the unembolized lobe.

Compensatory hepatic hypertrophy after occlusion of branches of the portal vein or bile duct

The effect on the liver of portal or bile duct branch occlusion was examined in rabbits by measuring hepatic tissue blood flow and cellular kinetics, using the bromodeoxyuridine labeling index. The portal branch bile duct branch, or both, to the main lobe and caudate lobe (80.4% of total liver weight) were ligated or embolized just above the right posterior lobe (19.6%), resulting in compensatory hypertrophy of the right posterior lobe and atrophy of the main and caudate lobes. Twenty-four days after ligation, the degree of compensatory hypertrophy in the different groups was comparable. There were significant differences in the pattern of the development of hypertrophy. Ligation of both a portal branch and the corresponding bile duct resulted in more rapid hypertrophy and atrophy than ligation of a portal branch alone. Ligation of a branch of the bile duct resulted in slow development of hypertrophy and atrophy. In the embolization group, the increase in the right posterior lobe stopped 6 days after the operation, resulting that it was about 40% thereafter. Histological findings showed that the fibrin clot had contracted and was floating in the portal branch to the main lobe. These results suggested that portal blood flow to the main lobe had resumed and was gradually increasing as the clot contracted. Portal branch ligation gave results superior to those with portal branch embolization with regard to application to preoperative procedure in extended hepatobiliary surgery.