title: A new percutaneous porcine coronary model of chronic total occlusion.
abstract: OBJECTIVE
  Chronic total occlusion (CTO) of coronary arteries represents a challenge for percutaneous treatment. Although ameroid constrictors have been used to create CTOs from extrinsic compression of coronary arteries, this model is not suitable for evaluation of novel angioplasty equipment. Thus, the objective of this study was to create a new percutaneous animal model of CTO.
  
  
  METHODS
  To create an animal model of CTO, we implanted copper-plated stents in the left circumflex coronary arteries of 18 pigs, and assigned the pigs to early group (n = 6; sacrifice at approximately 1 week), intermediate group (n = 6; sacrifice at approximately 4 weeks), and late group (n = 6; sacrifice at approximately 8 weeks).
  
  
  RESULTS
  Follow-up angiography prior to sacrifice revealed complete occlusion in 14 of 17 animals, with the subtotal occlusive lesions (mean 60% stenosis) only in the early group. Most of the pigs with total occlusions (12 of 14) showed bridging collateral flow greater than or equal to grade 2 (grade 2: 4; grade 3: 8). Histology revealed organizing thrombus in the early group with persistent inflammation, and organized thrombus with fibrosis and calcification in the intermediate and late groups. Interestingly, there were fibrotic components in the proximal and distal edges of the occlusions with softer, organizing thrombus in the middle of the CTO in the late group, suggesting that the major areas of difficulty are at the entrance and exit segments of the CTO with percutaneous recanalization.
  
  
  CONCLUSIONS
  This study shows the feasibility and reproducibility of a new porcine coronary percutaneous CTO model. This model may be useful in improving our percutaneous treatment of CTO.
authors.affiliation: Department of Medicine, Weill Cornell Medical College, 525 East 68th Street, F439, New York, Nork 10021, USA.
authors.forename: Woohyuk
authors.initials: W
authors.lastname: Song
authors.forename: Jaeung
authors.initials: J
authors.lastname: Lee
authors.forename: Hyunjoong
authors.initials: H
authors.lastname: Kim
authors.forename: Jinho
authors.initials: J
authors.lastname: Shin
authors.forename: Dongjoo
authors.initials: D
authors.lastname: Oh
authors.forename: Fermin
authors.initials: F
authors.lastname: Tio
authors.forename: S Chiu
authors.initials: SC
authors.lastname: Wong
authors.forename: Mun K
authors.initials: MK
authors.lastname: Hong
mesh_terms: D000818:Animals; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D002908:Chronic Disease; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D003331:Coronary Vessels / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005500:Follow-Up Studies; D010865:Pilot Projects; D015203:Reproducibility of Results; D015607:Stents; D013552:Swine; D016896:Treatment Outcome