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Pediatric Imaging |
1 From the Departments of Radiology (B.F., J.D.R., J.A.L., G.X.Z., T.F., J.L.) and Pediatrics (L.B.), the University of Chicago Hospitals, 5841 S Maryland Ave, MC 2026, Chicago, IL 60637. Received April 16, 1999; revision requested June 10; revision received July 2; accepted July 20. Address reprint requests to B.F. (e-mail: bfunaki@midway.uchicago.edu).
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Abstract |
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MATERIALS AND METHODS: During the past 5 years, percutaneous transhepatic balloon venoplasty was attempted in 25 children and adolescents with anastomotic portal venous stenoses that occurred after reduced-size hepatic transplantation. All procedures were performed with direct puncture of the intrahepatic portal vein and with subsequent balloon dilation. Intravascular stents were deployed in patients with suboptimal results after dilation or with recurrent stenoses.
RESULTS: Percutaneous venoplasty was technically successful in 19 of 25 patients. In the remaining six patients, portal venous occlusion precluded access to the extrahepatic portal vein. Intravascular stents were deployed in 12 patients for "elastic" (n = 5) or recurrent (n = 7) stenoses. Seven patients who underwent successful venoplasty without stent placement have required no further intervention. All stents have remained patent without further intervention. Portal venous patency has been maintained for 5–61 months (mean time, 46 months) in all 19 patients.
CONCLUSION: Percutaneous treatment of portal venous stenoses is effective and long lasting in children with reduced-size hepatic transplants. In patients with elastic or recurrent lesions, portal venous stents have excellent long-term primary patency despite continued patient growth. Successful, percutaneous transhepatic venoplasty eliminates the need for surgical revision, portacaval shunting, or repeat transplantation.
Index terms: Portal vein, stenosis or obstruction, 957.1282, 957.1286, 957.458 • Portal vein, transluminal angioplasty (new), 957.1282, 957.1286 • Liver, blood supply, 761.458, 957.452, 957.458, 957.75 • Liver, transplantation, 761.458 • Liver, US, 761.12984
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Introduction |
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One of the technical difficulties associated with this procedure is the creation of the portal venous anastomosis. Since the donor portal venous segment is relatively short, interposition grafts occasionally are used to reduce tension on the anastomosis (2). These conduits are used successfully to reduce the incidence of perioperative portal venous thrombosis but are prone to delayed stenosis, which is difficult to manage surgically (2). When encountered, this vascular complication is alleviated effectively with percutaneous venoplasty (3–6). Metallic stents have been used to treat recurrent and elastic stenoses (6–8). To our knowledge, the long-term patency of the portal vein after these interventions has not been reported.
Our purpose was to review the long-term results of percutaneous portal venous dilation in 25 children and adolescents with left lateral segment hepatic transplants from living, related donors.
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MATRIALS AND METHODS |
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These patients were identified by their clinical signs or symptoms or by using routine Doppler ultrasonography (US). Clinical signs or symptoms led to diagnosis in eight patients and included gastrointestinal tract bleeding from varices in two patients, gastrointestinal tract bleeding and ascites in one patient, splenomegaly in two patients, and ascites in three patients. One patient was asymptomatic but exhibited elevated liver function test results.
The criteria used in US studies to identify patients with portal vein stenosis were direct gray-scale US depiction of a portal vein 2
mm or less in diameter or an acceleration of flow at the stricture or a poststenotic jet of portal vein flow revealed at Doppler US.
Sixteen asymptomatic patients were identified at routine Doppler US surveillance (Table). All patients, except one who underwent venoplasty, underwent US examinations before venography. Follow-up data were obtained in all 25 patients, In successful procedures, routine clinical evaluation and Doppler US surveillance was performed on postprocedural days 1, 2, and 3; at 2 weeks; at 1, 2, 3, 6, and 12 months; and annually thereafter. In patients with recurrent stenosis, repeat venoplasty with stent placement was performed.
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Immediately after the procedure, the patient underwent systemic anticoagulation with heparin sodium (Elkins Sinn, Cherry Hill, NJ) for 48–72 hours to maintain a partial thromboplastin time of 1.5 times higher than normal levels.
The following parameters were documented prospectively: technical success and complications, stent location, clinical improvement, stenosis recurrence, and stent patency.
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RESULTS |
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In 14 of the 19 patients in whom initial technical success was achieved, the initial venoplasty resulted in successful reduction of portal venous stenosis. In five patients, elastic stenoses were unresponsive to balloon dilation, and metallic stents were placed.
Seven of 14 patients who underwent venoplasty without stent placement have required no further intervention, with portal venous patency being maintained for 9–56 months (mean, 36.7 months).
Seven of 14 patients who underwent initial venoplasty without stent placement developed recurrent stenosis 1–13 months (mean, 6.3 months) after the procedure. These recurrent stenoses were detected with Doppler US and were verified with portal venography. In five patients, the gradients in these recurrent stenoses were 12–23 mm Hg (mean, 17.5 mm Hg). In two patients, gradients were not obtained because the 5-F catheter used to cross the stenotic segment occluded hepatopetal flow. Metallic stents were placed in all patients who developed recurrent stenoses.
Intravascular stents were placed in 12 patients, with a follow-up of 5–61 months (mean, 47 months). All stents were placed in the region of the proximal or distal part of the anastomosis to the interposition graft or within the graft itself. At the time this article was completed, all stents had remained patent and none had required repeat dilation.
Two of the 12 patients in whom intravascular stents were placed underwent repeat transplantation for chronic rejection at 5 and at 41 months after stent placement. At the time of transplantation, both patients' stents were widely patent. Both patients' stents were placed across a stenosis of the proximal portion of an interposition graft and extended near the superior mesenteric vein–splenic vein confluence. Because the stents were close to the superior mesenteric vein, a direct anastomosis was not possible. In the first patient, a 3-year-old girl, a length of iliac vein that was harvested at the time of the hepatic procurement from a cadaveric donor was used as a jump graft from the superior mesenteric vein to the donor's portal vein. In the second patient, a 6-year-old girl, the stent was left in vivo and the portal vein anastomosis was fashioned distal to the stent. This stent remained patent at a 6-month follow-up examination.
Three procedure-related complications occurred. In a 3-year-old boy, the flexible end of the 0.018-inch nitinol guide wire fractured into the portal vein during the removal of both the guide wire and the introducer needle. The fractured segment was left in place and to our knowledge has resulted in no further complications. In a 1-year-old girl, femoral arterial thrombosis developed after arteriography before the procedure. The patient underwent surgical thrombectomy, without further complications. In a 2-year-old girl, a portal venous thrombus formed when the stenotic segment of the portal vein was occluded by the 5-F catheter used during venoplasty, despite the administration of 50 U/kg of heparin intravenously. This thrombus resolved after the direct infusion of 50,000 U of urokinase (Abbott Laboratories, North Chicago, Ill).
A postprocedural complication developed in a 2-year-old boy when heparin administration was inadvertently delayed after the procedure and the portal vein thrombosed. The thrombus was successfully lysed with direct pulsed spray administration of urokinase (250,000 U diluted in 20 mL of normal saline and administered as 1-mL boluses every 30 seconds through a Mewissen multiple-side-hole infusion catheter [Boston Scientific]).
In each of the six patients with technically unsuccessful procedures, the portal vein was already occluded and could not be traversed. Neither guide wires nor catheters could be manipulated beyond the occlusion into the native portal circulation.
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DISCUSSION |
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Zajko et al (5) later reported the intermediate results of venoplasty in four children with portal venous stenosis after orthotopic hepatic transplantation. All procedures were successful, and the patients remained asymptomatic for 8–30 months (5). Funaki et al (6) reported similar midterm results in 16 children with portal venous patency maintained for 4–29 months (mean, 20 months). To our knowledge, the long-term results of portal venous venoplasty in children with or without stent implantation have not been reported. These data are especially relevant, since the life expectancy of pediatric patients exceeds that of their adult counterparts. To our knowledge, our series represents the largest of patients undergoing portal venous dilation, with the longest follow-up. It is also to our knowledge the only series documenting the patency of metallic stents deployed in growing veins.
The majority of patients with portal venous stenosis successfully treated in our series initially responded to balloon dilation (74% [14 of 19 patients]). Stents were reserved for elastic portal venous stenoses or for recurrent lesions. In five of 19 (26%) patients in our series, elastic lesions, which expanded during dilation but immediately recoiled as the venoplasty balloon was deflated, were encountered at the time of initial venoplasty. Stents were deployed in this situation to act as a scaffold to maintain the luminal diameter.
All recurrent stenoses in our series also were elastic when repeat dilation was attempted. Therefore, metallic stents were placed across all recurrent lesions. The reason for the variable intermediate response to percutaneous venoplasty is unknown. Patients who developed recurrent lesions after venoplasty did not differ markedly with regard to age, sex, or clinical presentation compared with those who demonstrated long-term patency after venoplasty, although, because of the small sample size, the achievement of statistical significance is difficult. The results at initial venoplasty also did not differ markedly between patients with treated lesions that exhibited long-term primary patency and patients with lesions that did not.
