Cardiovasc Intervent Radiol DOI 10.1007/s00270-015-1084-5
CASE REPORT
Successful Portal Vein Stent Placement in a Child with Cavernomatous Replacement of the Portal Vein After Partial Liver Transplantation: The Importance of a Recognizable Portal Vein Remnant Roberto Miraglia • Luigi Maruzzelli • Settimo Caruso Calogero Ricotta • Silvia Riva • Gaetano Burgio • Marco Spada • Angelo Luca
•
Received: 22 January 2015 / Accepted: 22 February 2015 Ó Springer Science+Business Media New York and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2015
Abstract Late portal vein thrombosis with cavernomatous replacement has been reported in 4.5 % of pediatric patients who have undergone partial liver transplantation. In such cases, minimally invasive radiological treatments have a high failure rate. We report a successful case of percutaneous recanalization of the portal vein remnant, and subsequent stent placement, in a pediatric patient who underwent left lateral split liver transplantation with cavernomatous replacement of the portal vein. Keywords Portal hypertension Interventional radiology Complication Thrombosis Pediatric
R. Miraglia (&) L. Maruzzelli S. Caruso A. Luca Radiology Service, Department of Diagnostic and Therapeutic Services, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Via Ernesto Tricomi 5, 90127 Palermo, Italy e-mail: [email protected] C. Ricotta M. Spada Abdominal Surgery and Organ Transplantation Unit, Department for the Treatment and Study of Abdominal Diseases and Abdominal Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy S. Riva Pediatric Unit, Department for the Treatment and Study of Abdominal Diseases and Abdominal Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy G. Burgio Operating Room Service, Department of Anesthesia and Intensive Care, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy
Introduction Postoperative portal vein thrombosis (PVT) has been reported in 7 % of pediatric partial liver transplantation, and late portal vein thrombosis, defined as occurrence of PVT later than 1 month after transplantation, has been reported in 4.5 % of cases [1]. In patients with PVT, the normal hepatopetal flow from the superior mesenteric vein and the splenic vein is impeded by obstruction of the main portal vein. This results in the development of pre-hepatic portal hypertension and subsequent cavernomatous replacement of the portal vein in the presence of an otherwise normal liver. Hepatopetal collaterals can provide sufficient portal flow to maintain normal liver function. In these patients, morbidity is due to possible variceal bleeding, symptomatic portal biliopathy, sequelae of hypersplenism, and possible growth retardation [1–4]. We report a successful case of percutaneous recanalization of the portal vein remnant and stent placement in a pediatric patient who underwent left lateral split liver transplantation with cavernomatous replacement of the portal vein.
Case Report A 3-year-old male child affected with biliary cirrhosis due to biliary atresia received an orthotopic liver transplant with a split liver left lateral graft from a deceased donor. Portal vein reconstruction was performed by direct anastomosis of the donor’s left portal vein with the recipient’s portal vein trunk, without an interposed graft conduit. The postoperative course was characterized by persistent production of ascites, with normal findings on sequential Doppler ultrasound exams. A transjugular liver biopsy was
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R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
done, and histology was consistent with reperfusion injury, the transjugular approach was chosen for a low platelet count, 62.000/mcl, and high international normalized ratio 2.02. After a slow recovery of function of the transplanted organ the patient was discharged home after 7 weeks, with normal liver function tests, normal ultrasound findings, and no abdominal ascites. Clinical and Doppler ultrasound at 3-month follow-up were unremarkable. Six months after discharge, the patient showed mild abdominal discomfort and a reduction in platelet count compared with the previous clinical exam (from 110.000 to 65.000/mcl). A Doppler ultrasound showed cavernomatous replacement of the portal vein associated with increased spleen volume (longitudinal length of the spleen from 12 to 15.5 cm). A contrastenhanced computed tomography was done. Axial and 3Dreconstruction images confirmed main portal vein thrombosis, with cavernomatous replacement of the main portal vein, and patent splenic-mesenteric confluence (Fig. 1), though the portal vein remnant was still detectable. After consulting with our surgical team, an interventional radiology procedure was planned in order to