• Journal of Korean Neurosurgical Society
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• v.56 no.6
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• pp.463-468
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• 2014

Objective : Unexpected Solitaire stent detachment can occur during mechanical Solitaire thrombectomy. The purpose of this study was to retrospectively evaluate the influencing factors causing unexpected Solitaire stent detachment and the clinical outcomes. Methods : Between October 2011 to December 2013, 232 cases of mechanical Solitaire thrombectomy for acute ischemic stroke were performed in 3 stroke centers. During this period, we encountered unexpected Solitaire stent detachments during mechanical Solitaire thrombectomies in 9 cases. Results : Solitaire stents unexpectedly detached in 9 cases (3.9%) during the retrieval of Solitaire stents. The median patient age was 76 years. The occlusion sites of the unexpected stent detachment were the proximal middle cerebral artery (MCA) in 7 cases and the internal carotid artery in 2 cases. The sizes of the stents that unexpectedly detached were $6{\times}30$ mm in 7 cases, $5{\times}30$ mm in 1 case, and $4{\times}20$ mm in 1 case. Four patients had unexpected detachment at the first retrieval, 1 patient at the second, 3 patients at the third, and 1 patient at the fifth. In all of the cases of unexpected detachment at the first retrieval, the stent deployment site was the proximal MCA. After detachment, a proximal marker of the Solitaire stent was observed in 3 patients. However, no marker was visible in the remaining 6 patients. Conclusion : Unexpected Solitaire stent detachment should be considered in the first instance of stent retrieval for a relatively large-diameter stent, especially in elderly patients with MCA occlusions.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.1
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• pp.67-71
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• 1996

During a 2-year period microsurgical vasovasostomies using permanent silicone stent(c-shaped stent with 0.6mm slit, 5mm in length, 0.8mm in outer diameter, 0.5mm in inner diameter) were performed in 30 patients for vasectomy revesal. The stent-assisted vasovasostomy(SVV) was intended to decrease the technical demand, the time requirement and the occurrence of reobstruction due to postoperative stricture. The effectiveness of the permanent silicone stent for vasovasostomy was compared with that of microsurgical two-layered vasovasostomy(VV). Sperms were present in all the ejaculates of the 25 men on semen analysis 1-2 months after SVV. Pregnancy occurred in 10 of 22 couples(45.5%) during 2-24 months of follow-up and it took 4-10 months(average 7.2 months) to get pregnant. Average operation time for the VV was 150 minutes and that for the SVV 125 minutes. Among 12 men who had sperms in the ejaculates 1-2 months after SVV, 4 revealed azoospermia 3-17 months postoperatively. Among the 4 patients with postoperative azoospermia, 2 underwent reoperation. On histopathologic examination, previously anastomsed sites showed obliterated lumen of the stent and strictures of vas proximal and/or distal to the stents due to granulation tissues. In conclusion, the SVV was not more efficacious in terms of patency and pregnancy rate than the VV.

• Journal of Korean Neurosurgical Society
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• v.51 no.3
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• pp.155-159
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• 2012

The treatment of bilateral vertebral artery dissecting aneurysms (VADAs) presenting with subarachnoid hemorrhage (SAH) is still challenging. The authors report a rare case of bilateral VADA treated with coil trapping of ruptured VADA and covered stents implantation after multiple unsuccessful stent assisted coiling of the contralateral unruptured VADA. A 44-year-old woman was admitted to our hospital because of severe headache and sudden stuporous consciousness. Brain CT showed thick SAH and intraventricular hemorrhage. Cerebral angiography demonstrated bilateral VADA. Based on the SAH pattern and aneurysm configurations, the right VADA was considered ruptured. This was trapped with endovascular coils without difficulty. One month later, the contralateral unruptured VADA was protected using a stent-within-a-stent technique, but marked enlargement of the left VADA was detected by 8-months follow-up angiography. Subsequently two times coil packing for pseudosacs resulted in near complete occlusion of left VADA. However, it continued to grow. Covered stents graft below the posterior inferior cerebellar artery (PICA) origin and a coronary stent implantation across the origin of the PICA resulted in near complete obliteration of the VADA. Covered stent graft can be used as a last therapeutic option for the management of VADA, which requires absolute preservation of VA flow.

