Evaluation of Mechanical Stability for a Patent Ductus Arteriosus Device

Abstract

Patent ductus arteriosus (PDA) is a condition that occurs when the ductus arteriosus vessel, a vessel connecting the aorta to the main pulmonary artery, does not close after birth, causing irregularities in blood flow. A nitinol cage device has been created to address this pathology by straddling this opening and occluding it with a polymeric foam placed in the center of the device. As the pulsating high flow environment may contribute to unwanted device migration [1], stability testing for extraction is required to ensure the device has appropriate mechanical strength to withstand physiological conditions. Dislocation force testing was performed to evaluate device stability using an Instron 5965 test-frame (Instron, Norwood, MA) on bare foams (small and large pores) and hydrogel-clotted foams, i.e. foams covered in a gel that simulates conditions once a clot has formed within the prototype PDA device. The dislocation force provides the maximum force required to dislodge the prototype PDA device once positioned inside the PDA immediately after deployment (bare foam) and once clotted (hydrogel foam) to determine changes in stability as compared with the current clinical gold standard, the Amplatz Canine Ductal Occluder.