title: Crimping may affect the durability of transcatheter valves: an experimental analysis.
abstract: BACKGROUND
  Transcatheter aortic valve implantation has gained widespread acceptance to treat elderly high-risk patients with aortic stenosis. We used a subcutaneous rat model to evaluate whether crimping may affect valve long-term durability.
  
  
  METHODS
  Standard Sapien transcatheter valves (Edwards Lifesciences, Irvine, CA) were crimped for different durations (1 hour, 1 day, 1 month) and uncrimped, and leaflet pieces as well as control tissue (Perimount Magna, Edwards) were then implanted subcutaneously in 15 male weanling Sprague-Dawley rats for 12 weeks. Grade of calcification was measured by freeze-dried mass and van Kossa staining. Histologic and electron microscopic examination were performed to investigate potential leaflet-fragmentation caused by crimping.
  
  
  RESULTS
  There were no differences in calcification among the groups. The calcium carbonate concentrations in all samples ranged from 0.1 to 100 mg/g dry weight. Leaflet morphology, however, differed from no fragmentation (control group) to highly fragmented tissue (1-month crimped). These differences reached statistical significance between crimped and non-crimped leaflets (p<0.003).
  
  
  CONCLUSIONS
  Transcatheter valve crimping does not necessarily affect leaflet calcification. However, the structural changes of the leaflets that were caused by crimping may have clinical significance. Duration of crimping should be as short as possible, and very tight crimping to small diameters should be avoided.
authors: Department of Cardiac Surgery, Heart Center, Institute of Pathology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany. p.kiefer@med.uni-leipzig.de
authors: Philipp
authors: P
authors: Kiefer
authors: Felix
authors: F
authors: Gruenwald
authors: Joerg
authors: J
authors: Kempfert
authors: Heike
authors: H
authors: Aupperle
authors: Joerg
authors: J
authors: Seeburger
authors: Friedrich Wilhelm
authors: FW
authors: Mohr
authors: Thomas
authors: T
authors: Walther
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000473:pathology / Q000601:surgery*; D001705:Bioprosthesis; D006328:Cardiac Catheterization; D004195:Disease Models, Animal; D019544:Equipment Failure Analysis; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D007150:Immunohistochemistry; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D011300:Preoperative Care / Q000379:methods*; D011474:Prosthesis Design / Q000379:methods; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018570:Risk Assessment; D016896:Treatment Outcome