Heart Valve Replacement
Throughout the world, 95% of all valve replacements are performed for mitral or
aortic valves. The mitral valve is positioned in the heartīs left side, between
the left upper chamber (left atrium) and the left lower chamber (left
ventricle). The aortic valve separates the left ventricle from the aorta (which
carries blood to the body).
Today, there are two types of prosthetic valves used for replacement: mechanical
or tissue. Select a link below to jump down the page:
Mechanical Valves
A mechanical valve is carefully designed to mimic the native heart valve. It has
a ring, like your own natural heart valve, to support the leaflets. Like your
own heart valve, the mechanical valve opens and closes with each heartbeat,
permitting proper blood flow through the heart. To prevent any blood clots from
developing on the valve, which can cause complications, a mechanical valve
replacement requires you to take anticoagulation medicine (blood thinners)
daily. The dosage of this medication is different for each person, so you will
be closely monitored to make sure you are on the correct dosage for you.
Regular blood tests will be performed at the physician's office, an
anticoagulation clinic, or at home with a specialized testing kit.
Tissue Valves
The tissue valve is a native valve taken from an animal. Once the tissue is
explanted (removed), it is chemically treated and prepared for human use. Some
tissue valves have a frame, or stent, that supports the valve, and some valves
are stentless (no framework). A very thin polyester mesh cuff is sewn around
the outside of the valve for easier implantation. Eliminating the stent makes
it possible for the surgeon to implant a larger valve. Larger valves generally
provide more surface area for blood flow; this allows more blood to flow
through the valve to accommodate the body's needs.
Homografts or Allografts
A homograft or allograft is a human valve obtained from a donor. This type of
valve is particularly beneficial for pregnant women and children, because it
does not require long-term anticoagulation therapy. In addition, it can provide
excellent hemodynamic performance, allowing for natural function of the
surrounding structures. Because the availability of these valves depends on
donors, supply is limited.
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