BACKGROUND: Adjustment of pulmonary artery banding (PAB) may be a challenging procedure in complex congenital heart defects. Whatever the technique used, subsequent re-operations are frequently needed to control the pulmonary blood flow or pressures. OBJECTIVE: To report the efficacy of a new telemetric adjustable PAB (FloWatch-PAB) operated with the help of an external control unit that transmits to the implant energy and commands to further narrow or release the pulmonary artery using radiofrequency waves. METHODS AND RESULTS: In a multicenter, prospective, nonrandomized, single-arm clinical investigation, 13 children (median age, 4.5 months; range, 6 days to 11 years; median weight, 4.2 kg; range, 3.1 to 27 kg) underwent implantation of the FloWatch-PAB through median sternotomy in 8 and left thoracotomy in 5. The diagnosis was multiple ventricular septal (VSD) defects with complex anatomy in 3, single ventricle without pulmonary stenosis in 2, VSD with elevated pulmonary vascular resistance (PVR) in 2, atrio-ventricular canal (AVC) with elevated pulmonary vascular resistance in 1, AVC with diminutive right ventricle in 1, complex transposition of the great arteries in 3, and pulmonary atresia with complex pulmonary arteries anatomy in 1. All patients had normosystemic systolic pulmonary artery pressure. Additional procedures were performed in 7: atrial septectomy in 2, double aortic arch division in 1, patent ductus arteriosus ligation in 2, and coarctation repair in 2. There were no early or late deaths or device-related complications in a mean follow-up of 24 weeks (range, 18 to 42 weeks). A mean of 5.8 telemetric regulations per patient using the FloWatch-PAB were required to adjust the tightening of the PAB to the clinical needs (narrowing 74%, releasing 26%). At last follow-up, systolic pulmonary artery pressure was within normal range in all patients but 1. Systemic oxygen saturation demonstrated optimal regulation of the pulmonary blood flow in all according to each specific defect. Four patients were successfully corrected (VSD closure, AVSD repair, and 2 arterial switches with VSD closure). The device was easily removed and the pulmonary artery re-expanded spontaneously. CONCLUSIONS: This new device is safe and allows optimal adjustment of PAB in complex heart defects. In children requiring PAB, the use of this technology can obviate the need for early re-operations and appears to be a valuable option in the panel of surgical alternatives for selected infants.