attempt a percutaneous recanalization of the main portal vein. The thrombosis, though in the presence of a cavernomatous replacement, was no older than 3 months, or less, based on the previous ultrasound examination, which showed a patent portal vein. The informed consent for the procedure was obtained from the parents of the patient. Peri-procedural ultrasound was done, and identified the main portal vein remnant as an iso/hyperechoic fibrotic band around which the various channels forming the portal cavernoma intertwined. The procedure was performed under general anesthesia in an angiographic suite, with a flat panel detector-based system (Innova 4100, General Electric Medical Systems, USA). Trans-hepatic puncture of portal vein was
performed under real-time ultrasound guidance (GE Logiq E9—GE Healthcare, Milwaukee, WI, USA), using a 6 to 15 MHz linear transducer, with a 20 Ga Chiba needle (Biopsybell, Modena, Italy). The needle was advanced in what seemed to be an intra-hepatic portal radicle in communication with the portal vein remnant. An introducer system (Neff Percutaneous Access Sett—Cook, Bjaverrkov, Denmark) was advanced in the portal branch, over a nitinol (comment 3) wire (Cope Mandril Wire Guide— Cook, Bjaverrkov, Denmark), and then exchanged, over a 0.035-inch wire (Starter—Boston Scientific, Natick, MA, USA), for a 7F vascular sheath (St. Jude Medical, Plymouth, MN, USA). Manual portography showed patent intra-hepatic portal radicles. It was not possible to catheterize the portal remnant using a 5F-angled hydrophilic catheter (Terumo Corporation, Tokyo, Japan) advanced over a 0.038-inch hydrophilic wire (Terumo Corporation, Tokyo, Japan). As a result, the distal end of the vascular sheath was placed at the origin of the thrombosed portal vein remnant. The position was confirmed by ultrasound. A gentle contrast material injection showed a stagnant linear pool of contrast tracking along the anatomical position of the portal vein, indicating that the tip of the vascular sheath was in the portal vein remnant and not in a collateral vessel. A 0.038-inch hydrophilic wire was advanced in the portal vein remnant. The wire was backtracked with the dilator of the sheath, in the hope of giving more direction and steerability to the wire. The wire was advanced in the superior mesenteric vein, and a 5F catheter advanced. Portography showed filling of multiple collateral vessels, and the origin of the thrombosis at the level of the splenic-mesenteric confluence (Fig. 2A). A bolus of 500 UI of heparine was performed. Angioplasty was performed with an 8 mm diameter, 40 mm length balloon catheter (Wanda Standard, Boston Scientific Natick, MA,
Fig. 1 Contrast-enhanced computed tomography. Axial and coronal 3D-reconstruction images show main portal vein thrombosis with cavernomatous replacement of the main portal vein, and patent
splenic-mesenteric confluence. The portal vein remnant is still detectable (arrows). Of note is the large splenomegaly
123
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
Fig. 2 A Digital subtraction angiographic image. Portography done after portal vein remnant catheterization showed filling of multiple collateral vessels, and origin of the thrombosis at the level of the splenic-mesenteric confluence; B fluoroscopic image. 5F sizing catheter was placed in the portal system for accurate measurement
USA). Portography showed filling of the portal vein, with persistent filling of collateral vessels. The 5F hydrophilic catheter was replaced with a 5F sizing catheter (Centimeter Sizing Catheter, Cook, Bjaverrkov, Denmark) for accurate measurement of the distance between the splenic-mesenteric confluence and the Rex segment of the portal vein (Fig. 2B). An 8 mm diameter, 57 mm length uncovered stent (Express LD Vascular, Boston Scientific Natick, MA, USA) was finally deployed in the portal vein with the proximal end approximately 1 cm above the splenic-mesenteric confluence, and the distal end approximately 1 cm below the Rex segment of the portal vein. Portography showed good flow in the stent, with no filling of the collateral vessels (Fig. 2C). The trans-hepatic track was embolized with a coil. Procedure time was 85 min, total anesthesia time was 170 min, and overall radiation exposure was 2508 cGy cm2 (dose–area product), including fluoroscopy and digital subtraction angiography runs. The patient was maintained on low-molecular-weight heparin for 1 week, followed by oral anticoagulation with warfarin to maintain an international normalized ratio between 1.5 and 2 for 6 months. After a follow-up of 12 months, the patient is in good clinical condition, with patent portal vein on Doppler ultrasound (Fig. 3) and longitudinal length of the spleen reduced from 15.5 to 12.5 cm.
