title: Investigation on radiofrequency and laser (980 nm) effects after endoluminal treatment of saphenous vein insufficiency in an ex-vivo model.
abstract: OBJECTIVE
  An ex-vivo model for the experimental evaluation of endoluminal thermal procedures for occlusion of saphenous veins was developed. Radiofrequency obliteration (RFO) and endovenous laser therapy (ELT) were compared using this model.
  
  
  METHODS
  Experimental ex-vivo treatment study.
  
  
  METHODS
  The model consists of the subcutaneous foot veins from freshly slaughtered cows which were reperfused in situ with heparinised bovine blood. The veins were treated with either radiofrequency (RFO n=5) or with endoluminal 980 nm laser light (ELT n=5) using a continuous pull-back for RFO and a stepwise illumination and pull-back protocol for ELT. Immediately after treatment perivenous tissue and veins were examined macroscopically. In a second study the same treatment parameters were used in four further vein segments with RFO (n=2) and ELT (n=2). These vein segments were examined microscopically in HE-stained histological sections.
  
  
  RESULTS
  Induration of the vessel wall and contraction of the vessel lumen were observed after RFO. Laser treatment produced carbonised lesions of the vein wall. After 12-24 laser exposures these lesions often became transmural, causing complete perforation of the vessel wall. Histological evaluation after radiofrequency treatment demonstrated homogenous circular thermal tissue alteration with disintegration of intima and media structures. Histological evaluation after endovenous laser treatment showed large variations of thermal tissue effects. Tissue effects ranged from major tissue ablation and vessel wall disruption to minor effects located between laser exposures and on the opposite vessel wall.
  
  
  CONCLUSIONS
  Our model is suitable for systematic scientific evaluation of endovenous thermal occlusion procedures. Our first results and theoretical considerations indicate that endovenous laser treatment should be modified in order to ensure controlled homogenous circular thermal damage, avoiding vessel wall perforation and damage to perivascular structures.
authors.affiliation: Clinic for Surgery, Department for Vascular Surgery and Phlebology, Ludwig-Maximilians-University Munich, Nussbaumstrasse, Munich, Germany. clausgeorg.schmedt@med.uni-muenchen.de
authors.forename: C-G
authors.initials: CG
authors.lastname: Schmedt
authors.forename: R
authors.initials: R
authors.lastname: Sroka
authors.forename: S
authors.initials: S
authors.lastname: Steckmeier
authors.forename: O A
authors.initials: OA
authors.lastname: Meissner
authors.forename: G
authors.initials: G
authors.lastname: Babaryka
authors.forename: K
authors.initials: K
authors.lastname: Hunger
authors.forename: V
authors.initials: V
authors.lastname: Ruppert
authors.forename: M
authors.initials: M
authors.lastname: Sadeghi-Azandaryani
authors.forename: B M
authors.initials: BM
authors.lastname: Steckmeier
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods; D002417:Cattle; D005528:Foot / Q000098:blood supply; D006614:Hindlimb / Q000098:blood supply; D053685:Laser Therapy; D023421:Models, Animal; D010477:Perfusion; D012501:Saphenous Vein; D014689:Venous Insufficiency / Q000601:surgery / Q000628:therapy*