Allogeneic Valve Transplantation

This study tests using donated human heart valves (allograft transplantation) as a more durable alternative to artificial valves for patients, especially younger people, who need a heart valve replaced. The goal is to find a valve option that lasts longer and grows with the patient. **You may be eligible if...** - You need a heart valve replacement (aortic, pulmonary, mitral, or tricuspid) - You are at least 30 days old and under 50 years old - You have limited standard options available for your valve replacement - You and your family can travel to Boston Children's Hospital within 48 hours and attend follow-up appointments **You may NOT be eligible if...** - You are younger than 30 days - You have irreversible failure of multiple organ systems - You have severe chromosomal, neurological, or genetic conditions affecting survival - You are severely obese (BMI over 35) - You have a serious immune deficiency - You have an active infection, history of endocarditis, or HIV/hepatitis B or C - You had a cancer diagnosis within the last 5 years Talk to your doctor to see if this trial is right for you.