Patent Ductus Arteriosus (PDA) is one of the most common cardiovascular congenital diseases. Detachable coils are the preferred method for transcatheteral PDA occlusion. The objective of this work was to design, develop and test a coupled coil and latex balloon device for PDA occlusion in an in vitro circuit. Methods: The designed device consisted of a 7-Fr Corodyn® balloon catheter (B. Braun Melsungen AG, Germany) with its tip cut and reattached with a 1-ml syringe needle, a 0.03-in dia silicone tubing cover (BAXTER Healthcare Corp., Deerfield, IL, USA), coupled to a PDA Cook® detachable coil (William Cook Europe A/S, Denmark), a SCIMED® guide wire (0.025in x 150cm, Boston Scientific Corp., USA), and a 0.07-mm latex seal at the balloon inlet. The device was tested in a motor-driven in vitro circuit simulating physiological conditions of a PDA, with a Systemic Compartment (SC) and a Pulmonary Compartment (PC). The PDA was simulated by a rubber conduit connecting the SC and the PC. To implant the device, the catheter tip was placed in the PDA, the balloon inflated with contrast agent, the detachable coil taken to the PDA and liberated so the coil expanded at both sides of the balloon, and the device detached by pushing the guide wire. Efficacy and safety of the liberation system and the implanted device were evaluated. Endurance (n=10) and overpressure (n=5) tests were performed. Results: Liberation system: The device was successfully liberated in 11 of 18 attempts (61%). Embolization occurred as follows: one before the implantation procedure (in the PC), one during the implantation procedure (in the SC), and one immediately after the implantation procedure (in the PC). Silicone tubing cover overfitting was the most common difficulty during implantation (3 of 18, 17%), followed by obstruction of balloon inlet (2 of 18, 11%), and guide wire interference (1 of 18, 6%). Implanted device (balloon-coil): Endurance: Failure time of the device was 89 ± 56 min (Mean ± SD). Overpressure: Failure pressure was 182 ± 30 mmHg. Leakage of the latex seal at the inlet of latex balloon was the most common failure in both endurance and overpressure tests. Conclusions: A balloon-coil liberation system for PDA occlusion was designed and tested in vitro. Initial testing indicates high efficacy and safety of both the liberation system and the implanted device. The device uses standard medical components, shows relatively low cost, and suitability for commercial production. Currently, the system is being optimized regarding catheter-device coupling fitting and balloon inlet sealing. In vivo animal testing is forthcoming.