Tracheal Bifurcation Metallic Stent: An Experimental Study In Dogs

Objective To investigate the histopathologic airway change after placement of the tracheal bifurcation bare and covered metallic stent in dogs,in order to provide some experimental data for the clinical application.Materials and Methods The tracheal bifurcation covered and bare metallic stents were made for the experiment in dogs after the measure of relative airway data on computed tomography (CT) scanning. The total 12 dogs were divided into bare stent group and covered stent group, with 6 dogs each group. The tracheal bifurcation stent was deployed in the airway of dog under general anesthesia and fluoroscopic guidance. After the placement of the stent, the symptoms including dyspnea, cough, stridor, tachypnea, and dysphagia were observed. The chest CT scanning was performed in order to evaluate the migration of the stent and change of airway and lungs immediately 2, 4 and 8 week after stenting. The dogs were killed immediately after the follow-up CT scanning for pathologic examination.Results One dog with bare stent died 4 week after the stent placement, because of pneumonia and pulmonary infarction. Two dogs with covered stent died several hours after the stent placement. The other dogs had slightly stridulous in the first few days and a long-time cough. The CT scanning showed that one covered stent migrated upwards obviously 4 week after the stent placement. One dog had pneumonia; two dogs had pneumonia, bullae, and pulmonary infarction; one dog had pneumonia and pulmonary infarction. Granulation proliferation was more severe in bare stent group than that in covered stent group. Pathologic examination indicated that the proliferation of the granulation in covered stent group was slighter than that in the bare stent group. And the proliferation of the upper margin of the stent was more serious than that of mid-portion of the stent area in bare guoup.Conclusion The deployment of tracheal bifurcaton stent is relative easy. The CT scanning is very useful in choice of the stent size and in the follow-up evaluation. The bare stent can result in more severe proliferation of the granulation than covered stent.