RESUMO
BACKGROUND AND AIMS OF THE STUDY: 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. CONCLUSION: 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.
