Development of a new transvenous patent ductus arteriosus occlusion technique using a shape memory polymer

A novel percutaneous patent ductus arteriosus (PDA) occlusion technique, without the potential problems associated with conventional techniques, has been long awaited. The development of a novel transvenous PDA occlusion technique using a temperature-shape changeable occluder device, and the verification of its in vitro performance, were demonstrated in this study. The principles of this technique are: 1) the bar form device was inserted into the PDA transvenously by a guide wire and a pushing catheter, 2) the device was dashed with hot water through catheters, 3) the device was expanded by hot water in the PDA, and the PDA was occluded. The occluder device, made of a shape memory polymer (polynorbornene), was designed to have the monobloc configuration of a thin disk with a hole for a guide wire in the center and a cone. The barlike device by hot press was fully expanded within 10 sec upon immersion into 45 degrees C water. The mock-circulation test with the "great arteries" and a specially designed "PDA" showed 1) the introduction of hot water (45 degrees C) through the catheters caused expansion of the device which stayed in the "PDA" without any support, 2) the "aortic" pressure and the distal "aortic" flow increased rapidly, and the "pulmonary" flow reduced promptly. This resulted in a drastically reduced shunt ratio at the PDA from 68% to 30%. Thus, the novel PDA occlusion technique developed here functioned well to occlude the PDA in a great arteries model.