J Hepatobiliary Pancreat Sci (2015) 22:498–504 DOI: 10.1002/jhbp.240
ORIGINAL ARTICLE
Cryopreserved arterial grafts as a conduit in outflow reconstruction in living donor liver transplantation Mahmoud Abdelwahab Ali · Chee-Chien Yong · Hock-Liew Eng · Chih-Chi Wang · Ting-Lung Lin · Wei-Feng Li · Shih-Ho Wang · Chih-Che Lin · Anthony Yap · Chao-Long Chen Published online: 18 March 2015 © 2015 Japanese Society of Hepato-Biliary-Pancreatic Surgery
Abstract Background Few reports have addressed the use of cryopreserved arterial grafts (CAG) for anterior section drainage in right lobe living donor liver transplantation (RL LDLT), and the impact of atherosclerosis on patency rate (PR) is not well studied. Also, those reports have limited case numbers. The aim of the present study is to report the largest experience with CAG in outflow reconstruction in RL LDLT and the impact of atherosclerosis on its patency. Methods During 2010 and 2011, 62 of 243 patients who underwent LDLT received outflow reconstruction with CAG for RL grafts. Atherosclerosis in CAG was classified into early, intermediate and advanced lesions according to the classification adopted by the American Heart Association: group 1 with grafts having no atherosclerosis or early lesions; and group 2 with grafts having intermediate and advanced lesions. Patency rates of CAG correlated with atherosclerotic change of CAG were retrospectively analyzed.
Results The study group comprised 65 CAGs with 1, 3 and 6 months PR of 86.2%, 84.6% and 75.2% respectively. Histopathological examination was successful in 53 CAGs. The 1, 3 and 6 months PR of group with no/early atherosclerosis were 86%, 83.7% and 76.7%, respectively, while for groups with intermediate/advanced lesions they were 90%. However, there was no significant difference between the two groups (P = 0.384). Conclusions Cryopreserved arterial grafts can be used for outflow reconstruction in RL LDLT with a good patency rate. Atherosclerosis appears to have minimal effect on CAG patency, yet further studies with larger cohorts are needed to support our results.
M. A. Ali · C.-C. Yong · C.-C. Wang (✉) · T.-L. Lin · W.-F. Li · S.-H. Wang · C.-C. Lin · A. Yap · C.-L. Chen Liver Transplant Program and Department of Surgery, Kaohsiung Chang Gung Memorial Hospital, 123 Ta-Pei Road, Niao-Song, Kaohsiung 833, Taiwan e-mail: [email protected]
To overcome the scarcity of deceased donor organs, living donor liver transplantation (LDLT) is widely practiced for recipients with end stage liver disease in Asian countries. More and more right liver (RL) grafts are used for adult LDLT making the problem of anterior section drainage (RAS) a major concern. Anterior section congestion may result in postoperative graft dysfunction and even mortality [1, 2]. Using RL graft including the middle hepatic vein (MHV) or conserving MHV in the donor with outflow reconstruction of segment 5 and 8 hepatic veins (V5, V8) in the recipient are two techniques usually performed to prevent RAS congestion [3, 4]. As donor safety is the cornerstone in LDLT, RL grafts with interposition grafts for reconstruction of significant V5 and V8 is widely accepted, conserving the MHV to the donor [4]. Different graft materials are used as interposition grafts for hepatic venous outflow reconstruction [5–8]. Cryopreserved
H.-L. Eng Department of Pathology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan C.-C. Wang Department of Surgery, Chang Gung Memorial Hospital Chiayi, Chang Gung University College of Medicine, Kaohsiung, Taiwan This study was presented at the 2014 Joint International Congress of the International Liver Transplantation Society, the European Liver and Intestine Transplant Association and the Liver Intensive Care Group of Europe, London.
Keywords Arterial grafts · Cryopreservation · Living donor liver transplantation · Outflow reconstruction · Patency Introduction
J Hepatobiliary Pancreat Sci (2015) 22:498–504
venous grafts are one of the most commonly used conduits as interposition vascular graft. Increasing number of grafts used especially in high volume centers of LDLT with their depletion from tissue banks arouse the need for using cryopreserved arterial grafts (CAG) [5]. However, data available about CAGs and their patency are scarce and with limited case number. Moreover, the impact of atherosclerosis on their patency is not well studied. Discarding atherosclerotic arteries from cryopreservation is practiced in vascular surgery [9, 10] and endarterectomy of the atherosclerotic cryopreserved artery, which may result in damage of the CAG, was reported in hepatic venous outflow reconstruction [11]. To our knowledge, no published data are available concerning the use of atherosclerotic CAGs for RAS drainage in RL LDLT. In this article, we discuss the largest experience to date with using CAGs and the impact of atherosclerosis on their patency in outflow reconstruction of RL graft. Patients and methods Retrospective analysis of prospectively collected data for 243 cases that underwent LDLT during 2010 and 2011 in Kaohsiung Chang Gung Memorial Hospital showed that outflow reconstruction with CAGs for right lobe grafts was used in 62 patients, of which 49 patients (79%) were males. Mean age was 54.4 ± 6.5 years old (range 36–66). The indications for LDLT are shown in Table 1.
