Transjugular Access Research Articles

Transjugular Access for Endovascular Treatment of Immature Autogenous Arteriovenous Fistulae

PurposeTo assess the feasibility and outcome of transjugular access for endovascular treatment of immature arteriovenous fistulae (AVFs). Materials and MethodsBetween August 2013 and January 2016, 90 patients (mean age, 64.5 y ± 12.8) underwent endovascular treatment of immature AVFs via transjugular access. The mean age of fistulae was 3.3 months ± 1.8. Total procedure time and technical and clinical success rates of endovascular procedures were assessed. Primary and secondary patency rates were calculated according to the Kaplan–Meier method, and complications were assessed. ResultsAll patients had inflow lesions, among which 19 (21.1%) had occlusions. The juxtaanastomotic segment was the most common site (44.3%). Transjugular access was successful in 83 patients (92.2%), and 7 required additional standard or transarterial access. The mean procedure time was 36.5 minutes. Technical and clinical success rates were 98.9% and 90.5%, respectively. Mean primary and secondary patency durations were 14.3 months ± 1.7 and 31.0 months ± 0.7, respectively. Primary patency rates at 3, 6, and 12 months were 84.4%, 67.3%, and 48.8%, respectively. Secondary patency rates at 6 and 18 months were 98.6% and 95.5%, respectively. Venous rupture occurred as a result of balloon inflation in 9 patients (10%), and was managed by balloon tamponade. There were no complications related to transjugular access during a mean follow-up period of 12.6 months. ConclusionsTransjugular access for angioplasty of immature AVFs is feasible and safe. Potential problems associated with access in the outflow vein could be avoided by transjugular access.

925 Intrahepatic Portosystemic Shunt: An Endoscopic Approach

Transjugular intrahepatic portosystemic shunt, also known as TIPS, involves the creation of a channel between the portal vein (PV) and the hepatic vein (HV). This is typically performed via angiography, and is effective treatment for complications of portal hypertension. However, this requires transjugular access, and inadvertent biliary and arterial injury can occur.

Original approach for thrombolytic therapy in patients with Ilio-femoral deep vein thrombosis : 2years follow-up.

ObjectiveThe aim of the study was to discuss the results of catheter-directed thrombolysis and complementary procedures to treat acute iliofemoral deep vein thrombosis (DVT) evaluating the safety and effectivness of an easy access such as the Great Saphenous Vein.Methods and materialsA total of 22 consecutive patients with iliofemoral thrombosis and two patients with femoro-popliteal thrombosis on recent onset diagnosed with Ultrasound Doppler and contrast venography underwent intrathrombus drip infusion of urokinase while intravenous heparin was continued using saphenical access. Residual venous stenosis were treated in six patients by percutaneous balloon Angioplasty and stenting. All patients underwent routine venous duplex imaging at 30 days, 3 months, 6 months and every 6 months thereafter.ResultsComplete patency of thrombosed veins was restored in 22 patients (91 %) with prompt symptomatic relief. There were no major complications in the immediate outcomes. At follow-up, two patients reported a persistant slim iliac vein stenosis, two patients had post-thrombotic syndrome, and two patients showed Deep Vein Reflux.ConclusionLocal thrombolysis using saphenical access was a safe and effective approach for the treatment of acute iliofemoral deep vein thrombosis. It seems to be a valid, easy and safe alternative, reducing the risks of haematoma and venous lesions, which can be observed when using femoral, popliteal, and trans-jugular access.

Role of interventional radiology in the management of complications after pancreatic surgery: a pictorial review.

Pancreatic resections are surgical procedures associated with high incidence of complications, with relevant morbidity and mortality even at high volume centres. A multidisciplinary approach is essential in the management of these events and interventional radiology plays a crucial role in the treatment of patients developing post-surgical complications. This paper offers an overview on the interventional radiological procedures that can be performed to treat different type of complications after pancreatic resection. Procedures such as percutaneous drainage of fluid collections, percutaneous transhepatic biliary procedures, arterial embolisation, venous interventions and fistula embolisation are viable treatment options, with fewer complications compared with re-look surgery, shorter hospital stay and faster recovery. A selection of cases of complications following pancreatic surgery managed with interventional radiological procedure are presented and discussed. Teaching Points • Interventional radiology is crucial to treat complications after pancreatic surgery • Percutaneous drainage of collections can be performed under ultrasound or computed tomography guidance • Percutaneous biliary procedures can be used to treat biliary complications • Venous procedures can be performed effectively through transhepatic or transjugular access • Fistulas can be treated effectively by percutaneous embolisation

Dural arteriovenous fistulas of the hypoglossal canal: systematic review on imaging anatomy, clinical findings, and endovascular management.

