Case Report: A non-diabetic, morbid obese 62 years old female was operated and 23 mm Medtronic Freestyle stentless xenograft was implanted using root inclusion technique. Forty-two months later, she was re-operated for valvular dysfunction and Medtronic Freestyle bioprosthesis was explanted. A 21 mm Sulzer Carbomedics aortic mechanical prosthesis was implanted in addition to bypasses to left anterior descending and first diagonal branch. After an uneventful early period, she was discharged from hospital on 7th postoperative day. Pathologic examination of the explanted Medtronic Freestyle aortic porcine bioprosthesis revealed that there were dystrophic calcifications in large areas at medial layer, at midportion of the media but not at inner or outer layers. In closer aspects, endothelial layer was lost and there were histiocytic cells and a few multinuclear cells at the subendothelial region. Microscopic sections of the leaflets showed loss of corrugations. No evidence of leaflet inflammation or thrombus could be discovered.Conclusions: Alpha-amino-oleic acid is not as effective as it is thought to prevent tissue calcification. Degenerative process, which ends up with the structural dysfunction of the xenografts is due to modified ionic fluxes to nonviable cells of the device rather than an immunologic chronic rejection mechanism.

Keywords: Freestyle, structural detoriation, stentless bioprosthesis