Published online before print April 21, 2005, 10.1148/radiol.2353040489
(Radiology 2005;235:1078-1083.)
© RSNA, 2005
Vascular and Interventional Radiology |
Percutaneous Transhepatic Balloon Dilation of Portal Venous Stenosis in Patients with Living Donor Liver Transplantation1
Toyomichi Shibata, MD,
Kyo Itoh, MD,
Takeshi Kubo, MD,
Yoji Maetani, MD,
Toshiya Shibata, MD,
Kaori Togashi, MD and
Koichi Tanaka, MD
1 From the Departments of Radiology (Toyomichi Shibata, K.I., T.K., Y.M., Toshiya Shibata, K. Togashi) and Transplantation and Immunology (K. Tanaka), Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. From the 2003 RSNA Annual Meeting. Received March 15, 2004; revision requested May 25; revision received July 18; accepted August 18. Address correspondence to Toyomichi Shibata (e-mail: toyomich@kuhp.kyoto-u.ac.jp).
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ABSTRACT
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PURPOSE: To retrospectively evaluate the long-term effectiveness of percutaneous transhepatic balloon dilation of portal venous stenosis in patients who have undergone living donor liver transplantation.
MATERIALS AND METHODS: Institutional review board approval and informed consent were not required. From June 1996 to August 2003, obstructed portal venous blood flow was diagnosed in 45 patients (21 male, 24 female) with a history of living donor liver transplantation; patients ranged in age from 9 months to 61 years (mean, 9.2 years). All stenoses occurred in the extrahepatic portal vein near the anastomosis of the portal vein. All dilation procedures were performed with percutaneous transhepatic puncture of the intrahepatic portal vein and subsequent balloon dilation of the stenosis. Patients who experienced recurrent stenosis underwent another balloon dilation session. Intravascular metallic stents were not deployed because of the possible need for repeated transplantation. The authors used paired t tests to compare patients successfully treated with one venoplasty procedure and those requiring repeated venoplasty, with regard to age and stenosis diameter percentages before and after the initial procedure.
RESULTS: Percutaneous balloon dilation was technically successful in 35 of 45 patients. In the remaining 10 patients, portal venous thrombotic occlusion precluded access to the mesenteric side of the portal vein. Twenty-five patients were successfully treated with a single session of balloon dilation (group 1). Results at follow-up ultrasonography revealed restenosis in 10 of 35 patients. Recurrent stenosis was resolved by means of repeated balloon dilation in nine patients (group 2). There were no significant differences between groups 1 and 2 in age (P = .87) or in stenosis diameter percentages before (P = .053) or after (P = .95) the initial procedure.
CONCLUSION: Percutaneous transhepatic balloon dilation seems to be an effective method for treatment of portal venous stenosis after living donor liver transplantation.
© RSNA, 2005
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INTRODUCTION
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Liver transplantation is an important option in managing the end stages of liver diseases. Living donor liver transplantation has recently been introduced to solve the problem of liver graft shortages. Improvements in surgical techniques and immunosuppression have contributed to improved outcomes after transplantation, but biliary and vascular complications are still important causes of graft failure in liver transplant recipients (1,2). Percutaneous transluminal angioplasty is an established, safe, and effective method for treating anastomotic vascular stenosis after liver transplantation (3–5). In this study, our purpose was to retrospectively evaluate the long-term effectiveness of percutaneous transhepatic balloon dilation of portal venous stenosis in patients who have undergone living donor liver transplantation.
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MATERIALS AND METHODS
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Patients
Our institutional review board did not require its approval or patients’ informed consent for this retrospective study. Between June 1996 and August 2003, 58 patients with a history of living donor liver transplantation were suspected of having obstructed portal venous blood flow because of clinical signs, such as hematemesis or ascites, or findings at routine Doppler and B-mode ultrasonography (US), computed tomography (CT), and/or magnetic resonance imaging. In 45 patients, portal venous stenosis was confirmed by means of percutaneous transhepatic portography followed by interventional procedures. All stenoses occurred in the extrahepatic portal vein near the anastomosis of the portal vein and/or the interposition venous graft.
