An Experimental Research For A Newly-designed Temporary Stent In Treatment Of Achalasia Cardia In Canine Models

PartⅠEstablishment of a Canine Model of Achalasia CadiaObjectiveTo develop a canine model of achalasia cadia for subsequent experimental study of a newly-designed temporary stent in the treatment of achalasia.MethodsTetradecyl-dimethyl-benzyl ammonium chloride (BAC) (4 mmol/L, 12 mL), under the guidance of endoscopy, was injected circumferentially into the lower esophageal sphincters (LES) of 24 adult beagles. Esophageal manometry and timed barium esophagography (TBE) were performed for each dog before and six months after injection, respectively. The resting LES pressure and a timed barium esophagram were assessed. The occurrence and frequency of clinical manifestation were observed.ResultsThe resting LES pressures (LESP) showed a significantly difference between pre- and post-treatment by BAC (22.88±3.13 mmHg vs 47.14±6.12 mmHg;P<0.001). Esophageal barium retention was observed in all dogs after BAC-treatment in comparison with normal esophageal emptying before treatment. The width, height and product of retained barium column 5-min after barium injection pre-treatment were 0.96±0.55 cm, 3.87±2.19 cm and 4.55±3.74 cm2,respectively, while post-treatment they were 3.04±0.47 cm, 9.74±1.33 cm and 29.39±4.35 cm2,respectively. The prevalence of food-intake decrease, regurgitation, weight loss was 62.5% (15/24), 50% (12/24), and 54.2% (13/24), respectively. All the beagles survived the period of modeling.Conclusion An achalasia model with highly resemblance to that in humankind can be established in beagles by injection of BAC into LES.PartⅡThe Efficacy of a Newly-designed Temporary Stent versus the Routine Esophageal Stent: Treating Achalasia Cardia in Canine ModelsObjectiveTo assess the efficacy and complications of a newly designed temporary covered cardia stent in the treatment of achalasia in canine models.MethodsTwenty-four dogs were randomly divided into two groups of 12, a control group (CG, routine esophageal stents) and a treatment group (TG, newly designed temporary covered cardia stents). The occurrence and frequency of stent migration were observed for each group. Stents were removed 4 days after stent insertion both in the CG and TG. Resting LES pressures and timed barium esophagrams (TBEs) were assessed before and after modeling, and at 1-week, 1-, 3- and 6-month follow-up. Three dogs in each group were killed for histological examination at each follow-up.ResultsStent insertion/removal and the follow-up procedures were well tolerated. Compared to the CG, the TG exhibited less likelihood in stent migration (n=1 in TG versus n=5 in CG), better improved resting LES pressures (at 6-month follow-up, p=0.027), and greater product (barium column height×width) differences between 0-min and 5-min TBE (at 3-month follow-up, p=0.009). Mouse anti–proliferating cell nuclear antigen (PCNA) andα-smooth muscle actin (α-SMA) staining revealed that the inflammatory reaction peaked at 1-month follow-up. Trichrome staining indicated fibrosis stabilized by 3 months after stent removals.ConclusionIn this study, the newly designed cardia stent was safe and effective in the treatment of achalasia in a canine model, and superior to the routine esophageal stent in respect of efficacy. Compared to other analyzed TBE variables, product differences between 0-min and 5-min TBE are more consistent with resting LES pressures in respect of evaluating the efficacy during follow-up. Studies with larger sample size and longer follow-up are necessary to further evaluate the efficacy and safety of the newly designed cardia stent in treatment of achalasia both in the basic and clinical.