title: A new self-expanding aortic stent valve with annular fixation: in vitro haemodynamic assessment.
abstract: OBJECTIVE
  Balloon-expandable stent valves require flow reduction during implantation (rapid pacing). The present study was designed to compare a self-expanding stent valve with annular fixation versus a balloon-expandable stent valve.
  
  
  METHODS
  Implantation of a new self-expanding stent valve with annular fixation (Symetis, Lausanne, Switzerland) was assessed versus balloon-expandable stent valve, in a modified Dynatek Dalta pulse duplicator (sealed port access to the ventricle for transapical route simulation), interfaced with a computer for digital readout, carrying a 25 mm porcine aortic valve. The cardiovascular simulator was programmed to mimic an elderly woman with aortic stenosis: 120/85 mmHg aortic pressure, 60 strokes/min (66.5 ml), 35% systole (2.8 l/min).
  
  
  RESULTS
  A total of 450 cardiac cycles was analysed. Stepwise expansion of the self-expanding stent valve with annular fixation (balloon-expandable stent valve) resulted in systolic ventricular increase from 120 to 121 mmHg (126 to 830+/-76 mmHg)*, and left ventricular outflow obstruction with mean transvalvular gradient of 11+/-1.5 mmHg (366+/-202 mmHg)*, systolic aortic pressure dropped distal to the valve from 121 to 64.5+/-2 mmHg (123 to 55+/-30 mmHg) N.S., and output collapsed to 1.9+/-0.06 l/min (0.71+/-0.37 l/min* (before complete obstruction)). No valve migration occurred in either group. (*=p<0.05).
  
  
  CONCLUSIONS
  Implantation of this new self-expanding stent valve with annular fixation has little impact on haemodynamics and has the potential for working heart implantation in vivo. Flow reduction (rapid pacing) is not necessary.
authors.affiliation: Department of Cardio-Vascular Surgery, CHUV, Lausanne, Switzerland. mathieu.vergnat@chu-lyon.fr
authors.forename: Mathieu
authors.initials: M
authors.lastname: Vergnat
authors.forename: Roland
authors.initials: R
authors.lastname: Henaine
authors.forename: Martins
authors.initials: M
authors.lastname: Kalejs
authors.forename: Sandra
authors.initials: S
authors.lastname: Bommeli
authors.forename: Enrico
authors.initials: E
authors.lastname: Ferrari
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Obadia
authors.forename: Ludwig Karl
authors.initials: LK
authors.lastname: Von Segesser
mesh_terms: D001021:Aortic Valve / Q000601:surgery*; D001794:Blood Pressure / Q000502:physiology; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D015607:Stents; D017725:Ventricular Pressure / Q000502:physiology