Heart valve disease can significantly impair the heart’s ability to pump blood, leading to symptoms like shortness of breath, fatigue, and chest pain. When heart valves are damaged, they may not open or close properly. In severe cases, valve replacement surgery becomes necessary to restore proper blood flow and improve a patient’s quality of life. Among the available prosthetic options, those derived from animal tissue are commonly used.
Key Animal Sources
Animal-derived heart valves, or xenografts, primarily come from pigs (porcine valves) and cows (bovine valves). These animals are chosen because their heart structures closely resemble human valves. Pig heart valves, particularly the aortic valve, are structurally and functionally similar to human valves. Bovine valves are made from the pericardial tissue, the tough membrane surrounding the cow’s heart, which is engineered into a valve structure.
Why Animal Valves Are Used
Animal-derived heart valves offer several advantages for patients requiring valve replacement. A primary benefit is the reduced need for lifelong anticoagulation therapy, or blood thinners, compared to mechanical valves. This is particularly beneficial for older patients or those with a higher risk of bleeding. Bioprosthetic valves also exhibit natural blood flow characteristics, mimicking the function of native human valves. They are suitable for specific patient populations, such as elderly individuals or women of childbearing age.
Preparing Valves for Implantation
The preparation of animal heart valves for human implantation involves processes to ensure biocompatibility, durability, and sterility. After harvesting, the tissue undergoes decellularization, which removes animal cells to minimize the risk of immune rejection. Following this, the tissue is treated with a cross-linking agent, typically glutaraldehyde. This stabilizes the tissue, enhancing its mechanical strength and durability, and reducing its tendency for calcification. This chemical treatment helps the valve withstand the constant mechanical stresses within the heart.
Other Valve Replacement Options
While animal-derived valves are a common choice, other options exist for heart valve replacement. Mechanical valves, constructed from durable materials like pyrolytic carbon, offer exceptional longevity and can last a patient’s lifetime. However, their use necessitates lifelong anticoagulation medication to prevent blood clot formation, which carries bleeding risks. Another alternative is allografts, human donor valves obtained from cadavers. These valves are biologically compatible but have limited availability. The choice among these options depends on factors like the patient’s age, overall health, lifestyle, and willingness to manage medication regimens.
Living with a Bioprosthetic Valve
Patients who receive a bioprosthetic heart valve generally experience an improved quality of life due to the restoration of normal heart function. The durability of these valves varies, but they typically last between 10 to 20 years. The lifespan can be influenced by factors such as the patient’s age at implantation, with valves tending to last longer in older individuals. Due to the finite lifespan of bioprosthetic valves, there is a potential need for future re-operation. However, advancements in transcatheter procedures mean that subsequent valve replacements may sometimes be performed less invasively, avoiding traditional open-heart surgery. Regular follow-up care and monitoring are important to assess valve performance and detect any signs of deterioration over time.