Discussion Percutaneous minimally invasive radiological treatments (angioplasty with or without stent placement) are
of the distance between the splenic-mesenteric confluence and the Rex segment of the portal vein; C digital subtraction angiographic image. Final portography done after stent deployment showed good flow in the stent, without filling of collateral vessels
Fig. 3 Doppler ultrasound done at 12-month follow-up showed widely patent portal vein
successfully performed in most transplanted children with portal vein stenosis, thus minimizing the need for surgical revision or re-transplantation [5]. However, in the case of complete PVT, interventional procedures are more challenging, and may fail as a result of the difficulty of passing the guidewire through the level of obstruction, or the possible catheterization of small collateral vessels without accessing the major splanchnic veins. Recent cases of challenging bidirectional approaches,
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R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
i.e., trans-hepatic/trans-splenic and trans-hepatic/transmesenteric through a mini-laparotomy for successful stent placement in pediatric recipients with PVT, have been described [6, 7]. The only surgical procedure with the potential to restore a physiologic hepatopetal flow is the meso-Rex shunt, which restores the physiologic intrahepatic portal vein perfusion, and thus avoids the complications of long-term porto-systemic shunting, particularly encephalopathy. This shunt has been proposed, with good clinical results, as a possible surgical alternative to treat transplanted pediatric patients with PVT [8– 10]. The meso-Rex shunt has good patency, though shunt stenosis or thrombosis have been reported, and it can be a challenging procedure in recipients of a left lateral split liver graft. In a recent study, 6 of 14 meso-Rex shunts performed in patients with portal vein thrombosis after liver transplant required a surgical revision [10]. In this scenario, it is useful to be aware of the possibility of catheterizing the portal vein remnant. A clear detectability of the portal vein remnant by ultrasound and computed tomography, in association with the patency of the major splanchnic vessels and temporal evidence of recent cavernomatous replacement of the portal vein, could conceivably be used as criteria to select those transplanted children with PVT who could benefit from minimally invasive procedures as a first therapeutic approach. However, a paucity of data in the literature renders a more or less precise definition of recent cavernomatous replacement of the portal vein difficult. It is worth noting that a precondition for the meso-Rex shunt procedure is a patent splenic-mesenteric confluence and a patent Rex segment of the left portal vein. Therefore, it is mandatory, in the case of a minimally invasive approach, to preserve the patency of the splenic-mesenteric confluence and the Rex segment of the left portal vein for possible future surgical procedures. An accurate measurement of the distance between those two anatomical structures is necessary, and the use of a sizing catheter can help in the choice of the appropriate length of stent to deploy. Unfortunately, in pediatric patients no data are available on long-term patency of stents in the portal vein, though excellent mid-term primary patency without the need for repeat dilatation, despite continued patient growth, has been reported in 12 transplanted children with portal vein stenosis treated with stents, and with a mean follow-up of 47 months [5]. In our patient, we used a balloon-expandable stent; however, the use of a self-expandable stent, with possible overestimation of the diameter in the follow-up, could be considered theoretically an advantage in growing patient; of note in the largest experience of pediatric transplanted children with portal vein stenosis treated with self-expandable stents no interventional radiology procedures to overestimate di diameter of the stent were reported [5].
