title: The rationale of retinal endovascular fibrinolysis in the treatment of retinal vein occlusion: from experimental data to clinical application.
abstract: OBJECTIVE
  We describe a retinal endovascular fibrinolysis technique to directly reperfuse experimentally occluded retinal veins using a simple micropipette.
  
  
  METHODS
  Retinal vein occlusion was photochemically induced in 12 eyes of 12 minipigs: after intravenous injection of 10% fluorescein (1-mL bolus), the targeted retinal vein segment was exposed to thrombin (50 units) and to Argon laser (100-200 mW) through a pars plana approach. A beveled micropipette with a 30-μm-diameter sharp edge was used for micropuncture of the occluded vein and endovascular microinjection of tissue plasminogen activator (50 μg/mL) in 11 eyes. In one control eye, balanced salt solution was injected. The lesion site was examined histologically.
  
  
  RESULTS
  Retinal vein occlusion was achieved in all cases. Endovascular microinjection of tissue plasminogen activator or balanced salt solution led to reperfusion of the occluded retinal vein in all cases. Indicative of successful reperfusion were the following: continuous endovascular flow, unaffected collateral circulation, no optic disk ischemia, and no venous wall bleeding. However, balanced salt solution injection was accompanied by thrombus formation at the punctured site, whereas no thrombus was observed with tissue plasminogen activator injection.
  
  
  CONCLUSIONS
  Retinal endovascular fibrinolysis constitutes an efficient method of micropuncture and reperfusion of an experimentally occluded retinal vein. Thrombus formation at the punctured site can be prevented by injection of tissue plasminogen activator.
authors.affiliation: Laboratory of Neurobiology and Physiology of Retinal Circulation, Department of Ophthalmology, University of Geneva, Geneva, Switzerland. constantin.pournaras@hcuge.ch
authors.forename: Constantin J
authors.initials: CJ
authors.lastname: Pournaras
authors.forename: Ioannis K
authors.initials: IK
authors.lastname: Petropoulos
authors.forename: Jean-Antoine C
authors.initials: JA
authors.lastname: Pournaras
authors.forename: Alexandros N
authors.initials: AN
authors.lastname: Stangos
authors.forename: Nicole
authors.initials: N
authors.lastname: Gilodi
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Rungger-Brändle
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D057510:Endovascular Procedures; D005342:Fibrinolysis; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006490:Hemostatics / Q000633:toxicity; D008845:Microinjections; D011677:Punctures; D012039:Regional Blood Flow; D015424:Reperfusion; D012169:Retinal Vein / Q000503:physiopathology; D012170:Retinal Vein Occlusion / Q000188:drug therapy* / Q000503:physiopathology; D012599:Sclerostomy; D013552:Swine; D013556:Swine, Miniature; D013917:Thrombin / Q000633:toxicity; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*
chemical_list: D005343:Fibrinolytic Agents; D006490:Hemostatics; D013917:Thrombin; D010959:Tissue Plasminogen Activator