Early catastrophic stentless valve failure secondary to possible immune reaction.

Aortic valve replacement with stentless xenografts has become routine since their introduction in the early 1990s. Although concerns of structural valve deterioration and long-term durability have been voiced, the reports on the causes or pathology associated with early valve failure have been sparse. We report two unusual cases of failure leading to patient death within the first year after implantation of the aortic valve and root with the Freestyle prostheses (Medtronic Inc, Minneapolis, MN). We suggest an early immunologic reaction to the xenograft, leading to a fatal inflammatory process, as a mechanism for unusual early valve failure in these patients.