123
A major disadvantage of minimally invasive radiological procedures is the use of ionizing radiation. The small liver volume in partial liver transplant recipients makes such interventional procedures challenging, with the need for long fluoroscopy time, and large radiation dose. Radiation exposure is particularly relevant when treating children because of their greater radio-sensitivity compared with adults. Children also have a relatively long lifespan during which this potentially augmented oncological risk can manifest [11, 12]. In our case, a dose-area product of 2508 cGy cm2 was measured. However, knowledge of the magnitude of radiation exposure in pediatric interventional radiology is very limited. To the best of our knowledge, no data on radiation exposure are available on the reported cases of radiological treatment of pediatric transplanted patients with portal vein thrombosis. We try to reduce the radiation exposure using a flat panel detector-based system with dedicated low-dose acquisition protocols for fluoroscopy and digital subtraction angiographic runs. During the procedure a low fluoroscopy level without magnification was used, with high detail fluoroscopy and/or magnification used only during the most critical steps. An adequate collimation limited only to the area of interest was used for the entire procedure. In conclusion, in our opinion, percutaneous recanalization of the portal vein remnant, and subsequent stent placement can be considered a first therapeutic approach in select pediatric transplanted patients with late portal vein thrombosis. Given the lower technical success and increased incidence of post-procedural complications, if a stent is positioned within the venous channels constituting the portal cavernoma, the recanalization of the portal vein remnant should be considered the only radiological option. The preservation of the patency of the splenic-mesenteric confluence and of the Rex segment of left portal vein should be considered mandatory in order not to compromise the possibility for the patient to have future access to meso-Rex bypass. Conflict of interest Roberto Miraglia declares no conflict of interest, Luigi Maruzzelli declares no conflict of interest, Settimo Caruso declares no conflict of interest, Calogero Ricotta declares no conflict of interest, Silvia Riva declares no conflict of interest, Gaetano Burgio declares no conflict of interest, Marco Spada declares no conflict of interest, Angelo Loca declares no conflict of interest.
References 1. Neto JS, Fonseca EA, Feier FH et al (2014) Analysis of factors associated with portal vein thrombosis in pediatric living donor liver transplant recipients. Liver Transplant 20:1157–1167 2. Lykavieris P, Gauthier F, Hadchouel P et al (2000) Risk of gastrointestinal bleeding during adolescence and early adulthood in children with portal vein obstruction. J Pediatr 136:805–808
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant 3. Sarin SK, Sollano JD, Chawla YK et al (2006) Consensus on extra-hepatic portal vein obstruction. Liver Int 26:512–519 4. Chiu B, Superina R (2004) Extrahepatic portal vein thrombosis is associated with an increased incidence of cholelithiasis. J Pediatr Surg 39:1059–1061 5. Funaki B, Rosenblum JD, Leef JA et al (2000) Percutaneous treatment of portal venous stenosis in children and adolescents with segmental hepatic transplants: long-term results. Radiology 215:147–151 6. Chen C-Y, Tseng H-S, Lin N-C et al (2013) Bidirectional approach for portal vein stent placement in a child with complete portal vein occlusion after living donor liver transplantation. Pediatr Transplant 17:E137–E140 7. Carnevale FC, Santos AC, Seda-Neto J et al (2011) Portal vein obstruction after liver transplantation in children treated by simultaneous minilaparotomy and transhepatic approaches: initial experience. Pediatr Transplant 15(1):47–52
8. de Ville de Goyet J, Lo Zupone C et al. (2013) Meso-Rex bypass as an alternative technique for portal vein reconstruction at or after liver transplantation in children: review and perspectives. Pediatr Transplant 17(1):19–26 9. Cho YP, Kim KM, Ha TY et al (2014) Management of late-onset portal vein complications in pediatric living-donor liver transplantation. Pediatr Transplant 18(1):64–71 10. Krebs-Schmitt D, Briem-Richter A, Grabhorn E et al (2009) Effectiveness of Rex shunt in children with portal hypertension following liver transplantation or with primary portal hypertension. Pediatr Transplant 13:540–544 11. Kleinerman R (2006) Cancer risks following diagnostic and therapeutic radiation exposure in children. Pediatr Radiol 36(Suppl 2):121–125 12. Linet M, Kim K, Rajaraman P (2009) Children’s exposure to diagnostic medical radiation and cancer risk: epidemiologic and dosimetric considerations. Pediatr Radiol 39(Suppl 1):S4–S26
