title: Impairment of pericardial leaflet structure from balloon-expanded valved stents.
abstract: OBJECTIVE
  Malpositioning is one of the major problems in transcatheter aortic valve implantation. To evaluate the influence of mechanical balloon inflation on aortic valve stent positioning, the expansion process and the impact on the valve leaflet's structure were investigated.
  
  
  METHODS
  Custom-made stents were laser cut from a 22-mm diameter stainless steel tube and mounted with a glutaraldehyde-treated bovine pericardial valve. The valved stents were crimped onto a standard balloon catheter and expanded by inflation of the balloon with 2 bar for 3 seconds. Expansion was studied using a high-speed camera, and the histology of the pericardial tissue was analyzed.
  
  
  RESULTS
  The valved stents were fully expanded within 3 seconds. Balloon inflation was observed to be asymmetric starting proximally. At the beginning of expansion, the valved stents were pulled proximally. During further inflation, the stents slipped distally on the balloon and experienced a total displacement of 13.5 mm. Macroscopic examination showed severe imprinting of the stent struts into the pericardial tissue. Histology revealed disrupted tissue layers and collagen fibers.
  
  
  CONCLUSIONS
  Analysis of valved stent expansion showed a displacement of the stent on the catheter during balloon inflation. Therefore, precise placement of the valved stent cannot be accomplished. Histologic analysis of the expanded pericardial tissue revealed disruption of collagen fibers. Disruption of pericardial tissue structures due to balloon expansion may result in early functional valve failure.
authors.affiliation: Central Laboratory Animal Facility, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
authors.forename: Wiebke
authors.initials: W
authors.lastname: de Buhr
authors.forename: Stefan
authors.initials: S
authors.lastname: Pfeifer
authors.forename: Julia
authors.initials: J
authors.lastname: Slotta-Huspenina
authors.forename: Erich
authors.initials: E
authors.lastname: Wintermantel
authors.forename: Georg
authors.initials: G
authors.lastname: Lutter
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Goetz
mesh_terms: D000818:Animals; D001021:Aortic Valve; D001705:Bioprosthesis; D006328:Cardiac Catheterization / Q000295:instrumentation*; D002417:Cattle; D019544:Equipment Failure Analysis; D005404:Fixatives; D005976:Glutaral; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation*; D008422:Materials Testing; D010496:Pericardium / Q000473:pathology / Q000637:transplantation*; D011312:Pressure; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013193:Stainless Steel; D013314:Stress, Mechanical; D013997:Time Factors; D014741:Video Recording
chemical_list: D005404:Fixatives; D013193:Stainless Steel; D005976:Glutaral