Persistence of the ductus arteriosus (DA) after birth leads to the congenital heart disease known as patent ductus arteriosus (PDA). The objective of this study is to develop an evaluation protocol and to propose a new and innovative intraductal design for a PDA occluder in order to conform to the varied morphology of the DA and to overcome the problems associated with devices relying on the anchorage mechanism. The new design, an assembly of 36 planar thermally treated Nitinol wires called Novel Device 36 (ND36), is in the shape of a frustum of a cone with a larger diameter of 12 mm, smaller diameter of 6 mm, and length of 11 mm. In-vitro biomimetic evaluations, namely, hemolysis tests and platelet adhesion studies, were conducted to ascertain the biocompatibility of the thermally treated Nitinol wires. These tests were also conducted on two different dimensions of Dacron fibers, which were to be sutured onto the device to induce thrombogenesis while in the duct, thereby facilitating better occlusion. Flow dynamics tests, which help simulate the dynamic conditions prevalent in the duct, were carried out on the ND36 and a commercially used PDA occlusion device. An analysis of the scanning electronic microscopy images showed no platelet adhesion on the Nitinol wires. The tested wires also showed nearly 0% hemolysis. Dacron fibers 0.2 mm thick and having an area density of 77 GSM proved to be best suited. Comparative analysis carried out with the commercially available Amplatzer duct occluder during the flow dynamics tests showed that the ND36 was capable of effectively occluding the duct as well as remaining stable under the dynamic conditions encountered in the duct. The ND36 has the potential to efficiently serve as a simplistic and cost effective alternative for PDA occlusion.
Mechanical and in vitro evaluation of an experimental canine patent ductus arteriosus occlusion device
