An Artificial Vascular Graft Is a Useful Interpositional Material for Drainage of the Right Anterior Section in Living Donor Liver Transplantation

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1 LIVER TRANSPLANTATION 13: , 2007 ORIGINAL ARTICLE An Artificial Vascular Graft Is a Useful Interpositional Material for Drainage of the Right Anterior Section in Living Donor Liver Transplantation Nam-Joon Yi, Kyung-Suk Suh, Hae Won Lee, Eung-Ho Cho, Woo Young Shin, Jai Young Cho, and Kuhn Uk Lee Department of Surgery, Seoul National University College of Medicine, Seoul, Korea Congestion in the anterior section in a right liver (RL) without a middle hepatic vein (MHV) may lead to graft dysfunction. To solve this problem, an RL draining MHV branches with autologous or cryopreserved vessels can be introduced. However, these vessels are often unavailable, and their preparation is time-consuming. An expanded polytetrafluoroethylene (eptfe) graft may be used for anterior section drainage. Between February and November 2005, 26 recipients underwent RL liver transplantation draining MHV branches with an eptfe graft (group P). Twenty-six eptfe grafts (6 or 7 mm in internal diameter) drained 35 MHV branches on the back table to the graft right hepatic vein or to the recipient s inferior vena cava. The patency of the eptfe graft was checked with computed tomography scans of the liver. The outcome of group P was compared with those of an RL group with MHV (group M, n 17) and an RL group without reconstruction of MHV or its tributaries (group R, n 85). The 1-month and 4-month patency rates (PRs) of the eptfe grafts were 80.8% (21/26) and 38.5% (10/26). All showing early obstruction of the eptfe graft had congestion in the anterior section, but all showing late obstruction were asymptomatic. The 1-month PRs of group P were comparable to, but the 4-month PRs were lower than, those of group M (both 94.1%; P 0.05). However, 1-year patient and graft survival rates of group P (both 100%) were comparable to those of group M (94.1% and 100%) and better than those of group R (83.5% and 88.2%; P 0.05). In conclusion, the early PR of group P was good, and late obstruction of the eptfe graft had no impact on congestion in the anterior section or patient survival. Therefore, an eptfe graft may be a useful interposition material for anterior section drainage in RL transplantation without serious complications. Liver Transpl 13: , AASLD. Received December 20, 2006; accepted March 28, See Editorial on Page 1075 Since 1989, when the first living donor liver transplantation (LDLT) was reported, 1,2 LDLT has become a common practice at numerous transplantation centers and now achieves results comparable to those of deceased donor liver transplantation. A right liver (RL) graft has been used in many centers to meet the metabolic demands of large recipients, but problems may occur when the middle hepatic vein (MHV) is not included in an RL graft. It has been reported that hepatic venous congestion in the anterior section of an RL graft sometimes causes serious complications, such as sepsis, early graft dysfunction, and even mortality. 3 To prevent this congestion in the anterior section, various types of anterior section drainage have been devised for RL grafts. Lo et al. 4 introduced an extended Abbreviations: ALDLT, adult-to-adult living donor liver transplantation; CT, computed tomography; eptfe, expanded polytetrafluoroethylene; HCC, hepatocellular carcinoma; IVC, inferior vena cava; LDLT, living donor liver transplantation; MELD, model for end-stage liver disease; MHV, middle hepatic vein; MRL, modified right liver; MRSA, methicillin-resistant Staphylococcus aureus; POD, postoperative day; PR, patency rate; RHV, right hepatic vein; RL, right liver; Sg4, segment 4; UNOS, United Network for Organ Sharing; US, ultrasonography; V5, segment V hepatic vein; V8, segment VIII hepatic vein. Presented at the 12th Annual Congress of the International Liver Transplantation Society, Milan, Italy, May 3-6, Address reprint requests to Kyung-Suk Suh, M.D., Ph.D., Department of Surgery, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul , Korea. Telephone: ; FAX: ; kssuh@plaza.snu.ac.kr DOI /lt Published online in Wiley InterScience ( American Association for the Study of Liver Diseases.

