title: Chronic, preclinical assessment of the Medtronic Advantage aortic valve prosthesis.
abstract: OBJECTIVE
  Medtronic, Inc. has designed and developed a new bileaflet, aortic prosthesis (Advantage) and, following an in-vitro analysis, a chronic in-vivo 20-week evaluation was performed in sheep.
  
  
  METHODS
  Fourteen adult male and female sheep underwent implantation of either a 19 mm Advantage or St. Jude Medical (SJM) aortic prosthetic valve for chronic in-vivo evaluation, using a previously reported aortic model technique.
  
  
  RESULTS
  There were two operative deaths, and the remaining sheep (eight with Advantage, four with SJM prostheses) underwent chronic hemodynamic and pathologic evaluations at approximately 140 days. One sheep (SJM prosthesis) died unexpectedly at 122 days; postmortem evaluation revealed valvular thrombosis, though the valve was well seated with no excessive pannus formation or paravalvular leaks. Hemodynamic and hematologic data in the remaining sheep were comparable. Pathologic examination of the remaining implanted valves revealed well-seated prostheses, with no evidence of thrombosis, no excessive pannus formation, and no evidence of paravalvular leaks.
  
  
  CONCLUSIONS
  This preclinical animal study showed that the Advantage prosthesis has acceptable features, including equivalent hemodynamic and hematologic data, and a lack of pathological abnormalities when compared with a commercially available prosthetic bileaflet mechanical valve.
authors.affiliation: Physiological Research Laboratories, Medtronic, Inc., Minneapolis, MN, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Rakow
authors.forename: Dale
authors.initials: D
authors.lastname: Nelson
authors.forename: Carolyn
authors.initials: C
authors.lastname: McClay
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rose
authors.forename: Lenny
authors.initials: L
authors.lastname: Leuer
authors.forename: Charles
authors.initials: C
authors.lastname: Boldt
authors.forename: Linda
authors.initials: L
authors.lastname: Shecterle
authors.forename: John
authors.initials: J
authors.lastname: St Cyr
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000473:pathology / Q000601:surgery*; D004869:Equipment Safety; D005080:Exercise Test; D005260:Female; D006350:Heart Valve Prosthesis; D006439:Hemodynamics / Q000502:physiology; D015994:Incidence; D008297:Male; D023421:Models, Animal; D008955:Models, Cardiovascular; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000592:standards; D012756:Sheep; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology