This early feasibility study was designed to obtain in vivo data to confirm assumptions on device loading conditions of the Medtronic Harmony transcatheter pulmonary valve (TPV). Secondary objectives included procedural feasibility, safety, and valve performance. The Harmony TPV was developed for nonsurgical pulmonary valve replacement in non–right ventricle-pulmonary artery conduit patients. The Native Outflow Tract TPV Research Clinical Study was the first study approved under the Food and Drug Administration Early Feasibility Study guidance. Enrollment required that patient anatomy be precisely matched to the single-size Harmony TPV implant, necessitating a rigorous selection process. The study was nonrandomized, prospective, and performed at 3 sites. All patients met standard indications for surgical pulmonary valve replacement. The goal of the screening committee was to match the candidate anatomy to predetermined engineering criteria thought to be predictive of secure Harmony TPV implantation for the single-size device under study. A majority of the screening committee was required to recommend a patient as eligible for implant. A total of 270 patients underwent prescreening cardiac magnetic resonance imaging, 66 were enrolled and received a computed tomography scan (24%), 21 met criteria for implant and were catheterized (8%), and 20 underwent implant. Nineteen of 20 met criteria for implant success. In conclusion, the Medtronic Harmony TPV represents an emerging therapeutic option for patients with complex postoperative right ventricular outflow tract failure. The initial clinical evaluation of this technology was unique, and the highly variable anatomy of this population required careful screening to ensure acceptable device fit.