A prosthetic valve refers to a valve used in or right outside of the heart to replace an injured, damaged or missing heart valve. There are four places in the heart structure in which prosthetic valves may be used. These are the mitral and tricuspid valves, and the aortic valve (aorta) and pulmonary valve.
Prosthetic valve placement has become quite common and is often considered one of the simpler heart repairs, though these are still serious surgeries. A number of different valve prostheses exist. These include mechanical valves, allograft or human valves, and animal valves. There are pluses and minuses to each type.
One of the principal differences between mechanical and most biological tissue valves is that mechanical valves more accurately replace function. Most of the times, using biological tissue means the valve will provide a conduit, but doesn’t truly function as a well valve would. This is one of the reasons that virtually every mitral valve replacement surgery uses a mechanical valve. It’s necessary for the valve to open and shut accordingly, and this can’t be duplicated with one made of tissue, unless it is a tissue/mechanical hybrid.
In replacing aortic or pulmonary valves, mechanical function may not be as important, and especially in the pulmonary valve there appears a preference for using human tissue valves or those constructed of porcine tissue. These will not last as long as mechanical valves but they have one distinct advantage over them. Any time a mechanical valve is used, anticoagulation, or Coumadin (warfarin) therapy is required for life. This may affect quality of life and the valve raises risk for stroke, even with warfarin. Tissue valves don’t tend to require warfarin therapy.
Prosthetic valve replacement is quite common in children with congenital heart defects. Children may be born with insufficient, or stenotic (narrowed) valves that will not allow the heart to adequately function. In kids the most common valves replaced are the aortic and pulmonary valves, and again preference might lean toward tissue valves.
One of the things that is of concern in using prosthetic valve replacement in kids is that they will need future replacements. The valve put in today may only last for a few years before the child grows out of it. It’s not uncommon for kids to undergo two to three valve replacements if they have the first one early in life. As adults, need to replace the prosthetic valve will be based more on how the current valve is performing.