2 1160 YI ET AL. right hepatectomy in which MHV and some portion of segment 4 (Sg4) were harvested to the graft side. This alleviated the problem of graft congestion and allowed a larger graft to be obtained, but often the remnant donor liver was too small, and the remnant Sg4 became congested. We previously reported a modified extended right liver graft in which MHV was excavated while all of Sg4 to the donor side was preserved because this minimized volumetric loss on the donor side during the operation and did not increase the extent of the donor operation. 5 However, the initial regenerating power of Sg4 in the donor was impaired versus that in the donor after a right hepatectomy saving MHV. A modified right liver (MRL) graft was introduced by Lee et al. 3,6 in which MHV branches are drained with interpositional vessel grafts in the recipient side; this theoretically offers an ideal solution to the problem in terms of both donor and recipient safety. However, this procedure requires additional vessel grafts, which are either cryopreserved or autologous vein grafts, such as a greater saphenous vein, left portal vein, or paraumbilical vein, 6-11 and the required preparation is complex and time-consuming. Moreover, such grafts are often unavailable. Thus, we considered that an artificial vessel graft could be used easily as a vascular substitute to overcome the shortage of vessel grafts and to simplify the procedure of anterior section drainage. However, no literature was found concerning the use of artificial vessel grafts in liver transplantation recipients. Here we describe our early experiences with anterior section drainage in which we used an artificial vessel graft in RL transplantation. PATIENTS AND METHODS Right Liver Recipients and Donors. Between February and November 2005, 26 recipients underwent adult-to-adult living donor liver transplantation (ALDLT) using an MRL graft with an artificial vessel graft (group P). Between April 2000 and July 2004, RL transplantation without reconstruction of MHV or its tributaries, that is, conventional RL transplantation, was performed in 85 cases (group R), and between July 2002 and July 2005, RL transplantation with MHV was performed in 17 cases (group M). Most cases of group R were performed during the early period of our ALDLT program. 12 Since 2005, we have usually performed MRL transplantation using an artificial vessel graft instead of conventional RL transplantation if the recipient s condition requires a right liver graft and there are significant MHV tributaries ( 5 mm in diameter) during the donor hepatectomy. A right hepatectomy with MHV is considered only for donors whose estimated remnant liver volume is greater than 35% of the whole liver, whose liver is free of steatosis, and whose recipients are in a poor pretransplant condition. 5 The pretransplant clinical data were comparable for the 3 groups, except for the donor age (Table 1). Young donors were favored in the early period of the LDLT program at our institution (P 0.016). The mean follow-up period was months in group R, months in group P, and months in group M (P 0.000); the differences were due to the historical natures of groups R and M. Donor Right Hepatectomy and Venous Reconstruction of MHV Branches. The surgical technique used for the donor right hepatectomy is described elsewhere in detail. 12,13 In the relevant donors of group R, MHV tributaries were not saved. In the relevant donors of group M, MHV was excavated, and the entire Sg4 was preserved to the donor. In the relevant donors of group P, a major MHV branch greater than 5 mm in diameter was clamped with a temporary clip, and then it was divided during parenchymal dissection. Some MHV branches less than approximately 5 mm in diameter were sacrificed to avoid multiple complex anastomoses. On the back table, the donor surgeon carefully examined the congested area and its MHV branch in group P. If the congested area was dominant (patch discoloration 20% of the volume of the anterior section), the temporary clip of the MHV branch was removed. Afterward, perfusion with a histidine-tryptophan-ketoglutarate solution was started to ensure good drainage of the anterior section. Subsequently, the donor surgeon decided on the drainage type of MHV branch. The artificial vascular grafts used were 6-mm-internal-diameter or 7-mm-internal-diameter thin-walled expanded polytetrafluoroethylene (eptfe) grafts (GORE-TEX, W.L. Gore & Associates, Inc., United States), (Fig. 1A). In principle, the segment V hepatic vein (V5) was anastomosed to the proximal end of an eptfe graft in an end-to-end fashion