To our knowledge, there have been no studies in which investigators have assessed the long-term patency of venous intravascular stents in children. Early in our experience, we were hesitant to deploy stents for two reasons. First, since the child is expected to grow and the stent is relatively fixed in size, the stent ultimately could function as a stenosis. Second, all stents are susceptible to intimal hyperplasia, which may lead to repeat stenosis. In-stent stenoses usually are more difficult to dilate, since these lesions are effectively reinforced by existing stents. We expected initially that stent placement would serve as a temporizing measure and that most patients would return for periodic repeat dilation. Therefore, a US follow-up program was instituted to detect recurrent stenoses. The goal of US surveillance was to diagnose recurrent stenoses before these lesions caused marked symptoms or evolved into occlusions.
We have had much less success in treating children and adolescents with portal venous occlusion, in contrast with children and adolescents with portal venous stenoses, because of an inability to successfully cross this lesion with the guide wire. It is interesting that there have been no patients with a mean follow-up of nearly 4 years with significant stent-related repeat stenoses. The reasons for such excellent patency are not entirely clear, but one factor likely is the relatively low pressure in the portal venous system.
The primary patency of the stents in this series was 100% (12 of 12) at the 3-year follow-up examination. While our patency rates were extremely high, this degree of patency with portal venous stents is not unique. Cherukuri et al (7) placed stents after percutaneous thrombolysis in two adult patients with hepatic transplants and reported portal venous patency at the 2- and 4-year follow-up examinations. The use of intravascular stents in children with congenital heart disease also is encouraging. The rates of repeat stenosis have been low, and repeat stenoses have been treated easily with repeat balloon dilation (9–12).
One of the pitfalls of metallic stent deployment is that a metallic stent placed across a proximal portal venous lesion may interfere with future portal venous anastomoses if repeat transplantation becomes necessary. Two patients who underwent stent placement in our series required repeat transplantation. The first patient underwent repeat surgery early in our experience. At the time of laparotomy, the stent was excised, and a jump graft from the superior mesenteric vein to the donor portal vein was placed. The second patient underwent repeat transplantation later in our experience, after the excellent patency of portal venous stents had been established. Therefore, the stent was left in vivo, and an anastomosis was fashioned distal to it.
The surgical repair of portal venous stenoses is difficult because of the abundant scar tissue that surrounds the transplant. In the past, patients were treated with repeat transplantation, with venous reconstruction, or with portacaval shunting. The six patients in our series in whom percutaneous venoplasty was technically unsuccessful all died. One patient underwent repeat transplantation and later died of infectious complications. Another patient died during repeat transplantation, and the others died of complications associated with portal hypertension and with hepatic failure.
Venoplasty is generally considered the treatment of choice for posttransplantation portal venous stenosis. In 19 of 25 patients, we successfully dilated portal venous stenoses and increased hepatopetal flow, thus alleviating portal hypertension. We have maintained portal venous patency in all of these patients for up to 5 years.
It is important to note that elastic and recurrent stenoses are effectively treated with metallic stents, which exhibit excellent long-term patency despite continued patient growth. Percutaneous venoplasty of portal venous stenosis is a less invasive alternative to surgery and has proved to be effective and long lasting.
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Footnotes |
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References |
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TOPAbstractIntroductionMATRIALS AND METHODSRESULTSDISCUSSIONReferences |
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This article has been cited by other articles:
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  R. Miraglia, L. Maruzzelli, S. Caruso, G. Marrone, V. Carollo, M. Spada, A. Luca, and B. Gridelli Interventional Radiology Procedures in Pediatric Patients with Complications after Liver Transplantation RadioGraphics, March 1, 2009; 29(2): 567 - 584. [Abstract] [Full Text] [PDF]
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 T. Shibata, K. Itoh, T. Kubo, Y. Maetani, T. Shibata, K. Togashi, and K. Tanaka Percutaneous Transhepatic Balloon Dilation of Portal Venous Stenosis in Patients with Living Donor Liver Transplantation Radiology, June 1, 2005; 235(3): 1078 - 1083. [Abstract] [Full Text] [PDF]
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 K. M. Unsinn, M. C. Freund, H. Ellemunter, R. Ladurner, A. Koenigsrainer, I. Gassner, and W. R. Jaschke Spectrum of Imaging Findings After Pediatric Liver Transplantation: Part 2, Posttransplantation Complications Am. J. Roentgenol., October 1, 2003; 181(4): 1139 - 1144. [Full Text] [PDF]
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