Small graft for living donor liver transplantation

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.

Partial liver transplantation

Partial liver transplantation, including reducedsize liver transplantation, split liver transplantation, and living donor liver transplantation, has been developed with several innovative techniques because of donor shortage. Reduced-size liver transplantation is based on Couinaud's anatomical classification, benefiting children and small adult recipients but failing to relieve the overall donor shortage. Split liver transplantation provides chances to two or even more recipients when only one liver graft is available. The splitting technique must follow stricter anatomical and physiological criteria either ex situ or in situ to ensure long-term quality. The first and most important issue involving living donor liver transplantation is donor safety. Before surgery, a series of donor evaluations-including anatomical, liver volume, and liver function evaluations-is indispensable, followed by ethnic agreement. At different recipient conditions, auxiliary liver transplantation and auxiliary partial orthotopic liver transplantation, which employ piggyback techniques, are good alternatives. Partial liver transplantation enriches the practice and knowledge of the transplant society.

Partial hepatectomy in mice: current status of research and implications for clinical practice

The classic model of partial hepatectomy was first established in the 1930s and played a key role in the research of liver regeneration and liver disease in mammals. Rats and mice are the most commonly used animals for research, but surgery is usually performed in rats. Considering many differences between rats and mice, this paper aims to summarize the crucial points in the surgical procedure for mice and the principles and methods of partial hepatectomy.

Small for size syndrome following living donor and split liver transplantation

The field of liver transplantation is limited by the availability of donor organs. The use of living donor and split cadaveric grafts is one potential method of expanding the donor pool. However, primary graft dysfunction can result from the use of partial livers despite the absence of other causes such as vascular obstruction or sepsis. This increasingly recognised phenomenon is termed “Small-for-size syndrome” (SFSS). Studies in animal models and humans have suggested portal hyperperfusion of the graft combined with poor venous outflow and reduced arterial flow might cause sinusoidal congestion and endothelial dysfunction. Graft related factors such as graft to recipient body weight ratio < 0.8, impaired venous outflow, steatosis > 30% and prolonged warm/cold ischemia time are positively predictive of SFSS. Donor related factors include deranged liver function tests and prolonged intensive care unit stay greater than five days. Child-Pugh grade C recipients are at relatively greater risk of developing SFSS. Surgical approaches to prevent SFSS fall into two categories: those targeting portal hyperperfusion by reducing inflow to the graft, including splenic artery modulation and portacaval shunts; and those aiming to relieve parenchymal congestion. This review aims to examine the controversial diagnosis of SFSS, including current strategies to predict and prevent its occurrence. We will also consider whether such interventions could jeopardize the graft by compromising regeneration.

Standard formula for liver volume in Middle Eastern Arabic adults

OBJECTIVES

To determine a formula for estimating the standard liver volume (SLV) in Middle Eastern Arabic adults and to compare it with the 12 standard liver volume (SLV) formulas reported for eastern and western populations.

METHODS

Liver volume measured using computed tomography (CTLV) was determined in 351 Saudi Arabian adults older than 16 years without liver or body build abnormality. This measurement was correlated with body indices including age, sex, height, weight, body mass index, and body surface area to derive a new formula using multiple-step linear regression analysis. The CTLV was compared with the 12 SLV formulas using the t test, with error % as (SLV - CTLV)/CTLV × 100.

RESULTS

Body weight was the only significant factor that correlated with CTLV, that is, 12.26 × body weight (kg) + 555.65 (R(2) = .37; P = .000). Only the Vauthey formula (1267.28 × body surface area (m(2)) - 794.41) yielded an estimation of SLV that did not differ significantly from CTLV (P = .26), and had the least mean % error of +1% (underestimation by 15.7 mL) and the closest agreement, that is, 62.4% demonstrated less than ±16% error). Other formulas also yielded acceptable agreement with mean % error less than 12%, although the differences from actual measurements were statistically significant. The Chengdu and Chouker formulas were the exceptions, with more than 16% underestimation or overestimation.

CONCLUSIONS

Either the formulas derived in the present study and the Vauthey formula could be used to estimate SLV in Middle East Arabic adults. However, the moderate coefficient of determination (R(2) = .37) suggested wide interindividual variation. Caution must be exercised when using these formulas in preoperative planning.

Impact of splenectomy in patients with liver cirrhosis: Results from 18 patients in a single center experience

AIM

  With the recent advances in medical or surgical treatments in chronic hepatic disorders, the indications for splenectomy in hepatic disorders have greatly expanded. We performed splenectomy for cirrhotic patients and investigated the effects of splenectomy on hepatic functional reserve and nutrition metabolism.

METHODS

  Eighteen patients (Child-Pugh B/C: 12/6; Child-Pugh A: excluded) who underwent splenectomy at our institute between 2005 and 2008 were enrolled. Twelve patients (67%) had hepatocellular carcinoma (HCC), eight of whom met the Milan criteria.

RESULTS

  Overall survival rate was 83.3% at 1 year and 62.7% at 2 years. The survival rate of six patients with liver cirrhosis classified a Child-Pugh C was 80.0% at 1 year and 60.0% at 2 years. Three patients underwent hepatic resection and nine patients received ablation therapy against hepatocelluar carcinoma. Portal pressure decreased after splenectomy in most patients (mean decrease, 4.7 mmHg). Four weeks after the operation, the markers of hepatic functional reserve, indocyanine green retention rate at 15 min (ICGR15) and Technetium-99m-galactosyl human serum albumin value ((99m)Tc-GSA), improved from 38.5% to 35.1% and from 0.773 to 0.788 (LHL15), respectively. The non-protein respiratory quotient (npRQ) did not change in short period after the operation. Other outcomes, including liver function test in cirrhotic patients with long-term (1 year) follow-up after splenectomy (n = 7), did not improve significantly. Post-operative complications included portal thrombus (n = 2), ascites (n = 2) were observed in six patients (33%).