Dural arteriovenous fistulas (DAVFs) of the hypoglossal canal (HCDAVFs) are rare and display a complex angiographic anatomy. Hitherto, they have been referred to as various entities (for example, "marginal sinus DAVFs") solely described in case reports or small series. In this in-depth review of HCDAVF, the authors describe clinical and imaging findings, as well as treatment strategies and subsequent outcomes, based on a systematic literature review supplemented by their own cases (120 cases total). Further, the involved craniocervical venous anatomy with variable venous anastomoses is summarized. Hypoglossal canal DAVFs consist of a fistulous pouch involving the anterior condylar confluence and/or anterior condylar vein with a variable intraosseous component. Three major types of venous drainage are associated with distinct clinical patterns: Type 1, with anterograde drainage (62.5%), mostly presents with pulsatile tinnitus; Type 2, with retrograde drainage to the cavernous sinus and/or orbital veins (23.3%), is associated with ocular symptoms and may mimic cavernous sinus DAVF; and Type 3, with cortical and/or perimedullary drainage (14.2%), presents with either hemorrhage or cervical myelopathy. For Types 1 and 2 HCDAVF, transvenous embolization demonstrates high safety and efficacy (2.9% morbidity, 92.7% total occlusion). Understanding the complex venous anatomy is crucial for planning alternative approaches if standard transjugular access is impossible. Transarterial embolization or surgical disconnection (morbidity 13.3%-16.7%) should be reserved for Type 3 HCDAVFs or lesions with poor venous access. A conservative strategy could be appropriate in Type 1 HCDAVF for which spontaneous regression (5.8%) may be observed.

8:40 AM Abstract No. 122 - Portal vein thromboembolectomy/TIPS: a novel preliver transplant interventional approach to rendering the untransplantable patient transplant-ready

Purpose Introduction: Complete portal vein occlusion is considered a relative contraindication to liver transplantation (LT). Intra-operative techniques (interposition grafts, portal arterialization, cavoportal transposition, multivisceral transplantation) are suboptimal solutions to this challenging problem. Portal vein thrombo-embolectomy/TIPS (PVTE-TIPS) is a novel pre-transplantation approach to re-establish portal flow making traditional LT possible in the otherwise potentially untransplantable. Aim: To evaluate the feasibility/efficacy of PVTE-TIPS to re-establish PV continuity prior to LT and confirm LT candidature. Materials and Methods LT candidates assessed in transplant clinic presenting between 2007 and 2011 with complete PVT (complete non-visualization of PV on cross-sectional imaging) were considered for PVTE-TIPS. Subjects were considered candidates in the absence of visualization of any portal vein by imaging, rendering them less than optimal candidates for transplantation. Results 30 patients underwent successful PVTE-TIPS. There were no technical failures; none required main portal vein stenting. Average procedure time was 3 hours (range 2-8). A combination of percutaneous and transjugular access (with snaring) was necessary in most cases. There were 2 periprocedural adverse events (1 hemoperitoneum not requiring operative intervention, 1 hemobilia with decompensation/subsequent transplantation). 15/30 have been transplanted; >1.5 cm of patent PV was encountered in all subjects with excellent antegrade flow permitting standard end-end anastomoses. Postoperative PV flows (doppler-postop day # 1) were in excess of 1.5 ml/min. Follow-up 1 and 3 month splenoportography demonstrated patent PVs in all cases despite no stenting. Conclusion Pre-LT PVTE/TIPS is a novel approach to a challenging, if not untransplantable population. As the technique evolves, so too will patient selection in order to identify optimal candidates and periprocedural management (anticoagulation). With these advances, PVTE/TIPS may become standard of care in management of LT candidates with complete PVT.