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CASE REPORT
Successful Portal Vein Stent Placement in a Child with Cavernomatous Replacement of the Portal Vein After Partial Liver Transplantation: The Importance of a Recognizable Portal Vein Remnant Roberto Miraglia • Luigi Maruzzelli • Settimo Caruso Calogero Ricotta • Silvia Riva • Gaetano Burgio • Marco Spada • Angelo Luca
•
Received: 22 January 2015 / Accepted: 22 February 2015 Ó Springer Science+Business Media New York and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2015
Abstract Late portal vein thrombosis with cavernomatous replacement has been reported in 4.5 % of pediatric patients who have undergone partial liver transplantation. In such cases, minimally invasive radiological treatments have a high failure rate. We report a successful case of percutaneous recanalization of the portal vein remnant, and subsequent stent placement, in a pediatric patient who underwent left lateral split liver transplantation with cavernomatous replacement of the portal vein. Keywords Portal hypertension Interventional radiology Complication Thrombosis Pediatric
R. Miraglia (&) L. Maruzzelli S. Caruso A. Luca Radiology Service, Department of Diagnostic and Therapeutic Services, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Via Ernesto Tricomi 5, 90127 Palermo, Italy e-mail: [email protected] C. Ricotta M. Spada Abdominal Surgery and Organ Transplantation Unit, Department for the Treatment and Study of Abdominal Diseases and Abdominal Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy S. Riva Pediatric Unit, Department for the Treatment and Study of Abdominal Diseases and Abdominal Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy G. Burgio Operating Room Service, Department of Anesthesia and Intensive Care, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy
Introduction Postoperative portal vein thrombosis (PVT) has been reported in 7 % of pediatric partial liver transplantation, and late portal vein thrombosis, defined as occurrence of PVT later than 1 month after transplantation, has been reported in 4.5 % of cases [1]. In patients with PVT, the normal hepatopetal flow from the superior mesenteric vein and the splenic vein is impeded by obstruction of the main portal vein. This results in the development of pre-hepatic portal hypertension and subsequent cavernomatous replacement of the portal vein in the presence of an otherwise normal liver. Hepatopetal collaterals can provide sufficient portal flow to maintain normal liver function. In these patients, morbidity is due to possible variceal bleeding, symptomatic portal biliopathy, sequelae of hypersplenism, and possible growth retardation [1–4]. We report a successful case of percutaneous recanalization of the portal vein remnant and stent placement in a pediatric patient who underwent left lateral split liver transplantation with cavernomatous replacement of the portal vein.
Case Report A 3-year-old male child affected with biliary cirrhosis due to biliary atresia received an orthotopic liver transplant with a split liver left lateral graft from a deceased donor. Portal vein reconstruction was performed by direct anastomosis of the donor’s left portal vein with the recipient’s portal vein trunk, without an interposed graft conduit. The postoperative course was characterized by persistent production of ascites, with normal findings on sequential Doppler ultrasound exams. A transjugular liver biopsy was
123
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
done, and histology was consistent with reperfusion injury, the transjugular approach was chosen for a low platelet count, 62.000/mcl, and high international normalized ratio 2.02. After a slow recovery of function of the transplanted organ the patient was discharged home after 7 weeks, with normal liver function tests, normal ultrasound findings, and no abdominal ascites. Clinical and Doppler ultrasound at 3-month follow-up were unremarkable. Six months after discharge, the patient showed mild abdominal discomfort and a reduction in platelet count compared with the previous clinical exam (from 110.000 to 65.000/mcl). A Doppler ultrasound showed cavernomatous replacement of the portal vein associated with increased spleen volume (longitudinal length of the spleen from 12 to 15.5 cm). A contrastenhanced computed tomography was done. Axial and 3Dreconstruction images confirmed main portal vein thrombosis, with cavernomatous replacement of the main portal vein, and patent splenic-mesenteric confluence (Fig. 1), though the portal vein remnant was still detectable. After consulting with our surgical team, an interventional radiology procedure was planned in order