Each year approximately 2000 children are born with a form of congenital heart disease that would benefit from mechanical restriction, or banding, of the pulmonary artery. [1,2] Installing or changing the setup of the banding requires an open chest surgery and during the first 6 months of the patient’s life, physiological parameters evolve rapidly, resulting in need for frequent reoperations. Mortality for those treated patients may be as high as 10–20%. [3] While many devices have been patented, none of them have been adopted due to size, adjustability, or reliability constraints with regard to implantation in newborns, especially below 6 months of age. Here we present the conception, design, and scale model testing of a novel pulmonary banding system for infants. This system features a hydraulic mechanical stepper actuator that offers great advantages in both reliability and compactness. As a proof of concept, we built a 5:1 scale working prototype that demonstrated the desired functionality of the device. Further steps involve scaling down the device so first porcine trials can be started.