| Objective Eustachian tube dysfunction(ETD)is a common disease in otolaryngology,which can lead to secretory otitis media.In recent years,endoscopic or fluoroscopic balloon dilatation for patients with ETD has achieved satisfactory efficacy.Although Eustachian tube balloon dilation has shown a good clinical prospect,the pathological changes and mechanism of intervention therapy after balloon dilation are still unclear.In addition,a few clinical studies have suggested that ETBD has a poor long-term follow-up result with a high recurrence rate.Stent implantation has been widely used in clinical non-vascular interventional therapy and has achieved good clinical effects on various benign and non-vascular stenosis.However,stent placement on Eustachian tubes(E-tube)is still in the initial stage of the preclinical study.Therefore,the purpose of this study is to:(1)investigate the anatomical characteristics of the eustachian tube(E-tube)of sheep and perform eustachian tubography to evaluate the feasibility of eustachian tube intervention;(2)investigate the pathological changes after balloon dilation and stent placement of Eustachian tube and evaluate the feasibility and safety of Eustachian tube intervention on the basis of an animal model of Eustachian tube dysfunction.Methods In this study,the anatomy of 4 sheep heads was explored by preliminary experiment to obtain the anatomical data of sheep eustachian tube,and then the eustachian tube angiography was performed.Thereafter,ten New Zealand sheep were used in this study.They were randomly assigned to five groups.Group A and B(n=8)received stent placement on the left-side E-tube.Group C and D(n=8)received ETBD on the right-side E-tube.Group E(n=2)was used as blank control.Eight sheep in Group A and Group C were sacrificed at 4 weeks after surgery,while another eight sheep in Group B and D were sacrificed at 12 weeks after surgery.CBCT scan for each sheep was performed immediately after execution,and All samples of the E-tube were harvested for pathological analysis.Results The technical success rate of eustachian tubography was 83.3%,and the average operation time was 4.7±1.6 min.The total length of sheep eustachian tube is31.72±3.07 mm,the cartilage length is 21.34±2.27 mm,and the diameter of the cartilaginous portion is 2.49±0.31 mm.The technical success rate of stent placement was 100%,and which of balloon dilatation was 87.5%.One stent migrated and dropped into the nasopharyngeal cavity 12 weeks after the procedure.The occlusion rate of the E-tube was 50%(2/4)at 4 weeks after stent placement,and 100%(3/3)at12 weeks after the procedure.The eustachian tube remained patent at 4 and 12 weeks after balloon dilation.There were significant differences in the area percentage of granulation tissue and the thickness of submucosal fibrosis between Group A and B,and Group C and D.The value in Group A and B were much higher.For the area of the free lumen,Group B was small compared with Group A.For the degree of collagen deposition,Group C was severe compared with Group D.Conclusion In this study,we successfully performed Eustachian tubography for sheep using a trans-tympanic approach.Also,we achieved the data of the sheep E-tube.Based on the establishment of an animal model of ETD,balloon dilation and stent placement were carried out.Balloon dilatation causes mild to moderate inflammation reaction on the E-tube.Stent implantation causes severe inflammation reaction on the E-tube resulting in occluded E-tube lumen.The area of the free lumen was significantly reduced due to the granulation tissue formation,which was the main factor leading to the occlusion of the lumen.The novel self-expandable stents with good conformability to the configuration of E-tube and the ability to inhibit the excessive inflammation induced by the stent need to be further investigated. |
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