Hepatic veins anatomy and piggy-back liver transplantation

Ying-Zi Ming, Ying Niu, Ming-Jie Shao, Xing-Guo She and Qi-Fa Ye

Changsha, China

Clinical Summary

Hepatic veins anatomy and piggy-back liver transplantation

Ying-Zi Ming, Ying Niu, Ming-Jie Shao, Xing-Guo She and Qi-Fa Ye

Changsha, China

BACKGROUND:The piggy-back caval anastomosis technique is widely used in orthotopic liver transplantation although it carries an increased risk of complications, including outflow obstruction and Budd-Chiari syndrome. The aim of this study is to clarify the anatomy and variations of hepatic veins (HVs) draining into the inferior vena cava (IVC), and to classify the surgical techniques of piggy-back liver transplantation (PBLT) based on the anatomy of HVs which can reduce the occurrence of complications.

METHODS:PBLT was performed in 248 consecutive cases at our hospital from January 2004 to August 2011. The anatomy of recipients’ HVs was determined when removing the native diseased livers. Both anatomy of HVs and short HVs draining into the IVC were recorded. These data were collected and analyzed.

RESULTS:We classified anatomic variations of HVs in the 248 livers into five types according to the way of drainage into the IVC: typei(trunk type of left and middle HVs), 142 (57.3%) patients; type II (trunk type of right and middle HVs), 54 (21.8%); type III (trunk type of left, middle and right HVs), 14 (5.6%); type IV (non-trunk type of left, middle and right HVs), of which, type IVa, 16 (6.5%), in the same horizontal plane; type IVb, 18 (7.3%), in different horizontal planes; and type V (segment type), 4 (1.6%). The patients whose HVs anatomy belonged to types I, II and III underwent classical piggy-back liver transplantation. Type IVa patients had classical PBLT via HV venoplasty prior to piggy-back anastomosis, while type IVb patients and type V patients could only have modified PBLT.

CONCLUSION:This study demonstrates that HVs can be classified according to the anatomy of their drainage into the IVC and we can use this classification to choose the best operative approach to PBLT.

(Hepatobiliary Pancreat Dis Int 2012;11:429-433)

hepatic vein; classification; piggy-back liver transplantation

Introduction

Liver transplantation is a well-known and widely accepted therapeutic option for the treatment of end-stage liver diseases. Over the past 4 decades, the surgical techniques of liver transplantation have evolved and been modified to become technically less challenging and more routinely feasible.[1]Orthotopic liver transplantation (OLT) traditionally involves a complete replacement of the retrohepatic/infrahepatic vena cava.[2,3]During the anhepatic phase, however, there is a substantial decrease in venous return to the heart, causing hemodynamic instability, metabolic alterations, and overall reduction in renal flow.[4]In contrast to the caval replacement of the standard bicaval orthotopic technique, a method of preserving the inferior vena cava (IVC) was first described by Calne and Williams[5]in 1968. Twenty years later, this technique, better known as piggy-back, was reintroduced by Tzakis et al[6]in a more detailed fashion. The partial clamping of the IVC and maintenance of venous blood return eventually made venovenous bypass a more selective procedure.[7-11]The piggy-back technique is currently the most widely used technique in the world for caval anastomosis in liver transplantation. As piggy-back liver transplantation (PBLT) is widely applied clinically, study on the anatomic variations of recipient's hepatic veins (HVs) draining into the IVC is important for the selection of the best technique variations in liver transplantation. Until now, the anatomic variability has not been well studied.

Clinical summary

From January 2004 to August 2011, PBLT was performed in 248 patients at our hospital. We prospectivelyexamined the anatomy of HVs while performing the native hepatectomy during a liver transplant. The anatomy of HVs and short HVs draining into the IVC at the second and third hepatic hili was recorded, respectively. The data included: 1) the confluence of left and middle HVs, 2) the confluence of right and middle HVs, 3) drainage into the IVC of left, middle and right HVs, 4) the confluence of left, middle and right HVs, and 5) drainage into the IVC of short HVs of each segment. Their classification was made according to the anatomic variations of HVs draining into the IVC so as to decide which operative mode of OLT should be chosen.

The patients' mean age was 41.4±9.1 years. In the 248 patients, the male/female ratio was 2.82:1, and the causes of cirrhosis were hepatitis B (103 patients), hepatitis C (22), hepatocellular cancer (65), liver metabolic disease (34), drugs (4), alcoholic cirrhosis (7), and others (13). Anatomic variations of the HVs were classified into five types. Typei(trunk type of left and middle HVs): the left and middle HVs joined together before draining into the IVC, 142 patients, accounting for 57.3% of the total cases. Type II (trunk type of right and middle HVs): the right and middle HVs joined together before draining into the IVC, 54 (21.8%). Type III (trunk type of left, middle and right HVs): the left, middle and right HVs joined together before draining into the IVC, 14 (5.6%). Type IV (non-trunk type of the left, middle and right HVs): the left, middle and right HVs drained into the IVC separately. It could be divided into two subtypes: type IVa (the three HVs drained into the IVC in the same horizontal plane; 16, 6.5%) and type IVb (the three HVs drained into the IVC in different horizontal planes; 18, 7.3%). Type V (segment type): the HVs drained into the IVC as segments, 4 (1.6%). The classification and incidence of HVs anatomy and technical norms of OLT in the 248 patients are summarized in the Table.

