Congenital heart disease (CHD) is the most common birth defect in the United States, occurring in 1 out of every 100 babies. In most cases, babies born with CHD must undergo a risky procedure with a 47% reintervention rate in which a modified adult coronary stent is implanted into the ductus arteriosus, an artery that closes shortly after birth. Starlight Cardiovascular is attempting to solve this problem by developing a self-expanding stent tailored specifically to the ductus arteriosus. ResiStent’s radial force testing system will enable Starlight to compare the radial stiffnesses of their various stent designs and will help them to select a design that provides sufficient radial force to hold open the ductus arteriosus. Our hydrostatic-pressure-based device measures the radial force exerted by stents as they undergo both compression and expansion, while also mitigating the friction between device and stent that can lead to inaccurate readings.