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

Understanding Local Hemodynamic Changes After Liver Transplant: Different Entities or Simply Different Sides to the Same Coin?

Liver transplantation is an extremely complex procedure performed in an extremely complex patient. With a successful technique and acceptable long-term survival, a new challenge arose: overcoming donor shortage. Thus, living donor liver transplant and other techniques were developed. Aiming for donor safety, many liver transplant units attempted to push the viable limits in terms of size, retrieving smaller and smaller grafts for adult recipients. With these smaller grafts came numerous problems, concepts, and definitions. The spotlight is now aimed at the mirage of hemodynamic changes derived from the recipients prior alterations. This article focuses on the numerous hemodynamic syndromes, their definitions, causes, and management and interconnection with each other. The aim is to aid the physician in their recognition and treatment to improve liver transplantation success.

Imaging Evaluation of Living Liver Donor Candidates: Techniques, Protocols, and Anatomy

The need for liver transplants is increasing because the prevalence of liver diseases and the indications for transplants are growing. In response to the shortage of grafts from deceased donors, more transplants are being performed worldwide with grafts from living donors. Radiologic evaluation is an integral component in the assessment of donor candidates to ensure their eligibility and to choose the most appropriate surgical approach. MRI is the preferred modality for evaluation of the liver parenchyma and biliary tree. In most centers, a combination of MRI and CT is used to take advantage of the higher spatial resolution of CT for evaluation of arteries. However, MRI-only assessment is feasible. In addition to assessment of the liver parenchyma for abnormalities such as steatosis, a detailed evaluation of the hepatic vascular and biliary system for pertinent anatomic variants is crucial, because these variants can affect surgical techniques and outcomes in both recipients and donors. In this pictorial article, after a brief review of the most common surgical techniques and postsurgical liver anatomy, the biliary and vascular anatomy are discussed, with specific attention paid to the variants that are pertinent to this surgical procedure. The roles of liver segmentation and volumetric assessment and current imaging techniques and protocols are also discussed. Online supplemental material is available for this article. ©RSNA, 2021.

Hepatic vein in living donor liver transplantation

Right lobe living donor liver transplantation (LDLT) is a major development in adult LDLT that has significantly increased the donor pool by providing larger graft size and by decreasing risk of small-for-size graft syndrome. However, right lobe anatomy is complex, not only from the inflow but also from the outflow perspective. Outflow reconstruction is one of the key requirements of a successful LDLT and venous drainage of the liver graft is just as important as hepatic inflow for the integrity of graft function. Outflow complications may cause acute graft failure which is not always easy to diagnose. The right lobe graft consists of two sections and three hepatic venous routes for drainage that require reconstruction. In order to obtain a congestion free graft, several types of vascular conduits and postoperative interventions are needed to assure an adequate venous allograft drainage. This review described the anatomy, functional basis and the evolution of outflow reconstruction in right lobe LDLT.

Conceptual changes in small-for-size graft and small-for-size syndrome in living donor liver transplantation

Early series in living donor liver transplantation (LDLT) in adults demonstrated a lower safe limit of graft volume standard liver volume ratio 25%–45%. A subsequent worldwide large LDLT series proposed a 0.8 graft recipient weight ratio (GRWR) to define small-for-size graft (SFSG) in adult LDLT. Thereafter, researchers identified innate and inevitable factors including changes in liver volume during imaging studies and graft shrinkage due to perfusion solution. Although the definition of small-for-size syndrome (SFSS) advocated in the 2000s was mainly based on prolonged cholestasis and ascites output, the term SFSS was inadequate to describe clinical manifestations possibly caused by multiple factors. Thus, the term “early allograft dysfunction (EAD),” characterized by total bilirubin >10 mg/dL or coagulopathy with international normalized ratio >1.6 on day 7, has become prevalent to describe graft dysfunction including SFSS after LDLT. Although various efforts have been made to overcome EAD in LDLT, graft selection to maintain an expected GRWR >0.8 and full venous drainage, as well as inflow modulation using splenic artery ligation, have become standard in recent LDLT.

Anatomy of the Right Anterior Sector of the Liver and Its Clinical Implications in Surgery

BACKGROUND

Surgery remains the gold standard both for delimited hepatocellular carcinoma by selective anatomic liver segentectomy and for colorectal liver metastases by parenchymal sparing liver resection. Right anterior sector (RAS) (segments V-VIII; Couinaud) is the largest and most difficult sector to operate on. A better knowledge of its segmentation could prevent postoperative remnant liver ischemia and its impacts on patient's survival.

METHODS

A literature search was conducted in PubMed for papers on anatomy and surgery of the right anterior sector.

RESULTS

Segmentation of the RAS depended of the anatomic variations of the third-order portal branches. Cranio-caudal segmentation was the most commonly found (50-53%), followed by ventro-dorsal (23-26%), trifurcation (13-20%), and quadrifurcation types (5-11%). Ventral and dorsal partial or total subsegmentectomy seemed accessible in 47 to 50% of patients, including bifurcation, trifurcation, and quadrifurcation types, and could spare up to 22% of the total liver volume. The RAS hepatic vein was present in 85-100% of the patients and could be used as a landmark between RAS dorsal and ventral part in 63% of patients. Reported overall morbidity rate of RAS subsegmentectomy ranged from 33 to 59% among studies with a postoperative major complication rate (Clavien-Dindo ≥ III) ranging around 18% and a biliary leakage rate from 16 to 21%. In-hospital reported mortality rate was low (0-3%), and results were comparable to "classic" liver resections. RAS subsegmentectomy remains a complex procedure; median operating time ranged from 253 to 520 min and median intraoperative blood loss reached 1255 ml.

CONCLUSION

Better knowledge of RAS anatomy could allow for parenchymal preservation by using subsegmentectomy of the RAS, selective or as a part of a major hepatectomy.