The 45 patients ranged in age from 9 months to 61 years (mean, 9.2 years) and included 21 male and 24 female patients. The underlying disease most frequently observed in the recipients was biliary atresia (n = 32). Other diseases included fulminant hepatitis (n = 2), Alagille syndrome (n = 2), hepatoblastoma (n = 2), liver cirrhosis (n = 2), Wilson disease (n = 1), hepatocellular carcinoma (n = 1), liver fibrosis (n = 1), cholangiectasis (n = 1), and glucose storage disease (n = 1). The interval between transplantation and initial intervention ranged from 9 days to 98.3 months (mean, 18.0 months). Lateral segments of the left lobe had been used as grafts in 36 patients, including one patient who received an auxiliary partial orthotopic liver transplant, while nine patients had received right lobe grafts. Portal venous anastomosis was performed with end-to-end anastomosis. In four patients the remaining portal vein was short, and a donor’s vein (ovarian or external iliac) was used as an interposition venous graft.
Balloon Dilation
Before treatment, informed consent was obtained from all patients or their parents. In pediatric patients (age, <18 years), the procedure was conducted with use of general anesthesia, while in adults (age, 
18 years), the procedure was conducted after administration of local anesthetic and/or intravenous administration of 15 mg pentazocine (Sosegone; Yamanouchi Pharmaceuticals, Tokyo, Japan).
Two authors performed percutaneous transhepatic balloon dilation. One author (K.I.) had 16 years of experience in interventional radiology, and the other (Toyomichi Shibata) had 6 years of experience. The portal vein was punctured with an 18-gauge needle (Hanako, Saitama, Japan) under US and fluoroscopic guidance. After the portal vein was entered, a sheath was inserted into the vein with a 7-F interventional sheath introducer (Brite Tip; Cordis, Roden, the Netherlands). A 0.032-inch angled hydrophilic guidewire (Terumo, Tokyo, Japan) and a 5-F catheter with a hockey stick–shaped tip (Cook, Bloomington, Ind) were then used to traverse the stenotic segment.
After passage through the stenosis, venograms of the portal and superior mesenteric veins were obtained. To confirm the site and degree of stenosis, balloon dilation was attempted with a percutaneous transluminal angioplasty catheter (Powerflex Plus; Cordis). The balloon had a diameter of 6–12 mm, which was altered according to the diameter of the mesenteric side of the stenosis, and a length of 40 mm. Sixty seconds of balloon inflation with an atmospheric pressure of 10 atm was exerted on the stenotic segment. Dilation was performed twice, after which a second portal venogram was obtained to evaluate the effectiveness of the procedure. On completion of these interventional procedures, the sheath tract was occluded with collagen material (Avitene; Zeria Pharmaceuticals, Tokyo, Japan), and prophylactic anticoagulation was commenced. Warfarin (Eisai, Tokyo, Japan) was administered to produce an international normalized ratio of 1.0–1.5.
In all cases, the stenosis diameter percentage was measured before and after balloon dilation, and stenoses of more than 50% were considered hemodynamically significant. In 16 cases, pressure gradients in the stenosis were obtained before and after balloon dilation. In many of the initial cases, we performed the interventional procedures without obtaining a pressure gradient. Pressure gradients of more than 3 mm Hg were defined as significant.
Effectiveness of Dilation
Doppler and B-mode abdominal US was performed every month after completion of the interventional procedure. All US examinations were performed by one of the board-certified physicians in our institution, who all had more than 5 years of experience in performing vascular US. US was performed with a real-time scanner and a 3.5-MHz transducer (model SSD-5500; Aloka, Tokyo, Japan). The shape of the portal vein was assessed with B-mode US, and the blood flow was assessed with Doppler US.
CT was performed with a Hispeed Advantage scanner (GE Medical Systems, Milwaukee, Wis) in patients who had clinical signs of portal venous stenosis and in whom US failed to depict the portal vein because of the intervening intestine. At contrast material–enhanced CT, portal venous phase scans were obtained after the injection of iopamidol (2 mL per kilogram of body weight, 300 mg of iodine per milliliter) (Iopamiron 300; Nihon Schering, Osaka, Japan). The portal venous phase was attained 60 seconds after the initiation of contrast material injection with a mechanical injector (Auto Enhance A-50; Nemoto Kyorindo, Tokyo, Japan) at a rate of 1–3 mL/sec. The CT scans were interpreted by three abdominal radiologists (T.K., Y.M., and Toshiya Shibata), each with more than 5 years of experience in abdominal imaging.
Patients with recurrent stenosis underwent another balloon dilation session performed by the aforementioned authors. Intravascular metallic stents were not deployed because of the possible need for repeated transplantation. The follow-up period ranged from 1.0 to 73.9 months (mean, 24.8 months). We divided the patients into two groups to evaluate the effectiveness. Group 1 included patients who were successfully treated with a single session of balloon dilation, and group 2 included patients who needed to undergo another balloon dilation session because of recurrent stenosis.
Statistical Analysis
We compared groups 1 and 2 in terms of age and the stenosis diameter percentage before and after the initial procedure. For multiple comparisons, a paired t test was performed with statistical software (SPSS version 11.0; SPSS, Chicago, Ill). Compensation of multiplex nature was performed by using the Dunnett method. P values less than .05 were considered to indicate a statistically significant difference.
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RESULTS
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Initial Stenosis
Percutaneous balloon dilation was technically successful in 35 of 45 patients (Fig 1, Tables 1–3). In the remaining 10 patients, portal venous thrombotic occlusion precluded access to the mesenteric side of the portal vein. Eight of the 10 patients had left lobe grafts. Twenty-five (71.4%) of the 35 patients, ranging in age from 1 to 60 years (mean, 10.8 years), were successfully treated with a single session of balloon dilation (group 1) (Table 2, Figs 2 and 3). Among these 25 patients, three had postprocedural stenosis of 60%. We judged that balloon dilation was effective in these patients because the pressure gradient decreased to less than 3 mm Hg. Portal venous patency in these patients was maintained for 2.5–67.1 months (mean, 24.4 months). The mean stenosis diameter percentage was 81.6% before and 18.4% after the initial procedure. The interval between transplantation and balloon dilation ranged from 14 days to 98.3 months (mean, 18.5 months).
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Figure 2a. Images of portal venous stenosis diagnosed at US screening in a 3-year-old girl. (a) Frontal portal venogram obtained after percutaneous puncture and contrast medium injection into the extrahepatic portal vein. (b) Lateral portal venogram clearly shows severe stenosis (arrow) and poststenotic dilatation. (c) Lateral fluoroscopic image demonstrates stenotic segment (arrow) venoplasty. (d) Lateral fluoroscopic image shows dilated stenotic segment during venoplasty. (e) Lateral portal venogram shows improvement (arrow) immediately after venoplasty.
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Figure 2b. Images of portal venous stenosis diagnosed at US screening in a 3-year-old girl. (a) Frontal portal venogram obtained after percutaneous puncture and contrast medium injection into the extrahepatic portal vein. (b) Lateral portal venogram clearly shows severe stenosis (arrow) and poststenotic dilatation. (c) Lateral fluoroscopic image demonstrates stenotic segment (arrow) venoplasty. (d) Lateral fluoroscopic image shows dilated stenotic segment during venoplasty. (e) Lateral portal venogram shows improvement (arrow) immediately after venoplasty.
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Figure 2c. Images of portal venous stenosis diagnosed at US screening in a 3-year-old girl. (a) Frontal portal venogram obtained after percutaneous puncture and contrast medium injection into the extrahepatic portal vein. (b) Lateral portal venogram clearly shows severe stenosis (arrow) and poststenotic dilatation. (c) Lateral fluoroscopic image demonstrates stenotic segment (arrow) venoplasty. (d) Lateral fluoroscopic image shows dilated stenotic segment during venoplasty. (e) Lateral portal venogram shows improvement (arrow) immediately after venoplasty.
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Figure 2d. Images of portal venous stenosis diagnosed at US screening in a 3-year-old girl. (a) Frontal portal venogram obtained after percutaneous puncture and contrast medium injection into the extrahepatic portal vein. (b) Lateral portal venogram clearly shows severe stenosis (arrow) and poststenotic dilatation. (c) Lateral fluoroscopic image demonstrates stenotic segment (arrow) venoplasty. (d) Lateral fluoroscopic image shows dilated stenotic segment during venoplasty. (e) Lateral portal venogram shows improvement (arrow) immediately after venoplasty.
