• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.331-334
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• 2004

In clinical use, coronary stents keep coronary arteries open after expansion with a balloon catheter and prevent the expanded artery from collapsing. Coronary stents are positioned in artery by catheter with a balloon along a guide wire to the lesion site. Flexibility is one of important ability for delivery. In this paper, Palmaz-Schatz stent and Tenax complete stent were selected because these are the most representative of tubular stents. Finite element analyses for the stent system were performed using ABAQUS/Standard code. The present study estimated the flexibility of coronary stents due to loading directions. Moreover the present paper suggests a numerical method to test the flexibility of stents. In conclusion this paper shows how the finite element analysis can be effectively organized in the stent development.

• Korean Journal of Bronchoesophagology
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• v.2 no.2
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• pp.213-221
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• 1996

To evaluate the clinical effectiveness of expandable metallic stents, the stents were implanted under endoscopic guidance with local anesthesia or general anesthesia for maintenance of the constructed subglottic space of trachea. The nine patients with respiration difficulty were subjected for expandable stents. The stenosis of upper airway were due to the framework problem of subglottic trachea and tracheostoma after total laryngectomy. Stents were constructed of 0.4 m stainless steel win in a zigzag configuration of 8 bends. A single stent was 20 m in diameter when fully expanded and 20 mm long. The stents were placed accurately to the stenotic site and followed to the 5 month after stent placement. The stenotic area became narrowed with overgrowing of granuloma in all patients and the metallic stents were removed and the stenotic area reconstructed surgically. As conclusion, this technique for the treatment of the subglottic trachea showed simple and safe, but highly recurred due to overgrowing of granuloma. We suggest that the expandable metallic stent is not encouraging in this study.

• Journal of Biomedical Engineering Research
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• v.34 no.3
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• pp.111-116
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• 2013

Finite element analysis(FEA) has been extensively applied in the analyses of biomechanical properties of stents. Geometrically, a closed-cell stent is an assembly of a number of repeated unit cells and exhibits periodicity in both longitudinal and circumferential directions. This study concentrates on various parameters of the FEA models for the analysis of drug-eluting biodegradable polymeric stents for application to the treatment of coronary artery disease. In order to determine the mechanical characteristics of biodegradable polymeric stents, FEA was used to model two different types of stents: tubular stents(TS) and helicoidal stents(HS). For this modeling, epigallocatechin-3-O-gallate (EGCG)-eluting poly[(L-lactide-co-${\varepsilon}$-caprolactone), PLCL] (E-PLCL) was chosen as drug-eluting stent materials. E-PLCL was prepared by blending PLCL with 5% EGCG as previously described. In addition, the effects of EGCG blending on the mechanical properties of PLCL were investigated for both types of stent models. EGCG did not affect tensile strength at break, but significantly increased elastic modulus of PLCL. It is suggested that FEA is a cost-effective method to improve the design of drug-eluting biodegradable polymeric stents.

• Journal of Korean Neurosurgical Society
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• v.45 no.5
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• pp.284-288
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• 2009

Objective : Our retrospective study aimed to determine whether 16-slice computerized tomography (CT) angiography optimized sharp kernel is suitable for the evaluation of visibility, luminal patency and re-stenosis of intracranial stents in comparison with conventional angiography. Methods : Fifteen patients with symptomatic intracranial stenotic lesions underwent balloon expandable stent deployment of these lesions (10 middle cerebral arteries, 2 intracranial vertebral arteries, and 3 intracranial internal carotid arteries). CT angiography follow-up ranged from 6 to 15 months (mean follow-up, 8 months) after implantation of intracranial stents and conventional angiography was confirmed within 2 days. Curved multiplanar reformations with maximal intensity projection (MIP) with optimal window settings for assessment of lumen of intracranial stents were evaluated for visible lumen diameter, stent patency (contrast distal to the stent as an indirect sign), and re-stenosis by two experienced radiologists who blinded to the reports from the conventional angiography. Results : All of stents deployed into symptomatic stenotic lesions. All stents were classified as patent and no re-stenosis, which was correlated with results of conventional angiography. Parts of the stent lumen could be visualized in all cases. On average, 57% of the stent lumen diameter was visible using optimized sharp kernel. Significant improvement of lumen visualization (22%, p<0.01) was observed using the optimized sharp kernel compared with the standard sharp kernel. Inter-observer agreements on the measurement of lumen diameter and density were judged as good, respectively (p<0.05). Conclusion : Sixteen-slice CT using the optimized sharp kernel may provide a useful information for evaluation of lumen diameter patency, and re-stenosis of intracranial stents.

• Journal of Veterinary Science
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• v.23 no.3
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• pp.46.1-46.8
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• 2022

Background: Stenting is an effective treatment option for tracheal collapse in dogs. Cross-braided tracheal stents are currently the norm in veterinary medicine, but cross-and-hook braided stents have recently been adopted in human medicine. We examined whether stents manufactured using this novel braiding technique provided additional advantages for the treatment of tracheal collapse in dogs. Objectives: To evaluate the outcomes of cross-and-hook braided stent implantation in the treatment of tracheal collapse in dogs. Methods: The medical records of 22 client-owned dogs that underwent luminal placement of cross-and-hook braided Fauna Stents for the treatment of tracheal collapse between January 2018 and July 2021 were examined and data on canine signalment, clinical signs, diagnostic test results, surgical outcomes, and postoperative complications were retrieved and analyzed statistically. Results: Twenty-six stents were surgically implanted, with 20 dogs (90.9%) receiving one stent and the remaining two (9.1%) receiving two or more stents. All dogs survived the procedure. The median survival time at a median follow-up of 990 days was 879 days. At the final follow-up examination, loss or mild improvement of cough was observed in all dogs. Conclusions: Compared with conventional lumen stents, the cross-and-hook braided Fauna Stent offered a higher survival rate and improved clinical symptoms in all patients. The results of this study suggest that the Fauna Stent may be a promising treatment option for dogs with tracheal collapse.