Impact of Functional Hepatic Venous Outflow Obstruction on Perioperative Outcome After Living-Donor Liver Transplant

OBJECTIVES

An optimal initial graft function after living-donor liver transplant depends on optimal graft hemodynamics. Nonmechanical impediments to free hepatic venous outflow, due to elevated central venous pressure, may obstruct the "functional" hepatic venous outflow. Here, we evaluated whether central venous pressure affected early graft function and outcomes in adult living-donor liver transplant recipients.

MATERIALS AND METHODS

This prospective observational study included 61 living-donor liver transplant recipients without technical complications who received transplants from August 2013 to November 2014. Hemodynamic variables were measured preoperatively, at anhepatic phase, 30 minutes postreperfusion, at end of surgery, and during postoperative days 1-5.

RESULTS

Patients with high central venous pressure showed functional hepatic venous outflow obstruction, which caused delayed recovery of graft function. Although postoperative central venous pressure was the only identified independent risk factor for mortality, all 5 deaths in our study group occurred in those who had high central venous pressure at the anhepatic, postreperfusion, end of surgery, and postoperative phases. A postoperative central venous pressure value of ~11 mm Hg was determined to be the cutoff for high-risk mortality, with area under the curve of 0.859 (sensitivity of 80%, specificity of 68%). Increased central venous pressure was associated with increased portal venous pressure (increase of 45%, range, 28%-89%; P = .001). Central venous pressure at end of surgery (r = 0.45, P ≤ .001) and at posttransplant time points (r = 0.29, P = .02) correlated well with portal venous pressure at end of surgery. Other risk factors for early allograft dysfunction were Model for End-Stage Liver Disease and cardiac output posttransplant.

CONCLUSIONS

High central venous pressure, modulating portal venous pressure, can result in functional hepatic venous outflow obstruction, causing delayed graft function recovery and increased risk of mortality. Maintaining a central venous pressure below 11 mm Hg is beneficial.

Adult-to-adult living donor liver transplantation: Operative techniques to optimize the recipient's outcome

Adult-to-adult living donor liver transplantation (LDLT) is widely accepted today with good outcomes and safety reported worldwide for both donor and recipient. Nonetheless, it remained a highly demanding technical and complex surgery if undertaken. The last two decades have seen an increased in adult-to-adult LDLT following our first report of right lobe LDLT in overcoming graft size limitation in adults. In this article, we discussed the operative techniques and challenges of adult right lobe LDLT incorporating the middle hepatic vein, which is practiced in our center for the recipient operation. The various issues and challenges faced by the transplant surgeon in ensuring good recipient outcome are explored and discussed here as well. Hence, it is important to understand that a successful recipient operation is dependent of multifactorial events starting at the preoperative stage of planning, understanding the intraoperative technical challenges and the physiology of flow modulation that goes hand-in-hand with the operation. Therefore, one needs to arm oneself with all the possible knowledge in overcoming these technical challenges and the ability to be flexible and adaptable during LDLT by tailoring the needs of each patient individually.

Venous outflow reconstruction in living donor liver transplantation: Dealing with venous anomalies

The reconstruction of the vascular outflow tract of partial liver grafts has received considerable attention in the past, especially in the setting of right liver grafts with undrained segments. Hepatic venous outflow reconstruction is an important factor for successful living donor liver transplantation outcome. However, in presence of undrained anterior sector and presence of multiple short hepatic veins that drain substantial portions of liver, outflow reconstruction without backtable venoplasty may lead to severe graft congestion and subsequent graft dysfunction. Various backtable venoplasty techniques in presence of multiple hepatic veins that can be used in either right- or left-lobe liver transplantation are devised to ensure a single, wide outflow channel. In this overview, various techniques to overcome the hepatic venous variations of liver allograft and outflow reconstruction are discussed.

Current status and perspectives in split liver transplantation

Growing experience with the liver splitting technique and favorable results equivalent to those of whole liver transplant have led to wider application of split liver transplantation (SLT) for adult and pediatric recipients in the last decade. Conversely, SLT for two adult recipients remains a challenging surgical procedure and outcomes have yet to improve. Differences in organ shortages together with religious and ethical issues related to cadaveric organ donation have had an impact on the worldwide distribution of SLT. Despite technical refinements and a better understanding of the complex liver anatomy, SLT remains a technically and logistically demanding surgical procedure. This article reviews the surgical and clinical advances in this field of liver transplantation focusing on the role of SLT and the issues that may lead a further expansion of this complex surgical procedure.

The role of adult living donor liver transplantation and recent advances

Twenty years since the first cases were described, adult living donor liver transplantation (ALDLT) is now considered a valid option to expand the donor pool in view of the ongoing shortage of organs and the high waiting list mortality rate. Despite the rapid evolution and acceptance of this complex process of donation and transplantation in clinical practice, the indications, outcome, ethical considerations and quality and safety aspects continue to evolve based on new data from large cohort studies. This article reviews the surgical and clinical advances in the field of liver transplantation, focusing on technical refinements and discussing the issues that may lead to a further expansion of this complex surgical procedure and the role of ALDLT.

Segment 4 and the left lateral segment regeneration pattern after resection of the middle hepatic vein in a living donor right hepatectomy

BACKGROUND

Inclusion of the middle hepatic vein (MHV) with a right hepatectomy (RH) in live donor liver transplantation improves venous drainage of the anterior sector of the graft. Its long-term effects on donor left liver (LL) regeneration are not well described.

METHODS

Donors who underwent RH with MHV (MHV+, n = 12) were compared with donors who underwent RH with preservation of the MHV (MHV-, n = 24). Peri-operative complications and volume of the entire liver and individual segments were evaluated at 1 year post-donation.

RESULTS

There was a trend towards a higher complication rate in the MHV+ group (41% versus 25%), without reaching statistical significance (P = 0.3). Males, high body mass index (BMI) and a smaller residual liver volume (RLV) were predictors for greater LL regeneration. MHV+ donors had impaired regeneration of segment 4 (S4) at 1 year, and compensatory greater left lateral segment regeneration. The absence of venous drainage of S4 (V4) to left hepatic vein (LHV) was a predictor of impaired S4 regeneration.