CONCLUSION

  Splenectomy improved hepatic functional reserve and nutritional metabolism in some cases. However, the long-term outcomes should still be evaluated.

Comparative proteome profile during the early period of small-for-size liver transplantation in rats revealed the protective role of Prdx5

BACKGROUND & AIMS

In living-donor liver transplantation (LDLT), "small-for-size graft (SFSG) syndrome" is a complex process resulting primarily from ischemia-reperfusion injury (IRI) and portal hypertension associated with size mismatch between graft and recipient. In the early period of LDLT, molecular events related to subsequent apoptosis, necrosis, proliferation and regeneration appeared in specific protein expression patterns.

METHODS

We used 2D-PAGE and MALDI-TOF/TOF technology to construct a comparative proteome profile for small-for-size liver grafts (SFSGs) during the early period of LDLT in rats (ischemia 1h, and 2, 6, 24, 48 h post-reperfusion); sham-operated liver was the control. Western blotting was used to confirm the proteomics results and immunohistochemistry was carried out to explore the cellular localization of selected proteins. We further performed cluster and bioinformatics analyses of differential proteins. Lastly, we overexpressed Prdx5 in liver grafts using an adenoviral vector to evaluate its protective role.

RESULTS

We identified 314 differential protein spots corresponding to 259 different proteins. Cluster analyses revealed six expression patterns, and bioinformatics analyses revealed that each pattern was related to many specific cell processes. We also showed that Prdx5 overexpression could attenuate injury to SFSGs and increase survival in recipients.

CONCLUSIONS

Taken together, these results reveal an important proteome profile that is functional in SFSGs during early period of LDLT, and provide a strong basis for further research.

Estimation of standard liver volume in Chinese adult living donors

AIM

To determine a formula predicting the standard liver volume based on body surface area (BSA) or body weight in Chinese adults.

MATERIALS AND METHODS

A total of 115 consecutive right-lobe living donors not including the middle hepatic vein underwent right hemi-hepatectomy. No organs were used from prisoners, and no subjects were prisoners. Donor anthropometric data including age, gender, body weight, and body height were recorded prospectively. The weights and volumes of the right lobe liver grafts were measured at the back table. Liver weights and volumes were calculated from the right lobe graft weight and volume obtained at the back table, divided by the proportion of the right lobe on computed tomography. By simple linear regression analysis and stepwise multiple linear regression analysis, we correlated calculated liver volume and body height, body weight, or body surface area.

RESULTS

The subjects had a mean age of 35.97 +/- 9.6 years, and a female-to-male ratio of 60:55. The mean volume of the right lobe was 727.47 +/- 136.17 mL, occupying 55.59% +/- 6.70% of the whole liver by computed tomography. The volume of the right lobe was 581.73 +/- 96.137 mL, and the estimated liver volume was 1053.08 +/- 167.56 mL. Females of the same body weight showed a slightly lower liver weight. By simple linear regression analysis and stepwise multiple linear regression analysis, a formula was derived based on body weight. All formulae except the Hong Kong formula overestimated liver volume compared to this formula.

CONCLUSIONS

The formula of standard liver volume, SLV (mL) = 11.508 x body weight (kg) + 334.024, may be applied to estimate liver volumes in Chinese adults.

Alleviating the burden of small-for-size graft in right liver living donor liver transplantation through accumulation of experience

The issue of small-for-size graft (SFSG) containing the middle hepatic vein in right liver living donor liver transplantation from 1996 to 2008 (n = 320) was studied. Characteristics of donors, grafts and recipients were comparable between Era I (first 50 cases) and Era II (next 270 cases) except that the median model for end-stage liver disease (MELD) score was higher in Era I (29 vs. 24; p = 0.024). The median graft to standard liver volume ratio (G/SLV) in Era I was 49.0% (range, 32.8-86.2%), versus 49.3% (range, 28.4-89.4%) in Era II (p = 0.498). Hospital mortality rate, the study endpoint, dropped from 16.0% (8/50) in Era I to 2.2% (6/270) in Era II (p = 0.000). Univariate analysis showed that MELD score (p = 0.002), pretransplant hepatorenal syndrome (p = 0.000) and Era I (p = 0.000) were significant in hospital mortality. Logistic regression analysis showed that only Era I (relative risk 9.758; 95% confidence interval, 2.885-33.002; p = 0.000) was significant. In Era I, G/SLV<40% had a relative risk of 7.8 (95% confidence interval, 1.225-49.677; p = 0.030). The hospital mortality rates for G/SLV<40% were 50% (3/6) and 1.9% (1/52) in Era I and II respectively. In conclusion, through accumulation of experience, SFSG became less important as a factor in hospital mortality.

Dual living donor liver transplantation with ABO-incompatible and ABO-compatible grafts to overcome small-for-size graft and ABO blood group barrier

ABO blood group compatibility has been regarded as an essential prerequisite for successful adult living donor liver transplantation (LDLT). Novel strategies for overcoming the ABO blood group barrier, however, have markedly improved the results of ABO-incompatible (ABOi) LDLT. We describe our strategies for dual graft LDLT to cope with ABO-incompatibility and small-for-size graft syndrome in 3 patients who underwent dual graft LDLT with ABOi and ABO-compatible (ABOc) grafts. One patient received a modified right lobe graft from an ABOi living donor and a left lateral section graft from an ABOc deceased donor, whereas the other 2 patients received 2 left lobe or left lateral section grafts from ABOi and ABOc living donors. To overcome the ABO-blood barrier, each patient was treated with preoperative anti-CD20 antibody (rituximab 375 mg/m(2)), perioperative plasma exchange, and hepatic arterial infusion. All 3 patients were males, of mean age 47.7 years (range, 40 approximately 52 years) and mean Model for End-Stage Liver Disease score 12.3 (range, 9 approximately 15). The mean graft-to-recipient weight ratio was 0.99%. All patients remain alive after a mean follow-up period of 9.5 months (range, 8.0 approximately 10.7 months). All 6 grafts have functioned normally. There were no episodes of antibody-mediated rejection or biliary complication. Dual LDLT with ABOi and ABOc grafts can be a feasible solution for simultaneously overcoming both the ABO blood group barrier and small-for-size graft syndrome.

