The CryoValve SG aortic human heart valve is recovered from deceased human donors, treated with the SynerGraft® (SG) process,which is designed to reduce the donor cells present on the graft. The valve is then cryopreserved for storage until use. Removing cells from the heart valve has been shown to reduce a component of the immune response after implant compared to a standard allograft valve. However, it is not known how this affects the long-term durability of the valve.