TIPS Placement via Combined Transjugular and Transhepatic Approach for Cavernous Portal Vein Occlusion: Targeted Approach

Purpose. We report a novel technique which aided recanalization of an occluded portal vein for transjugular intrahepatic portosystemic shunt (TIPS) creation in a patient with symptomatic portal vein thrombosis with cavernous transformation. Some have previously considered cavernous transformation a contraindication to TIPS. Case Presentation. 62-year-old man with chronic pancreatitis, portal vein thrombosis, portal hypertension and recurrent variceal bleeding presents with melena and hematemesis. The patient was severely anemic, hemodynamically unstable, and required emergent portal decompression. Attempts to recanalize the main portal vein using traditional transjugular access were unsuccessful. After percutaneous transhepatic right portal vein access and navigation of a wire through the occluded main portal vein, an angioplasty balloon was inflated at the desired site of shunt takeoff. The balloon was targeted and punctured from the transjugular approach, and a wire was passed into the portal system. TIPS placement then proceeded routinely. Conclusion. Although occlusion of the portal vein increases difficulty of performing TIPS, it should not be considered an absolute contraindication. We have described a method for recanalizing an occluded portal vein using a combined transhepatic and transjugular approach for TIPS. This approach may be useful to relieve portal hypertension in patients who fail endoscopic and/or surgical therapies.

Abstract No. 410: The use of the patent ductus venosus as an access for portal vascular interventions in children

The ductus venosus, a fetal communication between the portal and systemic venous circulations, spontaneously closes early in the neonatal period. The persistence of the ductus venosus is rare and can be primary (congenital) or secondary to abnormal portal hemodynamics. Vascular anomalies of the portal vein can be associated with serious clinical presentation and pose technical challenges at interventions. In such patients, the patent ductus venosus provides a safe and valuable alternative access for endovascular treatment. 4 children (age: 2 months 6 years) underwent interventional treatment of vascular anomalies of the portal vein using the patent ductus venosus as a vascular conduit to the portal vein via a transjugular approach. Two patients had arterioportal fistulae; one had a large portosystemic shunt with severe gastrointestinal bleeding and one congenital hemangioma with heart and liver failure. Mesenteric arteriography was initially performed followed by transjugular access of the patent ductus venosus and embolization of the portal anomaly. All the procedures were technically successful using the patent ductus venosus. In patient # 1 with a fistula between the inferior phrenic artery and portal vein, the shunt was embolized with coils. Patient # 2 had a complex arterioportal shunt with a giant portal aneurysm was embolized with an Amplatzer septal occluder and coils. The portosystemic shunt in patient # 3 was closed using an Amplatzer vascular plug. Embolization of the portal feeding tributaries to the liver hemangioma in patient # 4 was done with coils. The procedures were technically successful in the four children without complications. The arterioportal fistula (patient # 1) and the portosystemic shunt (patient # 3) were completely obliterated and clinically successfully. Though technically successful, the response to embolization in patients # 2 and 3 (complex arterioportal fistula and congenital liver hemangioma, respectively) was partial; largely related to other serious comorbidity. Patent ductus venosus provides an invaluable safe access for endovascular portal venous interventions in children.

Cavernous Redirection of Venous Drainage after Partial Transvenous Coil Occlusion of a Sigmoid Sinus dAVF: Coil Mass Retrieval with Flexible Cysto-Urethroscopy Grasping Forceps

We describe the case of a patient who presented with ocular symptoms (chemosis, proptosis, increased intra-ocular pressure, impaired visual acuity) eight months after the transvenous coil occlusion of an ipsilateral sigmoid sinus dural arteriovenous fistula (dAVF). Digital substraction angiography revealed a partial occlusion of the left sigmoid sinus with coils. Since the connection from the sigmoid sinus to the internal jugular vein was obliterated by coils without interrupting the arteriovenous shunt, the venous drainage was redirected into the inferior petrosal sinus, the cavernous sinus and the superior ophthalmic vein. The transjugular access to the inferior petrosal sinus was obstructed by a large coil mass in the jugular bulb. Several attempts to remove these coils with an Alligator retrieval device and a goose neck snare failed. The coil mass was withdrawn via a direct access to the internal jugular vein using flexible cysto-urethroscopy grasping forceps, an urological device designed for the removal of kidney stones. After establishing anterograde drainage, the now accessible inferior petrosal sinus was occluded with fibered coils and the dAVF was completely obliterated. The ocular symptoms resolved within ten days.

