Prosthetic valves are usually implanted through open heart surgery. They allow surgeons to restore regular blood flow within the heart after a valve has become damaged because of disease. Valve replacement surgery is often performed when a person has a blockage that prevents blood from flowing into one chamber of the heart from another. Blood sometimes flows backward as well, which often requires valve replacement surgery to correct the problem. There are different kinds of these prosthetic valves which can be made of biological tissue or mechanical components.
A mechanical device implanted during prosthetic valve replacement surgery can be in various forms. One type is the caged ball valve, which was the first type that was implanted in humans. It typically features a silicon ball that moves inside of a metal cage in response to blood pressure. After the heart contracts, the ball normally moves back to close the valve. The product often causes blood clotting and high doses of medications to prevent such problems are typically needed.
Tilting disc prosthetic valves usually have a circular mechanism called an occluder, which is controlled by a metal strut. The metal disc typically opens and closes the valve to enable the heart to pump blood from one chamber to the next. Another type is the bileaflet valve, which has two parts that usually rotate around the device’s struts. People who have this prosthetic valve implanted often require fewer anti-coagulating drugs; the device is generally more responsive to blood flow as well.
Mechanical prosthetic valves are typically reliable and can also last a long time. Most of them can function in excess of 30 years. A biological valve, however, usually lasts anywhere from 12 to 15 years, but does not typically require a patient to be on anti-coagulation drugs. Such a device can be made of tissue from animals, such as pigs or cows, or be fabricated from other tissues such as pericardium, the layer of cells that surrounds the heart. Sometimes human valves are preserved to be implanted into patients as well.
Prosthetic valves constructed of artificial materials are usually difficult to monitor with common tests such as ultrasound, while biological ones can be seen this way. Other tests performed for monitoring the valves include a special type of echocardiogram, as well as color or spectral imaging techniques. Regular monitoring is typically necessary in case prosthetic valve repair is necessary, and to avoid the dangerous consequences of a problem with the device.