In typei(Fig. 1) left and middle HVs trunk, the left HV joined together with the middle HV. After the ligation or transfixion of the right HV, PBLT was routinely performed in these patients. Because the anastomosed pedicle can deviate to the left after PBLT, it's easy to develop left deviation technical obstruction of venous reflex. Therefore, constriction of the right part of the diaphragmatic surface of the liver should be performed in order to prevent the graft from leaning to left.

In type II (Fig. 2) right and middle HV trunk, PBLT was performed after the venoplasty of the right and middle HVs. When end-to-end anastomosis of the right and middle HVs and the donor's IVC was carried out, venous return obstruction of the transplanted liver was rare, but avoiding the overlong anastomotic HVs and IVC is prudent. Otherwise, the pedicle compression may occur, or venous obstruction of the transplanted livermay occur because of tortuous veins.

Table. Classification and incidence of HVs anatomy and technical norms of OLT

Fig. 1. Ligation of the right HV and the left-middle HV trunk. 1: ligated right HV; 2: left-middle HV trunk.

Fig. 2. Ligation of the left HV and the right-middle HV trunk. 1: ligated left HV; 2: right-middle HV trunk.

Fig. 3. One trunk type of the left, middle and right HVs. 1: left, middle and right HVs formed a trunk; 2: retrohepatic IVC of donor.

Fig. 4. A: The left, middle and right HVs in the same horizontal plane; B: The left, middle and right HVs in the different horizontal planes. 1: left HV; 2: middle HV; 3: right HV; 4: suprahepatic IVC of donor.

Fig. 5. Short HVs with tiny and disordered branches. 1: inverted triangle of short HVs; 2: IVC of recipient; 3: IVC of donor.

In type III (Fig. 3) where the left, middle and right HVs formed a trunk before draining into the IVC, endto-end anastomosis of the left, middle and right HVs and the donor's IVC was performed.

In type IVa (Fig. 4A) where the left, middle and right HVs drained into the IVC separately in the same horizontal plane, plastic operation was done, followed by end-to-end anastomosis of these veins and the suprahepatic IVC or classic OLT (COLT).

In type IVb (Fig. 4B) where the left, middle and right HVs drained into the IVC separately in different horizontal planes, it was very hard to perform hepatic venoplasty. HVs could only be ligated or transfixed. Endto-side or side-to-side anastomosis was done using IVCs of the donor and the recipient, or COLT was carried out.

Type V (Fig. 5) was rare clinically, and since each segment formed short HVs which had tiny and disordered branches and could not have plastic operation as some cases in type IVb. HVs could only be ligated or transfixed, and ameliorated PBLT (APBLT) was carried out using cavo-caval IVCs with inverted triangle or shuttle shaped incisions along the posterior and anterior median planes of the IVCs, or side-to-side and end-to-side APBLT was performed, or COLT was carried out.

Based on the anatomy and variations of HVs and their drainage into the IVC, we performed classical PBLT (CPBLT), APBLT or COLT to best accommodate the anatomy encountered. This allowed standardization of the techniques used in PBLT and allowed us to prevent undesirable consequences arising out of nonstandard operative techniques with many surgeons in a transplant program.

Discussion

The anatomy of HVs and their drainage into the IVC in our series were investigated according to the data gathered from our clinical practice. Several methods of graft-to-inferior vena cava implantation have been delineated: early studies used a side-to-side or end-toside anastomosis of the graft cava to the recipient cava after the closure of both ends or the lower end of the graft IVC, respectively.[7,12]Others anastomosed the graft IVC to the recipient's common trunk of the left and middle HVs after dividing the intervening septum with or without an additional short cavotomy (i.e, the two-vein technique).[13,14]Anastomosis of the graft IVC to the joined orifice of the 3 main HVs with partial caval occlusion was first reported in 1997.[15]In accordance with different anatomic presentations of HVs' joining with each other and their drainage into the IVC in these 248 patients, combined with OLT technique, we subsequently classified and named 5 patterns of anatomic variations of HVs.

Typeiis the trunk type of the left and middle HVs, accounting for 57.3%; type II is the trunk type of the right and middle HVs, accounting for 21.8%. In type III, three HVs join together to form a trunk and then drain into the IVC. CPBLT can be performed in typeiand II, while it is most applicable to type III. In type IV three HVs drain into the IVC respectively, which is 13.7% of the total cases (among them, nearly 50% of the HVs drain into the IVC in different planes). In type IVa the HVs drain into the IVC in the same plane, and the routine plastic operation of the three HVs can be performed before CPBLT. In type IVb the three HVs do not drain into the IVC in the same plane and venoplastyof the HVs can't be carried out. There are no three constant HVs in type V and short HVs directly drain into the IVC from each segment. The anatomy of HVs and their drainage into the IVC in the 248 patients have offered us the anatomic basis that we can rely on in implementation and normalization of the technical types during liver transplantation.