Criteria and techniques for MHV tributary reconstruction The operative techniques of the donor and recipient surgery were mentioned elsewhere [12, 13]. Reconstruction of V5, V8 and right inferior hepatic vein (RIHV) was considered when a significant portion of the RL graft was drained by MHV tributaries as estimated by simultaneous clamping of right hepatic artery and right hepatic vein (RHV) during donor hepatectomy, a small RL graft, V5 and V8 tributaries more than 5 mm in diameter, a graft size less than 40% of the recipient’s estimated standard liver volume, and the presence of severe portal hypertension [14]. In the RL graft side, CAG was anastomosed in an end-to-end fashion to MHV tributaries. Venoplasty and reconstruction of the interposition CAG are always carried out on the back table (Fig. 1a). Once the back-table procedure is completed, the graft is kept immersed in cold (4°C) histidine-tryptophan-ketoglutarate solution before implantation. The diseased liver of the recipient is removed using the inferior vena cava (IVC) sparing technique; the RHV and the common trunk of the middle and left hepatic veins (LHV) are clamped separately. The recipient’s IVC is cross clamped above the right renal vein and 2 cm above the opening of the hepatic veins followed by release of the
499 Table 1 Baseline characteristics of the study group Age (years) 54.4 ± 6.5 (range, 36–66) Gender Male 49 (79%) Female 13 (21%) Indication for transplantation HCC 30 (54%) HBV cirrhosis 15 (27%) HCV cirrhosis 7 (13%) Combined HBV and HCV cirrhosis 3 (6%) Virology HBV 32 (58%) HCV 17 (31%) Combined HBV and HCV 3 (6%) NBNC 3 (6%) Number of veins reconstructed by CAGs 1 33 (53%) 2 28 (45%) 3 1 (2%) Management of multiple reconstructions (n = 29) Single CAG 26 (90%) Double CAG 3 (10%) CAG cryopreserved arterial graft, HBV hepatitis B virus, HCC hepatocellular carcinoma, HCV hepatitis C virus
RHV and common trunk of MHV and LHV clamps. This maneuver allows better flushing of the IVC. The RHV is first reconstructed. This anastomosis between the graft RHV and the IVC opening is done by placing two corner stitches of 5–0 polydioxanone suture (PDS, Ethicon, Somerville, NJ, USA). The suture in the superior corner is tied once the graft and the vessels are correctly oriented. Afterwards, two 6–0 Prolene stay-sutures are placed on the mid part and anterior portion of both vessels. All of these sutures are pulled to their respective direction in order to properly visualize the posterior side of the anastomosis. To facilitate the posterior row anastomosis, an additional 6–0 Prolene stay-suture, placed in the mid portion of the vessel lumen, is used to better present the posterior row of the suture. Once the posterior row of the anastomosis is completed, the graft is flushed with cold Ringer’s lactate solution through the portal vein cannula in order to shorten warm ischemia time and to prevent air trapping within the vena cava, thereby avoiding air embolism. An alternative way to manage the hepatic venous outflow of RL graft is to make a venoplasty between CAG and RHV of the graft to create a single orifice. The single orifice is anastomosed directly to IVC. The RL perfusion is continued until the final knot where a growth factor is applied. If present, the anastomosis of RIHV is carried out after the RHV anastomosis. This anastomosis requires a venotomy in the IVC in order to create an oblique hole, which is slightly bigger (2–3 mm longer) than
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(a)
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MHV-LHV in an end-to-side fashion. In most situations, a venoplasty joining the lumina of the MHV and LHV is done in order to obtain one single wide orifice; redundant tissues are trimmed when necessary. The diameter of this newly created lumen should be wider than that of the lumen of the vascular graft. Often the MHV-LHV venoplasty is much wider than the opening of the interposition graft; this orifice can then be narrowed by approximating the venous edge on its sides. Once the venoplasty is completed, the interposition vascular graft, connected to one or both venous tributaries, is anastomosed using the classical previously described suturing technique. Technique of cryopreservation and thawing and selection of the CAG
(b)
The technique of cryopreservation and thawing was mentioned elsewhere [14, 15]. Limited availability of cadaveric grafts in Taiwan and the high rate of RL LDLT in our program urged us to use CAG in addition to cryopreserved venous grafts. Arterial grafts with apparent calcification were discarded. The selection criteria for using CAG for MHV tributary reconstruction included ABO compatibility, length, and side branches. Cryopreserved arterial grafts with a cryopreservation time >5 years were discarded according to protocol regulations of the Kaohsiung Chang Gung Memorial Hospital tissue bank. Classification of atherosclerosis (Fig. 2) Fig. 1 (a) Back table procedure of cryopreserved arterial graft (CAG) to segment 5 (V5) and 8 (V8) hepatic veins (HV) of middle hepatic vein (MHV). RHA right hepatic artery, RPV right portal vein. (b) Completion of anastomosis of cryopreserved arterial graft (CAG) to common trunk of middle hepatic vein (MHV) and left hepatic vein (LHV). IVC inferior vena cava, RHA right hepatic artery, RPV right portal vein, V5 HV segment 5 hepatic vein, V8 HV segment 8 hepatic vein
that of the lumen of the RIHV; the suture technique of this anastomosis is similar to the above-described one. The anastomosis of the interposition CAG, connected to V5, V8 or both tributaries, can be carried out separately following the realization of the RHV and RIHV anastomoses. In high degree of atherosclerosis, separation of intima is quite common. The technique of reconstruction suture includes sharp cut of edge at CAG and whole layer suture with both tributaries of hepatic veins at liver graft and veins on the recipient side the same as in reconstruction of the portal vein (PV) with intimal hyperplasia or partial thrombosis in the recipient’s PV. The orifice of CAG can be anastomosed to the stump of MHV-LHV in the recipient (Fig. 1b) or to a new opening of IVC instead of the common orifice of
Various degrees of atherosclerosis in the CAGs were classified by Stary et al. [16]; type I lesion, which is adaptive intimal thickening, type II lesion, which is characterized by intimal thickening, type III lesion, the intermediate stage between type II and type IV, type IV lesion (atheroma; a lesion that is potentially symptom-producing) usually have a lipid core may also contain thick layers of fibrous connective tissue, and type V lesions are classified into type Va; fibroatheroma, type Vb; calcified plaque and type Vc; fibrous plaque and type VI lesion; complicated lesions, are type IV or V lesions complicated by surface defect, and/or hematoma-hemorrhage, and/or thrombotic deposit. They were allocated into three main groups; early lesions comprising types I and II lesions, intermediate lesions, which refers to type III lesions, and advanced lesions, including types IV, V and VI, lesions. Follow up for patency of cryopreserved arterial grafts Graft patency was followed up using Doppler ultrasonography (DUS) daily for 2 weeks, weekly until discharge and
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Fig. 2 Various degrees of atherosclerotic changes in cryopreserved artery grafts (CAGs). (a) Type I atherosclerosis: adaptive intimal thickening. Vascular wall with early arteriosclerotic lesion shows mild intimal fibrous thickening and scattered macrophage foam cells. (b) Type II atherosclerosis: intimal fibrous thickening, myxoid degeneration and layers of macrophage foam cell (FC) and lipid-laden smooth muscle cells. (c) Type III atherosclerosis: the intermediate stage, lipid-laden cells, scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. (d) Type IV atherosclerosis: atherosclerotic plaque with fibrous thickened intima and necrotic core (NC) with degeneration and macrophage foam cells, accumulation of extracellular lipid particles. (e) Type Va atherosclerosis: containing several lipid cores, separated by multilayered thick fibrous connective tissue. (f) Type Vb (calcified) atherosclerosis: lipid cores and thick layers of fibrous connective tissue, dominated by mineralization (C)
then monthly until 6 months. Computed tomography angiography was performed 6 months after liver transplantation. A measurable velocity flow on DUS was considered an indicator of patency; when this was absent, a CAG was considered to be occluded. When the graft was found to be obstructed in one examination, the time of obstruction was estimated as the median between the last date of examination the graft was found to be functioning and the date of confirmation of obstruction.