Erste Erfahrungen mit intravenösen Portsystemen mit der Zulassung zur Hochdruckinjektion von Kontrastmittel in der Computertomografie

The aim of this prospective study was to examine two port systems for intravenous chemotherapy, authorized for high pressure injection, with respect to implantation, complications, implementation, and patency. 40 high pressure port systems of the two available models (20 x Power Port [Bard], 20 x T-Port-Contrast [PFM]) and 20 standard port systems (X-Port [BARD]) as the control group were implanted. Both high pressure systems are authorized for injection with a maximum pressure of 300 PSI. The patient population was comprised of patients with different malignomas and liver metastases. At regular intervals following the protocol of the chemotherapy, multiphasic CT for tumor staging was carried out. The intravenous port systems were implanted without complications under sonographic guidance with transjugular access. The mean implantation time was 30 min (range: 22 - 40 min). After a median follow-up time of 6 months, the port patency was 100%. No port infections and no complications during high pressure injection of contrast agent occurred during this period. The level of contrast measured in the aorta was equivalent to the level of contrast in the vessels when contrast agent is administered over a large peripheral intravenous access. The intravenous high pressure port systems are equivalent to standard systems with regard to implantation and implementation. Intravenous chemotherapy can be performed as usual. The advantage is the possibility of multiphasic CT with authorized flow rates of up to 5 ml/sec.

Percutaneous Extrahepatic Portacaval Shunt with Covered Prostheses: Feasibility Study

To assess the anatomic feasibility of creating a percutaneous extrahepatic portosystemic shunt (PEPS) between the main portal vein (MPV) and the inferior vena cava (IVC) in patients with cirrhosis and to evaluate the feasibility of this approach in an animal model. In human studies, computed tomographic (CT) scans from 34 patients with cirrhosis were reviewed to assess the distance and anatomic structures found between the MPV and IVC. The MPV was divided into upper, middle, and lower thirds for analysis. In the experimental model, PEPS were created in 10 beagle dogs by placing between the MPV and IVC a tubular polyurethane-covered prosthesis with flared ends designed for this study. Different approaches, devices, and prostheses were assayed. In human studies, the shortest mean distance between the IVC and the MPV was found in the lower third of the MPV (1.18 cm +/- 0.6). The lower third, the nearest to the confluence of splenic and superior mesenteric veins, also presented fewer intervening structures, and the spatial relationship between the veins at this level was predictable. In the experimental model, direct portography was performed, with a small mesenteric vein catheterized through a minilaparotomy and a transjugular access to the IVC. A needle was advanced from the MPV to the IVC, and a polyurethane cone-shaped covered prosthesis was placed to bridge the path between the veins. Six of 10 animals died from bleeding that occurred either because several punctures were made during the procedure or because the prosthesis became dislodged when the mesentery was moved before suturing the minilaparotomy. The remaining four were kept alive for 1, 5, 60, and 90 days after the procedure. PEPS creation in patients with cirrhosis is anatomically possible. The lower third of the MPV should be the most suitable level at which to create the shunt. Preliminary studies carried out in beagle dogs support the feasibility of this approach. However, further work is needed to improve the efficacy of this technique.

Intravascular Ultrasonography: a Promising Imaging Tool in Transjugular Intrahepatic Portosystemic Stent Shunts

Transjugular intrahepatic portosystemic shunts (TIPS) have become an important therapeutic option in managing the complications of portal hypertension. One major limitation to the universal use of TIPS, however, might be concern about shunt insufficiency due to stenosis caused by neointimal hypertrophy. Close follow-up surveillance of the patients treated by TIPS is therefore of great importance in the early detection of shunt stenosis and thus in avoiding reoccurrence of portal hypertension encompassing esophageal rebleeding, recurrent ascites, or mortality (1). We report on two patients who benefited from the use of intravascular ultrasonography (IVUS) performed during TIPS angiography. Methods Two patients with portal hypertension treated by TIPS underwent Doppler sonography, upper gastrointestinal endoscopy, and portography. For IVUS, a 2.0 mm, 20 MHz ultrasound miniprobe (Aloka Co., Ltd., Tokyo, Japan) with a sterile cover sheath was inserted via transjugular access through a long introducer sheath. Images were recorded under retraction of both ultrasound probe and sheath. In the case of shunt tract stenosis, biopsy specimens were obtained via transjugular access using sterile endoscopic forceps. The study protocol was approved by the local Ethics Committee of ! #$% %& ’ !( )()* $% $%+,-$

Transjugular liver biopsy: assessment of safety and efficacy of the Quick-Core biopsy needle