Portal hyperperfusion: mechanism of injury and stimulus for regeneration in porcine small-for-size transplantation

Understanding the pathogenesis of small-for-size (SFS) syndrome is critical to expanding the applicability of partial liver transplantation. We aimed to characterize its acute presentation and association with alterations in hepatic hemodynamics, microstructure, and regeneration in a porcine model. Eighteen SFS liver transplants were performed. Donors underwent 70% hepatectomy. Partial grafts were implanted into larger recipients. Whole liver transplants were also performed (n = 6). Recipients were followed until death or for 5 days. Hemodynamics were measured, and tissue was sampled intraoperatively and at the study end. Serum was sampled regularly during follow-up. Seventeen SFS transplants and 6 whole liver transplants were included. SFS grafts represented 23.2% (19.3%-25.3%) of the recipients' standard liver volume. The survival rate was 29% and 100% in the SFS and whole liver groups, respectively. The portal venous flow, pressure gradient, and resistance were significantly higher in recipients of SFS grafts versus whole livers after portal and arterial reperfusion. Arterial flow as a percentage of the total liver blood flow was significantly lower after reperfusion in SFS grafts and remained so when measured again after 5 days. Markers of endothelial cell injury increased soon after reperfusion, and those of hepatocellular injury increased later; both predicted the appearance of either graft failure or histological recovery. Proliferative activity peaked earlier and higher among nonsurvivors in the SFS group. Surviving grafts demonstrated a slower but maintained rise in regenerative activity, although metabolic activity failed to improve. In SFS transplantation in the acute setting, portal hyperperfusion is a stimulus for regeneration but may simultaneously cause irreparable endothelial injury. This porcine model not only helps to elucidate the inciting factors in SFS pathogenesis but also offers a clinically relevant means to study its prevention.

Sinusoidal microcirculatory changes after small-for-size liver transplantation in rats

Small-for-size graft injury is characterized by portal venous hypertension and loss of intracellular homeostasis early after transplant. The long-term alteration of sinusoidal microcirculatory hemodynamic state remains unknown. A syngeneic rat orthotopic liver transplantation model was developed using small-for-size grafts (35% of recipient liver weight) or whole grafts (100% of recipient liver weight). Graft survival, portal pressure, liver function, hepatocellular apoptosis as well as morphological changes (by light microscopy and electron microscopy) were assessed. Sinusoidal microcirculatory hemodynamics was examined by intravital fluorescence microscopy. Although portal hypertension lasted only for 1 h after performance of small-for-size liver transplantation, a sustained microcirculatory disturbance was accompanied by dramatic reduction of sinusoidal perfusion rate, elevation of sinusoidal diameter as well as increase in the number of apoptotic hepatocytes during the first 7 days. These resulted in lower survival rate (50% vs. 100%, P = 0.012), higher level of liver function, and more severe morphological changes, which could induce small-for-size syndrome. In conclusion, persistent microcirculatory hemodynamic derangement during the first 7 days after reperfusion as well as transient portal hypertension is significant manifestation after small-for-size liver transplantation. Long-term microcirculation disturbance displayed as decrease of sinusoidal reperfusion area and increase of spread in functional liver mass seems to be the key factor for graft injuries.

The technical advance and impact of caudate lobe venous reconstruction in left liver: additional safety for living-related donor liver transplantation

The key to obtaining good overall outcomes in small-for-size liver-graft transplantation is ensuring sufficient blood flow to the graft during the initial period after surgery. In left lobe liver grafting, various reconstruction techniques have been devised to maximize the limited graft volume. The reconstructions of the caudate lobe (CL) vessels were one of the main streams. In this article, we focus on the clinical significance of CL vessel reconstructions after small-for-size liver-graft transplantation and discuss the roles of various techniques. These techniques contribute to the enlargement of the margin of safety with respect to small-for-size liver-graft transplantation.

A graft to body weight ratio less than 0.8 does not exclude adult-to-adult right-lobe living donor liver transplantation

