The current finite element analysis of vascular stent expansion does not take into account the effect of the stent release pose on the expansion results. In this study, stent and vessel model were established by Pro/E. Five kinds of finite element assembly models were constructed by ABAQUS, including 0 degree without eccentricity model, 3 degree without eccentricity model, 5 degree without eccentricity model, 0 degree axial eccentricity model and 0 degree radial eccentricity model. These models were divided into two groups of experiments for numerical simulation with respect to angle and eccentricity. The mechanical parameters such as foreshortening rate, radial recoil rate and dog boning rate were calculated. The influence of angle and eccentricity on the numerical simulation was obtained by comparative analysis. Calculation results showed that the residual stenosis rates were 38.3%, 38.4%, 38.4%, 35.7% and 38.2% respectively for the 5 models. The results indicate that the pose has less effect on the numerical simulation results so that it can be neglected when the accuracy of the result is not highly required, and the basic model as 0 degree without eccentricity model is feasible for numerical simulation.
Objective To analyze the near-term clinical efficacy of two different surgical procedures (Sun's procedure and Debranching combined endovascular stent-graft procedure) to cure Stanford type A aortic dissection, and summarize the clinical experience to help better master the indications of the two surgical procedures. Methods We retrospectively analyzed the clinical data of 46 patients with Stanford A aortic dissection in our hospital between September 2014 and September 2017. There were 39 males and 7 females at age of 20–74 (48.67±11.80) years. According to different surgical methods, the patients were divided into a Sun's procedure group (26 patients) and a debranching combined endovascular stent-graft procedure group (20 patients). The clinical effect of the two groups was compared. Results The debranching combined endovascular stent-graft procedure group was significantly superior to the Sun's group in cardiopulmonary bypass (CPB) time, aortic cross clamp(ACC) time, intraoperative urine output, postoperative mechanical ventilation time, postoperative 24 h volumes of drain, CICU time, renal function recovery of postoperative 72 h and total hospital stay(P<0.05). The incidence of transient neurological damage after operation in the debranching combined endovascular stent-graft procedure group was significantly lower than that of the Sun's procedure group(P<0.05). The follow-up time ranged from 3 to 36 months. And the follow-up rate was 90.5%. One patient in the Sun's procedure group died of serious pulmonary infection postoperative 30 days. One patient in the debranching combined endovascular stent-graft group was found to have internal leakage in the early postoperative examination and disappeared after 6 months. Sun's procedure group did not find endoleak. All patients during the follow-up time did not appear brain, coagulation disorders, stroke, paraplegia, upper limb ischemia and other complications. Conclusion For Stanford type A aortic dissection, debranching combined surgery may have the risk of postoperative endoleak, but the overall effect is superior to Sun's operation. Therefore, debranching combined surgery should be preferred for the treatment of this type of dissection.
To solve the problem of stent malapposition of intravascular stents, explore the design method of intravascular body-fitted stent structure and to establish an objective apposition evaluation method, the support and apposition performance of body-fitted stent in the stenotic vessels with different degrees of calcified plaque were simulated and analyzed. The traditional tube-mesh-like stent model was constructed by using computational aided design tool SolidWorks, and based on this model, the body-fitted stent model was designed by means of projection algorithm. Abaqus was used to simulate the crimping-expansion-recoil process of the two stents in the stenotic vessel with incompletely calcified plaque and completely calcified plaque respectively. A comprehensive method for apposition evaluation was proposed considering three aspects such as separation distance, fraction of non-contact area and residual volume. Compared with the traditional stent, the separation distances of the body-fitted stent in the incompletely calcified plaque model and the completely calcified plaque model were decreased by 21.5% and 22.0% respectively, the fractions of non-contact areas were decreased by 11.3% and 11.1% respectively, and the residual volumes were decreased by 93.1% and 92.5% respectively. The body-fitted stent improved the apposition performance and was effective in both incompletely and completely calcified plaque models. The established apposition performance evaluation method of stent considered more geometric factors, and the results were more comprehensive and objective.
ObjectiveTo compare the improvement of clinical symptoms and patency of stents in patients with left and right non-thrombotic iliac vein compression syndrome (NIVCS) after endovascular stent therapy. MethodsThe clinical data of patients with NIVCS admitted to the First Affiliated Hospital of Chongqing Medical University from January 2016 to January 2021 were analyzed retrospectively. The venous clinical severity score of the patients’ veins before therapy and on month 12 after therapy was analyzed. At the same time, the patencies of stents on month 1, 3, 6, and 12 after stenting were also analyzed. ResultsA total of 164 patients with NIVCS were collected, including 144 left NIVCS and 20 right NIVCS. The surgical technique success rate of endovascular stent therapy was 100% (164/164). There was no statistical difference of the venous clinical severity score between the patients with left and right NIVCS on month 12 after therapy (t=1.265, P=0.208), but the venous clinical severity score of left and right NIVCS patients on month 12 after therapy were lower than those before therapy (t=27.534, P<0.001; t=10.047, P<0.001). The accumulative one-stage stent patency rate on month 12 after therapy was 96.5% and 94.7% in the patients with left and right NIVCS, respectively (χ2=0.160, P=0.689). After the stent was fully supported and completely covered the extent of the lesion, the short-term (within 12 months) stent patency rates of the patients with different compression site of the iliac vein, as well as type, diameter, and length of stent placement had no statistical differences (P>0.05). ConclusionFrom the results of this study, whether left NIVCS or right NIVCS, endovascular stent therapy is safe and effective.