title: Leaflet opening and closing dynamics of stentless bioprostheses.
abstract: OBJECTIVE
  Stiffening of the aortic root may entail asynchronous aortic leaflet movement, and result in enhanced flexion-stress in specific areas of the cusps. As stentless prostheses are more flexible than their stented counterparts, they are more likely to exhibit physiologic leaflet movements. The study aim was to compare leaflet movement dynamics in stented versus non-stented aortic valves implanted in pigs.
  
  
  METHODS
  Aortic bioprostheses were implanted surgically into adult pigs as follows: stented Mitroflow (n = 6), stentless Solo (n = 5), and stentless Toronto SPV (n = 4). In five control animals, the native aortic valve leaflets were untouched. Postoperatively, the aortic valve was displayed by epicardial echocardiography. M-mode display of the non-coronary leaflet was applied to assess rapid valve-opening velocity (V(open)) and rapid valve-closing velocity (V(close)).
  
  
  RESULTS
  The mean V(open) values were 29.2, 25.5, 37.8, and 31.9 cm/s, respectively, for the native, Toronto SPV, Solo, and Mitroflow valves. The mean V(close) values were 23.2, 21.9, 34.1, and 34.3 cm/s, respectively. A comparison of V(open) values showed no statistically significant difference between the valves. The Mitroflow and Solo valves yielded significantly higher V(close) values than the native and Toronto SPV valves. The Toronto SPV exhibited marked systolic leaflet folding.
  
  
  CONCLUSIONS
  The stent of a bioprosthetic valve does not appear to affect leaflet velocities when compared to the stentless bioprosthetic valve. The Solo and Mitroflow valves closed more abruptly than the porcine native aortic valve; however, the Toronto SPV valve displayed diverging systolic leaflet movement patterns.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Aarhus N, Denmark.
authors.forename: Markus W
authors.initials: MW
authors.lastname: Frost
authors.forename: Jonas A
authors.initials: JA
authors.lastname: Funderl
authors.forename: Kaj Erik
authors.initials: KE
authors.lastname: Klaaborg
authors.forename: Per
authors.initials: P
authors.lastname: Wierup
authors.forename: Erik
authors.initials: E
authors.lastname: Sloth
authors.forename: Hans
authors.initials: H
authors.lastname: Nygaard
authors.forename: J Michael
authors.initials: JM
authors.lastname: Hasenkam
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000601:surgery*; D001696:Biomechanical Phenomena; D001705:Bioprosthesis; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation*; D006439:Hemodynamics; D008422:Materials Testing; D011474:Prosthesis Design; D013552:Swine; D014463:Ultrasonography