Chronic, Preclinical Assessment of the Medtronic Advantage™ Aortic Valve Prosthesis
Nancy Rakow DVM, Dale Nelson BS, Carolyn McClay DVM, PhD, Rebecca Rose DVM, Lenny Leuer BS, Charles Boldt BS, Linda Shecterle BS, John St. Cyr MD

Fourteen adult male and female sheep underwent implantation of either a 19 mm Medtronic, Inc., Advantage™ or St. Jude Medical (SJM) aortic prosthetic valve for chronic in-vivo evaluation, using a previously reported aortic model technique. There were two operative deaths, with the remaining sheep (eight Advantage, four SJM prostheses) undergoing chronic hemodynamic and pathologic evaluations at ~140 days. One sheep (SJM prosthesis) died unexpectedly at 122 days; post-mortem 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.