Heart Valve Replacement
Heart valve replacements (artificial valves) are very important, because in many cardiac patients they allow proper functioning of the heart, improve and prolong life and decrease risk of heart failure.
The main indications of artificial valves are heart valve diseases including certain forms of infective endocarditis. There are four valves in the heart cavities. They allow proper flow of blood in the desired direction and prevent its undesired backflow. However, there exist many valve disorders, some of them congenital and some acquired. Narrowed valves may cause a resistance to the blood flow and insufficient valves may cause leakage of blood in wrong direction. Less serious disorders of heart valves may be treated symptomatically with medications, severe conditions should be treated surgically with valve replacement. When left untreated, the situation may easily progress into heart failure. The type and severity of particular valve's disorder can be evaluated by echocardiography.
The cardiac surgery should be preceded by a thorough preoperative examination including echocardiography and eventually even coronary angiography to evaluate the overall cardiovascular reserve and risk of the procedure. The implantation of an artificial heart valve is performed under general anesthesia. The approach is from front middle chest by cutting and opening the breastbone. The operation leaves a quite long vertical scar in the middle of breastbone.
There may be distinguished two main basic types of the valve replacements – mechanical and biological valves. Mechanical valves are made of metal; the biological ones are usually made from pig or cow tissues. Both types of valves have their advantages and disadvantages.
Their main advantage is durability. Once we manage to implant a mechanical valve, there is a good chance that it will work until the patient's death. However, there is also a big disadvantage. The mechanical flap is risky from occurrence of blood clots on its surface. These blood clots may have very serious consequences. They may tear off, travel with the blood stream and occlude various arteries in the body, or they may get infected by bacteria, causing serious infective endocarditis. Therefore, people with mechanical valves should take lifelong anticoagulation. Other problem may be disintegration of red blood cells when passing the valve, which may cause anemia.
The endurance of biological valves is limited to 10-15 years and after that; the valve must be replaced, which exposes the patient to additional surgery. On the other hand, the patient does not have to regularly use the anticoagulants. The total risk of infective endocarditis is higher than in people with natural valves.
Which flap should be chosen? The choice is strictly individual. Generally speaking, younger people rather get the mechanical valves and biological valves are designed for elderly patients. The main goal is always maximal benefit with minimal risk.
The implantation of artificial heart valve is an extensive cardiac operation and chronic presence of the valve replacement has some disadvantages. Therefore, the procedure should be cautiously indicated and performed only when really needed. However, in a properly indicated patient with a severe valve disorder, the procedure may be life-saving (from the long-term point of view).