Statistical analysis Continuous variables were expressed as means and standard deviations. Categorical variables were expressed as numbers and percentages. Patency rates were estimated using Kaplan–Meier method and were compared using log-rank test. The impact of atherosclerosis on graft patency was further demonstrated using Cox regression analysis. The analyses were performed with SPSS 16 for Windows (SPSS, Chicago, IL, USA).
Results The characteristics of the 62 cases of the study are summarized in Table 1. Forty-nine cases (79%) were males with mean age 54.4 ± 6.5 years (range, 36–66). The number of veins (V5, V8, and/or RIHV) drained by CAGs in each RL graft was as follows: single vein in 33 cases (53.2%), two veins in 28 cases (45.2%) and three veins in one case (1.6%). For multiple veins they were managed by single CAG in 26 (89.7%) cases and by double CAGs in three (10.3%) cases, so the total number of CAGs used was 65 grafts. The characteristics of the 65 CAGs used for outflow reconstruction are summarized in Table 2. The types of CAGs were as follows: 59 (90.8%) grafts were iliac arteries, three (4.6%) grafts were carotid arteries and one (1.5%) for each of aorta, innominate artery and carotid artery. The CAGs were anastomosed to the following veins on the RL graft side: V5 in 34 (52.3%) grafts, both V5 and V8 in 19 (29.2%) grafts, two V5 in seven (10.8%) grafts, V8 in two (3.1%) grafts, RIHV in two (3.1%) grafts and two RIHV in only one graft (1.5%). Most of the CAGs (40, 61.5%) were anastomosed to the common orifice of the MHV and LHV on the IVC side,
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Table 2 Characteristics of the cryopreserved arterial grafts (CAGs) used for outflow reconstruction Artery type Iliac artery Carotid artery Aorta/superior mesenteric artery/inominate artery Anastomosis to graft side V5 V5, V8 2 V5 V8 IRHV 2 IRHV Anastomosis to IVC side Common orifice of MHV and LHV New IVC venotomy All in one technique Grading of atherosclerosis No Type I Type II Type III Type IV Type V Not available Atherosclerosis on histopathology No atherosclerosis and early lesions Intermediate and advanced lesions Not available
59 (90%) 3 (5%) 1/1/1 (5%) 34 (52%) 19 (29%) 7 (11%) 2 (3%) 2 (3%) 1 (2%) 40 (62%) 19 (29%) 6 (9%) 1 (1.5%) 4 (6.2%) 38 (58.5%) 7 (10.8%) 2 (3.1%) 1 (1.5%) 12 (18.5%) 43 (66.2%) 10 (15.4%) 12 (18.5%)
IVC inferior vena cava, LHV left hepatic vein, MHV middle hepatic vein, RIHV right inferior hepatic vein, V5 segment 5 hepatic vein, V8 segment 8 hepatic vein
19 CAGs (29.1%) were anastomosed to a new IVC venotomy and six CAGs (9.2%) were anastomosed as a part of all in one technique [17].
Atherosclerosis No data were available for histopathological examination of 12 (18.5%) CAGs, and the remaining 53 grafts (81.5%) were reviewed by only one expert pathologist (HL Eng); 43 (66.2%) of which were found to have no atherosclerosis or early lesions, while 10 CAGs (15.4%) were found to have intermediate and advanced lesions (Table 2). The characteristics of the grafts with intermediate and advanced atherosclerosis are enlisted in Table 3. Patency rate of cryopreserved arterial grafts On comparing the patency of CAGs with that of the 33 cryopreserved venous grafts used in the same time interval, we found that 1-, 3-, and 6-month patency rates of the CAGs were 86.2%, 84.6% and 75.2%, respectively, and those of venous grafts were 93.9%, 84.8%, and 81.6%, respectively (P = 0.526) (Fig. 3a). The 53 CAGs for which histopathological data were available were classified into two groups according to the degree of atherosclerosis: group 1 with grafts having no atherosclerosis or early lesions and group 2 with grafts having intermediate and advanced atherosclerosis (Fig. 3b). The 1, 3 and 6 months patency rates of group 1 were 86%, 83.7% and 76.7%, respectively, while for group 2 they were 90%. However, no significant difference was present between the two groups (P = 0.384). Cox regression analysis was done also to study the impact of degree of atherosclerosis on graft patency without dichotomization, the results showed that increasing the degree of atherosclerosis has no impact on graft patency (P = 0.288, hazard ratio 1.088, 95% confidence interval 0.931–1.272). Discussion To date, this is the largest experience addressing the use of CAG in LDLT. We started using cryopreserved venous
Table 3 Characteristics of the cryopreserved arterial grafts (CAGs) with intermediate and advanced atherosclerosis No. CAG
Types of CAG
HV type
Stump at IVC of recipient
Grade of atherosclerosis
Patency
1 2 3 4 5 6 7 8 9 10
Iliac artery Aorta Iliac artery Iliac artery Iliac artery Iliac artery Iliac artery Common carotid artery Inominate artery Iliac artery
V5, V8 V5 V5, V8 V5, V8 2 V5 V5 V5, V8 V8 V5 V5, V8
M-LHV M-LHV M-LHV M-LHV IVC-venotomy M-LHV M-LHV M-LHV All in one IVC-venotomy
Type III (intermediate) Type III (intermediate) Type Vb (advanced) Type III (intermediate) Type IV (advanced) Type III (intermediate) Type III (intermediate) Type III (intermediate) Type IV (advanced) Type III (intermediate)
≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months 3 weeks 4 months (died) ≥ 6 months
IVC inferior vena cava, LHV left hepatic vein, MHV middle hepatic vein, RIHV right inferior hepatic vein, V5 segment 5 hepatic vein, V8 segment 8 hepatic vein
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Fig. 3 (a) The 1-, 3- and 6- month’s patency rates of the cryopreserved artery grafts (CAGs) and cryopreserved venous grafts (CVGs) were 86.2% and 93.9%, 84.6% and 84.8%, 75.2% and 81.6% respectively. (b) The CAGs were classified into two groups according to the degree of atherosclerosis: group 1 with grafts having no atherosclerosis or early lesions, and group 2 with grafts having intermediate and advanced atherosclerosis (Fig. 2). The 1-, 3- and 6-month patency rates of group 1 were 86%, 83.7% and 76.7%, respectively, while for group 2 they were 90%. However, no significant difference was present between the two groups (P = 0.384)
