title: Fluid-dynamic results of in vitro comparison of four pericardial bioprostheses implanted in small porcine aortic roots.
abstract: OBJECTIVE
  Small-sized aortic bioprostheses may cause high postoperative gradients. In clinical practice, it is difficult to compare bioprostheses from different manufactures, owing to the discrepancy between the true size and the nominal size of the prosthesis and the inter-patient variability in aortic root characteristics. In vitro studies provide accurate data, and using a system in which it is possible to implant bioprostheses in a true aortic root should enable a fair comparison to be made. The present study compared the four most widely used pericardial stented bioprostheses from different manufacturers surgically implanted in small annulus, to detect any differences in their fluid-dynamic performance.
  
  
  METHODS
  The four types of bioprostheses, each implanted in a randomized sequence in eight porcine aortic roots, with a native annulus of 2.1 cm, were tested in a mock loop at 65 ml of stroke volume by calculating hydrodynamic parameters, namely mean pressure drop and effective orifice area, performance index, valve resistance and % of energy loss. The prostheses that fitted the aortic root after sizing were as follows: a Magna Ease 21, a Trifecta 21, a Soprano-Armonia 20 and a Mitroflow 23.
  
  
  RESULTS
  Effective orifice areas were 1.57 ± 0.2, 1.77 ± 0.2, 2.3 ± 0.3 and 1.75 ± 0.2 cm(2) (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The mean gradients were 13.2 ± 3, 10.2 ± 3, 6.1 ± 2 and 9.6 ± 2 mmHg (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The performance indices were 0.50 ± 0.06, 0.63 ± 0.08, 0.89 ± 0.13 and 0.56 ± 0.07 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The valve resistance, expressed in (dyn*s/cm(5)), was 69 ± 16, 55 ± 13, 33 ± 10 and 51 ± 11 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The percent of energy loss was 13.5 ± 0.5, 10.7 ± 2.5, 6.6 ± 1.6, 10.9 ± 1.8 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively.
  
  
  CONCLUSIONS
  Our study combined the fluid-dynamic reproducibility of the in vitro study with, by using porcine aortic roots, the specificity of surgery. The results confirmed that bioprostheses are inherently obstructive compared with the native aortic valve and showed that bioprostheses with the pericardium outside the stent are more efficient.
authors.affiliation: Cardiovascular Department, Cardiac Surgery Unit, Ospedale 'A. Manzoni' di Lecco, Lecco, Italy Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy giordano.tasca67@gmail.com.
authors.forename: Giordano
authors.initials: G
authors.lastname: Tasca
authors.affiliation: Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Vismara
authors.affiliation: Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy.
authors.forename: Gianfranco Beniamino
authors.initials: GB
authors.lastname: Fiore
authors.affiliation: FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy Cardiovascular Surgery Department, 'L. Sacco' Hospital, Università Degli Studi di Milano, Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mangini
authors.affiliation: FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy Cardiovascular Surgery Department, 'L. Sacco' Hospital, Università Degli Studi di Milano, Milan, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Romagnoni
authors.affiliation: Cardiovascular Department, Cardiac Surgery Unit, 'Ca Granda' Niguarda Hospital, Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pelenghi
authors.affiliation: FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy Cardiovascular Surgery Department, 'L. Sacco' Hospital, Università Degli Studi di Milano, Milan, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Antona
authors.affiliation: Department of Electronic, Information and Bioengeering, Politecnico di Milano, Milan, Italy FoRCardioLab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Redaelli
authors.affiliation: Cardiovascular Department, Cardiac Surgery Unit, Ospedale 'A. Manzoni' di Lecco, Lecco, Italy.
authors.forename: Amando
authors.initials: A
authors.lastname: Gamba
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery*; D001705:Bioprosthesis; D006350:Heart Valve Prosthesis; D006439:Hemodynamics; D008955:Models, Cardiovascular; D010496:Pericardium / Q000601:surgery*; D011474:Prosthesis Design; D013552:Swine
keywords: Adult; Aortic valve replacement; Prosthesis