title: Transvenous extrahepatic portacaval shunt with use of a modified prototype stent-graft: experimental study in animals.
abstract: OBJECTIVE
  To evaluate the safety and short-term patency of an experimental transvenous extrahepatic portacaval shunt (TEPS) in an animal model.
  
  
  METHODS
  With use of intravascular ultrasound (IVUS) guidance, the main portal vein (PV) was accessed from the inferior vena cava in six pigs and a TEPS was created with use of a prototype flanged stent-graft. Partial PV embolization was then performed to increase the post-TEPS PV pressure. Baseline and postprocedural hemoglobin and hematocrit measurements were obtained and liver function studies were conducted. Immediate postprocedural computed tomography (CT) of the abdomen was used to identify procedural complications. Follow-up venography was performed at 2, 4, and 12 weeks to assess short-term patency. Necropsy was performed at 3 months.
  
  
  RESULTS
  IVUS-guided PV access was accomplished with a mean of two punctures per animal (range, 1-4). TEPS creation was successful in five of six animals. One animal was killed immediately after unsuccessful shunt creation after stent-graft misdeployment and hemorrhage. A second animal required the insertion of a conventional stent coaxially because portions of the leading arms were inadvertently deployed in the portacaval space and the initial flow through the shunt was venographically suboptimal. CT images obtained after successful TEPS creation (n = 5) revealed no evidence of hemoperitoneum, and there was no decrease in hemoglobin or hematocrit levels from baseline values. All five TEPSs were widely patent at 2-week and 4-week venography with only mild pseudointimal hyperplasia (<50% diameter stenosis) identified in one shunt. Twelve-week venography and necropsy demonstrated no evidence of shunt stenosis in one animal, less than 50% diameter stenosis in one animal, 50%-75% diameter stenosis in two animals, and shunt occlusion in one animal.
  
  
  CONCLUSIONS
  Early results with TEPS with use of a modified prototype flanged stent-graft are promising as a potentially safe alternative means of portal decompression. Additional refinements of the stent-graft delivery process are needed to improve the accuracy of deployment.
authors.affiliation: John S. Dunn Center for Radiological Sciences, Section of Vascular and Interventional Radiology, Department of Diagnostic Radiology, The University of Texas M. D. Anderson Cancer Center, Unit 325, Houston, Texas 77030-4009, USA. mwallace@mdanderson.org
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wallace
authors.forename: Kamran
authors.initials: K
authors.lastname: Ahrar
authors.forename: Peggy
authors.initials: P
authors.lastname: Tinkey
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Wright
mesh_terms: D000818:Animals; D001807:Blood Vessel Prosthesis; D019160:Endosonography; D006083:Graft Occlusion, Vascular / Q000209:etiology; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006965:Hyperplasia; D008099:Liver / Q000502:physiology; D023421:Models, Animal; D010690:Phlebography; D011167:Portacaval Shunt, Surgical / Q000295:instrumentation / Q000379:methods*; D017082:Portal Pressure / Q000502:physiology; D011169:Portal Vein / Q000601:surgery; D011474:Prosthesis Design; D015607:Stents; D013552:Swine; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D017539:Tunica Intima / Q000473:pathology; D018084:Ultrasonography, Interventional; D014654:Vascular Patency
chemical_list: D006454:Hemoglobins