We assessed the safety and efficacy of transjugular liver biopsy with the Quick-Core biopsy needle. Fifty consecutive patients with liver failure and contraindications to percutaneous liver biopsy were referred for transjugular liver biopsy. Eighteen (36%) patients had thrombocytopenia (platelet range = 44-92/microL, mean = 66/microL), 31 (62%) patients had elevated prothrombin times (international normalized ratio range = 1.3-3, mean = 1.6), and 19 (38%) patients had ascites. The Cook Quick-Core biopsy needle was used. Average procedure time was 30 min. Transjugular access to the hepatic veins was successful in 49 of 50 cases. A transfemoral approach was used in one patient. Tissue specimens were satisfactory for histologic diagnosis in all cases. Established cirrhosis was present in 37 (74%) patients. The mean number of cores was 2.2 (range = 1-3). The mean number of portal triads per core was 10.4 (range = 6-20). There were no procedure-related complications. Transjugular liver biopsy with the Quick-Core biopsy needle is safe and effective in patients in whom the percutaneous route is contraindicated by coagulopathy or ascites.

Catheter-directed thrombolysis with transjugular access in portal vein thrombosis secondary to pancreatitis

A case of portal vein thrombosis (PVT) secondary to pancreatitis is presented. Patient was treated with catheter-directed thrombolysis using urokinase solution. Because the percutaneous transhepatic approach is associated with higher risk of hemorrhage we used the catheter-directed thrombolysis via the transjugular intrahepatic access to restore the patency of the thrombosed portal vein. This case shows that catheter-directed thrombolysis with transjugular approach can be effectively used in the treatment of PVT.

Intravascular US-guided Direct Intrahepatic Portacaval Shunt with a PTFE-covered Stent-Graft: Feasibility Study in Swine and Initial Clinical Results

To determine the feasibility of the creation of a direct intrahepatic inferior vena cava (IVC)-to-portal-vein shunt with puncture guided by a transfemorally placed intravascular ultrasound (IVUS) probe and use of a polytetrafluoroethylene (PTFE)-covered stent-graft. In five swine, transjugular access was used to perform a direct puncture from the IVC to the portal vein with use of a modified Rosch-Uchida Portal Access set directed with real-time IVUS (9 MHz) introduced from a transfemoral venous approach. The direct intrahepatic portocaval shunt (DIPS) was then created with single or overlapping PTFE-covered Palmaz stents placed through a 10-F sheath and dilated to a diameter of 8 mm. Follow-up was performed with transhepatic portography at 2, 4, and 8 weeks. Animals were killed when shunts occluded or at the termination of the study at 8 weeks. Gross and microscopic histologic study was performed on sacrificed animals. A similar technique was used to create DIPS in five patients with intractable ascites, with follow-up by US and venography. All experimental DIPS created in swine were created without complications. Portal vein punctures were achieved in four of five swine on the first or second pass of the needle. Follow-up transhepatic portography at 2 weeks demonstrated occlusion of two shunts, both explained by technical reasons at sacrifice. At 4 and 8 weeks, the remaining three shunts were patent on portography. Histology showed a thin neointimal lining with no significant tissue ingrowth or hyperplasia. Clinically, in five patients, successful puncture of the portal vein from the IVC was achieved in one to three passes. Creation of DIPS led to a reduction of mean portosystemic gradient from 18-29 mm Hg (mean, 24 mm Hg) to 9-10 mm Hg (mean, 9 mm Hg). One patient died of liver failure 2 days after creation of DIPS. The other four patients were doing well 2-15 months (mean, 8 months) after the procedure, with patency confirmed by US and venography. Creation of DIPS is technically feasible, and the direct IVC-to-portal-vein puncture can be done accurately with real-time IVUS guidance. Further studies and longer follow-up are necessary to determine if the short length of the PTFE-covered stent-graft and avoidance of the hepatic vein will increase the long-term patency compared to standard transjugular intrahepatic portosystemic shunt creation.