to attempt a percutaneous recanalization of the main portal vein. The thrombosis, though in the presence of a cavernomatous replacement, was no older than 3 months, or less, based on the previous ultrasound examination, which showed a patent portal vein. The informed consent for the procedure was obtained from the parents of the patient. Peri-procedural ultrasound was done, and identified the main portal vein remnant as an iso/hyperechoic fibrotic band around which the various channels forming the portal cavernoma intertwined. The procedure was performed under general anesthesia in an angiographic suite, with a flat panel detector-based system (Innova 4100, General Electric Medical Systems, USA). Trans-hepatic puncture of portal vein was
performed under real-time ultrasound guidance (GE Logiq E9—GE Healthcare, Milwaukee, WI, USA), using a 6 to 15 MHz linear transducer, with a 20 Ga Chiba needle (Biopsybell, Modena, Italy). The needle was advanced in what seemed to be an intra-hepatic portal radicle in communication with the portal vein remnant. An introducer system (Neff Percutaneous Access Sett—Cook, Bjaverrkov, Denmark) was advanced in the portal branch, over a nitinol (comment 3) wire (Cope Mandril Wire Guide— Cook, Bjaverrkov, Denmark), and then exchanged, over a 0.035-inch wire (Starter—Boston Scientific, Natick, MA, USA), for a 7F vascular sheath (St. Jude Medical, Plymouth, MN, USA). Manual portography showed patent intra-hepatic portal radicles. It was not possible to catheterize the portal remnant using a 5F-angled hydrophilic catheter (Terumo Corporation, Tokyo, Japan) advanced over a 0.038-inch hydrophilic wire (Terumo Corporation, Tokyo, Japan). As a result, the distal end of the vascular sheath was placed at the origin of the thrombosed portal vein remnant. The position was confirmed by ultrasound. A gentle contrast material injection showed a stagnant linear pool of contrast tracking along the anatomical position of the portal vein, indicating that the tip of the vascular sheath was in the portal vein remnant and not in a collateral vessel. A 0.038-inch hydrophilic wire was advanced in the portal vein remnant. The wire was backtracked with the dilator of the sheath, in the hope of giving more direction and steerability to the wire. The wire was advanced in the superior mesenteric vein, and a 5F catheter advanced. Portography showed filling of multiple collateral vessels, and the origin of the thrombosis at the level of the splenic-mesenteric confluence (Fig. 2A). A bolus of 500 UI of heparine was performed. Angioplasty was performed with an 8 mm diameter, 40 mm length balloon catheter (Wanda Standard, Boston Scientific Natick, MA,
Fig. 1 Contrast-enhanced computed tomography. Axial and coronal 3D-reconstruction images show main portal vein thrombosis with cavernomatous replacement of the main portal vein, and patent
splenic-mesenteric confluence. The portal vein remnant is still detectable (arrows). Of note is the large splenomegaly
123
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
Fig. 2 A Digital subtraction angiographic image. Portography done after portal vein remnant catheterization showed filling of multiple collateral vessels, and origin of the thrombosis at the level of the splenic-mesenteric confluence; B fluoroscopic image. 5F sizing catheter was placed in the portal system for accurate measurement
USA). Portography showed filling of the portal vein, with persistent filling of collateral vessels. The 5F hydrophilic catheter was replaced with a 5F sizing catheter (Centimeter Sizing Catheter, Cook, Bjaverrkov, Denmark) for accurate measurement of the distance between the splenic-mesenteric confluence and the Rex segment of the portal vein (Fig. 2B). An 8 mm diameter, 57 mm length uncovered stent (Express LD Vascular, Boston Scientific Natick, MA, USA) was finally deployed in the portal vein with the proximal end approximately 1 cm above the splenic-mesenteric confluence, and the distal end approximately 1 cm below the Rex segment of the portal vein. Portography showed good flow in the stent, with no filling of the collateral vessels (Fig. 2C). The trans-hepatic track was embolized with a coil. Procedure time was 85 min, total anesthesia time was 170 min, and overall radiation exposure was 2508 cGy cm2 (dose–area product), including fluoroscopy and digital subtraction angiography runs. The patient was maintained on low-molecular-weight heparin for 1 week, followed by oral anticoagulation with warfarin to maintain an international normalized ratio between 1.5 and 2 for 6 months. After a follow-up of 12 months, the patient is in good clinical condition, with patent portal vein on Doppler ultrasound (Fig. 3) and longitudinal length of the spleen reduced from 15.5 to 12.5 cm.
