Heart Valve Replacement
The first attempts to surgically repair damaged heart valves occurred in the 1920s. Early attempts at heart valve repair were rarely successful and patients often died of surgical complications like thrombosis (blood clots). The first mechanical heart valve replacement surgery was performed in 1962, but early replacement valve replacement surgery was plagued by complications. Improved surgical techniques, technology and medications have made the surgery safe and effective.
Reasons for Heart Valve Replacement
Heart valve failure may be the result of a birth defect, infectious disease, injury or chronic illness. One of the most common causes is group A streptococcus bacteria which causes rheumatic fever, an infection of the heart muscle. Physical changes related to aging may also cause weakening of the heart valves. When the heart valves fail to function properly, the heart is deprived of oxygen which can lead to a heart attack. Heart valve replacement surgery improves oxygen flow.
Artificial Heart Valves
The first artificial heart valves were a ball in cage design. They were quite loud and made a noise like a clock ticking, but design improvements reduced the noise. In 1969 a disc design was introduced and in 1977 the first bileaflet design was developed. All artificial valves work by opening to allow blood to flow through the heart and closing to prevent the blood from flowing backward. The type of valve used depends on the surgeon's preference and the patient's needs.
Artificial heart valves rarely wear out and may last from eight to twenty years or even longer. Each year about 265,000 artificial heart valve implant surgeries are performed worldwide. Over two million people are currently living with artificial valves. The failure rate of artificial valves is believed to be less than 1%. There was one recall of silver coated valves in 2000 when a leaking problem was found in 2% of patients. Artificial valves are one of the most reliable prosthetic devices made.
The Future of Artificial Valves
Researchers are working with new technologies to develop plastic valves that will be stronger and have thinner walls than current designs. It is hoped that new designs will eliminate that need for patients to remain on blood thinners following valve replacement surgery. Artificial heart valves are currently made from metal alloys including titanium and pyrolytic carbon because these materials can withstand the harsh conditions in the body and they do not elicit a rejection response.
In addition to plastic heart valves, researchers in the biomedical community are attempting to “grow” heart valves from the patient's own tissue. Experiments with sheep have been successful, but this technology is still decades away from use in humans. It would eliminate the need for anti-rejection drugs and anticoagulants in post surgical patients, which doctors consider a big advantage, and it would also minimize post surgical complications like thrombosis.
Heart valve replacement surgery has increased the life span and the quality of life for millions of patients of all ages. Artificial heart valves are long lasting and dependable allowing individuals with heart valve defects to live relatively normal lives. Improvements in medical technology have made the surgery one of the best options for treatment of heart valve disease.