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Figure 2e. Images of portal venous stenosis diagnosed at US screening in a 3-year-old girl. (a) Frontal portal venogram obtained after percutaneous puncture and contrast medium injection into the extrahepatic portal vein. (b) Lateral portal venogram clearly shows severe stenosis (arrow) and poststenotic dilatation. (c) Lateral fluoroscopic image demonstrates stenotic segment (arrow) venoplasty. (d) Lateral fluoroscopic image shows dilated stenotic segment during venoplasty. (e) Lateral portal venogram shows improvement (arrow) immediately after venoplasty.
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Figure 3. Lateral venogram of portal venous stenosis diagnosed at US screening in an 8-year-old girl shows stenosis (arrow) and poststenotic dilatation. Kinking of the stenotic segment was resolved with a single session of venoplasty.
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Recurrent Stenosis
Follow-up US results revealed restenosis in 10 (28.6%) of the 35 patients who underwent successful balloon dilation. In nine (25.7%) of these patients, this restenosis was resolved by means of repeated balloon dilation (group 2; Table 3, Fig 4); dilation was repeated once or twice. The age range of patients in this group was 9 months to 61 years (mean, 9.9 years). Six patients required two balloon dilation sessions to maintain patency, and three patients required three sessions. In group 2, all patients except one had received left lobe segment grafts, and interposition venous grafts had been necessary in two patients. Patency was maintained for 5.5–67.1 months (mean, 23.9 months). The mean stenosis diameter percentage was 93.9% before and 14.4% after the initial procedure. The interval between balloon dilation sessions ranged from 2.3 to 8.9 months (mean, 5.3 months). In one patient, the portal vein occluded despite two balloon dilation sessions. Because this patient had received an auxiliary partial orthotopic liver transplant, the native liver helped maintain liver function and the patient was treated conservatively. The differences between groups 1 and 2 in age (P = .87) and in the stenosis diameter percentage before (P = .053) and after (P = .95) the initial procedure were not significant (Table 1).
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Figure 4a. Lateral venograms of portal vein stenosis in a 9-month-old boy; two balloon dilation sessions were necessary. Images show (a) severe stenosis (arrow) and collateral vessels, (b) dilated stenotic segment after initial venoplasty, and (c) recurrent stenosis (arrow) in the same segment 214 days after initial venoplasty.
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Figure 4b. Lateral venograms of portal vein stenosis in a 9-month-old boy; two balloon dilation sessions were necessary. Images show (a) severe stenosis (arrow) and collateral vessels, (b) dilated stenotic segment after initial venoplasty, and (c) recurrent stenosis (arrow) in the same segment 214 days after initial venoplasty.
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Figure 4c. Lateral venograms of portal vein stenosis in a 9-month-old boy; two balloon dilation sessions were necessary. Images show (a) severe stenosis (arrow) and collateral vessels, (b) dilated stenotic segment after initial venoplasty, and (c) recurrent stenosis (arrow) in the same segment 214 days after initial venoplasty.
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Portal Venous Thrombotic Occlusion
The 10 patients with portal venous thrombotic occlusions (eight with left lobe and two with right lobe grafts) were also treated by means of conservative methods (n = 7), surgical reanastomosis (n = 2), or repeated transplantation (n = 1). In seven patients, the intrahepatic portal vein remained patent with the help of cavernous transformation and stable liver functions; therefore, these patients were also treated conservatively, without surgical revision. Two patients needed to undergo surgical reanastomosis because of gastrointestinal bleeding and hypofunction of the liver graft, and one patient required another transplant because of graft failure that resulted from bile duct stenosis (Fig 1).
Complications
Procedure-related complications occurred in two of the 45 patients examined. In a 39-year-old man, an intrahepatic pseudoaneurysm of the hepatic artery was detected 6 days after the procedure and was successfully treated with microcoil embolization. In a 33-year-old woman, an intrahepatic portal venous thrombus formed during balloon dilation. It was resolved by means of direct infusion of 60 000 IU of urokinase (Mitsubishi Pharma, Osaka, Japan).