The blood in hepatic sinusoid from the hepatic portal vein and hepatic artery proper often runs into the central veins, then into the HVs, and finally into the retrohepatic portion of the IVC. The left, middle and right HVs (placed in the plane of the portal fissures) drain in the upper third of the retrohepatic portion of the IVC. In the middle and lower thirds of the retrohepatic portion of the IVC the short HVs drain.[16-21]

From an anatomical viewpoint, some authors have tried to classify HVs for the purposes of liver transplantation. For example, De Cecchis et al[22]divided the right HV into 4 types. Nakamura and Tsuzuki[23]have classified HVs to 3 types based on the right HV, right accessory HV and middle HV, while Kawasaki et al[24]according to different ways of drainage of IVb classified IVb to typeiin which IVb drained into the middle HV, and type II in which IVb drained into the left HV. Pathological study by Mehran et al[25]radiological studies by Kamel et al[26]and Marcos et al,[27]and others all have their respective limitations. Their classification is imperfect (just 3 or 4 types) and do not have a consistent classification scheme that translates to practical utility in liver transplantation.

The results of our series show that patients of type I, II, III and IVa all can undergo CPBLT. However, the technical challenge is determined by the length of the anastomotic vascular vessels. They are often tortuous and compressed because they can be relatively long. As a result, intraoperative Budd-Chiari syndrome, and postoperative acute or chronic Budd-Chiari syndrome may develop; moreover, stomal stenosis is the common complication clinically.[28,29]In type I, since CPBLT is performed, the anastomosis pedicle is leaning to the left, and therefore, it is easy to have left deviation and develop venous return obstruction; in type II stoma press could occur since the cavo-caval IVC and HV are too long; in type III the three HVs join together to form a trunk before their drainage into the IVC, routine CPBLT can be performed and it's the best anatomical type for CPBLT; in type IVa since the three HVs drain into the IVC in the same plane, it's easy for the patients to undergo HV venoplasty and CPBLT; and in type IVb the three HVs drain into the IVC separately in different planes, the patients can only have end-toside or side-to-side anastomosis or COLT by using the cavo-caval IVC, or the three HVs are cut to form the inverted triangle openings which are anastomosed with the inverted triangle opening of the retrohepatic IVC of the donor liver. There were 22 (8.9%) patients belonging to type V and IVb. For the HVs of the similar types, APBLT should be carried out including the cavocaval IVC anastomosis and the ameliorated operation of IVC triangle cut, ameliorated operation of IVC shuttleshaped cut, or APBLT of half or whole IVC anastomosis, or COLT.

It's worth pointing out that typeiand II account for 79.0% of the total cases, and relatively satisfactory results have been achieved by clinical application of CPBLT techniques. However, approximately 20% of postoperative donor livers have intraoperative swelling that may be related to the ligated right HV or left HV. If the transplanted liver becomes swollen and the determined portal pressure is over 20 cmH2O, revision should be considered promptly after performing CPBLT to ensure outflow obstruction will not occur. This is a problem in our series.

Large studies have shown that optimal outflow is essential to a successful piggy-back procedure.[30-32]However, the anatomy of HVs and their drainage into the IVC have provided favorable experience for the determination of PBLT operative plans (CPBLT and APBLT). Following the improvement of split liver transplantation and living donor liver transplantation techniques, we have acquired further understanding of the HVs drainage into the IVC.

In this study, we classified HVs into five types according to the anatomy of their drainage into the IVC and we can use this classification to choose the best operative approach to PBLT. However, there are some limitations in our study. Pre-operative venography or 3D-MR angiography which can obtain exact anatomy of HVs will be required in the future.

Contributors:YQF proposed the study. MYZ and SXG performed research and wrote the first draft. NY and SMJ collected and analyzed the data. All authors contributed to the design and interpretation of the study and to further drafts. YQF is the guarantor.

Funding:None.

Ethical approval:Not needed.

Competing interest:No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

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January 3, 2012

Accepted after revision June 14, 2012

Author Affiliations: Research Center of Chinese Health Ministry on Transplantation Medicine Engineering and Technology, The Third Xiangya Hospital, Central South University, Changsha 410013, China (Ming YZ, Niu Y, Shao MJ, She XG and Ye QF)

Qi-Fa Ye, MD, PhD, Research Center of Chinese Health Ministry on Transplantation Medicine Engineering and Technology, The Third Xiangya Hospital, Central South University, Changsha 410013, China (Tel: 86-731-88618313; Email: yqf_china@163.com)

? 2012, Hepatobiliary Pancreat Dis Int. All rights reserved.

10.1016/S1499-3872(12)60203-3