Many centers require a minimal graft to body weight ratio (GBWR) >or= 0.8 as an arbitrary threshold to proceed with right-lobe living donor liver transplantation (RL-LDLT), and there is often hesitancy about transplanting lower volume living donor (LD) liver grafts into sicker patients. The data supporting this dogma, based on the early experience with RL-LDLT at Asian centers, are weak. To determine the effect of LD liver volume in the modern era, we investigated the impact of GBWR on the outcome of RL-LDLT with a GBWR as low as 0.6 at the University of Toronto. Between April 2000 and September 2008, 271 adult-to-adult RL-LDLT procedures and 614 deceased donor liver transplants were performed. Twenty-two living donor liver transplantation (LDLT) cases with a GBWR of 0.59 to 0.79 (group A) were compared with 249 LDLT cases with a GBWR >or= 0.8 (group B) and with 66 full-graft deceased donor liver transplants (group C), who were matched 3:1 according to donor and recipient age, Model for End-Stage Liver Disease score, and presence of hepatitis C and hepatocellular carcinoma with the low-GBWR group. Portal vein shunts were not used. Markers of reperfusion injury [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)], graft function (international normalized ratio and bilirubin), complications graded by the Clavien score, and graft and patient survival were compared. As expected, LD recipients had a significantly shorter cold ischemia time (94 +/- 43 minutes for A, 96 +/- 57 minutes for B, and 453 +/- 152 minutes for C, P = 0.0001). However, the peak AST, peak ALT, absolute decrease in the international normalized ratio, day 7 bilirubin level, postoperative creatinine clearance, complication rate graded by the Clavien score, and median hospital stay were similar in all groups. The rate of biliary complications was higher with LD grafts than deceased donor grafts (19% for A versus 10% for B and 0% for C, P = 0.2). Patient survival was similar in all groups at 1, 3, and 5 years (91% for A versus 89% for B and 93% for C at 1 year, 87% for A versus 81% for B and 89% for C at 3 years, and 83% for A versus 81% for B and 87% for C at 5 years, P = 0.63). A Cox proportional regression analysis revealed only hepatitis C virus as a risk factor for poorer graft survival and not GBWR as a continuous or categorical variable. In conclusion, we found no evidence of inferior outcomes with smaller size grafts versus larger size LD grafts or full-size deceased donor grafts. Further studies are warranted to examine the factors affecting the function of smaller grafts for living liver donation and thereby define the safe lower limits for transplantation.

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.

Prognosis of adult patients transplanted with liver grafts < 35% of their standard liver volume

We have previously reported that a graft volume (GV) > 30% of the recipient's standard liver volume (SLV) can meet the recipient's metabolic demands. Here we report our experience with adult-to-adult living donor liver transplantation using left side grafts < 35% of the recipient's SLV. Of 143 adult living donor liver transplants, 13 auxiliary partial orthotopic liver transplants, 8 right side grafts, and 2 retransplantation cases were excluded. The resulting 120 cases were divided into 2 groups: group S consisted of 33 patients who received liver grafts < 35% of their SLV, and group L consisted of 87 patients who received liver grafts > or = 35% of their SLV. Patient characteristics, postoperative liver function, duration of hospital stay, and recipient survival rates were compared between the 2 groups. There were no significant differences between groups in recipient or donor background characteristics. The mean GV/SLV ratio of group S was 31.8%, whereas that of group L was 42.5%. There were no significant differences in the postoperative serum total bilirubin levels, prothrombin time international normalized ratio, daily ascites volume, or duration of postoperative hospital stay between the groups. The 1- and 5-year survival rates in group S were 80.7% and 64.2%, respectively, whereas those of group L were 90.8% and 84.9%, respectively, with no significant difference between groups. In conclusion, graft size was not considered to be the only cause of so-called small-for-size graft syndrome, and left side grafting appears to be the procedure of choice for adult-to-adult living donor liver transplantation because of the lower risk to donors in comparison with right lobe grafting.

Small-for-size liver graft injury--impact on tumor behavior

The success of liver transplantation has led to an ever-increasing demand for liver grafts. Since the first successful living donor liver transplantation, this surgical innovation has been well established in children and has significantly relieved the crisis of donor organ shortage for children. However, the extension of living donor liver transplantation to adult recipients is limited by the graft volume. The major concern of adult-to-adult living donor liver transplantation is the adequate graft that can be harvested from a living donor. Small-for-size graft injury is frequently observed. To develop novel effective treatments attenuating small-for-size liver graft injury during living donor liver transplantation, it is important to explore the precise mechanism of acute phase small-for-size graft damage. Recently, a number of clinical studies and animal experiments have been conducted to investigate the possible key issues on acute phase small-for-size liver graft injury, such as mechanical injury from shear stress, subsequent inflammatory responses, and imbalance of vasoregulatory factors. This review focuses on the mechanism of small-for-size liver graft injury based on the number of clinical and experimental studies. The latest research findings of the significance of acute phase liver graft injury on late phase tumor recurrence and metastasis are also addressed.

Influence of portosystemic shunt on liver regeneration after hepatic resection in pigs

Objective. The minimal amount of liver mass necessary for regeneration is still a matter of debate. The aim of the study was to analyze liver regeneration factors after extended resection with or without portosystemic shunt. Methods. An extended left hemihepatectomy was performed in 25 domestic pigs, in 15 cases after a portosystemic H-shunt. The expression of Ki-67, VEGF, TGF-α, FGF, and CK-7 was analyzed in paraffin-embedded tissue sections. Results. The volume of the remnant liver increased about 2.5-fold at the end of the first week after resection. With 19 cells/10 Glisson fields versus 4/10, Ki-67-expression was significantly higher in the H-shunt group. VEGF- and CK-7-expressions were significantly higher in the control group. No significant change was found in FGF-expression. The expression of TGF-α was higher, but not significantly, in the control group. Conclusions. The expression of Ki-67, and therefore hepatocyte regeneration, was increased in the shunt group. The expression of CK-7 on biliary epithelium and the expression of VEGF, however, were stronger in the control group.

Portal vein embolization in hilar cholangiocarcinoma

In patients with hilar cholangiocarcinoma, extended hepatectomy and caudate lobe resection are often performed to achieve an R0 resection. In patients whose standardized future liver remnant is less than or equal to 20% of total liver volume, portal vein embolization (PVE) should be performed. In patients with biliary dilatation of the future liver remnant, a biliary drainage catheter should be placed before PVE. If the planned surgery is an extended right hepatectomy, segment 4 branch embolization improves the hypertrophy of segments 2 and 3. In high-volume centers, PVE can be safely performed; it increases the resectability rate and results in the same survival rates as those in patients who undergo resection without PVE.