CONCLUSIONS

Regeneration of S4 is impaired in MHV+ donors. Caution should be taken when considering MHV removal on donors with dominant S4, especially on those with potential increased demand for liver regeneration, such as males, higher BMI and a smaller RLV.

Preoperative CT evaluation of potential donors in living donor liver transplantation

Living donor liver transplantation is an effective, life sustaining surgical treatment in patients with end-stage liver disease and a successful liver transplant requires a close working relationship between the radiologist and the transplant surgeon. There is extreme variability in hepatic vascular anatomy; therefore, preoperative imaging of potential liver donors is crucial not only in donor selection but also helps the surgeons in planning their surgical approach. In this article, we elaborate important aspects in evaluation of potential liver donors on multi-detector computed tomography (MDCT) and the utility of MDCT in presurgical assessment of the hepatic parenchyma, relevant hepatic vascular anatomy and segmental liver volumes.

Adult right living-donor liver transplantation with special reference to reconstruction of the middle hepatic vein

Two hundred fifty-three consecutive living-donor liver transplant recipients with a right liver graft (RLG) were divided into three groups: an extended right liver graft (ERLG) group (n = 47) in which the middle hepatic vein (MHV) trunk was included in the graft, a modified right liver graft (MRLG) group (n = 114) in which the MHV tributaries were reconstructed with cryopreserved homologous veins and a simple RLG group (n = 92) in which the MHV tributaries were sacrificed. The volume of the anterior sector was significantly impaired in the RLG group compared to the other two groups, whereas the volume of the posterior sector was significantly improved in the RLG group, indicating that the impaired anterior sector regeneration by MHV deprivation was compensated by the posterior sector regeneration. The regeneration rate of the anterior sector was highest in the ERLG group (92%), moderate in the MRLG group (71%) and lowest in the RLG group (52%). The whole graft regeneration rate of the ERLG group was significantly higher than that of the other two groups. Poor regeneration, however, was not correlated with delayed functional recovery or long-term outcome. Short-term, the patency of reconstructed MHV tributaries was over 90%, but occlusion occurred frequently over the long-term, especially in V5.

Reduced hepatic arterial perfusion impairs the recovery from focal hepatic venous outflow obstruction in liver-resected rats

BACKGROUND

Extended partial hepatectomy (PH) in patients is leading to portal hyperperfusion but reduced hepatic arterial perfusion (HAP), and is invariably causing focal hepatic venous outflow obstruction (FHVOO). We observed in a rat model that PH in combination with right median hepatic vein ligation (RMHV-L) caused confluent parenchymal necrosis interspersed with viable portal tracts in the obstructed territory and large sinusoidal vascular canals in the border zone. Lack of HAP impaired the spontaneous course of recovery in terms of enlarged parenchymal necrosis, delayed regeneration, and the absence of draining vascular canals. We aimed to investigate whether pharmacological intervention modulates the imbalance between portal venous and hepatic arterial inflow, aggravates the liver damage, and delays the recovery process after FHVOO in liver-resected rats.

METHODS

Male Lewis rats were subjected to 70% PH and RMHV-L. Molsidomine or NG-nitro-L-arginine methyl ester (L-NAME) or saline were applied daily. Hepatic damage, microcirculation, regeneration, and vascular remodeling were evaluated at postoperative days 1, 2, and 7. Animals subjected to RMHV-L only were used as "no HAP" control.

RESULTS

Significant increase of portal venous inflow with a concomitant decrease in HAP was observed in all groups after PH. Molsidomine treatment did neither affect hepatic hemodynamics nor the spontaneous recovery. In contrast, L-NAME treatment further decreased HAP which impaired hepatic microcirculation, aggravated parenchymal damage, decelerated recovery, and impaired the formation of sinusoidal canals.

CONCLUSIONS

Reduction of HAP through inhibition of nitric oxide production worsened the recovery from FHVOO. Drugs increasing HAP need to be evaluated to reverse the hyperperfusion-induced impairment of the spontaneous course after FHVOO.

Analysis of biliary anatomy according to different classification systems

PURPOSE

Variations in biliary anatomy are common, and different classifications have been described. These classification systems have not been compared to each other in a single cohort. We report such variations in biliary anatomy on magnetic resonance cholangiopancreatography (MRCP) using six different classification systems.

METHODS

In 299 patients undergoing MRCP for various indications, biliary anatomy was classified as described by Couinaud (1957), Huang (1996), Karakas (2008), Choi (2003), Champetier (1994), and Ohkubo (2004). Correlation with direct cholangiography and vascular anatomy was done. Bile duct dimensions were measured. Cystic duct junction and pancreaticobiliary ductal junction (PBDJ) were classified.

RESULTS

Normal biliary anatomy was noted in 57.8 %. The most common variants were Couinaud type D2, Choi type 3A, Huang type A1, Champetier type a, Ohkubo types D and J, and Karakas type 2a. The Ohkubo classification was the most appropriate; 3.1 % of right ducts and 6.3 % of left ducts with variant anatomy could not be classified using the Ohkubo classification. There was a good agreement between MRCP and direct cholangiography (ĸ = 0.9). Anomalous PBDJ was noted in 8.7 %. Variant biliary anatomy was not associated with gender (p = 0.194) or variant vascular anatomy (p = 0.24).

CONCLUSION

Although each classification system has its merits and demerits, some anatomical variations cannot be classified using any of the previously described classifications. The Ohkubo classification system is the most applicable as it considers most clinically relevant variations pertinent to hepatobiliary surgery.

