title: Stentless bioprostheses have ideal haemodynamics, even in the small aortic root.
abstract: OBJECTIVE
  To determine normal Doppler and 2D gradients and flow characteristics of the Freestyle stentless aortic bioprosthesis related to valve size.
  
  
  BACKGROUND
  The Freestyle stentless aortic bioprosthesis is one of the newer aortic xenografts. Only limited data are available of the echocardiographic flow characteristics during a mid-term follow-up period of this valve. Therefore valve performance related to valve size was measured during a follow-up period of two years.
  
  
  METHODS
  175 consecutive patients with a Freestyle aortic bioprosthesis underwent an echocardiographic and Doppler examination according to a common protocol. Investigations were done within 4 weeks after operation, after 3 to 6 months, and after 1 and 2 years.
  
  
  RESULTS
  With a valve size from 19 to 27 mm mean gradients decreased from 8.0 +/- 5.1 mmHg at discharge to 5.8 +/- 3.8 mmHg after 3-6 months (p < 0.001). Thereafter gradients remained stable. The performance index, the ratio of the measured effective orifice area in the patient divided by the effective orifice area measured in vitro increased from 69 +/- 20% at discharge to 79 +/- 29% after one, two and three years. Performance index was especially very high in the smaller sized valves with a performance index of 85 +/- 17% for the 21 mm valve. During follow-up mean gradients remained below 10 mmHg even in the 21 mm valve.
  
  
  CONCLUSIONS
  Stentless xenografts have ideal haemodynamics, even in the small aortic root.
authors.affiliation: Department of Cardiology, Atrium Medical Centre, Heerlen, The Netherlands. lhbaur@yahoo.com
authors.forename: L H
authors.initials: LH
authors.lastname: Baur
authors.forename: Y
authors.initials: Y
authors.lastname: Houdas
authors.forename: K H
authors.initials: KH
authors.lastname: Peels
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.forename: B
authors.initials: B
authors.lastname: van Straten
authors.forename: A
authors.initials: A
authors.lastname: Prat
authors.forename: A P
authors.initials: AP
authors.lastname: Kappetein
authors.forename: M
authors.initials: M
authors.lastname: Wolters-Geldoff
authors.forename: E E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: A V
authors.initials: AV
authors.lastname: Bruschke
authors.forename: H A
authors.initials: HA
authors.lastname: Huysmans
mesh_terms: D000818:Animals; D001021:Aortic Valve; D001705:Bioprosthesis; D004452:Echocardiography; D015150:Echocardiography, Doppler; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D011474:Prosthesis Design; D013552:Swine; D013997:Time Factors