title: In-vitro study on the relationship between progressive sinotubular junction dilatation and aortic regurgitation for several stentless aortic valve substitutes.
abstract: OBJECTIVE
  Stentless aortic valves are widely used due to their excellent hemodynamic properties. However, if the subcoronary implantation technique is used later dilatation of the sinotubular junction (STJ) can cause regurgitation. The aim of the study was to determine the dilatation tolerance of two commercially available stentless xenografts and fresh aortic and pulmonary roots against such dilatation.
  
  
  METHODS
  Four groups each comprising five specimens of fresh porcine aortic roots, pulmonary roots, Medtronic freestyle or Toronto SPV Xenografts were tested in a mock circulation using a special device for gradually increasing the diameter of the sinotubular junction. The smallest diameter D(r) where regurgitation occurs was measured and correlated with the starting diameter D(a) and expressed as per cent values. Opening and closing patterns were obtained by a high speed camera and flow characteristics were determined.
  
  
  RESULTS
  The highest dilatation tolerance of STJ was found in the fresh porcine aortic roots (165%+/-10) followed by fresh pulmonary roots (146%+/-12), the Freestyle (143%+/-4) and the SPV (132%+/-5) bioprostheses. All differences were significant with P< or =0.05 except that between the fresh pulmonary roots and the two commercial available bioprostheses.
  
  
  CONCLUSIONS
  Our results indicate that aortic homografts provide higher resistance against regurgitation induced by dilatation of the STJ than an autograft or the stentless xenografts, Freestyle xenograft followed by the Toronto SPV. The use of the full-root technique should be considered if aortic dilatation seems to be likely.
authors.affiliation: Department of Cardiac Surgery, University Hospital Schleswig-Holstein, Campus Lübeck, Germany. axel.noetzold@gmx.de
authors.forename: Axel
authors.initials: A
authors.lastname: Nötzold
authors.forename: Michael
authors.initials: M
authors.lastname: Scharfschwerdt
authors.forename: Lisa
authors.initials: L
authors.lastname: Thiede
authors.forename: Michael
authors.initials: M
authors.lastname: Hüppe
authors.forename: Hans-Hinrich
authors.initials: HH
authors.lastname: Sievers
mesh_terms: D001021:Aortic Valve / Q000473:pathology / Q000601:surgery*; D001022:Aortic Valve Insufficiency / Q000209:etiology* / Q000473:pathology; D001705:Bioprosthesis; D004108:Dilatation, Pathologic / Q000209:etiology; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods; D011183:Postoperative Complications / Q000209:etiology*; D011474:Prosthesis Design; D011664:Pulmonary Valve / Q000503:physiopathology