Donor risk in adult-to-adult living donor liver transplantation: impact of left lobe graft

BACKGROUND

To ensure donor safety in adult-to-adult living donor liver transplantation, we established a selection criterion for donors in which left lobe (LL) was the first choice of graft.

METHODS

Two hundred six consecutive donors were retrospectively studied. Donors were divided into two groups according to graft type: LL graft (n=137) and right lobe (RL) graft (n=69).

RESULTS

Although mean intraoperative blood loss of LL was significantly increased compared with RL, mean peak postoperative total bilirubin levels and duration of hospital stay after surgery were significantly less for LL than RL (P<0.05). No donor died or suffered a life-threatening complication during the study period. The overall complication rate was 34.0%, including biliary complications in 5.3%. The number of biliary complications was four (2.9%) in LL and seven (10.1%) in RL (P<0.05). Logistic regression analysis revealed that only graft type (LL vs. RL) is significantly related to the occurrence of biliary complications (odds ratio 0.11; P=0.0012). The cumulative overall graft survival rates in the recipients with LL were not significantly different from that in the recipients with RL.

CONCLUSIONS

LL grafting should be considered favorably when selecting donors for adult-to-adult living donor liver transplantation.

Estimation of standard liver volume for liver transplantation in the Chinese population

INTRODUCTION

The accurate assessment of standard liver volume (SLV) is necessary for the safety of both the donor and the recipient in living donor liver transplantation. However, the accuracy of SLV formulas relates to cohorts or races. This study examined the accuracy of a simple linear formula versus previous formulas of SLV for Chinese adults.

METHODS

Among 112 patients with normal liver, we created a new formula for SLV with stepwise regression analysis using the following variables: age, gender, body weight, body height, body mass index, and body surface area. The agreement between the actual liver volume (LV) and calculated LV using various formulas was prospectively evaluated among 63 living donors by paired-sample student's t-test and Lin's concordance correlation coefficient.

RESULTS

A new formula was developed SLV (mL) = 949.7 x BSA (m(2)) - 48.3 x age - 247.4 where age was counted as 1 for those <40, 2 if 41-60, and 3 if >60 years old. The calculated LV using our formula showed no significant difference from the actual LV using the paired-samples student's t-test (P = .653). Lin's concordance correlation coefficient showed substantial agreement between estimated LV using our formula and actual LV. Furthermore, this study also observed an almost perfect agreement between our formula and the Yoshizumi et al formula.

CONCLUSION

Our formula, which accurately estimated LV among Chinese adults, may be applicable to adults of other ethnicitis.

Graft size and donor age are independent factors for graft loss in adult-to-adult living-donor liver transplantation using the left liver

BACKGROUND/PURPOSE

Graft survival is affected by various factors, such as preoperative state and the ages of the recipient and donor, as well as graft size. The objective of this study was to analyze the risk factors for graft survival.

METHODS

From September 1997 to July 2005, 24 patients who had undergone living-donor liver transplantation (LDLT) were retrospectively analyzed. Sixteen patients survived and the eight graft-loss cases were classified into two groups according to the cause of graft loss: graft dysfunction without major post-transplantation complications (graft dysfunction group; n = 3), and graft dysfunction with such complications (secondary graft dysfunction group; n = 5). Various factors were compared between these groups and the survival group.

RESULTS

Mean donor age was 31.9 years in the survival group and 49.2 years in the secondary graft dysfunction group (P = 0.024). Graft weight/recipient standard liver volume ratios (G/SLVs) were 36.7% in the survival group, and 26.2% in the graft dysfunction group (P = 0.037). The postoperative mean PT% for 1 week was 48.6% in the survival group and 38.1% in the secondary graft dysfunction group (P = 0.05).

CONCLUSIONS

Our surgical results demonstrated that G/SLV and donor age were independent factors that affected graft survival rates.

Recent role of splenectomy in chronic hepatic disorders

For years splenectomy in hepatic disorders has been indicated only for the treatment of gastro-esophageal varices. However, with recent advances in medical and surgical treatments for chronic hepatic disorders, the use of splenectomy has been greatly expanded, such that splenectomy is used for reversing hypersplenism, for applying interferon treatment for hepatitis C, for treating hyperdynamic portal circulation associated with intractable ascites, and for controlling portal pressure during small grafts in living donor liver transplantation. Such experiences have shown the importance of portal hemodynamics, even in cirrhotic livers. Recent advances in surgical techniques have enabled surgeons to perform splenectomy more safely and less invasively, but the procedure still has considerable clinical outcomes. Splenectomy in hepatic disorders may become a more common procedure with expanded indications. However, it should also be noted that the long-term effects of splenectomy, in terms of improved hematological or hepatic function, is still not guaranteed. Moreover, the impact of splenectomy on immunologic status remains unclear and needs to be elucidated in both experimental and clinical settings.

Current concept of small-for-size grafts in living donor liver transplantation

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching called "small-for-size (SFS) graft syndrome." The initial trials to resolve this problem involved increasing the procured graft size, from left to right, and even extension to include a right lobe graft. Clinical cases of living right lobe donations have been reported since then, drawing attention to the risks of increasing the liver volume procured from a living donor. However, not only other modes of increasing graft volume such as auxiliary or dual liver transplantation, but also control of the increased portal pressure caused by an SFS graft, such as a portosystemic shunt or splenectomy, have been trialed with some positive results. To establish an effective strategy for transplanting SFS grafts and preventing SFS graft syndrome, it is essential to have precise knowledge and tactics to evaluate graft quality and graft volume, when performing these LDLTs with portal pressure control. We reviewed the updated literature on the pathogenesis of and strategies for using SFS grafts.