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DISCUSSION
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Vascular complications after liver transplantation include occlusion or stenosis at the site of anastomosis in the hepatic artery, portal vein, or vena cava (2,6–10). Among these complications, portal venous stenosis is rarely observed but nevertheless involves risks of graft failure (10). In 1991, Raby et al (3) reported on portal vein venoplasty in children. It has since been established in many hospitals as the treatment of choice for posttransplantation portal venous stenosis. Reports of the long-term outcomes of portal venous venoplasty in transplant recipients without metallic stent placement are rare, to our knowledge. Buell et al (2) reported long-term venous complications after liver transplantation and mentioned that living donor related transplants result in a higher incidence of portal venous stenosis than cadaveric liver transplants. With living donor liver transplantation, left lobe segments are frequently used as grafts (11). During left lobe graft transplantation, the extrahepatic portal vein slants to the right posterior, and the portal vein rotates backward to the left anterior into the liver. Stenotic areas almost always exist near the flexion. As the liver graft grows, it might kink or compress the flexion.
In this study, no significant differences were observed between groups 1 and 2 with regard to stenosis diameter percentages or age. Nine of the 10 patients in whom restenosis occurred had left lobe grafts, as did eight of the 10 patients whose portal veins were already occluded. Twenty-five (71.4%) of the 35 patients with portal venous stenosis were treated by means of a single balloon dilation session. Considering that long-term patency (mean, 27 months) was maintained without stent placement in 34 (97.1%) of 35 patients, we have shown that percutaneous transhepatic balloon dilation is a successful method for treating complications of portal venous stenosis after liver transplantation.
Funaki et al (4) reported long-term results of portal venoplasty in 25 patients who had undergone balloon dilation and metallic stent placement. They showed the effectiveness of metallic stents in the treatment of recurrent or "elastic" stenosis. In our series, recurrent stenosis was successfully treated with repeated balloon dilation in nine patients. Fortunately, we have not yet encountered any cases of elastic stenosis, which does not respond to balloon dilation. We are prepared to use metallic stents in such cases.
Stent placement is known to be more effective than balloon dilation alone in maintaining patency during the treatment of arterial stenosis, such as coronary, iliac, or renal artery stenosis with arteriosclerosis obliterans (12–14). In such cases, adjacent organ growth does not occur as it does after liver transplantation. With arterial stenting, the regions of stent placement are usually linear, whereas posttransplantation stenotic regions are often angulated, especially when left lobe grafts are used. If metallic stents are used, there is a risk of stent-edge stenosis and occlusion as a result of graft growth. In cases of occluded metallic stents, including those with intimal hyperplasia, repeated interventions may be necessary (15,16). Moreover, if repeated transplantation is required, metallic stent placements make operations even more difficult. Therefore, the use of metallic stents in portal venous stenosis after living donor liver transplantation should be avoided if possible.
In 10 (22.2%) of the 45 patients examined in this study, portal venous thrombotic occlusion precluded access to the extrahepatic portal vein. All 10 patients required sustained treatment for collateral vessels, and in the most severe case, repeated transplantation was necessary. Compared with biliary obstructions, early portal venous stenosis is difficult to detect from clinical signs and symptoms alone. Furthermore, sometimes the portal venous anastomotic site cannot be seen with US because of intestinal artifacts, and CT cannot be performed so many times in pediatric cases. Despite these difficulties, the early diagnosis of portal venous stenosis is very important.
There were limitations in our study. First, there were too few cases to compare the effectiveness of interventional procedures between right lobe and left lobe grafts. The statistical significance of the results cannot be determined with such small numbers to calculate sensitivities and specificities. Further clinical studies are needed to confirm these preliminary results. Second, pressure gradients in the stenosis were not obtained before and after balloon dilation in all cases, and obtaining pressure gradients is a more accurate way to assess the clinical condition than a gross index, such as the stenosis diameter percentage. In the future, we need to obtain pressure gradients in all cases. To conclude, our findings suggest that percutaneous transhepatic balloon dilation is a safe and effective method for the treatment of portal venous stenosis after living donor liver transplantation.
