Heart Valve Function
The heart consists of four chambers, which are the right and left atria and the right and left ventricle. Blood enters the heart via the right atrium and then travels to the right ventricle, which pumps blood to the lungs. Once the blood returns from the lungs it enters into the left atrium and proceeds into the left ventricle. The left ventricle ultimately pumps blood out into the body via the aorta. Each time the blood changes areas (between atria and ventricles or between the heart and blood vessels) a valve is necessary. The purpose of the heart valves is to make sure that blood only flows in the proper direction within the heart and does not reflux back.
Mechanical Valves
One type of replacement heart valve is called a mechanical valve. Mechanical valves can be made out of metal or plastic. The valves are designed so that they only permit blood to flow in one direction. The pieces of the valve are designed so that if the blood attempts to flow in the opposite direction, the valve will naturally be forced shut, preventing blood flow. Mechanical valves are extremely durable, so they rarely break down. On the other hand, because they are not made of tissue, there is a tendency for them to cause the red blood cells to begin to clot. As a result, patients who get a mechanical replacement valve typically need to take blood-thinning medications (such as warfarin) for the rest of their lives.
Tissue Valves
Tissue valves are replacement heart valves made from actual tissue. They are usually taken from the heart of an animal or a human cadaver. These valves work similarly to mechanical replacement heart valves in that they naturally close if blood is not flowing in the correct direction. Tissue valves are not as durable as mechanical valves and may need to be replaced every ten to 15 years. On the other hand, tissue valves do not cause an increased risk of blood clotting, so patients with them do not need to take blood thinners. Both types of valves typically are able to successfully replace the damaged valve, regardless of their material.