Estimation of standard liver volume for Japanese adults

INTRODUCTION

Accurate pretransplant estimation of the recipient's standard liver volume (SLV) is important. The purpose of this study was to compare reported formulas for clinical estimation of liver volume among Japanese adults.

METHODS

We reviewed data on 70 healthy adults (46 men, 24 women, ages 20 to 65 years old) evaluated for living donor liver transplantation. Liver volume (LV) was measured using two- or three-dimensional computed tomography volumetry (CTV). The formulas of DeLand (LV = 1020 x body surface area [BSA] - 220), Urata (LV = 706.2 x BSA + 2.4), Noda (LV = 50.12 x BW(0.78)), Heinemann (LV = 1072.8 x BSA - 345.7), Vauthey (LV = 18.51 x BW + 191.8) and Yoshizumi (LV = 772 x BSA) were applied to estimate LV. We calculated the differences for individual donors betwen CTV and LV estimated by each formula.

RESULTS

Mean LVs as estimated by the formulae of DeLand and Heinemann et al were significantly greater (P < .01) than the mean CTV, while LV estimated by the formula of Urata was significantly less (P < .05) than the CTV. The formulas of DeLand and Heinemann overestimated LV, while the formula of Urata underestimated it. The formulae of Noda et al and Yoshizumi et al tended to underestimate the LV when the CTV was greater than 1600 cm(3). When the Yoshizumi formula was applied, the number of donors with an acceptable difference (+/-15%) between CTV and estimated LV was 55 (78.6%).

CONCLUSIONS

The Yoshizumi formula was applicable, especially for patients with a BSA < 2.0, whereas the well-known Urata formula made LV underestimates.

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.

Graft size, donor age, and patient status are the indicators of early graft function after living donor liver transplantation

No reliable model for predicting early graft function and patient survival after living donor liver transplantation (LDLT) exists. The aim of this study was to establish a new formula for predicting early graft function and prognosis using technetium-99m galactosyl-human serum albumin (Tc-GSA) liver scintigraphy. The ratio of the hepatic uptake ratio of Tc-GSA to the clearance index of Tc-GSA (LHL/HH) was determined 7 days after LDLT. There were 22 patients with a ratio greater than 1.3 and 6 patients with a ratio less than 1.3. Graft function on the 14th postoperative day (POD) was compared between the 2 groups. A new formula to predict the LHL/HH score was established as follows: LHL/HH (predictive score) = 0.011 x graft weight (%) - 0.016 x donor age - 0.008 x Model for End-Stage Liver Disease score - 0.15 x shunt (if present) + 1.757 (r(2) = 0.497, P < 0.01). This predicted LHL/HH ratio was compared to the graft function on POD 14 for 110 LDLT patients. The total bilirubin (TB) and prothrombin time international normalized ratio (PT-INR) in the group with an LHL/HH score > or = 1.3 were lower than those in the group with an LHL/HH score < 1.3. The TB, PT-INR, and volume of ascites in the group with a predictive score > or = 1.3 (n = 86) were lower than those in the group with a score < 1.3 (n = 24). The 6-month survival probability was improved in the group with a predictive score > or = 1.3. In conclusion, this preoperative calculated LHL/HH score is correlated with graft function and short-term prognosis. Thus, this predictive model may allow transplant surgeons to use a living donor left lobe graft with greater confidence.

Strategies for improving the outcomes of small-for-size grafts in adult-to-adult living-donor liver transplantation

Living-donor liver transplantation (LDLT) has been refined and accepted as a valuable treatment for patients with end-stage liver disease in order to overcome the shortage of organs and mortality on the waiting list. However, graft size problems, especially small-for-size (SFS) grafts, remain the greatest limiting factor for the expansion of LDLT, especially in adult-to-adult transplantation. Various attempts have been made to overcome the problems regarding SFS grafts, such as increasing the graft liver volume and/or controlling excessive portal inflow to a small graft, with considerable positive outcomes. Recent innovations in basic studies have also contributed to the treatment of SFS syndrome. Herein, we review the literature and assess our current knowledge of the pathogenesis and treatment strategies for the use of SFS grafts in adult-to-adult LDLT.

Effect of the portacaval shunt on reperfusion injury after 65% hepatectomy in pigs

BACKGROUND

Portal flow diversion by portacaval shunts (PCS) has been shown to prevent primary graft nonfunction in liver transplantation using small-for-size grafts. In this study, we examine whether PCS can improve reperfusion injury after major hepatectomy in pigs.

MATERIALS AND METHODS

In 14 pigs, a partial PCS was constructed following 65% hepatectomy and 1 h of inflow ischemia. During 24 h of reperfusion, the shunt was either closed (group A, n = 7) or left open (group B, n = 7).

RESULTS

24 h after reperfusion, group A had higher levels of alanine aminotransferase (70 +/- 12 IU/l vs. 51 +/- 5.9 IU/l; p < 0.05), alanine aminotransferase per gram of liver remnant (0.41 +/- 0.07 IU/l/g vs. 0.21 +/- 0.05 IU/l/g; p < 0.05), prothrombin time (24.1 +/- 2.4 s vs. 14.3 +/- 2.9 s; p < 0.05), international normalized ratio (2.11 +/- 0.15 vs. 1.29 +/- 0.28; p < 0.05), hepatocyte necrosis scores and percentages of nuclei stained for proliferating cell nuclear antigen (52.57 +/- 8.9% vs. 36.71 +/- 6%; p < 0.05) compared to group B.

CONCLUSIONS

Partial portal flow diversion appears to attenuate reperfusion injury in a porcine model of major hepatectomy.

Does the permanent portacaval shunt for a small-for-size graft in a living donor liver transplantation do more harm than good?