Discussion Percutaneous minimally invasive radiological treatments (angioplasty with or without stent placement) are
of the distance between the splenic-mesenteric confluence and the Rex segment of the portal vein; C digital subtraction angiographic image. Final portography done after stent deployment showed good flow in the stent, without filling of collateral vessels
Fig. 3 Doppler ultrasound done at 12-month follow-up showed widely patent portal vein
successfully performed in most transplanted children with portal vein stenosis, thus minimizing the need for surgical revision or re-transplantation [5]. However, in the case of complete PVT, interventional procedures are more challenging, and may fail as a result of the difficulty of passing the guidewire through the level of obstruction, or the possible catheterization of small collateral vessels without accessing the major splanchnic veins. Recent cases of challenging bidirectional approaches,
123
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant
i.e., trans-hepatic/trans-splenic and trans-hepatic/transmesenteric through a mini-laparotomy for successful stent placement in pediatric recipients with PVT, have been described [6, 7]. The only surgical procedure with the potential to restore a physiologic hepatopetal flow is the meso-Rex shunt, which restores the physiologic intrahepatic portal vein perfusion, and thus avoids the complications of long-term porto-systemic shunting, particularly encephalopathy. This shunt has been proposed, with good clinical results, as a possible surgical alternative to treat transplanted pediatric patients with PVT [8– 10]. The meso-Rex shunt has good patency, though shunt stenosis or thrombosis have been reported, and it can be a challenging procedure in recipients of a left lateral split liver graft. In a recent study, 6 of 14 meso-Rex shunts performed in patients with portal vein thrombosis after liver transplant required a surgical revision [10]. In this scenario, it is useful to be aware of the possibility of catheterizing the portal vein remnant. A clear detectability of the portal vein remnant by ultrasound and computed tomography, in association with the patency of the major splanchnic vessels and temporal evidence of recent cavernomatous replacement of the portal vein, could conceivably be used as criteria to select those transplanted children with PVT who could benefit from minimally invasive procedures as a first therapeutic approach. However, a paucity of data in the literature renders a more or less precise definition of recent cavernomatous replacement of the portal vein difficult. It is worth noting that a precondition for the meso-Rex shunt procedure is a patent splenic-mesenteric confluence and a patent Rex segment of the left portal vein. Therefore, it is mandatory, in the case of a minimally invasive approach, to preserve the patency of the splenic-mesenteric confluence and the Rex segment of the left portal vein for possible future surgical procedures. An accurate measurement of the distance between those two anatomical structures is necessary, and the use of a sizing catheter can help in the choice of the appropriate length of stent to deploy. Unfortunately, in pediatric patients no data are available on long-term patency of stents in the portal vein, though excellent mid-term primary patency without the need for repeat dilatation, despite continued patient growth, has been reported in 12 transplanted children with portal vein stenosis treated with stents, and with a mean follow-up of 47 months [5]. In our patient, we used a balloon-expandable stent; however, the use of a self-expandable stent, with possible overestimation of the diameter in the follow-up, could be considered theoretically an advantage in growing patient; of note in the largest experience of pediatric transplanted children with portal vein stenosis treated with self-expandable stents no interventional radiology procedures to overestimate di diameter of the stent were reported [5].
