Translated Abstract
Background: The foramen ovale is an essential physiological pathway for the atrial septum in the embryonic period. The maternal umbilical cord blood does not pass through the fetal pulmonary circulation, but enters the systemic circulation from foramen ovale ,distributing to various organs to provide the fetal Essential oxygen and nutrients for growing . After the fetus born, the foramen ovale closed with the pulmonary circulation forming. From 5months to 7months after birth, the primary septum and secondary septum of most people are fused, eventually reach an anatomic closure. If the pathway is not closed after 3 years old, named as patent foramen ovale (PFO). In recent years,although there are some disagreements of percutaneous closure PFO to prevent CS,as the RESPECT long-term trial released (the closure of PFO is superior to drug treatment) and Amplatzer device was approved by the FDA for blocking PFO to prevent CS,closing PFO has attracted more and more attention. Current occluders used to close PFO include Amplatzer PFO occluder, Nit-Occlud PFO occluder, Lifetech ASD occluder, Spider PFO occluder, Helex/GSO occluder, among which Amplatzer occluder ). Although these occluders have their own advantages, they are all made of nickel-titanium memory alloys. besides fearing of safety hazards such as aortic-atrial perforation and valve damage after implantation in the body, for most young patients, later It is also difficult to puncture atrial septum for treating other diseases (such as radiofrequency ablation). Therefore, the development of biodegradable PFO occluder has become the focus of attention. In this study, an animal model of PFO was established by implanting polydioxanone (PDO) filaments, poly-L-lactic acid (PLLA) nonwovens, and biodegradable PFOs. Occluder, observing its degradation process in animals, tissue reaction around the occluder, etc., evaluating its feasibility, safety and effectiveness of sealing PFO.
Purposes: To construct a canine model of patent foramen ovale(PFO), in order to evaluate the feasibility, safety and effect of a fully biodegradable occluder for closure of PFO, which was important for providing experimental basis for further human application.
Methods: Canine models of PFO were constructed in 12 healthy canines by homemade PFO perforator. After the establishment of the model, two dogs were sacrificed. The anatomical observation showed that the location of PFO was suitable for closure.Then the PFO was closed immediately by the fully biodegradable PFO occluder under the TTE. The canines were observed by TTE and ECG were collected at 1, 3, 6, 9 and 12 months after operation.Histopathological study was based on the hematoxylin and eosin(HE) stain.
Results: PFO models were successfully created in 10 dogs, and occluders was successfully implanted in the PFO model. During the follow-up period, the occluder was not displaced, no epidermis and thrombus were formed on the surface, and no severe arrhythmia was detected on the ECG. The TTE examination showed that the occluder fixed well at each observation site, with no residual shunt, and the mitral valve and tricuspid valve were observed. No regurgitation was seen in the valve. The gross anatomy showed that the intimal tissue gradually covered the surface of the occluder gradually from the edge.The rivet on right plate was still exposed after 1 months after surgery.and it was covered by the endothelium after 3 months after surgery.,disappeared 3 month later, After 12 months, the occluder was almost integrated with the surrounding tissue, and the rivet structure of the occluder was not recognizable. The occluder’s riveting structure of the right plate completely disappeared. Histopathology showed that the occluder’s skeleton began to disintegrate from the edge at 3 months of postoperative. The occluder skeleton was almost completely degraded and integrated with the surrounding tissue at 6 months of postoperation. Collagen fibers were replaced by fibroblasts and fibers ,the morphology of cells, new capillaries, and PLLA’s shape are not exchange. After 12 months, the occluder skeleton was completely degraded and replaced by its own new tissue, PDO were degradated completely and part of the PLLA degradated .There were more inflammatory cells around the occluder at 1 month after surgery, which disappeared 2 months later, and no inflammatory cells were seen thereafter.
Conclusion: The canine PFO model by a small chest incision right atrium puncture method is safety, convenient and workable. The biodegradable PFO occluder apply to close the cannie＇s PFO has no residue in the body after the occluder degradating and with slight tissue reaction. It is a safe, effective and feasible method to close the PFO.It can be further applied in clinical practice.
Translated Keyword
[canine, fully biodegradable, occluder, patent foramen ovale]
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