Venous Outflow Reconstruction in Adult Living Donor Liver Transplant: Outcome of a Policy for Right Lobe Grafts without the Middle Hepatic Vein

Introduction. The difficulty and challenge of recovering a right lobe graft without MHV drainage is reconstructing the outflow tract of the hepatic veins. With the inclusion or the reconstruction of the MHV, early graft function is satisfactory. The inclusion of the MHV or not in the donor's right lobectomy should be based on sound criteria to provide adequate functional liver mass for recipient, while keeping risk to donor to the minimum. Objective. Reviewing the results of a policy for right lobe grafts transplant without MHV and analyzing methods of venous reconstruction related to outcome. Materials and Methods. We have two groups Group A (with more than one HV anast.) (n = 16) and Group B (single HV anast.) (n = 24). Both groups were compared regarding indications for reconstruction, complications, and operative details and outcomes, besides describing different modalities used for venous reconstruction. Results. Significant increase in operative details time in Group A. When comparison came to complications and outcomes in terms of laboratory findings and overall hospital stay, there were no significant differences. Three-month and one-year survival were better in Group A. Conclusion. Adult LDLT is safely achieved with better outcome to recipients and donors by recovering the right lobe without MHV, provided that significant MHV tributaries (segments V, VIII more than 5 mm) are reconstructed, and any accessory considerable inferior right hepatic veins (IRHVs) or superficial RHVs are anastomosed.

Importance of conserving middle hepatic vein distal branches for homogeneous regeneration of the left liver after right hepatectomy

BACKGROUND

Liver regeneration enables repeat surgical procedures to achieve a potential cure in liver cancer patients. However, data regarding segmental regeneration and liver anatomy after liver resection are scarce. This study examined left liver regeneration after right hepatectomy and the impact of hepatic venous drainage on the regeneration of the paramedian sector (Couinaud's segment IV).

METHODS

Twenty patients in whom right hepatectomy with conservation of the middle hepatic vein (MHV) on healthy liver had been performed were analysed for segmental volumes and vascular anatomy. Volumetric analysis of left liver segments and three-dimensional MHV reconstruction were conducted using pre- and postoperative computed tomography. The volumetric proportions represented by each segment within the left liver were compared and MHV anatomy was analysed to determine its potential role in the regeneration of left liver segments.

RESULTS

After right hepatectomy, the proportion represented by segment IV within the left liver decreases by 13%, whereas the proportion represented by segments II and III increases by 15%. This heterogeneous regeneration is particularly observed in patients in whom a venous branch for segment IVb is sacrificed, leading to an altered outflow similar to that observed in MHV deprivation. The risk for venous branch deprivation in IVb is correlated to the depth of the bifurcation of the MHV in liver parenchyma.

CONCLUSIONS

It is crucial to conserve the MHV in its distal part if homogeneous left liver regeneration after right hepatectomy that will allow potential repeat liver resection is to be achieved.

Hepatic veins anatomy and piggy-back liver transplantation

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: type I (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.

Clinical anatomy related to the hepatic veins for right lobe living donor liver transplantation

The complexity of liver reconstruction has limited partial right lobe living donor liver transplantation. It is largely due to the difficulty of dealing with the middle hepatic vein. We sought to define the anatomic features of hepatic veins. Forty-one fresh adult livers, 43 formalin-fixed adult cadaver livers, and 91 adult liver corrosion casts were used for the study. We determined the number of branches, the maximum diameter, the whole length, the extrahepatic length of the hepatic veins, and the deviation of the middle hepatic vein from the main portal fissure. Nakamura and Tsuzuki's classification of hepatic vein types was used. Type A, B, and C accounted for 59.4, 27.8, and 12.8% of all specimens in this study, respectively. The middle and left hepatic veins formed a common trunk in 60.3% of the specimens, and the length of the common trunk was 1.12 ± 0.62 cm. The degree of deviation to the right of the middle hepatic vein from the main portal fissure was 14.11° ± 12.65°. The frequency of hepatic vein types and the degree of deviation to the right of the middle hepatic vein in this study is markedly different from that reported in other literature. The anatomic features of the hepatic veins in this study suggest that right lobe living donor liver transplantation is more suitable for Chinese.

Hepatic arterial perfusion is essential for the spontaneous recovery from focal hepatic venous outflow obstruction in rats

We previously observed that focal hepatic venous outflow obstruction recovered spontaneously by the formation of sinusoidal canals in a rat model of portal hyperperfusion. We aimed to investigate whether the lack of hepatic arterial perfusion aggravates parenchymal damage, decelerates recovery and influences the formation of sinusoidal canals after focal hepatic venous outflow obstruction. Rats were subjected to arterialized versus nonarterialized syngeneic liver transplantation after ligating the right median hepatic vein in the donor. Hepatic damage, microcirculation, regeneration and vascular remodeling were evaluated. In arterialized-recipients, confluent necrosis interspersed with viable periportal islands of hepatocytes, and vascularized sinusoidal canals with visible blood flow, surrounded by normal sinusoidal structure, were visible on postoperative day (POD) 2. Complete parenchymal recovery was consequently established by resorption of necrosis and hepatocyte proliferation, detected in viable portal islands and border zone. Lack of hepatic arterial perfusion caused complete necrosis in the obstruction zone without viable hepatocytes in the periportal area on POD2. Hepatocyte proliferation was only visible in the border zone. On POD28, perfused vascular structures, without neighboring normal sinusoidal structures, were observed in the scar-like area. Hepatic arterial perfusion determined the extent of hepatic necrosis, the formation of vascularized sinusoidal canals and the parenchymal recovery, after focal hepatic venous outflow obstruction.

Morphometric analysis of conformational changes in hepatic venous system after right lobe living donor liver transplantation

AIM

  After living donor liver transplantation (LDLT), the graft liver regenerates to the standard liver volume. However, little is known about the influence of this phenomenon on the hepatic venous system.

METHODS

  Fourteen right lobe LDLT without the middle hepatic vein were included in this study. Computed tomography before and 1 month after LDLT was performed to measure the inflow angle of the right hepatic vein (RHV), the aspect ratio of the inferior vena cava (IVC), the coordinate position of IVC and diameter of RHV. In addition, the regeneration index (RI) was determined on each liver segment.

