title: Porous and nonporous polycarbonate urethane stent-grafts for TIPS formation: biologic responses.
abstract: OBJECTIVE
  To evaluate the biologic response to transjugular intrahepatic portosystemic shunts (TIPS) lined with polycarbonate urethane endografts and the effects of different porosity formulations.
  
  
  METHODS
  Seventeen TIPS were created in non-modified portal hypertensive miniswine with use of porous (n = 6), nonporous (n = 7) polycarbonate urethane stent-grafts, and control Wallstents TIPS (n = 4). Eight-week venography, histology, scanning electron microscopy, and immunohistochemical analyses were performed.
  
  
  RESULTS
  The mean 8-week percent parenchymal tract shunt stenosis was 75%, 46%, and 26% in the control, porous, and nonporous groups, respectively. Occlusions developed in one control, one porous, and two nonporous shunts. The biologic response to porous grafts included marked inflammation and encapsulation and permeation of the grafts by a thick fibrous pseudointima. Nonporous grafts evoked little inflammation or pseudointima. Mature thrombus lined the occluded shunts (under which little luminal pseudointima or endothelium was present). The control group showed typical pseudointimal hyperplasia enveloping the intraparenchymal portions of the stents.
  
  
  CONCLUSIONS
  The healing response of the porous and nonporous grafts markedly differed. Unlike the porous grafts and control stents, the nonporous endografts elicited little inflammation or luminal pseudointimal hyperplasia, although sporadic thrombosis was problematic in this normotensive model. Graft use in high-flow situations (ie, human TIPS, possibly in concert with antiplatelet agents) may allow desired shunt patency prolongation.
authors.affiliation: Department of Radiology, University of Pennsylvania Hospital, Philadelphia 19104, USA.
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Haskal
authors.forename: L J
authors.initials: LJ
authors.lastname: Brennecke
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation; D006083:Graft Occlusion, Vascular; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D011076:Polycarboxylate Cement; D011169:Portal Vein / Q000473:pathology; D019168:Portasystemic Shunt, Transjugular Intrahepatic / Q000295:instrumentation*; D011172:Portography; D015607:Stents; D013552:Swine; D013556:Swine, Miniature; D017539:Tunica Intima / Q000473:pathology; D014520:Urethane
chemical_list: D001672:Biocompatible Materials; D011076:Polycarboxylate Cement; C005506:polycarbonate; D014520:Urethane