**1. Introduction**

Cryopreserved heart and vascular allografts are major prostheses of choice in cardiac surgery today, used in variety of treatment situations. Right and left ventricular outflow tract reconstruction in congenital heart diseases, cases of infective endocarditis, mitral valve plasty, and aortic aneurysm of infective etiology are the major indications for allograft use. Saphenous vein grafts with small-sized valves have also been reported to be beneficial in particular cases in reconstructing the right ventricular flow to the pulmonary artery for neonates and infants, since these valved vein grafts offer good performance in preserving right ventricular function in small children, thus leading to better clinical outcomes [Murakami, 2002; Tam, 2001].

It has been over 40 years since the first heart valve allograft was performed by Dr. Ross for a case of congenital heart defect [Ross and Somerville, 1966]. Since then, heart valve allografts have entered into clinical use steadily, starting with the use of fresh grafts. Emerging techniques of cryopreservation, including programmed freezing methods and innovation of cryoprotective agents, have enabled long-term graft storage without the loss of morphological and biological benefits, and banking systems have made elective use possible. Tissue Banking system was introduced into Japan in 1997, and gradually became established as the method of choice mainly for congenital heart defects and infective cardiovascular diseases. The University of Tokyo Tissue Bank (UTTB) houses one of the biggest banks in Japan where related clinical investigations and scientific research is also conducted.

In this chapter we describe the allograft processing, the characteristics, and the clinical results of cryopreserved aortic valve allograft that were shipped from UTTB.