RESULTS

  RHV showed a clockwise rotation at early postoperative months, the average increase of the inflow angle being 14.5 ± 15.6 (mean ± standard deviation) degrees. IVC was shifted from right to left with a deformity to a long oval shape on horizontal sections. The center of IVC moved dorsally at an average of 0.55 ± 0.77 cm and leftward at an average of 0.82 ± 0.89 cm. Diameter of RHV decreased at an average of 0.65 ± 0.39 cm at its root. The extent of liver regeneration was more prominent in the posterior segment as compared to the anterior segment, the average RI values being 1.65 ± 0.65 and 1.17 ± 0.44, respectively (P < 0.05). Hepatic vein outflow block (HVOB) was encountered in two patients with a marked conformational deformity observed in the hepatic venous system at early postoperative months after LDLT.

CONCLUSION

  After right lobe LDLT, the hepatic venous system exhibits a profound conformational change, which most likely plays a role in the onset of HVOB.

Preoperative estimation of the liver graft weight in adult right lobe living donor liver transplantation using maximal portal vein diameters

An accurate preoperative estimate of the graft weight is vital to avoid small-for-size syndrome in the recipient and ensure donor safety after adult living donor liver transplantation (LDLT). Here we describe a simple method for estimating the graft volume (GV) that uses the maximal right portal vein diameter (RPVD) and the maximal left portal vein diameter (LPVD). Between June 2004 and December 2009, 175 consecutive donors undergoing right hepatectomy for LDLT were retrospectively reviewed. The GV was determined with 3 estimation methods: (1) the radiological graft volume (RGV) estimated by computed tomography (CT) volumetry; (2) the computed tomography-calculated graft volume (CGV-CT), which was obtained by the multiplication of the standard liver volume (SLV) by the RGV percentage with respect to the total liver volume derived from CT; and (3) the portal vein diameter ratio-calculated graft volume (CGV-PVDR), which was obtained by the multiplication of the SLV by the portal vein diameter ratio [PVDR; ie, PVDR = RPVD(2) /(RPVD(2) + LPVD(2) )]. These values were compared to the actual graft weight (AGW), which was measured intraoperatively. The mean AGW was 633.63 ± 107.51 g, whereas the mean RGV, CGV-CT, and CGV-PVDR values were 747.83 ± 138.59, 698.21 ± 94.81, and 685.20 ± 90.88 cm(3) , respectively. All 3 estimation methods tended to overestimate the AGW (P < 0.001). The actual graft-to-recipient body weight ratio (GRWR) was 1.00% ± 0.19%, and the GRWRs calculated on the basis of the RGV, CGV-CT, and CGV-PVDR values were 1.19% ± 0.25%, 1.11% ± 0.22%, and 1.09% ± 0.21%, respectively. Overall, the CGV-PVDR values better correlated with the AGW and GRWR values according to Lin's concordance correlation coefficient and the Landis and Kock benchmark. In conclusion, the PVDR method is a simple estimation method that accurately predicts GVs and GRWRs in adult LDLT.

Portal inflow and pressure changes in right liver living donor liver transplantation including the middle hepatic vein

The middle hepatic vein may be included in right liver living donor liver transplantation (LDLT) to optimize hepatic venous outflow. We studied the graft's ability to relieve portal hypertension and accommodate portal hyperperfusion with portal manometry and ultrasonic flowmetry. Surgical outcomes with respect to portal hemodynamometry were also investigated. The ages of the recipients and donors for 46 consecutive LDLT procedures were 50 (range, 16-66 years) and 31 years (range, 18-54 years), respectively. The graft to standard liver volume ratio was 47.4% (range, 32.4%-69.0%). The hospital mortality rate was 4.4% as 2 recipients died from a subarachnoid hemorrhage and sepsis. The portal pressure dropped by 8 mm Hg (range, -7 to 19 mm Hg) from 23 (range, 8-37 mm Hg) to 14 mm Hg (range, 10-26 mm Hg) after graft implantation. The portal inflow positively correlated with the portal pressure before native liver hepatectomy (R(2) = 0.305, P = 0.001) and not with the graft size. The portal inflow increased from 81 mL/minute/100 g (range, 35-210 mL/minute/100 g) before donor right hepatectomy to 318 mL/minute/100 g (range, 102-754 mL/minute/100 g) after graft implantation. The graft portal inflow had a positive linear correlation with the recipient portal pressure before native liver total hepatectomy (R(2) = 0.261, P = 0.001) but not after graft implantation, and it had a negative correlation with the graft to standard liver volume ratio (R(2) = 0.247, P = 0.001). Only 1 of the graft biopsies showed moderate sinusoidal congestion. Twelve recipients had Clavien grade 2+ complications that were not related to the portal inflow and pressure or graft size. Right liver LDLT including the middle hepatic vein effectively lowered the recipient portal pressure by allowing unimpeded venous outflow.

Three-dimensional computed tomography scan analysis of hepatic vasculatures in the donor liver for living donor liver transplantation

Because hepatic vasculatures exhibit variations, a preoperative evaluation of the vascular anatomy and an estimation of the volume of the liver graft are essential for successful adult living donor liver transplantation. Using 3-dimensional (3D) computed tomography (CT), we analyzed the volumetric and anatomical relationship of the hepatic vasculatures of liver grafts. The livers of 223 potential donors were analyzed by 3D CT. Volumetric analysis was performed for each hepatic vein and its tributaries. The anatomy of the portal vein and hepatic artery was assessed along with the biliary system via intraoperative cholangiography in 110 recipients. On the basis of the anatomical presentation of the inferior right hepatic vein (IRHV), the hepatic veins were classified as follows: in type I, the IRHV was absent; in type II, the IRHV was smaller than the right hepatic vein (RHV); and in type III, the IRHV was greater than or equal to the RHV in size. The drainage volume of the middle hepatic vein (MHV) and especially its tributaries in the right lobe increased with the size of the IRHV (P < 0.001). In type III hepatic veins with a large IRHV (17% of the donors), the MHV tributaries had the largest drainage volume in the right lobe (41.2% +/- 11.8%). Furthermore, type III hepatic veins typically exhibited biliary variations in 75% of the donors. No correlation was observed between variations in the hepatic artery and portal vein. In conclusion, a right lobe graft with a large IRHV is accompanied by a large drainage volume via the MHV and by bile duct variations in 17% of livers. Therefore, anatomical and volumetric analysis is important for preoperative evaluations.