In order to obviate a small-for-size graft syndrome (SFSGS), a portacaval (PC) shunt had been considered in a case of adult-to-adult living donor liver transplantation (AA-LDLT). In a recent AA-LDLT case, we adopted the PC shunt to resolve SFSGS; however, graft atrophy was observed in the late period of LDLT, thereby resulting in liver dysfunction. Due to the surgical closure of the PC shunt at 11 months post-LDLT, the graft regenerated gradually and resulted in the recovery of the liver function. This experience indicates that the portacaval shunt would overcome SFSGS in the early period of LDLT, while it would cause the graft atrophy and the graft dysfunction in the late period of LDLT.

Computed tomography volumetric follow-up of graft volume in living related liver recipients

AIM

Liver regeneration is a fascinating process that makes living related donor transplantation feasible for patients. In this study we evaluated the changes in graft volumes among living related liver transplantation (LRLT) patients using computerized tomography (CT)-assisted volumetry technique.

MATERIALS AND METHODS

Thirty three patients (17 adults, 16 children) who underwent liver transplantation were included in this study. Pediatric patients were referred to as group A, and adult patients were referred to as group B. The initial graft weight measured during operation was used as the initial graft volume. All patients' graft volumes were retrospectively calculated by CT volumetry technique. The data was compared with the initial graft volume in each patient. Paired samples Student t test was used for statistical analyses.

RESULTS

The graft volume increased from 2.7% to 285.6% with the mean increase 78% in group A, and 10.5% to 150.8% with a mean increase of 89% in group B. These changes were significant (P<.0001) in both groups.

DISCUSSION

The liver regeneration of recipient grafts is more complicated than that of the donors. There are a limited number of reports of complete volume recovery. We observed significant volume regeneration in liver grafts after transplantation, which was easily followed by CT-assisted volumetry.

Adult-to-adult living donor liver transplantation using left lobes: the importance of surgical modulations on portal graft inflow

BACKGROUND

Due to the shortage of available cadaveric organs, living donor liver transplantation (LDLT) has been recently applied extensively in adults. The use of the left lobe should be encouraged because of donor safety, but frequently the metabolic requirements of severely cirrhotic patients are great and subsequent graft dysfunction is encountered after transplantation. The importance of increased portal inflow to the graft in previously severely cirrhotic patients and other hemodynamic changes in LDLT using left lobes are still under debate, as are the surgical modulations to correct them. In this study, we have reported an initial series of adult-to-adult LDLT using left lobes, underlining the hemodynamic changes encountered during the transplant and the surgical modulations we applied to correct them.

METHODS

Eight adult recipients underwent left lobe liver transplantation from living donors. Portal vein pressure and central venous pressure were measured before and after surgical modulation.

RESULTS

We encountered four cases of small-for-size syndrome. Two patients were retransplanted; the other two died. Seventy-five percent of our recipients survived and 50% did not require further surgery.

CONCLUSION

Surgical portal inflow modulation should be considered in cases of left lobe liver transplantation between adults.

Impact of donor age and recipient status on left-lobe graft for living donor adult liver transplantation

Donor safety is the priority when performing a living donor adult liver transplantation (LDALT). We herein present our findings using left-lobe graft in LDALT. Data on 119 recipients who underwent the LDALT, and on 119 donors who underwent extended left lobectomy were reviewed. The recipients were divided into groups above (n = 19) and below (n = 100) 50 years of donor age, into groups above (n = 63) and below (n = 56) 40% of graft size (graft volume/standard liver volume, GV/SLV), and above (n = 25) and below (n = 94) 20 of pre-operative model for end-stage liver disease (MELD). Total bilirubin (TB), volume of ascites, prothrombin time international normalized ratio on postoperative day 14 or survival rates were compared. TB (mg/dl) or volume of ascites (ml) of the group in donor age < 50 years was better than that of the group in donor age > or = 50 years (7.4 vs. 14.7 or 788 vs. 1379, P < 0.001 or P < 0.005, respectively). The graft and patient survival rates of the lower MELD group tended to be better than that of the higher MELD group. LDALT can be safely performed using a left-lobe graft. However, when using the graft from the donor > or = 50 years, especially for the recipients with the MELD > or = 20, the indications should be carefully discussed.

Extended Indication for Living Donor Liver Transplantation in Patients With Hepatocellular Carcinoma

BACKGROUND

Liver transplantation is an accepted treatment option for patients with otherwise untreatable hepatocellular carcinoma (HCC). The present study assessed the outcome of living donor liver transplantation (LDLT) under extended selection criteria based on a single-center experience.

METHODS

A total of 60 patients who underwent LDLT for HCC were included. Our indication for LDLT included HCC without extrahepatic spread or macroscopic vascular invasion. The size and number of HCC nodules were not limited. Recurrence-free survival rates according to various factors were compared to identify risk factors for recurrence.

RESULTS

Forty patients (67%) preoperatively exceeded the Milan criteria. The median follow-up was 437 days (range: 23-1,385 days). The overall 1- and 3-year actuarial survival rates were 88.4 and 68.6%, respectively. HCC recurred in eight patients (14.3%) within a mean follow-up of 288 days; all were patients who exceeded the Milan criteria. The 1-, 2- and 3-year recurrence-free survival rates of patients who fulfilled the Milan criteria were 100%, 100%, and 100%, respectively, whereas those of patients who exceeded the criteria were 83.0%, 74.0%, and 74.0%, respectively. Tumor diameter >5 cm was significantly associated with worse prognosis, but the number of tumors was not. A preoperative des-gamma-carboxy prothrombin value >300 mAU/ml was strongly associated with the high recurrence rate. These two variables were significant in multivariate analysis.

