MASA Valve Early Feasibility Study

Inclusion Criteria: 1. At least one of the following: Right Ventricular to Pulmonary Artery mean gradient \> 35mm Hg, moderate or severe Pulmonary regurgitation (≥3+), or clinical indication for replacement of their native or prosthetic pulmonary valve with a prosthesis. 2. Age \< 22 years 3. Patient is geographically stable and willing to return for 1 year follow-up for the trial. 4. Patient's legal guardian should be willing to provide informed consent (IC) at the hospital location where they are being enrolled. 5. The patient, and the patient's parent / legal representative where appropriate, and the treating physician agree that the subject will return for all required post-procedure follow up visits and the subject will comply with clinical investigation plan required follow-up visits. Exclusion Criteria: 1. Patient is in need of or has presence of a prosthetic heart valve at any other position 2. Patient has a need for concomitant surgical procedures (non-cardiac) 3. Patients with previously implanted pacemaker (including defibrillators) or mechanical valves 4. Patient has an active bacterial or viral infection or requiring current antibiotic therapy (if temporary illness, patient may be a candidate 4 weeks after discontinuation of antibiotics) 5. Patient has an active endocarditis 6. Leukopenia, according to local laboratory evaluation of white blood cell count 7. Acute or chronic anemia, according to local laboratory evaluation of hemoglobin Patients can be transfused to meet eligibility criteria 8. Thrombocytopenia, defined as Platelet count \< 150,000/mm3 Patients can be transfused to meet eligibility criteria 9. Severe chest wall deformity, which would preclude placement of the PV conduit 10. Known hypersensitivity to anticoagulants and antiplatelet drugs and to the device materials 11. Immunocompromised patient defined as: autoimmune disease, patients receiving immunosuppressant drugs or immune stimulant drugs 12. Patient has chronic inflammatory / autoimmune disease 13. Need for emergency cardiac or vascular surgery or intervention 14. Major or progressive non-cardiac disease (liver failure, renal failure, cancer) that has a life expectancy of less than one year 15. Currently participating, or participated within the last 30 days, in an investigational drug or device study 16. Alcohol or drug abuse as defined by DSM IV-TR criteria for substance abuse - this includes the illicit use of cannabis within the last 12 months 17. Patient has medical, social or psychosocial factors that, in the opinion of the Investigator, could have impact on safety or compliance