with 6-0 prolen. In cases of double V5s, venoplasty of the V5s to achieve a single orifice was performed, or 1 of the V5s was anastomosed to eptfe in an end-to-side fashion. The segment VIII hepatic vein (V8) was anastomosed to the eptfe graft in an end-to-side fashion or to the graft right hepatic vein (RHV) in an end-to-end fashion with 6-0 prolen. When V8 could be directly anastomosed to the graft RHV, the eptfe graft draining V5 was directly anastomosed to the recipient inferior vena cava (IVC) so that the main outflow tract would not be made complex (n 13; Fig. 1B). When this was not the case, the eptfe graft draining both V8 and V5 was anastomosed to the graft RHV to form a triangular common orifice with 6-0 prolen (n 13; Fig. 1C); the newly created septum between the graft RHV and the eptfe graft was vertically divided at the middle, and the gap was transversely sutured to remove the ridge and to create a large opening. 14 MHV reconstruction in group M is described elsewhere. 5 Recipient Operation. In the recipient, the diseased liver was removed, and MHV and left hepatic vein orifices were closed. Then, the IVC was nearly totally clamped. A venovenous bypass was not used. The recipient RHV orifice was measured for the longitudinal dimension and divided

3 EPTFE GRAFT IN RIGHT LIVER TRANSPLANTATION 1161 TABLE 1. Clinical Features of the Recipients of Right Liver Transplantation Group R (n 85) Group P (n 26) Group M (n 17) P Gender (male:female) 65:20 18:8 16: Age (years; mean SD) Body weight (kg) Original liver disease Viral hepatitis 68 (80.0%) 22 (84.6%) 16 (94.1%) Other 17 (20.0%) 4 (15.4%) 1 (5.9%) Accompanying HCC 31 (36.5%) 14 (53.8%) 7 (41.2%) MELD score UNOS status (5.9%) 1 (3.8%) 2A 15 (17.6%) 2 (7.7%) 1 (5.9%) 2B or 3 65 (76.5%) 23 (88.5%) 16 (94.1%) Donor gender (male:female) 56:29 19:7 10: Donor age (years; mean SD) Graft weight (g; mean SD) Graft versus recipient weight ratio (%; mean SD) Macrovesicular steatosis of the graft (%; mean SD) Operative time (minutes; mean SD) Ischemic time (minutes; mean SD) Total Cold Warm Abbreviations: HCC, hepatocellular carcinoma; MELD, model for end-stage liver disease; SD, standard deviation; UNOS, United Network for Organ Sharing. caudally to create a larger opening than the longitudinal dimension of the graft RHV. The IVC was then divided horizontally for a distance corresponding to the transverse dimension of the common orifice of the graft RHV and the eptfe graft/v8. Cranial and caudal flaps were excised so that a large oval opening was created matching that of the graft. The anastomosis was completed with 4-0 prolen sutures. Intraoperative Doppler ultrasonography (US) was performed to immediately assess the patency of the MHV branches after hepatic artery anastomosis. No additional anticoagulant therapy was administered during or after the operation. For biliary anastomosis, a duct-to-duct reconstruction was usually performed in ALDLT. 15 Contraindications for such a procedure were primary sclerosing cholangitis, common bile duct dilatation (diameter 1.5 cm), or definite injury of the recipient s bile duct. Among the 128 study subjects, 1 (3.9%) of the 26 patients in group P, 1 (5.9%) of the 17 patients in group M, and 7 (8.2%) of the 85 patients in group R underwent a hepaticojejunostomy. Follow-Up of the MHV Branch Patency and Graft Regeneration. US was performed daily for 5-7 days after transplantation on all patients. After informed consent had been obtained from each patient by the surgical team, all recipients in group P (except for 3 renal-insufficient patients) underwent a multiphase dynamic liver computed tomography (CT) scan to evaluate graft tissue perfusion, venous outflow, and graft regeneration 2 weeks, 1 month, and 4 months after surgery. In the 3 cases of renal insufficiency, US was performed instead of 2-week and 1-month CT scans. The patency rate (PR) of the eptfe grafts was defined as the percentage of eptfe grafts that functioned well after implantation on a CT scan. The PR of group P was compared with that of group M. In group P, the volumes of the anterior and posterior sections were calculated as described. 16 A single investigator (N.J.Y.) with 4 years of experience reviewed all CT scans. Classification of the Posttransplant Complications. Definitions of complications were adapted from the Clavien grading system for negative outcomes Abdominal drains were removed if there were no abnormal findings by either physical examination or biochemical analysis and if the amount of abdominal drainage per day was less than 300 ml. In group P, an ascites culture was routinely performed before abdominal drain removal. Statistical Analysis. All values are expressed as the means the standard deviation. Categorical variables were compared with Fisher s exact test, and continuous variables were compared with the nonparametric Mann-Whitney U test. Patient survival was determined by Kaplan- Meier survival analysis, and groups were compared