Adenosine restores the hepatic artery buffer response and improves survival in a porcine model of small-for-size syndrome

The aim of the study is to define the role of the HABR in the pathophysiology of the SFS liver graft and to demonstrate that restoration of hepatic artery flow (HAF) has a significant impact on outcome and improves survival. Nine pigs received partial liver allografts of 60% liver volume, Group 1; 8 animals received 20% LV grafts, Group 2; 9 animals received 20% LV grafts with adenosine infusion, Group 3. HAF and portal vein flow (PVF) were recorded at 10 min, 60 min and 90 min post reperfusion, on POD 3 and POD 7 in Group 1, and daily in Group 2 and 3 up to POD 14. Baseline HAF and PVF (ml/100 g/min) were 29 +/- 12 (mean +/- SD) and 74 +/- 8 respectively, with 28% of total liver blood flow (TLBF) from the HA and 72% from the PV. PVF peaked at 10 mins in all groups, increasing by a factor of 3.8 in the 20% group compared to an increase of 1.9 in the 60% group. By POD 7-14 PVF rates approached baseline values in all groups. The HABR was intact immediately following reperfusion in all groups with a reciprocal decrease in HAF corresponding to the peak PVF at 10 min. However in the 20% group HAF decreased to 12 +/- 8 ml/100 g/min at 90 min and remained low out to POD 7-14 despite restoration of normal PVF rates. Histopathology confirmed evidence of HA vasospasm and its consequences, cholestasis, centrilobular necrosis and biliary ischemia in Group 2. HA infusion of adenosine significantly improved HAF (p < .0001), reversed pathological changes and significantly improved survival (p = .05). An impaired HABR is important in the pathophysiology of the SFSS. Reversal of the vasospasm significantly improves outcome.

Complications of right lobe living donor liver transplantation

BACKGROUND/AIMS

Right lobar living donor liver transplantation (LDLT) has been controversial because of donor deaths and widely variable reports of recipient and donor morbidity. Our aims were to ensure full disclosure to donors and recipients of the risks and benefits of this procedure in a large University center and to help explain reporting inconsistencies.

METHODS

The Clavien 5-tier grading system was applied retrospectively in 121 consecutive adult right lobe recipients and their donors. The incidence was determined of potentially (Grade III), actually (Grade IV), or ultimately fatal (Grade V) complications during the first post-transplant year. When patients had more than one complication, only the seminal one was counted, or the most serious one if complications occurred contemporaneously.

RESULTS

One year recipient/graft survival was 91%/84%. Within the year, 80 (66%) of the 121 recipients had Grade III (n=54) Grade IV (n=16), or Grade V (n=10) complications. The complications involved the graft's biliary tract (42% incidence), graft vasculature (15%), or non-graft locations (9%). Complications during the first year did not decline with increased team experience, and adversely affected survival out to 5 years. All 121 donors survive. However, 13 donors (10.7%) had Grade III (n=9) or IV (n=4) complications of which five were graft-related.

CONCLUSIONS

Despite the satisfactory recipient and graft survival at our and selected other institutions, and although we have not had a donor mortality to date, the role of right lobar LDLT is not clear because of the recipient morbidity and risk to the donors.

Liver transplantation

Liver transplantation has become a lifesaving procedure for patients who have chronic end-stage liver disease and acute liver failure. The satisfactory outcome of liver transplantation has led to insufficient supplies of deceased donor organs, particularly in East Asia. Hence, East Asian surgeons are concentrating on developing and performing living-donor liver transplantation (LDLT). This review article describes an update on the present status of liver transplantation, mainly in adults, and highlights some recent developments on indications for transplantation, patient selection, donor and recipient operation between LDLT and deceased-donor liver transplantation (DDLT), immunosuppression, and long-term management of liver transplant recipients. Currently, the same indication criteria that exist for DDLT are applied to LDLT, with technical refinements for LDLT. In highly experienced centers, LDLT for high-scoring (>30 points) Model of End-Stage Liver Disease (MELD) patients and acute-on-chronic liver-failure patients yields comparably good outcomes to DDLT, because timely liver transplantation with good-quality grafting is possible. With increasing numbers of liver transplantations and long-term survivors, specialized attention should be paid to complications that develop in the long term, such as chronic renal failure, hypertension, diabetes mellitus, dyslipidemia, obesity, bone or neurological complications, and development of de novo tumors, which are highly related to the immunosuppressive treatment.

[Controversies in living donor liver transplants]

Adult liver transplants from a living donor are a valid and effective alternative as a treatment in terminal liver disease. However, in the context of a donation from a brain dead donor, as in western countries (Spain), it is very high, and there are still controversial aspects that should be continuously assessed in order to ensure good results. Live donations are currently stable and represent about 5% of the total liver transplants performed in Europe. Morbidity and mortality is around 35% and 0.1%, respectively, probably reasonable figures given the characteristics of the intervention. The 1 and 5 year survival rates of the recipients of a living donor are currently 95% and 75%, which are similar to those coming from brain dead donors. However the level of biliary complications in this patient group is higher, with an incidence of around 35-40%. However, this incidence has not had any effect on the long-term results up until now.

Seeking beyond rejection: an update on the differential diagnosis and a practical approach to liver allograft biopsy interpretation

Pathologic evaluation of liver allograft biopsies plays an integral role in the management of patients after liver transplantation. This review summarizes the clinical context and classical histology of different types of allograft rejection and also the common entities that enter the differential diagnosis of allograft rejection, and provides practical approaches to liver allograft biopsy interpretation. In addition, some of the new developments in the field of liver transplant pathology are updated. The purpose of this review is to provide guidance for pathologists interpreting liver allograft biopsies, particularly those interested in developing expertise in the field of liver transplant pathology.