grafts exclusively in 2005 in our program. Cryopreserved venous grafts have many advantages: they have no donor site morbidity, not time consuming and variable lengths and sizes are available. The limited availability of cadaveric grafts in Taiwan and the high rate of RL LDLT in our program urged us to use CAG in addition. In a previous report, we showed our experience with cryopreserved vessel grafts and we found that there was no difference between arterial and venous grafts in terms of patency [14]. In this study, we studied CAGs separately after updating our cohort, increasing the number of grafts to be studied. We also investigated the impact of histopathological criteria of CAGs on graft patency. Cryopreserved arterial grafts have been used since the 1990s in vascular surgery for replacement of infected prosthesis and in revascularization of peripheral vessels when venous grafts are not available and the patient is at high risk of graft infection if synthetic grafts are used [9, 10, 18]. In contrast few reports about their use in outflow reconstruction in LDLT are available [5–7, 11]. Limited distensibility of the CAG’s in the low pressure hepatic venous flow may be responsible for the reluctance of its use. However, this disadvantage may be debatable. The thick wall of arterial grafts may be an advantage rather than a drawback because their configuration is not disturbed after restoration of hepatic venous flow [5]. Hwang et al. reported 6-month patency rates of cryopreserved iliac artery to be 35.2% (n = 43) [6]. In other graft types the 6-month patency is approximately 75% [6, 8]. In our series, the 6-month patency rate was 75.2%, and the 1- and 3-month patency rates were 86.2%, 84.6% respectively. In hepatic venous outflow reconstruction, only 1 month patency is sufficient to guard against graft congestion and failure, which is sufficient time for intrahepatic collaterals to open. Atherosclerosis may be an obstacle for using CAGs. In vascular surgery, atherosclerotic arteries are discarded from cryopreservation [9, 10]. This may be due to the high pressure
and flow velocity in arterial system and the fact that long term patency of grafts used is mandatory. Hepatic venous outflow, in contrast, has low pressure and only short term patency is needed to prevent hepatic congestion and graft failure. In RAS drainage, smooth thin plaque in CAGs is accepted, but for intermediate and advanced lesions, endarterectomy of atherosclerotic arterial allografts is done after cryopreservation, but this may result in damage of the graft and be discarded [5, 11]. In our program, arterial grafts with apparent calcification were discarded. Histological study of our procured grafts suggests that, although some degree of atherosclerotic changes can be seen, the pathologic findings remained within a clinically acceptable range, and with increasing the degree of atherosclerosis, their impact on patency was minimal. We classified the grafts into two groups: the first of which comprised grafts with no atherosclerosis or early lesions, and the second included grafts with intermediate and advanced lesions. There was no significant difference between the two groups in terms of 6 months patency (P = 0.384). Also, Cox regression analysis showed that increasing the degree of atherosclerosis has no impact on graft patency. Even for the three grafts with advanced atherosclerosis, none of them were obstructed during the 6-month follow up period (Table 3). Using cryopreserved arteries for hepatic venous outflow simply doubles the number of cryopreserved vessels available for reconstruction. Discarding atherosclerotic arteries or performing endarterectomy with potential damage to those vessels reduces the number of grafts available. This may not be an issue in western countries where deceased donor liver transplantation is widely practiced, but in high volume Asian centers where LDLT is mainly performed with insufficient deceased donor liver grafts and vascular grafts, more and more cases are in need for V5/8 reconstruction continuously depleting the cryopreserved grafts. This is a retrospective study with the largest number of CAGs studied, but with a small number of intermediate and
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advanced grade atherosclerotic CAGs. Further studies with more grafts are needed to support our results. However, we believe that those results may be beneficial in high volume centers depending mainly on cryopreserved vessel grafts for outflow reconstruction in LDLT. Conclusion Cryopreserved arterial grafts have good patency rate comparable to other types of grafts used for outflow reconstruction in RL LDLT. Although preliminary data show good patency of atherosclerotic CAGs, the small number in this series mandate further studies to support our results. Acknowledgment The authors thank Professors Makuuchi and Motomura of the Red Cross Hospital and The University of Tokyo for their help with the set-up of the KCGMH CVG Tissue Bank. Conflict of interest
None declared.
References 1. Lee S, Park K, Hwang S, Lee Y, Choi D, Kim K, et al. Congestion of right liver graft in living donor liver transplantation. Transplantation. 2001;71:812. 2. Kamei H, Fujimoto Y, Nagai S, Suda R, Yamamoto H, Kiuchi T. Impact of non-congestive graft size in living donor liver transplantation: new indicator for additional vein reconstruction in right liver graft. Liver Transpl. 2007;13:1295. 3. Lo CM, Fan ST, Liu CL, Wei WI, Lo RJ, Lai CL, et al. Adultto-adult living donor liver transplantation using extended right lobe grafts. Ann Surg. 1997;226:261. 4. Lee SG, Park KM, Hwang S, Kim KH, Choi D, Joo SH, et al. Modified right liver graft from a living donor to prevent congestion. Transplantation. 2002;74:54. 5. Hwang S, Lee SG, Ahn CS, Park KM, Kim KH, Moon DB, et al. Cryopreserved iliac artery is indispensable interposition graft material for middle hepatic vein reconstruction of right liver grafts. Liver Transpl. 2005;11:644. 6. Hwang S, Jung DH, Ha TY, Ahn CS, Moon DB, Kim KH, et al. Usability of ringed polytetrafluoroethylene grafts for middle hepatic vein reconstruction during living donor liver transplantation. Liver Transpl. 2012;18:955.