CONCLUSIONS

LDLT was shown to offer acceptable results in patients who exceeded the Milan criteria. The indication for LDLT can therefore be expanded beyond the Milan criteria, especially for patients with small multiple tumors <5 cm.

Estimation of standard liver volume in Japanese living liver donors

BACKGROUND

Standard liver volume (SLV) is an important concept in adult living liver donor transplantation. The purpose of this study was to re-evaluate and modify the authors' previous formula for predicting total liver volume (TLV).

METHODS

The TLV of 301 Japanese living donors was measured by computed tomography. This TLV was then compared with the liver volume calculated using established formulas. The correlation between TLV and several factors including body surface area (BSA) were analyzed and a new equation (SLVn) to better approximate TLV was determined. Factors related to the difference between TLV and SLVn were examined.

RESULTS

Average TLV was 1196.3 +/- 221.0 cm3. Urata's formula underestimated TLV by 17.6 cm3 and the other formulas overestimated it by 120.4-244.9 cm3. TLV could be approximated by BSA; SLVn (cm3) = -404.8 + 961.3 x BSA (m2, R2 = 0.58). SLVn tended to overestimate the TLV of older donors and to underestimate TLV of thin donors.

CONCLUSIONS

A new simple formula is presented that might be a better fit for calculating TLV in Japanese adults. This formula might be useful for evaluating the size of an adequate graft.

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.

Living Donor Right Liver Lobes: Preoperative CT Volumetric Measurement for Calculation of Intraoperative Weight and Volume

PURPOSE

To prospectively develop equations for the calculation of expected intraoperative weight and volume of a living donor's right liver lobe by using preoperative computed tomography (CT) for volumetric measurement.

MATERIALS AND METHODS

After medical ethics committee and state medical board approval, informed consent was obtained from eight female and eight male living donors (age range, 18-63 years) for participation in preoperative CT volumetric measurement of the right liver lobes by using the summation-of-area method. Intraoperatively, the graft was weighed, and the volume of the graft was determined by means of water displacement. Distributions of pre- and intraoperative data were depicted as Tukey box-and-whisker diagrams. Then, linear regressions were calculated, and the results were depicted as scatterplots. On the basis of intraoperative data, physical density of the parenchyma was calculated by dividing weight by volume of the graft.

RESULTS

Preoperative measurement of grafts resulted in a mean volume of 929 mL +/- 176 (standard deviation); intraoperative mean weight and volume of the grafts were 774 g +/- 138 and 697 mL +/- 139, respectively. All corresponding pre- and intraoperative data correlated significantly (P < .001) with each other. Intraoperatively expected volume (V(intraop)) in millilliters and weight (W(intraop)) in grams can be calculated with the equations V(intra)(op) = (0.656 . V(preop)) + 87.629 mL and W(intra)(op) = (0.678 g/mL . V(preop)) + 143.704 g, respectively, where preoperative volume is V(preop) in milliliters. Physical density of transplanted liver lobes was 1.1172 g/mL +/- 0.1015.

CONCLUSION

By using two equations developed from the data obtained in this study, expected intraoperative weight and volume can properly be determined from CT volumetric measurements.

Marginal hepatectomy in the rat: from anatomy to surgery

OBJECTIVE

Based on the 3-dimensional visualization of vascular supply and drainage, a vessel-oriented resection technique was optimized. The new surgical technique was used to determine the maximal reduction in liver mass enabling a 50% 1-week survival rate.

BACKGROUND DATA

Determination of the minimal liver mass is necessary in clinical as well as in experimental liver surgery. In rats, survival seems to depend on the surgical technique applied. Extended hepatectomy with removal of 90% of the liver mass was long regarded as a lethal model. Introduction of a vessel-oriented approach enabled long-term survival in this model.

METHODS

The lobar and vascular anatomy of rat livers was visualized by plastination of the whole organ, respectively, by corrosion casts of the portal vein, hepatic artery and liver veins. The three-dimensional models were used to extract the underlying anatomic structure. In 90% partial hepatectomy, the liver parenchyma was clamped close to the base of the respective liver lobes (left lateral, median and right, liver lobe). Piercing sutures were placed through the liver parenchyma, so that the stem of portal vein and the accompanying hepatic artery but also the hepatic vein were included.

RESULTS

A 1-week survival rate of 100% was achieved after 90% hepatectomy. Extending the procedure to 95% resection by additional removal of the upper caudate lobe led to a 1-week survival rate of 66%; 97% partial hepatectomy, accomplished by additional resection of the lower caudate lobe only leaving the paracaval parts of the liver behind, resulted in 100% lethality within 4 days.

CONCLUSIONS

Using a anatomically based, vessel-oriented, parenchyma-preserving surgical technique in 95% liver resections led to long-term survival. This represents the maximal reduction of liver mass compatible with survival.

Risk factors for graft dysfunction after adult-to-adult living donor liver transplantation

The aim of this study was to investigate the risk factors for graft dysfunction after adult-to-adult living donor liver transplantation (LDLT). Thirty-nine adults with chronic cirrhosis underwent LDLT between 1999 and 2004. Their postoperative courses were uneventful with no vascular or bile duct complications early after LDLT, except one mild hepatic artery stenosis. The preoperative MELD scores were significantly higher in the failed graft group (n=5) than the functioning graft group (n=34; P=.004), while the graft liver weight/standard liver volume ratio was similar between these groups. We concluded that a high preoperative MELD score was associated with postoperative graft failure and that graft size had little impact on graft outcome. Although large grafts would seem intuitively more suitable for sick recipients, we did not show a benefit among this cohort; the MELD score was the best predictor, a finding that is also most consistent with donor safety.