Anatomy of the common trunk of the middle and left hepatic veins: application to liver transplantation

Venous drainage of the left liver: an evaluation of anatomical variants and their clinical relevance

AIM

To evaluate the variations in venous drainage from the left liver.

MATERIALS AND METHODS

A retrospective evaluation was performed of all consecutive abdominal computed tomography (CT) examinations at a tertiary referral facility between 1 January and 30 June 2018. Osirix (Pixmeo SARL, Bernex, Switzerland) was used to examine the major hepatic veins and their tributaries in each scan. The classification of variants as proposed by Nakamura and Tsuzuki was used to describe the findings. The following information was collected: ramification pattern, number, length and diameter of middle (MHV) and left (LHV) hepatic vein tributaries. Two researchers collected data independently, and the average measurements were used as the final dimensions.

RESULTS

Of 102 examinations evaluated, only 27 demonstrated the conventional venous drainage patterns. The LHV and MHV combined to form a common trunk that emptied into the inferior vena cava (IVC) in 75 (73.5%) cases. The common trunk had a mean length of 8.89 mm and mean diameter of 20.18 mm. Other patterns included Nakamura and Tsuzuki type I (27.5%), type II (29.4%) and type III variants (16.7%). In addition, 4.9% of patients had absent superior middle veins and 80% had supernumerary short hepatic veins (4%).

CONCLUSION

Only 26.5% of patients in this population had conventional venous drainage from the left liver. Surgeons and radiologists in hepatobiliary practice should be aware of these variants in order to minimise morbidity when performing invasive procedures.

Anatomy of the retrohepatic segment of the inferior vena cava and the ostia venae hepaticae with its clinical significance

PURPOSE

The present study was undertaken to provide morphological data regarding the retrohepatic segment of the inferior vena cava (RHIVC) and ostia venae hepaticae with an emphasis on the clinical significance of the observations made.

METHODS

This was an observational study conducted on 160 apparently healthy, randomly selected, cadaveric adult human livers fixed in 10% formalin. The distribution of the hepatic venous openings was studied by dividing the interior of the RHIVC into 16 quadrants. These openings were classified as large, medium, small and very small openings based on their diameter and were also classified as single/double/triple/quadruple according to the number of veins opening into them.

RESULTS

The median length of RHIVC was 7.3 cm (6.2-8.4) and was directed obliquely with respect to the vertical axis of the liver in 92.5% of cases. A total of 1,376 ostia venae hepaticae were observed, and the median number of openings per liver was 7 (5-9). The right hepatic vein had a single opening in 156 (97.5%) and the left and middle hepatic veins had a common opening in 144 (90%) cases. A longitudinal area on the anterior wall of the RHIVC, to the right side of the midline, was relatively avascular with 10.1% of the venous openings, of which 70% were single openings of the right dorsal vein having a small diameter (0.1-0.5 cm).

CONCLUSION

During liver hanging maneuver, rightward direction of the dissecting forceps would avoid injury to the caudate vein and allow access to the safe avascular space in the RHIVC.

Liver tumors: MR imaging of radioactive holmium microspheres--phantom and rabbit study

PURPOSE

To investigate the use of magnetic resonance (MR) imaging in the administration and biodistribution of holmium-loaded poly(L-lactic acid) microspheres (Ho-PLLA-MS) in liver tumors.

MATERIALS AND METHODS

MR imaging measurements were obtained in phantoms, three ex vivo rabbit livers, and four livers in living rabbits. When applicable, measurements were compared with those on scintigraphic images. The transverse relaxivity R2* of the Ho-PLLA-MS was determined in a phantom study. The in vivo animal experiments were performed by using rabbits with an implanted VX2 tumor. Detection of passing Ho-PLLA-MS to estimate lung shunting was performed in a scaled model of the vena cava.

RESULTS

In the ex vivo liver experiments, the feasibility of real-time MR imaging during administration of microspheres was demonstrated. The in vivo rabbit experiments demonstrated that MR imaging can depict radioactive, nonradioactive, and decayed Ho-PLLA-MS after treatment for as long as they remain in the body. Furthermore, this study showed the ability of dynamic MR imaging to detect single doses of passing Ho-PLLA-MS.

CONCLUSION

Ho-PLLA-MS used for internal radionuclide therapy can be imaged clearly in vivo with MR imaging.

Functional venous anatomy for right-lobe grafting and techniques to optimize outflow

Right-lobe living donor liver transplantation has emerged as an alternative to cadaveric transplantation. An appreciation of the unique anatomy and behavior of the right lobe has emerged and has precipitated technical modifications. Living donors underwent right lobectomy, including preservation of significant inferior hepatic veins. The parenchyma was divided following a plane approximating the right border of the posterior two thirds of the midhepatic vein (MHV), but deviating anteriorly to include the distal one third of the MHV with the graft. Large venous tributaries from segment VIII were preserved. Anastomosis in the recipient was accomplished by means of complete cavoplasty. Significant inferior veins, tributaries to the MHV, and the distal portion of the MHV were reconstructed when technically possible. Forty-eight right-lobe resections and transplantations were performed in the manner described. There were no donor complications attributable to the technique. Forty-six of the 48 recipients are alive, and 44 of the 46 surviving patients have their original graft. Venous tributaries from segment VIII and/or the distal portion of the MHV were reconstructed in only 3 patients. Outflow obstruction was recognized intraoperatively in 2 patients; 1 patient had a caval web excised and the other patient required revision of the main anastomosis. Neither organ was lost. There were no other significant venous complications. The incidence of ascites was the same as that in recipients of whole organs. These methods of parenchymal transection and venous reconstruction resulted in a low rate of complications. The wide anastomosis and collateral pathways between the MHV and right hepatic vein seem to be more critical than reconstruction of tributaries from segment VIII or the distal MHV.

Right-lobe living donor liver transplantation

1. Living donor liver transplantation (LDLT) is currently performed at about 30 centers in the United States. 2. Careful and critical evaluation of donor and recipient is required for optimal outcome. 3. Right lobe donation is preferred over left lobe donation in adult LDLT. 4. There has been 1 donor death (<0.3%) in the US experiences. Donor biliary complications occur in approximately 4% of the cases. 5. Recipient survival after adult LDLT in the United States is approximately 88%. Hepatic artery thrombosis occurs in 3% and biliary complications in 18%.

Right lobe living donor liver transplantation: a review

The continuing shortage of organs for adult transplant recipients has generated enthusiasm for adult-to-adult living donor liver transplantation (LDLT). The major concern has been the ability to resect a graft of adequate size without subjecting the donor to undue risk. The right hepatic lobe is generally large enough for adult recipients, but because of the real and perceived risks of right lobe (RL) resection, surgeons have been hesitant to offer this option to their patients. The first series of RL resections that included a significant number of patients was reported in 1999, and the results were encouraging. Only minor complications occurred in donors, and the recipients fared quite well. Enthusiasm for these donor resections is growing, and more centers are beginning to perform them. There is a good deal of global experience with pediatric LDLT but little with adults, and there are unique considerations in this population. This review examines donor selection criteria for adult recipients, highlights technical points critical for good outcome, and examines the early results and complications in both donors and recipients. If the preliminary results continue to be reproduced, RL LDLT could have significant impact on the worsening organ shortage.