7. Pomposelli JJ, Akoad M, Khwaja K, Lewis WD, Cheah YL, Verbesey J, et al. Evolution of anterior segment reconstruction after live donor adult liver transplantation: a single-center experience. Clin Transplant. 2012;26:470. 8. Ikegami T, Soejima Y, Taketomi A, Yoshizumi T, Harada N, Uchiyama H, et al. Explanted portal vein grafts for middle hepatic vein tributaries in living-donor liver transplantation. Transplantation. 2007;84:836. 9. Jashari R, Van Hoeck B, Ngakam R, Goffin Y, Fan Y. Banking of cryopreserved arterial allografts in Europe: 20 years of operation in the European Homograft Bank (EHB) in Brussels. Cell Tissue Bank. 2013;14:589. 10. Bisdas T, Bredt M, Pichlmaier M, Aper T, Wilhelmi M, Bisdas S, et al. Eight-year experience with cryopreserved arterial homografts for the in situ reconstruction of abdominal aortic infections. J Vasc Surg. 2010;52:323. 11. Hwang S, Lee SG, Song GW, Lee HJ, Park JI, Ryu JH. Use of endarterectomized atherosclerotic artery allograft for hepatic vein reconstruction of living donor right lobe graft. Liver Transpl. 2007;13:306. 12. Chen CL, Chen YS, de Villa VH, Wang CC, Lin CL, Goto S, et al. Minimal blood loss living donor hepatectomy. Transplantation 2000;69:2580. 13. de Villa VH, Chen CL, Chen YS, Wang CC, Wang SH, Chiang YC, et al. Outflow tract reconstruction in living donor liver transplantation. Transplantation. 2000;70:1604. 14. Wang CC, Lopez-Valdes S, Lin TL, Yap A, Yong CC, Li WF, et al. Outcomes of long storage times for cryopreserved vascular grafts in outflow reconstruction in living donor liver transplantation. Liver Transpl. 2014;20:173. 15. Motomura N, Takamoto S, Murakawa T, Yoneda N, Shibusawa S, Maeda K, et al. Short-term result of aortic valve replacement with cryopreserved homograft valve in the University of Tokyo Tissue Bank. Artif Organs. 2002;26:449. 16. Stary HC, Chandler AB, Dinsmore RE, Fuster V, Glagov S, Insull W Jr, et al. A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association. Circulation. 1995;92:1355. 17. Chen CL, Yap AQ, Concejero AM, Liu CY. All-in-one sleeve patch graft venoplasty for multiple hepatic vein reconstruction in living donor liver transplantation. HPB (Oxford). 2012;14:274. 18. Rendal-Vazquez ME, San Luis Verdes A, Pombo Otero J, Segura Iglesias R, DomenechGarcia N, Andion Nunez C. Anatomopathological and immunohistochemical study of explanted cryopreserved arteries. Ann Vasc Surg. 2012;26:720.
ORIGINAL ARTICLE
Cryopreserved arterial grafts as a conduit in outflow reconstruction in living donor liver transplantation Mahmoud Abdelwahab Ali · Chee-Chien Yong · Hock-Liew Eng · Chih-Chi Wang · Ting-Lung Lin · Wei-Feng Li · Shih-Ho Wang · Chih-Che Lin · Anthony Yap · Chao-Long Chen Published online: 18 March 2015 © 2015 Japanese Society of Hepato-Biliary-Pancreatic Surgery
Abstract Background Few reports have addressed the use of cryopreserved arterial grafts (CAG) for anterior section drainage in right lobe living donor liver transplantation (RL LDLT), and the impact of atherosclerosis on patency rate (PR) is not well studied. Also, those reports have limited case numbers. The aim of the present study is to report the largest experience with CAG in outflow reconstruction in RL LDLT and the impact of atherosclerosis on its patency. Methods During 2010 and 2011, 62 of 243 patients who underwent LDLT received outflow reconstruction with CAG for RL grafts. Atherosclerosis in CAG was classified into early, intermediate and advanced lesions according to the classification adopted by the American Heart Association: group 1 with grafts having no atherosclerosis or early lesions; and group 2 with grafts having intermediate and advanced lesions. Patency rates of CAG correlated with atherosclerotic change of CAG were retrospectively analyzed.
Results The study group comprised 65 CAGs with 1, 3 and 6 months PR of 86.2%, 84.6% and 75.2% respectively. Histopathological examination was successful in 53 CAGs. The 1, 3 and 6 months PR of group with no/early atherosclerosis were 86%, 83.7% and 76.7%, respectively, while for groups with intermediate/advanced lesions they were 90%. However, there was no significant difference between the two groups (P = 0.384). Conclusions Cryopreserved arterial grafts can be used for outflow reconstruction in RL LDLT with a good patency rate. Atherosclerosis appears to have minimal effect on CAG patency, yet further studies with larger cohorts are needed to support our results.
M. A. Ali · C.-C. Yong · C.-C. Wang (✉) · T.-L. Lin · W.-F. Li · S.-H. Wang · C.-C. Lin · A. Yap · C.-L. Chen Liver Transplant Program and Department of Surgery, Kaohsiung Chang Gung Memorial Hospital, 123 Ta-Pei Road, Niao-Song, Kaohsiung 833, Taiwan e-mail: [email protected]
To overcome the scarcity of deceased donor organs, living donor liver transplantation (LDLT) is widely practiced for recipients with end stage liver disease in Asian countries. More and more right liver (RL) grafts are used for adult LDLT making the problem of anterior section drainage (RAS) a major concern. Anterior section congestion may result in postoperative graft dysfunction and even mortality [1, 2]. Using RL graft including the middle hepatic vein (MHV) or conserving MHV in the donor with outflow reconstruction of segment 5 and 8 hepatic veins (V5, V8) in the recipient are two techniques usually performed to prevent RAS congestion [3, 4]. As donor safety is the cornerstone in LDLT, RL grafts with interposition grafts for reconstruction of significant V5 and V8 is widely accepted, conserving the MHV to the donor [4]. Different graft materials are used as interposition grafts for hepatic venous outflow reconstruction [5–8]. Cryopreserved
H.-L. Eng Department of Pathology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan C.-C. Wang Department of Surgery, Chang Gung Memorial Hospital Chiayi, Chang Gung University College of Medicine, Kaohsiung, Taiwan This study was presented at the 2014 Joint International Congress of the International Liver Transplantation Society, the European Liver and Intestine Transplant Association and the Liver Intensive Care Group of Europe, London.