Accuracy of an age-adjusted formula in assessing the graft volume in living donor liver transplantation

In living donor liver transplantation, the estimated graft volume (GV) from young donors tends to be overestimated. One reason for this error may be a decrease in GV due to dehydration by University of Wisconsin (UW) solution. The aim of this study was to clarify (1) the usefulness of an age-adjusted formula and (2) the correlation between the decrease in GV and donor age. First, we created the age-adjusted formula using regression analysis retrospectively in 167 donors, and we evaluated the difference in the error ratio of GV from the age-adjusted formula and 3-dimensional computed tomography (3D-CT) prospectively in 49 donors. Second, we measured intraoperative GV both before and after flushing with UW solution and calculated the decrease ratio, and we then evaluated the difference in the decrease ratio between young donors and older donors prospectively in 41 donors. The age-adjusted formula was created as follows: age-adjusted GV = 70.767 + (0.703 x GV estimated with 3D-CT volumetry) + (1.298 x donor age). The mean error ratio for the age-adjusted formula (9.6%) was significantly lower than that from 3D-CT (14.0%). The mean decrease ratio in all 41 donors was 5.4%, and that in young donors (6.9%) was significantly higher than that in older donors (4.4%). In conclusion, although younger donor age is a major factor for estimation errors in hepatic volumetry, our age-adjusted formula is very useful in reducing the error in estimating GV.

Should we still offer split-liver transplantation for two adult recipients? A retrospective study of our experience

The role of split-liver transplantation (SLT) for two adult recipients is still a matter of debate, and no agreement exists on indications, surgical techniques, and results. The aim of this study was to retrospectively analyze the outcome of our series of SLT. From May 1999 to December 2006, 16 patients underwent SLT at our unit. We used 9 full right grafts (segments 5-8) and 7 full left grafts (segments 1-4). The splitting procedure was always carried out in situ with a fully perfused liver. Postoperative complications were recorded in 8 (50%) patients: 5 (55%) in full right grafts and 3 (43%) in full left grafts. No one was retransplanted. After a median follow-up of 55.82 months (range, 0.4-91.2), 5 (31%) patients died, and the 1-, 3-, and 5-year overall survival rate for patients and grafts was 69%. We considered as a control group for the global outcome 232 whole liver transplantations performed at our unit in the same period of time. Postoperative complications were recorded in 53 (23%) patients, and after a median follow-up of 57.37 months (mean, 55.11; range, 1-102.83), the 1-, 3-, and 5-year overall patient survival was 87%, 82%, and 80%, respectively. In conclusion, SLT for two adult recipients is a technically demanding procedure that requires complex logistics and surgical teams experienced in both liver resection and transplantation. Although the reported rate of survival might be adequate for such a procedure, more efforts have to be made to improve the short-term outcome, which is inadequate in our opinion. The true feasibility of SLT for two adults has to be considered as still under investigation.

Successful treatment of small-for-size syndrome in adult-to-adult living-related liver transplantation: single center series

The portal hyperperfusion, or small-for-size syndrome (SFSS), is a widely recognized clinical complication that may occur after segmental liver transplantation. Several surgical strategies have been proposed to reduce portal blood inflow and portal pressure after partial liver transplantation. In particular, splenic artery ligation and splenectomy have been used without a firm hemodynamic basis for these procedures. Our group recently demonstrated that, in patients with cirrhosis and portal hypertension, the occlusion of the splenic artery causes a significant reduction in the portal pressure gradient, which is directly related to the spleen volume and indirectly related to the liver volume. This concept is at the center of our strategy for performing early splenic artery embolization (SAE) for the treatment of SFSS after living-related liver transplantation (LRLT). Six patients developed small-for-size syndrome, defined as: onset within the first week after LRLT of progressive hyperbilirubinemia without mechanical cause; marked cholestasis; centrilobular sinusoidal dilatation and hepatocyte atrophy at liver biopsy; and refractory ascites in the absence of vascular complications. All six patients who underwent SAE rapidly improved their clinical condition, with an evident decrease in the value of bilirubin in the serum, in the production of ascites, and improvement in condition of pancytopenia. Coagulopathy expressed by the international normalized ratio value (INR) was not a reliable early marker of SFSS in this series; in fact a slight improvement in the result of this test was already present immediately after LRLT and before SAE. Because splenic flow clearly contributes to portal hyperperfusion, an early SAE can relieve the partial graft from the deleterious effect of this portal overflow.

Hepatic venous outflow reconstruction in right lobe graft without middle hepatic vein

BACKGROUND

We explored the pattern of hepatic venous outflow reconstruction in adult right lobe (segments V5-8) living donor liver transplantation (LDLT) without the middle hepatic vein (MHV). The difficulty and challenge of LDLT without MHV is the outflow reconstruction of hepatic vein. We have modified the surgical procedure and here report the results.

METHODS

Retrospective analysis was made of the clinical data of 50 recipients who underwent LDLT using right lobe without MHV.

RESULTS

Forty-five recipients (90.0%, 45/50) are alive at median follow up of 10 months. The graft-to-recipient bodyweight ratio (GRWR) was 1.21% +/- 0.49% (range, 0.72% to 1.98%). The recipients of GRWR <0.8% (extra-small graft), 0.8% < GRWR < 1.2% (small graft) and GRWR > 1.2% (ideal graft) were 14, 27 and 9, respectively. Total ratio venous outflowreconstruction of V5, V8 and inferior right hepatic vein was 66.0% (33/50). The overall incidence of small-for-size syndrome was 10.0% (n = 5), the overall graft survival rate was 92.0% (46/50).

CONCLUSIONS

Graft function and survival rates are not only influenced by graft size, but also by hepatic venous outflow reconstruction; the 'multiple-opening vertical anastomosis' for reconstruction of hepatic vein outflow was used when the GRWR was smaller than 1.2%. This technique alleviates surgical risk in living donors, ensures excellent venous drainage, and reduces the incidence of small-for-size syndrome.