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FOOTNOTES
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Authors stated no financial relationship to disclose.
Author contributions: Guarantor of integrity of entire study, K.I.; study concepts, K.I., K. Togashi; study design, Toyomichi Shibata; literature research, Toyomichi Shibata; clinical studies, Toyomichi Shibata, K.I., T.K., Y.M., Toshiya Shibata; data acquisition, Toyomichi Shibata, K.I., T.K., Y.M.; data analysis/interpretation, Toyomichi Shibata, K.I.; statistical analysis, Toyomichi Shibata; manuscript preparation, K.I., K. Tanaka; manuscript definition of intellectual content, Toyomichi Shibata; manuscript editing, all authors; manuscript revision/review and final version approval, Toyomichi Shibata, K.I., T.K., Y.M., Toshiya Shibata, K. Tanaka
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REFERENCES
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- Patkowski W, Nyckowski P, Zieniewicz K, et al. Biliary tract complications following liver transplantation. Transplant Proc 2003; 35:2316-2317.[CrossRef][Medline]
- Buell JF, Funaki B, Cronin DC, et al. Long-term venous complications after full-size and segmental pediatric liver transplantation. Ann Surg 2002; 236:658-666.[CrossRef][Medline]
- Raby N, Karani J, Thomas S, O’Grady J, Williams R. Stenoses of vascular anastomoses after hepatic transplantation: treatment with balloon angioplasty. AJR Am J Roentgenol 1991; 157:167-171.[Abstract/Free Full Text]
- Funaki B, Rosenblum JD, Leef JA, et al. Percutaneous treatment of portal venous stenosis in children and adolescents with segmental hepatic transplants: long-term results. Radiology 2000; 215:147-151.[Abstract/Free Full Text]
- Zajko AB, Sheng R, Bron K, Reyes J, Nour B, Tzakis A. Percutaneous transluminal angioplasty of venous anastomotic stenoses complicating liver transplantation: intermediate-term results. J Vasc Interv Radiol 1994; 5:121-126.[Medline]
- Hatano E, Terajima H, Yabe S, et al. Hepatic artery thrombosis in living related liver transplantation. Transplantation 1997; 64:1443-1446.[CrossRef][Medline]
- Zajko AB, Claus D, Clapuyt P, et al. Obstruction to hepatic venous drainage after liver transplantation: treatment with balloon angioplasty. Radiology 1989; 170(3 pt 1):763-765.[Abstract/Free Full Text]
- Wozney P, Zajko AB, Bron KM, Point S, Starzl TE. Vascular complications after liver transplantation: a 5-year experience. AJR Am J Roentgenol 1986; 147:657-663.[Abstract/Free Full Text]
- Egawa H, Inomata Y, Uemoto S, et al. Hepatic vein reconstruction in 152 living-related donor liver transplantation patients. Surgery 1997; 121:250-257.[CrossRef][Medline]
- Settmacher U, Nussler NC, Glanemann M, et al. Venous complications after orthotopic liver transplantation. Clin Transplant 2000; 14:235-241.[CrossRef][Medline]
- Yamaoka Y, Tanaka K, Ozawa K. Liver transplantation from living-related donors. Clin Transpl 1993; 179-183.
- Erbel R, Haude M, Hopp HW, et al. Coronary-artery stenting compared with balloon angioplasty for restenosis after initial balloon angioplasty. Restenosis Stent Study Group. N Engl J Med 1998; 339:1672-1678.
- Bosch JL, Hunink MG. Meta-analysis of the results of percutaneous transluminal angioplasty and stent placement for aortoiliac occlusive disease. Radiology 1997; 204:87-96.[Abstract/Free Full Text]
- van de Ven PJ, Kaatee R, Beutler JJ, et al. Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomised trial. Lancet 1999; 353:282-286.[CrossRef][Medline]
- Mehran R, Mintz GS, Popma JJ, et al. Mechanisms and results of balloon angioplasty for the treatment of in-stent restenosis. Am J Cardiol 1996; 78:618-622.[CrossRef][Medline]
- Holmes DR, Jr. In-stent restenosis. Rev Cardiovasc Med 2001; 2:115-119.[Medline]
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ABSTRACT
INTRODUCTION
