title: Comparison of hemodynamic performance of Medtronic Hall 21 mm versus St. Jude Medical 23 mm prostheses in pigs.
abstract: OBJECTIVE
  The ideal prosthesis for aortic valve replacement in the small annulus remains controversial, and has yet to be defined. In previous studies, the Medtronic Hall (MH) tilting disc valve showed superior hemodynamic performance in the hemodynamically optimum orientation compared to the St. Jude Medical (SJM) bileaflet valve, especially in smaller-sized valves. Using an animal model, the hemodynamics of 21 mm MH and 23 mm SJM valves, both of which have shown identical performance in previous clinical studies, were compared.
  
  
  METHODS
  A rotation device holding either a MH or a SJM aortic valve was implanted into eight pigs. The device allowed rotation of the implanted valve without reopening the aorta. In different orientations (best and worst orientation hemodynamically as defined previously), transvalvular pressure gradients and ventricular dimensions were measured using transesophageal echocardiography at constant hemodynamic conditions.
  
  
  RESULTS
  In the optimum hemodynamic orientation, pressure gradients of the MH valve (6.3+/-1.7 mmHg) corresponded to those obtained with the SJM valve (6.3+/-3.7 mmHg), whereas in the worst orientation the MH showed a tendency towards higher gradients (14.0+/-2.9 versus 10.3+/-4.0 mmHg) (p = not significant). A significant increase in left ventricular enddiastolic diameter was observed for both valve designs with rotation from the optimal into the worst orientation.
  
  
  CONCLUSIONS
  In the optimum hemodynamic orientation, the 21 mm MH valve matched the hemodynamic performance of the 23 mm SJM valve. Thus, implantation of the MH valve might be an alternative to root enlargement and implantation of a larger SJM valve in patients with a small aortic annulus, though optimum orientation is required.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Johann-Wolfgang-Goethe University, Frankfurt/Main, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Kleine
authors.forename: Ulf
authors.initials: U
authors.lastname: Abdel-Rahman
authors.forename: Armin A
authors.initials: AA
authors.lastname: Klesius
authors.forename: Mirella
authors.initials: M
authors.lastname: Scherer
authors.forename: Andreas
authors.initials: A
authors.lastname: Simon
authors.forename: Anton
authors.initials: A
authors.lastname: Moritz
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery; D002315:Cardiopulmonary Bypass; D017548:Echocardiography, Transesophageal; D005858:Germany; D006350:Heart Valve Prosthesis / Q000592:standards; D006439:Hemodynamics / Q000502:physiology*; D023421:Models, Animal; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D012016:Reference Values; D013552:Swine