title: Hemodynamic evaluation of a new bileaflet valve prosthesis: an acute animal experimental study.
abstract: OBJECTIVE
  A newly developed heart valve (Medtronic Parallel) was tested in an acute animal experimental model.
  
  
  METHODS
  Five prototype valves were implanted in the aortic position in seven 90 kg pigs to enable acute evaluation of the hemodynamic performance in terms of turbulent stresses and transvalvular pressure drop. Turbulent stresses in the ascending aorta were measured using a 10 MHz perivascular Doppler echocardiographic transducer designed to measure the radical velocity component at 17 different points covering the aortic cross-sectional area.
  
  
  RESULTS
  The drop in transvalvular peak pressure measured with fluid-filled catheters showed a non-linear relationship with cardiac output and was always < 12 mmHg. The Reynolds normal stresses were < 60 N/m2 in systole within 50 ms time windows, which is insufficient to cause mechanical damage of the formed elements of the blood.
  
  
  CONCLUSIONS
  From a hemodynamic point of view the performance of the Medtronic Parallel aortic valve is fully acceptable and within the range of other similar, currently available mechanical valves.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Skejby Sygehus, Aarhus University Hospital, Denmark.
authors.forename: J M
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: H
authors.initials: H
authors.lastname: Nygaard
authors.forename: K
authors.initials: K
authors.lastname: Terp
authors.forename: C
authors.initials: C
authors.lastname: Riis
authors.forename: P K
authors.initials: PK
authors.lastname: Paulsen
mesh_terms: D000818:Animals; D001021:Aortic Valve; D002302:Cardiac Output; D002315:Cardiopulmonary Bypass; D015150:Echocardiography, Doppler; D005069:Evaluation Studies as Topic; D005260:Female; D006350:Heart Valve Prosthesis; D006439:Hemodynamics / Q000502:physiology*; D008297:Male; D013314:Stress, Mechanical; D013552:Swine