Keywords Arterial grafts · Cryopreservation · Living donor liver transplantation · Outflow reconstruction · Patency Introduction
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venous grafts are one of the most commonly used conduits as interposition vascular graft. Increasing number of grafts used especially in high volume centers of LDLT with their depletion from tissue banks arouse the need for using cryopreserved arterial grafts (CAG) [5]. However, data available about CAGs and their patency are scarce and with limited case number. Moreover, the impact of atherosclerosis on their patency is not well studied. Discarding atherosclerotic arteries from cryopreservation is practiced in vascular surgery [9, 10] and endarterectomy of the atherosclerotic cryopreserved artery, which may result in damage of the CAG, was reported in hepatic venous outflow reconstruction [11]. To our knowledge, no published data are available concerning the use of atherosclerotic CAGs for RAS drainage in RL LDLT. In this article, we discuss the largest experience to date with using CAGs and the impact of atherosclerosis on their patency in outflow reconstruction of RL graft. Patients and methods Retrospective analysis of prospectively collected data for 243 cases that underwent LDLT during 2010 and 2011 in Kaohsiung Chang Gung Memorial Hospital showed that outflow reconstruction with CAGs for right lobe grafts was used in 62 patients, of which 49 patients (79%) were males. Mean age was 54.4 ± 6.5 years old (range 36–66). The indications for LDLT are shown in Table 1.
Criteria and techniques for MHV tributary reconstruction The operative techniques of the donor and recipient surgery were mentioned elsewhere [12, 13]. Reconstruction of V5, V8 and right inferior hepatic vein (RIHV) was considered when a significant portion of the RL graft was drained by MHV tributaries as estimated by simultaneous clamping of right hepatic artery and right hepatic vein (RHV) during donor hepatectomy, a small RL graft, V5 and V8 tributaries more than 5 mm in diameter, a graft size less than 40% of the recipient’s estimated standard liver volume, and the presence of severe portal hypertension [14]. In the RL graft side, CAG was anastomosed in an end-to-end fashion to MHV tributaries. Venoplasty and reconstruction of the interposition CAG are always carried out on the back table (Fig. 1a). Once the back-table procedure is completed, the graft is kept immersed in cold (4°C) histidine-tryptophan-ketoglutarate solution before implantation. The diseased liver of the recipient is removed using the inferior vena cava (IVC) sparing technique; the RHV and the common trunk of the middle and left hepatic veins (LHV) are clamped separately. The recipient’s IVC is cross clamped above the right renal vein and 2 cm above the opening of the hepatic veins followed by release of the
499 Table 1 Baseline characteristics of the study group Age (years) 54.4 ± 6.5 (range, 36–66) Gender Male 49 (79%) Female 13 (21%) Indication for transplantation HCC 30 (54%) HBV cirrhosis 15 (27%) HCV cirrhosis 7 (13%) Combined HBV and HCV cirrhosis 3 (6%) Virology HBV 32 (58%) HCV 17 (31%) Combined HBV and HCV 3 (6%) NBNC 3 (6%) Number of veins reconstructed by CAGs 1 33 (53%) 2 28 (45%) 3 1 (2%) Management of multiple reconstructions (n = 29) Single CAG 26 (90%) Double CAG 3 (10%) CAG cryopreserved arterial graft, HBV hepatitis B virus, HCC hepatocellular carcinoma, HCV hepatitis C virus
RHV and common trunk of MHV and LHV clamps. This maneuver allows better flushing of the IVC. The RHV is first reconstructed. This anastomosis between the graft RHV and the IVC opening is done by placing two corner stitches of 5–0 polydioxanone suture (PDS, Ethicon, Somerville, NJ, USA). The suture in the superior corner is tied once the graft and the vessels are correctly oriented. Afterwards, two 6–0 Prolene stay-sutures are placed on the mid part and anterior portion of both vessels. All of these sutures are pulled to their respective direction in order to properly visualize the posterior side of the anastomosis. To facilitate the posterior row anastomosis, an additional 6–0 Prolene stay-suture, placed in the mid portion of the vessel lumen, is used to better present the posterior row of the suture. Once the posterior row of the anastomosis is completed, the graft is flushed with cold Ringer’s lactate solution through the portal vein cannula in order to shorten warm ischemia time and to prevent air trapping within the vena cava, thereby avoiding air embolism. An alternative way to manage the hepatic venous outflow of RL graft is to make a venoplasty between CAG and RHV of the graft to create a single orifice. The single orifice is anastomosed directly to IVC. The RL perfusion is continued until the final knot where a growth factor is applied. If present, the anastomosis of RIHV is carried out after the RHV anastomosis. This anastomosis requires a venotomy in the IVC in order to create an oblique hole, which is slightly bigger (2–3 mm longer) than
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(a)
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MHV-LHV in an end-to-side fashion. In most situations, a venoplasty joining the lumina of the MHV and LHV is done in order to obtain one single wide orifice; redundant tissues are trimmed when necessary. The diameter of this newly created lumen should be wider than that of the lumen of the vascular graft. Often the MHV-LHV venoplasty is much wider than the opening of the interposition graft; this orifice can then be narrowed by approximating the venous edge on its sides. Once the venoplasty is completed, the interposition vascular graft, connected to one or both venous tributaries, is anastomosed using the classical previously described suturing technique. Technique of cryopreservation and thawing and selection of the CAG
(b)
The technique of cryopreservation and thawing was mentioned elsewhere [14, 15]. Limited availability of cadaveric grafts in Taiwan and the high rate of RL LDLT in our program urged us to use CAG in addition to cryopreserved venous grafts. Arterial grafts with apparent calcification were discarded. The selection criteria for using CAG for MHV tributary reconstruction included ABO compatibility, length, and side branches. Cryopreserved arterial grafts with a cryopreservation time >5 years were discarded according to protocol regulations of the Kaohsiung Chang Gung Memorial Hospital tissue bank. Classification of atherosclerosis (Fig. 2) Fig. 1 (a) Back table procedure of cryopreserved arterial graft (CAG) to segment 5 (V5) and 8 (V8) hepatic veins (HV) of middle hepatic vein (MHV). RHA right hepatic artery, RPV right portal vein. (b) Completion of anastomosis of cryopreserved arterial graft (CAG) to common trunk of middle hepatic vein (MHV) and left hepatic vein (LHV). IVC inferior vena cava, RHA right hepatic artery, RPV right portal vein, V5 HV segment 5 hepatic vein, V8 HV segment 8 hepatic vein