Live donor liver transplantation in adults

Live donor liver transplantation (LDLT) was initiated in 1988 for children recipients. Its application to adult recipients was limited by graft size until the first right liver LDLT was performed in Hong Kong in 1996. Since then, right liver graft has become the major graft type. Despite rapid adoption of LDLT by many centers, many controversies on donor selection, indications, techniques, and ethics exist. With the recent known 11 donor deaths around the world, transplant surgeons are even more cautious than the past in the evaluation and selection of donors. The need for routine liver biopsy in donor evaluation is arguable but more and more centers opt for a policy of liberal liver biopsy. Donation of the middle hepatic vein (MHV) in the right liver graft was considered unsafe but now data indicate that the outcome of donors with or without MHV donation is about equal. Right liver LDLT has been shown to improve the overall survival rate of patients with chronic liver disease, acute or acute-on-chronic liver failure and hepatocellular carcinoma waiting for liver transplantation. The outcome of LDLT is equivalent to deceased donor liver transplantation despite a smaller graft size and higher technical complexity.

Surgical techniques and long-term outcomes of living donor liver transplantation for Budd-Chiari syndrome

We have developed the surgical techniques of living donor liver transplantation (LDLT) for Budd-Chiari syndrome (BCS) and evaluated long-term outcomes including specific complications. BCS is characterized by hepatic outflow obstruction. Liver transplantation from living donors poses a unique challenge as liver replacement therapy does not replace the retrohepatic segment of inferior vena cava (IVC). We have performed 1105 LDLTs in 1055 patients from January 1990 to March 2005. Of these, nine patients (eight males and one female) underwent LDLT for BCS. Five out of nine patients underwent LDLT as a primary procedure and four patients had received other treatments before transplantation. Eight patients presented with chronic and one with fulminant liver failure. Predisposing factors were identified in three patients. IVC reconstruction without patch plasty was performed on four patients. Five patients needed cavoplasty using a replacement vein graft. Of the nine patients, seven are alive at a median follow-up of 58 months (range 1 month to 15.2 years) with two patients developing recurrent hepatic vein stenosis which were treated successfully with metallic stent placement. Two patients died: one from multiorgan failure and the other from pulmonary embolism secondary to disease recurrence. LDLT for BCS is highly effective by using modified cavoplasty and provides good long-term survival which may be obtained by life-long anticoagulant treatment and nonsurgical interventions.

Pathophysiologic observations and histopathologic recognition of the portal hyperperfusion or small-for-size syndrome

In an attempt to more completely define the histopathologic features of the portal vein hyperperfusion or small-for-size syndrome (PHP/SFSS), we strictly identified 5 PHP/SFSS cases among 39 (5/39; 13%) adult living donor liver transplants (ALDLT) completed between 11/01 and 09/03. Living donor segments consisting of 3 right lobes, 1 left lobe, and 1 left lateral segment, with a mean allograft-to-recipient weight ratio (GRWR) of 1.0 +/- 0.3 (range 0.6 to 1.4), were transplanted without complications, initially, into 6 relatively healthy 25 to 63-year-old recipients. However, all recipients developed otherwise unexplained jaundice, coagulopathy, and ascites within 5 days after transplantation. Examination of sequential posttransplant biopsies and 3 failed allografts with clinicopathologic correlation was used in an attempt to reconstruct the sequence of events. Early findings included: (1) portal hyperperfusion resulting in portal vein and periportal sinusoidal endothelial denudation and focal hemorrhage into the portal tract connective tissue, which dissected into the periportal hepatic parenchyma when severe; and (2) poor hepatic arterial flow and vasospasm, which in severe cases, led to functional dearterialization, ischemic cholangitis, and parenchymal infarcts. Late sequelae in grafts surviving the initial events included small portal vein branch thrombosis with occasional luminal obliteration or recanalization, nodular regenerative hyperplasia, and biliary strictures. These findings suggest that portal hyperperfusion, venous pathology, and the arterial buffer response importantly contribute to early and late clinical and histopathologic manifestations of the small-for-size syndrome.

Adult-to-adult live-donor liver transplantation: the current status

Adult-to-adult live-donor liver transplantation (ALDLT) has emerged successfully to partially relieve the refractory shortage of deceased donor grafts caused by the increasing demands of patients with endstage liver diseases. Following the first successful live-donor liver transplantation (LDLT) for a child with biliary atresia in 1989, further extension of the technique, using left-lobe liver grafts for LDLT for large adolescents and adults, has resulted in satisfactory graft and patient survival outcomes. However, small-for-size syndrome may occur in some patients with large body size, and in those with acute-on-chronic liver failure or severe portal hypertension. To overcome the problem of graft-to-body-size mismatch, ALDLT, using a right-lobe liver graft was developed. Although routine inclusion of the middle hepatic vein (MHV) in the right-lobe liver graft is still controversial, the importance of providing good venous drainage for the right anterior sector to ensure better early graft function has gained wide recognition. Preservation of the MHV in the donor is intuitively considered important in reducing the donor risk. However, there are scarce data supporting the contention that postoperative complication is related to the absence of the MHV in the left-liver remnant. Duct-to-duct biliary reconstruction has potential advantages over hepaticojejunostomy, and has become the preferred technique in ALDLT. However, biliary complications, especially biliary strictures on long-term follow-up, occur in about 30% of the recipients. The potential beneficial effect of internal or external biliary drainage in reducing the biliary complication rate after duct-to-duct biliary reconstruction in ALDLT also remains controversial. Dual-liver grafts and right-posterior sector grafts have been used in ALDLT, and are reported to result in satisfactory survival outcomes at selected transplant centers. There is no strong evidence supporting the postulate that patients with hepatitis C infection have an inferior survival outcome after ALDLT when compared with recipients of a deceased-donor liver transplant. ALDLT has contributed to satisfactory survival outcomes in patients with hepatocellular carcinoma (HCC). It allows early surgery for the patients and eliminates the uncertainty of prolonged waiting for a deceased-donor liver graft, and the risks of dropout related to disease progression. The exact selection criteria of patients with HCC for ALDLT have yet to be defined.