title: Water-soluble polyvinyl alcohol microspheres for temporary embolization: development and in vivo characteristics in a pig kidney model.
abstract: OBJECTIVE
  To preliminarily examine whether solubility of water-soluble polyvinyl alcohol (PVA) microspheres in blood plasma changes in proportion to their degrees of saponification. The study also examined their feasibility as a temporary embolic agents in the pig renal artery.
  
  
  METHODS
  Three types of PVA microspheres with the degrees of saponification of 97 mol% (S97), 98 mol% (S98), and 99 mol% (S99) were prepared. Seven kidneys in seven miniature pigs were embolized and divided into three groups so there would be at least two kidneys for each type of PVA. One animal in each group was euthanized immediately after angiography at 3 hours after embolization and the other one at 7 days after. In addition, one animal embolized with S99 microspheres was euthanized at 21 days after embolization.
  
  
  RESULTS
  With S97 microspheres, the vascular network had recovered to the preembolic state by 3 hours after embolization. With S98 microspheres, blood flow in the third-order branch had been restored in the same period. With S99 microspheres, the second- and lower order branches remained occluded until 21 days. Histopathologic specimens harvested at 3 hours revealed only a trace of PVA for S97 microspheres. With S98 microspheres, the vascular lumen was still found to be filled with PVA gel. With S99 microspheres, swollen microspheres densely filled the vascular lumen even on day 21.
  
  
  CONCLUSIONS
  Dissolution process in vitro and the duration of arterial occlusion in vivo were possibly related to the degree of saponification of PVA. This result may support feasibility of PVA microspheres as a temporary embolic agent.
authors.affiliation: Department of Radiology, Kansai Medical University, Hirakata Hospital, 2-3-1 Shinmachi, Hirakata, Osaka 573-1191, Japan. shomura@hirakata.kmu.ac.jp
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Shomura
authors.forename: Noboru
authors.initials: N
authors.lastname: Tanigawa
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Shibutani
authors.forename: Shinya
authors.initials: S
authors.lastname: Wakimoto
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Tsuji
authors.forename: Takanori
authors.initials: T
authors.lastname: Tokuda
authors.forename: Jiro
authors.initials: J
authors.lastname: Terada
authors.forename: Shuji
authors.initials: S
authors.lastname: Kariya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kojima
authors.forename: Atsushi
authors.initials: A
authors.lastname: Komemushi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sawada
mesh_terms: D000818:Animals; D001158:Arteries; D004621:Embolization, Therapeutic / Q000379:methods*; D006490:Hemostatics / Q000627:therapeutic use*; D008863:Microspheres; D011142:Polyvinyl Alcohol / Q000737:chemistry* / Q000627:therapeutic use*; D011859:Radiography; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging / Q000628:therapy*; D012995:Solubility; D013552:Swine; D014867:Water / Q000737:chemistry*
chemical_list: D006490:Hemostatics; D014867:Water; D011142:Polyvinyl Alcohol