that of the lumen of the RIHV; the suture technique of this anastomosis is similar to the above-described one. The anastomosis of the interposition CAG, connected to V5, V8 or both tributaries, can be carried out separately following the realization of the RHV and RIHV anastomoses. In high degree of atherosclerosis, separation of intima is quite common. The technique of reconstruction suture includes sharp cut of edge at CAG and whole layer suture with both tributaries of hepatic veins at liver graft and veins on the recipient side the same as in reconstruction of the portal vein (PV) with intimal hyperplasia or partial thrombosis in the recipient’s PV. The orifice of CAG can be anastomosed to the stump of MHV-LHV in the recipient (Fig. 1b) or to a new opening of IVC instead of the common orifice of
Various degrees of atherosclerosis in the CAGs were classified by Stary et al. [16]; type I lesion, which is adaptive intimal thickening, type II lesion, which is characterized by intimal thickening, type III lesion, the intermediate stage between type II and type IV, type IV lesion (atheroma; a lesion that is potentially symptom-producing) usually have a lipid core may also contain thick layers of fibrous connective tissue, and type V lesions are classified into type Va; fibroatheroma, type Vb; calcified plaque and type Vc; fibrous plaque and type VI lesion; complicated lesions, are type IV or V lesions complicated by surface defect, and/or hematoma-hemorrhage, and/or thrombotic deposit. They were allocated into three main groups; early lesions comprising types I and II lesions, intermediate lesions, which refers to type III lesions, and advanced lesions, including types IV, V and VI, lesions. Follow up for patency of cryopreserved arterial grafts Graft patency was followed up using Doppler ultrasonography (DUS) daily for 2 weeks, weekly until discharge and
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Fig. 2 Various degrees of atherosclerotic changes in cryopreserved artery grafts (CAGs). (a) Type I atherosclerosis: adaptive intimal thickening. Vascular wall with early arteriosclerotic lesion shows mild intimal fibrous thickening and scattered macrophage foam cells. (b) Type II atherosclerosis: intimal fibrous thickening, myxoid degeneration and layers of macrophage foam cell (FC) and lipid-laden smooth muscle cells. (c) Type III atherosclerosis: the intermediate stage, lipid-laden cells, scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. (d) Type IV atherosclerosis: atherosclerotic plaque with fibrous thickened intima and necrotic core (NC) with degeneration and macrophage foam cells, accumulation of extracellular lipid particles. (e) Type Va atherosclerosis: containing several lipid cores, separated by multilayered thick fibrous connective tissue. (f) Type Vb (calcified) atherosclerosis: lipid cores and thick layers of fibrous connective tissue, dominated by mineralization (C)
then monthly until 6 months. Computed tomography angiography was performed 6 months after liver transplantation. A measurable velocity flow on DUS was considered an indicator of patency; when this was absent, a CAG was considered to be occluded. When the graft was found to be obstructed in one examination, the time of obstruction was estimated as the median between the last date of examination the graft was found to be functioning and the date of confirmation of obstruction.
Statistical analysis Continuous variables were expressed as means and standard deviations. Categorical variables were expressed as numbers and percentages. Patency rates were estimated using Kaplan–Meier method and were compared using log-rank test. The impact of atherosclerosis on graft patency was further demonstrated using Cox regression analysis. The analyses were performed with SPSS 16 for Windows (SPSS, Chicago, IL, USA).
Results The characteristics of the 62 cases of the study are summarized in Table 1. Forty-nine cases (79%) were males with mean age 54.4 ± 6.5 years (range, 36–66). The number of veins (V5, V8, and/or RIHV) drained by CAGs in each RL graft was as follows: single vein in 33 cases (53.2%), two veins in 28 cases (45.2%) and three veins in one case (1.6%). For multiple veins they were managed by single CAG in 26 (89.7%) cases and by double CAGs in three (10.3%) cases, so the total number of CAGs used was 65 grafts. The characteristics of the 65 CAGs used for outflow reconstruction are summarized in Table 2. The types of CAGs were as follows: 59 (90.8%) grafts were iliac arteries, three (4.6%) grafts were carotid arteries and one (1.5%) for each of aorta, innominate artery and carotid artery. The CAGs were anastomosed to the following veins on the RL graft side: V5 in 34 (52.3%) grafts, both V5 and V8 in 19 (29.2%) grafts, two V5 in seven (10.8%) grafts, V8 in two (3.1%) grafts, RIHV in two (3.1%) grafts and two RIHV in only one graft (1.5%). Most of the CAGs (40, 61.5%) were anastomosed to the common orifice of the MHV and LHV on the IVC side,
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Table 2 Characteristics of the cryopreserved arterial grafts (CAGs) used for outflow reconstruction Artery type Iliac artery Carotid artery Aorta/superior mesenteric artery/inominate artery Anastomosis to graft side V5 V5, V8 2 V5 V8 IRHV 2 IRHV Anastomosis to IVC side Common orifice of MHV and LHV New IVC venotomy All in one technique Grading of atherosclerosis No Type I Type II Type III Type IV Type V Not available Atherosclerosis on histopathology No atherosclerosis and early lesions Intermediate and advanced lesions Not available
59 (90%) 3 (5%) 1/1/1 (5%) 34 (52%) 19 (29%) 7 (11%) 2 (3%) 2 (3%) 1 (2%) 40 (62%) 19 (29%) 6 (9%) 1 (1.5%) 4 (6.2%) 38 (58.5%) 7 (10.8%) 2 (3.1%) 1 (1.5%) 12 (18.5%) 43 (66.2%) 10 (15.4%) 12 (18.5%)
IVC inferior vena cava, LHV left hepatic vein, MHV middle hepatic vein, RIHV right inferior hepatic vein, V5 segment 5 hepatic vein, V8 segment 8 hepatic vein
19 CAGs (29.1%) were anastomosed to a new IVC venotomy and six CAGs (9.2%) were anastomosed as a part of all in one technique [17].
