OBJECTIVE: After positive experimental results were obtained with the FloWatch-R-PAB (EndoArt S.A., Lausanne, Switzerland), an implantable device for pulmonary artery banding with telemetric control, it was tested in a prospective, multicenter clinical trial. METHODS: From June to September 2002, 6 patients with a mean age of 10.6 months (1-31 months) and a mean weight of 6.5 kg (3.5-11 kg) underwent pulmonary artery banding with the implantation of the FloWatch-R-PAB device through median sternotomy (4 patients) or left thoracotomy (2 patients). The diagnoses were the following: univentricular heart (2 patients), complete atrioventricular septal defect (2 patients), ventricular septal defect (1 patient), and multiple ventricular septal defects with double aortic arch (1 patient). The associated procedures were atrioseptostomy with cardiopulmonary bypass (2 patients), closure of patent ductus arteriosus (2 patients), and division of double aortic arch (1 patient). RESULTS: In a mean follow-up of 7 months (6-9 months), there were no early or late deaths, reoperations, or device-related complications. A mean of 5 regulations per patient (range 2-14) were required to adjust the tightening of the pulmonary artery banding, 50% (15/30) within the first postoperative week, 20% (6/30) during the second week, and 30% (9/30) within 8 months after surgery. In 70% (21/30) of the cases, the regulation was required to further narrow the pulmonary artery, and in 30% (9/30) of the cases, the regulation was required to release the pulmonary artery. CONCLUSIONS: The initial trial confirmed the adequate functioning of the FloWatch-R-PAB device as telemetrically adjustable pulmonary artery banding. Repeated pulmonary artery banding adjustments, dictated by the clinical need in all patients even weeks after surgery, were accomplished without need for reoperation or invasive procedures. In children requiring pulmonary artery banding, the therapeutic strategies can be expanded by this promising technology. This device should be particularly indicated in patients with transposition of the great arteries requiring left ventricular retraining.