123
A major disadvantage of minimally invasive radiological procedures is the use of ionizing radiation. The small liver volume in partial liver transplant recipients makes such interventional procedures challenging, with the need for long fluoroscopy time, and large radiation dose. Radiation exposure is particularly relevant when treating children because of their greater radio-sensitivity compared with adults. Children also have a relatively long lifespan during which this potentially augmented oncological risk can manifest [11, 12]. In our case, a dose-area product of 2508 cGy cm2 was measured. However, knowledge of the magnitude of radiation exposure in pediatric interventional radiology is very limited. To the best of our knowledge, no data on radiation exposure are available on the reported cases of radiological treatment of pediatric transplanted patients with portal vein thrombosis. We try to reduce the radiation exposure using a flat panel detector-based system with dedicated low-dose acquisition protocols for fluoroscopy and digital subtraction angiographic runs. During the procedure a low fluoroscopy level without magnification was used, with high detail fluoroscopy and/or magnification used only during the most critical steps. An adequate collimation limited only to the area of interest was used for the entire procedure. In conclusion, in our opinion, percutaneous recanalization of the portal vein remnant, and subsequent stent placement can be considered a first therapeutic approach in select pediatric transplanted patients with late portal vein thrombosis. Given the lower technical success and increased incidence of post-procedural complications, if a stent is positioned within the venous channels constituting the portal cavernoma, the recanalization of the portal vein remnant should be considered the only radiological option. The preservation of the patency of the splenic-mesenteric confluence and of the Rex segment of left portal vein should be considered mandatory in order not to compromise the possibility for the patient to have future access to meso-Rex bypass. Conflict of interest Roberto Miraglia declares no conflict of interest, Luigi Maruzzelli declares no conflict of interest, Settimo Caruso declares no conflict of interest, Calogero Ricotta declares no conflict of interest, Silvia Riva declares no conflict of interest, Gaetano Burgio declares no conflict of interest, Marco Spada declares no conflict of interest, Angelo Loca declares no conflict of interest.
References 1. Neto JS, Fonseca EA, Feier FH et al (2014) Analysis of factors associated with portal vein thrombosis in pediatric living donor liver transplant recipients. Liver Transplant 20:1157–1167 2. Lykavieris P, Gauthier F, Hadchouel P et al (2000) Risk of gastrointestinal bleeding during adolescence and early adulthood in children with portal vein obstruction. J Pediatr 136:805–808
R. Miraglia et al.: The Importance of a Recognizable Portal Vein Remnant 3. Sarin SK, Sollano JD, Chawla YK et al (2006) Consensus on extra-hepatic portal vein obstruction. Liver Int 26:512–519 4. Chiu B, Superina R (2004) Extrahepatic portal vein thrombosis is associated with an increased incidence of cholelithiasis. J Pediatr Surg 39:1059–1061 5. Funaki B, Rosenblum JD, Leef JA et al (2000) Percutaneous treatment of portal venous stenosis in children and adolescents with segmental hepatic transplants: long-term results. Radiology 215:147–151 6. Chen C-Y, Tseng H-S, Lin N-C et al (2013) Bidirectional approach for portal vein stent placement in a child with complete portal vein occlusion after living donor liver transplantation. Pediatr Transplant 17:E137–E140 7. Carnevale FC, Santos AC, Seda-Neto J et al (2011) Portal vein obstruction after liver transplantation in children treated by simultaneous minilaparotomy and transhepatic approaches: initial experience. Pediatr Transplant 15(1):47–52
8. de Ville de Goyet J, Lo Zupone C et al. (2013) Meso-Rex bypass as an alternative technique for portal vein reconstruction at or after liver transplantation in children: review and perspectives. Pediatr Transplant 17(1):19–26 9. Cho YP, Kim KM, Ha TY et al (2014) Management of late-onset portal vein complications in pediatric living-donor liver transplantation. Pediatr Transplant 18(1):64–71 10. Krebs-Schmitt D, Briem-Richter A, Grabhorn E et al (2009) Effectiveness of Rex shunt in children with portal hypertension following liver transplantation or with primary portal hypertension. Pediatr Transplant 13:540–544 11. Kleinerman R (2006) Cancer risks following diagnostic and therapeutic radiation exposure in children. Pediatr Radiol 36(Suppl 2):121–125 12. Linet M, Kim K, Rajaraman P (2009) Children’s exposure to diagnostic medical radiation and cancer risk: epidemiologic and dosimetric considerations. Pediatr Radiol 39(Suppl 1):S4–S26
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