title: Finding the ideal biomaterial for aortic valve repair with ex vivo porcine left heart simulator and finite element modeling.
abstract: OBJECTIVE
  Aortic valve (AV) repair (AVr) has become an attractive alternative to AV replacement for the correction of aortic insufficiency; however, little clinical evidence exists in determining which biomaterial at AVr would be optimal. Cusp replacement in AVr has been associated with increased long-term AVr failure. We measured the hemodynamic and biomaterial properties using an ex vivo porcine AVr model with clinically relevant biomaterials and generated a finite element model to ascertain which materials would be best suited for valve repair.
  
  
  METHODS
  Porcine aortic roots with intact AVs were placed in a left heart simulator mounted with a high-speed camera for baseline valve assessment. The noncoronary cusp was excised and replaced with autologous porcine pericardium, glutaraldehyde-fixed bovine pericardial patch (Synovis), extracelluar matrix scaffold (CorMatrix), or collagen-impregnated Dacron (Hemashield). The hemodynamic parameters were measured for a range of cardiac outputs (2.5-6.5 L/min) after repair. The biomaterial properties and St Jude Medical pericardial patch were determined using pressurization experiments. Finite element models of the AV and root complex were constructed to determine the hemodynamic characteristics and leaflet stresses.
  
  
  RESULTS
  The geometric orifice areas after repair were significantly reduced in the Hemashield (P<.05) and CorMatrix (P=.0001) groups. Left ventricular work increased with increasing cardiac output (P=.001) in unrepaired valves, as expected, and was similar among all biomaterial groups. Finite element modeling of the biomaterials displayed differences in the percentage of changes in total Von Mises stress for both replaced (noncoronary cusp) and nonreplaced left and right cusps with the St Jude Medical pericardial patch (+4%, +24%) and autologous porcine pericardium (+5, +26%), with a lower percentage of changes than for the bovine pericardial patch (+12%, +27%), Hemashield (+30%, +9%), and CorMatrix (+13%, +32%).
  
  
  CONCLUSIONS
  The present study has shown that postrepair left ventricular work did not increase despite a decrease in geometric orifice areas in the Hemashield and CorMatrix groups. The autologous porcine pericardium and St Jude Medical pericardial patch had the closest profile to normal AVs; therefore, either biomaterial might be best suited. Finally, the increased stresses found in the bovine pericardial patch, Hemashield, and CorMatrix groups might, after prolonged tensile exposure, be associated with late repair failure.
authors.affiliation: Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Hadi Daood
authors.initials: HD
authors.lastname: Toeg
authors.affiliation: Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Ovais
authors.initials: O
authors.lastname: Abessi
authors.affiliation: Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Talal
authors.initials: T
authors.lastname: Al-Atassi
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
authors.forename: Laurent
authors.initials: L
authors.lastname: de Kerchove
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
authors.forename: Gebrine
authors.initials: G
authors.lastname: El-Khoury
authors.affiliation: Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Labrosse
authors.affiliation: Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. Electronic address: mboodhwani@ottawaheart.ca.
authors.forename: Munir
authors.initials: M
authors.lastname: Boodhwani
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery*; D001672:Biocompatible Materials; D001705:Bioprosthesis; D002417:Cattle; D004195:Disease Models, Animal; D020342:Finite Element Analysis; D006350:Heart Valve Prosthesis; D006439:Hemodynamics; D066298:In Vitro Techniques; D013552:Swine
chemical_list: D001672:Biocompatible Materials