• Journal of Chest Surgery
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• v.56 no.4
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• pp.264-271
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• 2023

Background: The optimal management strategy for aortoiliac occlusive disease (AIOD) remains debatable. This study compared early and late outcomes between direct surgical bypass and kissing stents for AIOD treatment. Methods: We retrospectively reviewed data, including age, sex, risk factors, comorbidities, symptoms, TransAtlantic Inter-Society Consensus (TASC) II classification, operation time, perioperative complications, in-hospital mortality, and length of hospital stay, from a cohort of 46 patients treated for AIOD (24 with kissing stents and 22 with direct surgical bypass) at Pusan National University Hostpital from January 2007 to December 2016. The primary, assisted primary, and secondary patency rates in both groups were compared. Results: The hospital stay (direct surgical bypass vs. kissing stents: 16.36±5.19 days vs. 9.08±10.88 days, p=0.007) and operation time (direct surgical bypass vs. kissing stents: 316.09±141.78 minutes vs. 99.54±37.95 minutes, p<0.001) were significantly shorter for kissing stents. Kaplan-Meier analysis revealed that the primary, assisted primary, and secondary patency rates in the direct surgical bypass group were 95.5%, 95.5%, and 95.5%, respectively, at 1 year; 86.4%, 86.4%, and 95.5% at 3 years; and 77.3%, 77.3%, and 95.5% at 5 years. The primary, assisted primary, and secondary patency rates in the kissing stent group were 100.0%, 100.0%, and 100.0%, respectively, at 1 year; 95.8%, 95.8%, and 100.0% at 3 years; and 95.8%, 95.8%, and 100.0% at 5 years. Conclusion: Except for special cases wherein endovascular revascularization is difficult, kissing stents are more advantageous for TASC II C and D lesions.

• Journal of Veterinary Clinics
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• v.36 no.5
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• pp.248-252
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• 2019

Tracheal collapse is a common respiratory disease in dogs. There are many ways to treat tracheal collapse, one of which is the use of an intraluminal stent. In this study, we divided 21 dogs into two groups and implant conventional stents and new nitinol stents. Comparison of two groups was based on following, feature of stent fracture, form of stent migration, clinical sign improvement, complication and prognosis. Approaching was established via C-arm under spontaneous breathing and placing a stent at the site of collapse. Using radiographic images, determine stent size accurately. For a comparison of identical condition, all intraluminal stents were placed 10 mm caudal from larynx to 10 mm cranial from carina. In this study, new nitinol stents improve the problems of conventional stents and may be effective in the treatment of tracheal collapse in small dogs.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1085-1087
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• 2009

Bare metal stents which were used to treat coronary artery disease have several biochemical problems. Polymerbased drug-eluting stents (DES) have opened up a new paradigm in the treatment of in-stent restenosis. Many studies and research programmes have proved that DES can prevent restenosis. In our study, paclitaxel-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles have been deposited along the three dimensional scaffold of coronary stents by a method using self-assembling properties of colloidal particles. We found that the nanoparticles were deposited uniformly and closely packed. The amount of paclitaxel was easily controlled by the drug content of the nanoparticles and the deposition count.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.335-336
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• 1996

Flexible, self-expanding metallic stent were developed using igzag wire bend and segmented polyurethane. Mechanical properties of these stents were tested using INSTRON. These stents were used for palliative treatment of mallignant esophagogastric strictures(3 case) and bawl preparation of collorectal obstruction(10 case). All stents were inserted with fluoroscopic guidance without techinal failures. According to the results, these stents are easy to insert, safe, and very effective for dilation of strictures in curved GI tract.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.523-530
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• 2022

Objective : To evaluate the safety and efficacy of an overlapped stenting-assisted coiling technique in treating vertebral artery dissecting aneurysm (VADA) via Low-profile Visualized Intraluminal Support (LVIS) stent-within-Neuroform EZ stent. Methods : From January 2017 to June 2019, 18 consecutive patients with VADAs (ruptured : unruptured=5 : 13) were treated with the overlapping stents assisted-coiling technique in our center. The overlapping manner was a Neuroform EZ stent being deployed first, followed by LVIS stents placement using the 'shelf' technique. The patients' clinical characteristics, technical feasibility and safety, and immediate and follow-up angiographic results were retrospectively reviewed. Results : Seventeen (94.4%) procedures were technically successful with an exact deployment of the stents and patent parent or perforator arteries. The immediate angiographies after procedure confirmed Raymond class I, II, and III occlusion of VADAs were in 12 (66.7%), two (11.1%), and four cases (22.2%), respectively. Post-procedural complications developed in one patient (5.6%) with minor brainstem infarctions, which resulted from an in-stent thrombosis during the procedure. Angiographic follow-up at 5.7 months (range 3 to 9 months) demonstrated Raymond class I and II occlusion were in all cases (100%). The modified Rankin Scale scores at 21.3 months (range 15 to 42 months) 0-2 in 17 cases (94.4%) and three in one case (5.6%). Conclusion : Overlapping stents via LVIS stent-within-Neuroform EZ stent combined with coiling is safe and effective for patients with VADA in the midterm results.