This is an excised porcine bioprosthesis; the undersurface is at the left and the outflow side is at the right. Note there are three cusps sewn into a synthetic ring. The main advantage of a bioprosthesis is the lack of need for continued anticoagulation. The drawback of this type of prosthetic heart valve is the limited lifespan, on average from 5 to 10 years (but sometimes shorter) because of wear and calcification.