A New Atrial Septal Defect Closure Device And Its Animal Experimental Study

Objective:To evaluate the safety,efficacy, feasibility and biocompatibility of the ASD closure device in an experimental canine model(in vivo). Material and Method: 1.Develop of a new device for atrial septal defect: A superelastic, self –centering, double-disk device consists of two around disk with a waist in between. The disk and the waist are lined with polyester fibers inside. The disk to left atrial was molded into flat. A stainless steel sleeve with a female thread is laser welded to the recessed right-atrial- end of the device. This sleeve is used to screw the delivery cable to the device. 2.Creation of ASD canine model. Sixteen dogs of either sex were selected, with weight ranging from 15 to 21kg.On guidance of fluoroscopy, ASD was established by using Brokenbrough needle and balloon dilatation. Tow dogs died from cardiac tamponade. Other fourteen dogs were created ASD successfully without complication.3.Experimental study of the new -type ASD occluder:Firstly, 12 canine models were undergone catheterization and a procedure of the closure ASD by the new-type occluder. The dogs were raised for 1 month, 2 months and three months after the procedure for observation. What about living of the dogs, the situation of the devices was observed by follow-up. Their hearts had been taken out for investigation of anatomy after 1 month, 2 months, 3 months. Histological study, light microscope and scan microscope examination (SEM) were done. Nickel serum concentrations levels were measured by atomic absorption spectrometry. Result: The new ASD closure device can be stretched into an linear configuration almostly and placed inside a small sheath for delivery, and then resiled to its original configuration within the ASD when not constrained by the sheath. 12 dogs were implanted successfully with new device. Four dogs were killed at 1 month, 2 months, 3 months respectively. Macroscopic examination showed that there were no excrescence, thrombus formation, arm fractures and corrosion .The device of the 1 month dogs had been covered by a layer of transparent membranous tissue. Some early discrete endothelia cell was found under scan microscope examination. After 3 months , endothelial cell covered the devices smoothly. The endothelial cell and fibrosis had been mature. While the inflammation reaction was mild. A rise in mean serum levels was observed, from 0.66ug/L before implantation to 1.81ug/L 1 month after implantation, which was statistically significant (P<0.05). During follow-up ,the values decreased .Clinical and biochemical investigation indicate acceptable biocompatibility of the occluder. Conclusion: The self-made ASD closure device has good structural stability and excellent biocompatibility. The study show the new-type device was safe, feasible and efficient to close the ASD. These results support the investigation of the device in human clinical trials.