The use of cardiovascular tissue allografts was pioneered by Alexis Carrel[1] in his work on vascular anastomosis. Toward the end of 1940s, Grossand Hufnagel demonstrated the feasibility of using arterial vascularallografts [2,3]. In the following decade there were many reports of use ofsuch allografts to replace patients’ aorta [4–6]. However, results were dis-appointing due to a high rate of degeneration and graft failure [7,8] with aresulting shift toward using synthetic fabric grafts.The early 1950s also marked the beginning of use of prosthetic heartvalves. Many prosthetic heart valves have been developed since then, andcan be broadly classified as mechanical or bioprosthetic. Mechanical valvesare composed of metals or composite materials, and have different struc-tures like the caged-ball [9], single-tilting [10], or bileaflet-tilting-disk valves[11]. Bioprosthetic valves may be human allografts or heterografts usingbovine or porcine tissues mounted on a metal ring.In general, mechanical valves are more thrombogenic, with a highthromboembolic potential, requiring long-term anticoagulation, whilebioprosthetic have a higher risk of structural failure and reoperation[12,13]. Based on this, mechanical valves are preferred in patients who areyoung, or have a life expectancy of more than 10 to 15 years, or need long-term anticoagulation for associated disease, while bioprosthetic valves arepreferred in elderly patients or in patients who cannot take long-termanticoagulation [14].