Tissue valves, also called biological or bioprosthetic valves, are made from animal tissue. The tissue may be bovine (cow) or porcine (pig) and constructed from the pericardium (the protective sac that surrounds the heart) or heart valve leaflet tissue. Both types of tissue valves work well and have similar defining characteristics. Tissue valves do not require lifelong blood thinners, such as warfarin (Coumadin) or some of the newer medicines, like apixaban (Eliquis). The disadvantage of tissue valves is that they wear out after about 12 to 15 years.
Mechanical valves are made from different types of metal and generally do not wear out, though patients will be required to take blood thinners for life. If the blood thinners are not taken properly, blood clots may form and potentially lead to strokes or prevent the valves from functioning properly.