Which kind of cardiac valve is a heterograft?

A heterograft (also called xenograft) cardiac valve is derived from an animal species, commonly porcine or bovine, and implanted into a human. These bioprosthetic valves are treated to reduce immunogenicity.

Option A describes an allograft (homograft). Option B refers to bioprosthetic valves but does not specify species. Option C describes an autograft, such as the Ross procedure.

This classification is standard in cardiac surgery and echocardiography literature【16:Textbook of Clinical Echocardiography, 6e†p.450-455】【12:ASE Valve Prosthesis Guidelines†p.200-205】.