4 1162 YI ET AL. Figure 2. Early posttransplant CT scans to evaluate eptfe graft patency. (A) Early eptfe graft obstruction with anterior congestion. The enhancement of the eptfe graft disappeared in CT scans (arrow), and there was a noticeable perfusion defect at segment V. (B) CT scans after a transjugular stent insertion in the eptfe graft to resolve anterior congestion. The wall stent was inserted through a transjugular approach to correct anastomosis stenosis of the eptfe graft draining V5 (arrow). Subsequently, the perfusion defect disappeared in follow-up CT. Abbreviations: CT, computed tomography; eptfe, expanded polytetrafluoroethylene; RHV, right hepatic vein; V5, segment V hepatic vein. and 35 of 39 MHV tributaries were drained to 26 eptfe grafts. The mean V5 and V8 internal diameters were cm ( cm) and cm ( cm), respectively, and there were 3 double V5 cases. Figure 1. Reconstruction of anterior section drainage in an MRL graft using an eptfe vascular graft. (A) Schematic figures of bench work. (B) V5 drainage using the eptfe graft. When V8 can be directly drained to the graft RHV as a common orifice, the eptfe graft draining V5 is directly anastomosed to the recipient IVC. (C) Common orifice of the graft RHV and eptfe graft. If this is not the case, the eptfe graft draining both V8 and V5 is anastomosed to the graft RHV on the back table. Subsequently, the common orifice of the RHV and eptfe graft is anastomosed to the recipient IVC. Abbreviations: eptfe, expanded polytetrafluoroethylene; IVC, inferior vena cava; RHV, right hepatic vein; V5, segment V hepatic vein; V8, segment VIII hepatic vein. with the log-rank test. Statistical analyses were performed with SPSS (release 10.0, SPSS, Inc., Chicago, IL), and P 0.05 was considered significant. RESULTS Operative Data. The intraoperative recipient and graft data are also summarized in Table 1. The intraoperative clinical data were comparable for the 3 groups (Table 1). In group P, a total of 39 MHV tributaries were reconstructed, PR of MHV Branches and Graft Regeneration. By early posttransplant US, all eptfe grafts functioned immediately, but 5 (19.2%) of the 26 recipients showed an abnormal eptfe graft flow pattern 1 week after transplantation. Overall, the 1-month PR of the eptfe graft was 80.8% (21 of 26 eptfe grafts); 5 patients showed eptfe graft thrombosis and perfusion defects in the anterior section by CT scans. Of these 5 patients, 2 had symptoms associated with congestion in the anterior section. A 35-year-old male patient experienced prolonged ascites and fever associated with congestion in the anterior section. His ascites was controlled by percutaneous drainage and diuretics 1 month after transplantation. The other patient, a 62-year-old woman, had an abnormal liver function test (more than 10 times the normal aminotransferase level and an increased serum bilirubin level) without evidence of acute cellular rejection on a liver biopsy. She underwent a liver CT scan, transjugular thrombectomy, and vascular stent insertion in the eptfe graft at postoperative day 7, after which the perfusion defect disappeared on a follow-up CT scan (Fig. 2). She was discharged 1 month after transplantation with a normal liver function. The postoperative recovery of the other 3 patients with early eptfe graft

5 EPTFE GRAFT IN RIGHT LIVER TRANSPLANTATION 1163 Figure 3. Late posttransplant CT scans to evaluate eptfe graft patency. Late obstruction of the eptfe graft (arrow) was asymptomatic, and no perfusion abnormality was evident in CT scans 4 months after the operation. Abbreviations: CT, computed tomography; eptfe, expanded polytetrafluoroethylene; IVC, inferior vena cava; RHV, right hepatic vein. obstruction was uneventful. The 4-month PR of the eptfe graft was 38.5% (10 of 26 eptfe grafts). All late eptfe graft obstructions were asymptomatic and did not accompany a perfusion abnormality on CT scans (Fig. 3). In group M, overall, 1-month and 4-month PRs were 94.1%. No significant difference in the 1-month PR was found between groups P and M (P 0.139). However, the 4-month PR was significantly higher in group M than that in group P (P 0.000). The regeneration of the anterior and posterior sections was compatible in the 1-month and 4-month CT examinations in group P (Fig. 4A). In addition, the difference in the regeneration rates was insignificant between the liver grafts with an obstructive eptfe graft and with an intact eptfe graft on CT examination (Fig. 4B). Postoperative Liver Function and Postoperative Recovery. In group P, the posttransplant serum alanine aminotransferase and total bilirubin levels and prothrombin times evolved appropriately and returned to an acceptable range for all study subjects within 1 month of surgery (Fig. 5). The number of abdominal drains was reduced appropriately within 2 weeks and the platelet counts improved within 1 week after transplantation in all study subjects of group P (Fig. 6). In group P, the total bilirubin levels (Fig. 4B) and amount of abdominal drainage (Fig. 5A) were significantly lower and the platelet counts (Fig. 5B) were significantly higher than those in the other 2 groups during the early postoperative period (P 0.05). In group P, ascitic cultures from the abdominal drain tube resulted in no growth in 21 patients, methicillinresistant Staphylococcus aureus (MRSA) in 4, and Enterococcus faecium in 1. Of the 4 patients with ascitic MRSA, 2 had pretransplant MRSA colonization, and the other 2 suffered from MRSA sepsis induced by MRSA pneumonia. In the patient with ascitic Enterococcus, it was also cultivated in urine and pleural effusion. Therefore, there was no active bacterial infection in the peritoneal cavity in group P. There was no significant difference between the 3 groups in the mean postoperative hospital stay [group R, Figure 4. Regeneration of the anterior and posterior sections 1 and 4 months after MRL transplantation using the eptfe graft. (A) Compatible regeneration between the anterior and posterior sections. (B) Compatible regeneration between liver grafts with an intact eptfe graft and with an obstructive graft. Abbreviations: eptfe, expanded polytetrafluoroethylene; MRL, modified right liver days (range: days); group P, days (range: days); and group M, days (range: days); P 0.561]. In group P, a 65- old-year woman with hepatitis C related cirrhosis experienced a prolonged hospital stay (11.5 months after transplantation) due to rehabilitation for paraplegia, which had been noted before transplantation. One-Year Survival Rates. There was no patient death or graft loss (both 1-year survival rates were 100%) during the study period. The 6-month and 1-year patient survival rates were significantly better in groups P (both 100%) and M (100% and 94.1%) than those in group R (84.7% and 83.5%; P 0.05). The 6-month and 1-year graft survival rates were significantly better in groups P (both 100%) and M (both 100%) than those in group R (89.4% and 88.2%; P 0.05). Regarding the cause of death within 1 year, 1 patient died of a recurrence of hepatocellular carcinoma (HCC) with a functioning graft in group M, but in group R, 5 of 14 died of graft failure, 4 died of sepsis,

6 1164 YI ET AL. Figure 6. Posttransplant clinical regression of portal hypertension. (A) Amount of abdominal drainage after transplantation. The total amount of abdominal drainage over the 7 days after transplantation was significantly lower in group P than in the other 2 groups (*P < 0.05). (B) Platelet count after transplantation. It was higher in group P than in the other 2 groups over the 7 days after transplantation (*P < 0.05). Abbreviation: POD, postoperative day. Figure 5. Posttransplant liver function test: (A) serum ALT, (B) serum total bilirubin (*P < 0.05), and (C) prothrombin time. Abbreviations: ALT, alanine aminotransferase; INR, international normalized ratio; POD, postoperative day. 2 died of a recurrence of HCC, and 1 each died of heart failure, brain death, and acute respiratory failure. Postoperative Complications. Table 2 shows detailed information about the postoperative complications. No significant difference was observed between the 3 groups in terms of the incidence complications (P 0.05). Most common major complications were biliary complications. Detailed biliary complications were biliary stricture at anastomosis (n 28), bile leakage from the cut surface (n 5), bile peritonitis after T-tube removal (n 3), recurrent ascending cholangitis (n 1), and bile duct necrosis (n 1). In group P, there were 5 biliary strictures at anastomosis and 1 bile leak at anastomosis, which were resolved through nonsurgical management. No patient death occurred in group P, but it should be recalled that the follow-up period was shorter in this group. Chronic graft dysfunction did not develop during the first year after transplantation, but there were 2 cases of chronic graft dysfunction during the long-term follow-up in group M. A 49-year-old male patient who suffered from hepatitis B related cirrhosis with HCC underwent retransplantation because of fibrosing cholestatic hepatitis 3 years after the first ALDLT but died of graft dysfunction 1 year after whole liver retransplan-