The Usefulness of CO2 Indirect Portography in Transjugular Intrahepatic Portosystemic Shunt(TIPS)

Purpose : To determine the usefulness of carbon dioxide() indirect portography during TIPS procedure.Materials and Methods : We evalvated eight patients who had undergone TIPS due to variceal hemorrhage or ascites caused by portal hypertension. All patients but one with complete situs inversus underwent wedged right hepatic venography for visualization of the portal vein using . For indirect portal venography, 50cc of was injected by hand without prior injection of a small amount of . In three patients a 5-F angiographic catheter was wedged into the right hepatic vein, and in the other five a 9-F sheath from a Ring’s transjugular access set was adjunctively wedged into the right hepatic vein over the 5-F catheter. The time requiredfor portal vein puncture was defined as the time between the indirect portal venography procedure and the first procedure after successful portal vein puncture.Results : All patients successfully underwent TIPS without any immediate complication. The portal vein was visualized by in 7 of 8 patients (87.5%). Two of three patients who underwent indirect portography withonly a 5-F catheter wedging demonstrated opacification of the right portal vein; in the remaining patient the portal venous system was not visualized. Of the five patients who underwent indirect portography with an adjunctive 9-F sheath wedged in the right hepatic vein, four showed opacification from the peripheral to themain portal vein, and in the other, the only right peripheral portal vein was opacified. The mean time for portal vein puncture was 20.5 minutes.Conclusion : For visualization of the portal venous system during TIPS procedure, the use of indirect portography is feasible.

Anatomic Considerations Related to the TIPS Procedure

Learning objectives: As a result of attending this plenary session, the attendee will be able to (1) Identify the technique-related complications oftransjugular intrahepatic portosystemic shunt (7IPS),. (2) identify the anatomic-dependent complications of TIPS,. (3) understand the anatomic landmarks necessary to successfully perform TIPS,. and (4) correctly understand the steps necessary to avoid complications when peljorming TIPS. THE creation of a TIPS is a recent development in the treatment of portal hypertension 0). In this procedure, the portal vein is decompressed by creating an artificial communication between one of the hepatic veins and the portal vein with a metallic stent mesh. Multiple reports suggest that the TIPS procedure is an effective, safe, reliable, and repeatable technique 0-13). However, as more experience was gained with the procedure, several anatomicand technique-related complications were reported that increased the difficulties in placing and maintaining the shunt 00,14-22). Technique-related complications include shunt occlusion, extraparenchymal puncture, creation of an intraperitoneal shunt, intraperitoneal bleeding, liver capsule perforation by the transjugular needle, misplacement and migration of the stent, and cardiac perforation 04-22). Anatomic-dependent complications are related primarily to traversing a hepatic arterial or venous branch or biliary radicle during parenchymal puncture and stent placement. In addition, failure to gain transjugular access, to find an adequate hepatic vein for puncture, or failure to perform the puncture of the portal vein due to an anatomic variation 04-23) complicates the performance of the TIPS procedure. Knowledge of the vascular and biliary liver anatomic structures is imperative to perform the TIPS procedure safely. The most common anatomic variations of the hepatic veins and portal vein, and the relation between the different structures of the portal triad must be mastered before attempting the procedure (24). The anatomic basis for performing the TIPS procedure is the assumption that the right hepatic vein (RHV) is located superior and posterior to the portal vein bifurcation. As the RHV courses along the right hepatic fissure, it receives branches from segments V and VIII anteriorly and segments VI and VII posteriorly. In the periphery of the liver, the RHV is located along the right fissure of the liver in a path between the anterior and posterior branches of the right portal trunk, whereas more centrally the ostium and the final few centimeters of the RHV are cranial and dorsal to the bifurcation of the portal vein and the right portal trunk. The transparenchymal puncture made to create the intrahepatic shunt is, therefore, performed from the more central portion of the RHV in a caudal and anterior (or medial) direction. The portal vein is punctured along the right portal trunk at the portal bifurcation or, less frequently, at the proximal left portal trunk. Alternatively, the portal vein may be approached from the middle hepatic vein (MHV) or left hepatic vein (LHV). In that case, the direction of the transparenchymal puncture must be posterior for the MHV and posteromedial for the LHV (24). Liver casts of 25 healthy liver specimens were injected with acrylic material into the vascular elements and bile duct at the hepatic pedicle. After corrosion with sodium hydroxide, the specimens were washed thoroughly to remove organic material. The anatomy of the RHV, MHV, and LHV; the position of the main portal vein bifurcation; the distance between the RHV, MHV, LHV and the portal bifurcation; the anatomy of the portal bifurcation; and the relation of the structures of the portal triad at the portal bifurcation and the proximal right and left portal trunks were reviewed (24).