Atherosclerosis No data were available for histopathological examination of 12 (18.5%) CAGs, and the remaining 53 grafts (81.5%) were reviewed by only one expert pathologist (HL Eng); 43 (66.2%) of which were found to have no atherosclerosis or early lesions, while 10 CAGs (15.4%) were found to have intermediate and advanced lesions (Table 2). The characteristics of the grafts with intermediate and advanced atherosclerosis are enlisted in Table 3. Patency rate of cryopreserved arterial grafts On comparing the patency of CAGs with that of the 33 cryopreserved venous grafts used in the same time interval, we found that 1-, 3-, and 6-month patency rates of the CAGs were 86.2%, 84.6% and 75.2%, respectively, and those of venous grafts were 93.9%, 84.8%, and 81.6%, respectively (P = 0.526) (Fig. 3a). The 53 CAGs for which histopathological data were available were classified into two groups according to the degree of atherosclerosis: group 1 with grafts having no atherosclerosis or early lesions and group 2 with grafts having intermediate and advanced atherosclerosis (Fig. 3b). The 1, 3 and 6 months patency rates of group 1 were 86%, 83.7% and 76.7%, respectively, while for group 2 they were 90%. However, no significant difference was present between the two groups (P = 0.384). Cox regression analysis was done also to study the impact of degree of atherosclerosis on graft patency without dichotomization, the results showed that increasing the degree of atherosclerosis has no impact on graft patency (P = 0.288, hazard ratio 1.088, 95% confidence interval 0.931–1.272). Discussion To date, this is the largest experience addressing the use of CAG in LDLT. We started using cryopreserved venous
Table 3 Characteristics of the cryopreserved arterial grafts (CAGs) with intermediate and advanced atherosclerosis No. CAG
Types of CAG
HV type
Stump at IVC of recipient
Grade of atherosclerosis
Patency
1 2 3 4 5 6 7 8 9 10
Iliac artery Aorta Iliac artery Iliac artery Iliac artery Iliac artery Iliac artery Common carotid artery Inominate artery Iliac artery
V5, V8 V5 V5, V8 V5, V8 2 V5 V5 V5, V8 V8 V5 V5, V8
M-LHV M-LHV M-LHV M-LHV IVC-venotomy M-LHV M-LHV M-LHV All in one IVC-venotomy
Type III (intermediate) Type III (intermediate) Type Vb (advanced) Type III (intermediate) Type IV (advanced) Type III (intermediate) Type III (intermediate) Type III (intermediate) Type IV (advanced) Type III (intermediate)
≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months ≥ 6 months 3 weeks 4 months (died) ≥ 6 months
IVC inferior vena cava, LHV left hepatic vein, MHV middle hepatic vein, RIHV right inferior hepatic vein, V5 segment 5 hepatic vein, V8 segment 8 hepatic vein
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Fig. 3 (a) The 1-, 3- and 6- month’s patency rates of the cryopreserved artery grafts (CAGs) and cryopreserved venous grafts (CVGs) were 86.2% and 93.9%, 84.6% and 84.8%, 75.2% and 81.6% respectively. (b) The CAGs were classified into two groups according to the degree of atherosclerosis: group 1 with grafts having no atherosclerosis or early lesions, and group 2 with grafts having intermediate and advanced atherosclerosis (Fig. 2). The 1-, 3- and 6-month patency rates of group 1 were 86%, 83.7% and 76.7%, respectively, while for group 2 they were 90%. However, no significant difference was present between the two groups (P = 0.384)
grafts exclusively in 2005 in our program. Cryopreserved venous grafts have many advantages: they have no donor site morbidity, not time consuming and variable lengths and sizes are available. The limited availability of cadaveric grafts in Taiwan and the high rate of RL LDLT in our program urged us to use CAG in addition. In a previous report, we showed our experience with cryopreserved vessel grafts and we found that there was no difference between arterial and venous grafts in terms of patency [14]. In this study, we studied CAGs separately after updating our cohort, increasing the number of grafts to be studied. We also investigated the impact of histopathological criteria of CAGs on graft patency. Cryopreserved arterial grafts have been used since the 1990s in vascular surgery for replacement of infected prosthesis and in revascularization of peripheral vessels when venous grafts are not available and the patient is at high risk of graft infection if synthetic grafts are used [9, 10, 18]. In contrast few reports about their use in outflow reconstruction in LDLT are available [5–7, 11]. Limited distensibility of the CAG’s in the low pressure hepatic venous flow may be responsible for the reluctance of its use. However, this disadvantage may be debatable. The thick wall of arterial grafts may be an advantage rather than a drawback because their configuration is not disturbed after restoration of hepatic venous flow [5]. Hwang et al. reported 6-month patency rates of cryopreserved iliac artery to be 35.2% (n = 43) [6]. In other graft types the 6-month patency is approximately 75% [6, 8]. In our series, the 6-month patency rate was 75.2%, and the 1- and 3-month patency rates were 86.2%, 84.6% respectively. In hepatic venous outflow reconstruction, only 1 month patency is sufficient to guard against graft congestion and failure, which is sufficient time for intrahepatic collaterals to open. Atherosclerosis may be an obstacle for using CAGs. In vascular surgery, atherosclerotic arteries are discarded from cryopreservation [9, 10]. This may be due to the high pressure
and flow velocity in arterial system and the fact that long term patency of grafts used is mandatory. Hepatic venous outflow, in contrast, has low pressure and only short term patency is needed to prevent hepatic congestion and graft failure. In RAS drainage, smooth thin plaque in CAGs is accepted, but for intermediate and advanced lesions, endarterectomy of atherosclerotic arterial allografts is done after cryopreservation, but this may result in damage of the graft and be discarded [5, 11]. In our program, arterial grafts with apparent calcification were discarded. Histological study of our procured grafts suggests that, although some degree of atherosclerotic changes can be seen, the pathologic findings remained within a clinically acceptable range, and with increasing the degree of atherosclerosis, their impact on patency was minimal. We classified the grafts into two groups: the first of which comprised grafts with no atherosclerosis or early lesions, and the second included grafts with intermediate and advanced lesions. There was no significant difference between the two groups in terms of 6 months patency (P = 0.384). Also, Cox regression analysis showed that increasing the degree of atherosclerosis has no impact on graft patency. Even for the three grafts with advanced atherosclerosis, none of them were obstructed during the 6-month follow up period (Table 3). Using cryopreserved arteries for hepatic venous outflow simply doubles the number of cryopreserved vessels available for reconstruction. Discarding atherosclerotic arteries or performing endarterectomy with potential damage to those vessels reduces the number of grafts available. This may not be an issue in western countries where deceased donor liver transplantation is widely practiced, but in high volume Asian centers where LDLT is mainly performed with insufficient deceased donor liver grafts and vascular grafts, more and more cases are in need for V5/8 reconstruction continuously depleting the cryopreserved grafts. This is a retrospective study with the largest number of CAGs studied, but with a small number of intermediate and
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advanced grade atherosclerotic CAGs. Further studies with more grafts are needed to support our results. However, we believe that those results may be beneficial in high volume centers depending mainly on cryopreserved vessel grafts for outflow reconstruction in LDLT. Conclusion Cryopreserved arterial grafts have good patency rate comparable to other types of grafts used for outflow reconstruction in RL LDLT. Although preliminary data show good patency of atherosclerotic CAGs, the small number in this series mandate further studies to support our results. Acknowledgment The authors thank Professors Makuuchi and Motomura of the Red Cross Hospital and The University of Tokyo for their help with the set-up of the KCGMH CVG Tissue Bank. Conflict of interest
None declared.
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