7 EPTFE GRAFT IN RIGHT LIVER TRANSPLANTATION 1165 TABLE 2. Morbidity After Liver Transplantation According to the Graft Type Group R (n 85) Group P (n 26) Group M (n 17) Minor complications Nephrotoxicity (n 45) 34 (40.0%) 5 (19.2%) 6 (35.3%) Posttransplant diabetes mellitus (n 31) 20 (23.5%) 6 (23.1%) 5 (29.4%) Acute cellular rejection (n 22) 15 (17.6%) 4 (15.4%) 3 (17.6%) Neurotoxicity (n 18) 14 (16.4%) 2 (7.7%) 2 (11.8%) Systemic infection (n 14) 13 (14.2%) 1 (3.9%) Intraperitoneal bleeding (n 7) 2 (2.4%) 4 (15.4%) 1 (5.9%) Ileus (n 6) 6 (7.1%) Other (n 3) 2 (2.4%) 1 (3.9%) Major complications Biliary complication (n 38) 24 (28.2%) 6 (23.1%) 8 (47.1%) Prolonged ascites, pleural effusion, or fluid collection (n 18) 10 (11.8%) 5 (19.2%) 3 (17.6%) Systemic infection (n 18) 6 (7.1%) 10 (38.5%) 2 (11.8%) Intraperitoneal or gastrointestinal bleeding (n 13) 12 (14.1%) 1 (3.9%) Recurrence of original disease or de novo hepatitis (n 12) 7 (8.3%) 4 (15.4%) 1 (5.9%) Vascular complication (n 13)* 6 (7.1%) 3 (11.7%) 4 (23.5%) Other (n 10) 5 (5.9%) 4 (15.4%) 1 (5.9%) Patient deaths Acute graft dysfunction (n 5) 5 (5.9%) Chronic graft dysfunction (n 2) 2 (11.8%) Recurrence of hepatocellular carcinoma (n 7) 6 (7.1%) 1 (5.9%) Sepsis (n 5) 4 (4.7%) 1 (5.9%) Acute respiratory failure (n 1) 1 (1.2%) Heart failure (n 1) 1 (1.2%) Brain death (n 1) 1 (1.2%) *Not associated with drainage of middle hepatic vein tributaries. tation. A 77-year-old male patient who suffered from hepatitis C related cirrhosis with HCC underwent retransplantation because of fibrosing cholestatic hepatitis 2 years after the first ALDLT but died of septic shock 3 weeks after whole liver retransplantation. DISCUSSION Hepatic venous congestion in the anterior section due to MHV outflow deprivation in a conventional RL graft can be prevented by a vessel graft interpositioned between major MHV branches and the recipient s IVC. In addition to the recipient s autologous vessels, homologous vessel grafts, such as cryopreserved veins and arteries, have been used for this purpose Recently, cryopreserved vessels have been widely used because these do not require time-consuming dissection of the recipient, who usually has a poor general condition, and these vessels are usually large and long enough. 11 According to the literature, cryopreserved vessel grafts for MRL are associated with a good short-term outcome (2-3 months) after transplantation. 10,11 Long-term PRs for cryopreserved vessels are lower than those for autologous vessel grafts for portal vein conduits, femoral arteries, or hemodialysis access. 20 However, the longterm patency of the interpositional vessel for anterior section drainage is not an important issue because its dysfunction causes no clinical problems during longterm follow-up. As for the duration of patency, 1-2 weeks is enough to achieve adequate graft function. Damaged sinusoids in congested RL regions will recover and function because intrahepatic venous collateral can be expected to develop by day 7 after transplantation. 6 For the same reason, the long-term patency of eptfe grafts for anterior section drainage may not be an important issue. As expected, late dysfunction of eptfe grafts caused no congestion in the anterior section or clinical symptoms such as graft dysfunction in this study, although the 4-month PR was less than 50%. In addition, 6-month and 1-year survival rates in group P were similar to those of group M and better than those of group R. The compatible regeneration of the anterior section compared with that of the posterior section might reflect the successful reconstruction of MHV tributaries, even though graft regeneration is affected by many factors In addition, the difference in the regeneration rates was insignificant between the liver grafts with an obstructive eptfe graft and with an intact eptfe graft on CT examination. This is because regeneration occurs during the first 2 weeks after transplantation, as noted previously. It is known that cryopreserved vessels potentially improve patency and infection resistance versus eptfe grafts because a large percentage of luminal endothelial cells that remain viable at implantation are repopulated with recipient fibroblasts, which make them less

8 1166 YI ET AL. thrombogenic. 26 Therefore, the eptfe graft implant may be a second best option when a donor s condition does not allow an extended right hepatectomy and there are no cryopreserved vessels available. However, this concept has not been introduced to LDLT. This may be because liver transplantation is not a totally clean surgery, and prosthetic insertion in the bacterially contaminated operative field is associated with high rates of graft infection, which leads to pseudoaneurysm formation, or disruption with catastrophic hemorrhaging. In fact, the recipient peritoneal cavity is not an infectious bed, and gastrointestinal contamination is uncommon because of the preference for duct-to-duct biliary reconstruction. Thus, contamination is better tolerated with aggressive care and antibiotic therapy. In group P, only 1 patient underwent hepaticojejunostomy for biliary reconstruction because of advanced HCC. On the other hand, some reports in the literature have indicated that artificial vessel grafts can be used without serious infectious complications in patients with an infectious vascular complication, a traumatic penetrating vascular wound, or liver resection combined with IVC reconstruction Moreover, eptfe grafts are believed to be more suitable in a contaminated field because they are inert, nonthrombogenic, and impervious in comparison with other artificial vessel grafts. 31,32 Fortunately, no evidence was derived during this study of clinical infectious complications. In addition, eptfe grafts are readily available and are easily handled. 26,31-33 In terms of cost, a cryopreserved vessel graft is more expensive than an artificial graft. 26 Taking all this into consideration, we decided to use an artificial vessel graft for RL transplantation. In fact, the ischemic time was not prolonged in group P versus group R. The prolongation of the cold ischemic time of group P versus group R was around 10 minutes on the back table. Moreover, bench work is not technically demanding and does not require a learning curve. For classical MRL grafts, 3,6 the anastomosis of an interpositional vessel graft in the recipient is technically challenging because it is anastomosed to the recipient s deep-seat MHV stump, whereas eptfe grafts were separately anastomosed to the recipient IVC after a partial IVC clamp in half of the patients in group P. This method shortened the length of the vessel grafts and simplified the anastomosis during the warm ischemic time; the procedure took around 10 minutes. For the other half of the patients in group P, the outflow tract was a common orifice of an eptfe graft and graft RHV. This has some benefits. First, it is easy to do, and second, it minimizes the warm ischemic time because the eptfe graft is anastomosed to the graft RHV on the back table. The 4-month PR was 23.1% (3 of 13) when the eptfe graft was separately anastomosed to the IVC, whereas it was 53.8% (7 of 13) when the common orifice was made. Therefore, we have recently favored the latter anastomotic technique. In conclusion, the early PR of the eptfe graft was good, and late obstruction of the eptfe graft had no impact on congestion in the anterior section or patient survival. Therefore, the eptfe graft may be a useful interpositional material for anterior section drainage in modified RL transplantation without serious complications. ACKNOWLEDGMENT The authors thank Seung Wook Hwang for his artistic contribution. REFERENCES 1. Raia S, Nery JR, Mies S. Liver transplantation from live donors. Lancet 1989;2: Strong RW, Lynch SV, Ong TH, Matsunami H, Koido Y, Balderson GA. Successful liver transplantation from a living donor to her son. N Eng J Med 1990;322: Lee SG, Park GM, Hwang S, Lee YJ, Choi DN, Kim KH, et al. Congestion of right liver graft in living donor liver transplantation. Transplantation 2001;71: Lo CM, Fan ST, Liu CL, Lo RJ, Lau GK, Wei WI, et al. Extending the limit on the size of adult recipient in living donor liver transplantation using extended right lobe graft. Transplantation 1997;63: Suh KS, Yi NJ, Cho JY, Kwon CH, Minn KW, Lee KU. Technical refinement preserving segment 4 to donor in extended right hepatectomy. Hepatogastroenterology 2006;53: Lee SG, Park GM, Hwang S, Kim KH, Choi DN, Joo SH, et al. Modified right liver graft from a living donor to prevent congestion. Transplantation 2002;74: Cattral MS, Greig PD, Muradali D, Grant D. Reconstruction of middle hepatic vein of a living-donor right lobe liver graft with recipient left portal vein. Transplantation 2001; 71: Lee KW, Lee DS, Lee HH, Joh JW, Choi SH, Heo JS, et al. Interposition vein graft in living donor liver transplantation. 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