• Journal of Korean Neurosurgical Society
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• v.53 no.4
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• pp.241-244
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• 2013

The authors describe the use of a self-expandable stent in a temporary deployment for treatment of a very wide-neck A1 segment of anterior cerebral artery (ACA) aneurysm following incomplete clipping. A 39-year-old hypertensive man presenting with seizure-like movement underwent computed tomography, which showed acute subarachnoid hemorrhage and an A1 segment of ACA aneurysm with superior and inferior projection. He underwent surgical clipping of the aneurysm, but superior and posterior portion of wide-neck aneurysm remained. We decided to treat the remnant aneurysm using an endovascular modality. After selection of the aneurysm, coil packing was performed assisted by the temporary semi-jailing technique. The Enterprise stent (Cordis Neurovascular, Miami, FL, USA) was deployed and recaptured repeatedly for angiography to ensure safety of the small caliber parent artery. Successful semi-deployment and recapture of the stent allowed subtotal coil occlusion of the aneurysm with good anatomic and clinical results. No complications were encountered. The stent could be recaptured up to the point where the proximal end of the stent marker was aligned with distal marker band of the microcatheter, approximately 70% of the stent length. The temporary semi-jailing technique is feasible for wide-neck aneurysm with small caliber parent artery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.915-922
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• 2004

A stent is small tube-like structure expanded into stenotic arteries to restore blood flow. The stent expansion behaviors define the effectiveness of the surgical operation. In this paper, finite-element method was employed to analyze expansion behaviors and fatigue life of a typical diamond-shaped balloon-expandable stent. Beyond safety considerations, this type of analysis provides mechanical properties that are often difficult to obtain by experiments. Mechanical properties of the stent expansion pressure, radial recoil, longitudinal recoil and foreshortening were simulated using commercial FEM code, ANSYS and fatigue life were estimated using NISAII ENDURE. The FEM results showed that the pressures necessary to expand the stent up to a diameter of 3mm, 4mm and 5mm were 0.75MPa, 0.82MPa and 0.97MPa. The fatigue lifes according to expansion diameter were 114${\times}$10$^{7}$cycles, 714${\times}$$^{6}$cycles and 163${\times}$10$^{6}$cycles. As a result, a finite element model used in this study can simulate expansion behaviors of stents and should be useful to design new stents or analyze actual stents.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.156-162
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• 2005

Stouts are frequently used throughout the human body, but the most critical areas are in coronary arteries. They open pathways in vessels and supply blood directly to the heart muscle. To simulate behavior of expansion for the coronary stent by balloon, the commercial finite element code LS-DYNA and ANSYS were used in the analysis. The explicit method is used to analyze the expansion of the stent and the implicit method is performed to simulate the springback that developed in a stent after the balloon pressure has been removed. Finally the experimental results for the expansion of the PS153 stents were compared with the FEM results. The springback was measured with the stents subjected to no external pressure to which stents are subjected in vivo. The simulated results were in good agreement with experimental results. Standard mechanical characteristics such as stress, plastic strains, and springback can be derived from the numerical results. These data can be used to determine maximum expansion diameter without fracture and expansion pressure considering elastic recoil.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.586-590
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• 2019

The aim of this study was to fabricate a dextran polyelectrolyte multi-layer on a bare metal stent (BMS) and to evaluate bio-physical properties of the layer. Diethylaminoethyl-dextran (DEAE-D) as a polycation and dextran sulfate (DS) as a polyanion were successively coated on the bare metal stent by a well-known layer-by-layer procedure. The morphology of the stent surface and its cell adhesion were studied after each coating step by scanning electron microscopy. The stent showed more blotched and slightly rougher morphology after dextran-DS coating. The contact angle of the DEAE-DS group ($39.5{\pm}0.15^{\circ}$) was significantly higher than that of the BMS group ($45.16{\pm}0.08^{\circ}$), indicating the improvement of hydrophilic. The SMC proliferation inhibition in the DEAE-DS-coated stent group ($20.9{\pm}0.04%$) was stronger than that in the control group ($21.7{\pm}0.10%$ in DS-coated group only). The DEAE-DS coating is desired for stent coating materials with biocompatibility and anti-restenosis effect.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.165-169
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• 2021

The objective of this study was to fabricate a novel hydrophobic stent for reducing restenosis by employing electron beam equipment. The stent was fabricated from a CoCr alloy tube by using a femtosecond laser and was treated with argon plasma. Subsequently, the stent's surface specification changed from hydrophilic to hydrophobic. Application of the electron beam offers several advantages such as a short processing time, whole surface reforming, and enhancement of material properties. As the surface of the stent was rendered hydrophobic, it can provide equivalent or enhanced mechanical properties and greater functionality with a higher radial force at the extended stent in a blood vessel. The obtained results corresponding to the mechanical properties indicate that the contact angle increased to approximately 130°, and the radial force increased to approximately 3 N. Furthermore, cell culture experiments were conducted for verifying whether cells were cultured on the surface-modified CoCr surface. Based on the obtained results, it is believed that an effective reduction in the restenosis of inserted vascular stents is possible.

• Journal of Gastric Cancer
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• v.18 no.1
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• pp.37-47
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• 2018

Purpose: The endoscopic management of a fully covered self-expandable metal stent (SEMS) has been suggested for the primary treatment of patients with anastomotic leaks after total gastrectomy. Embedded stents due to tissue ingrowth and migration are the main obstacles in endoscopic stent management. Materials and Methods: The effectiveness and safety of endoscopic management were evaluated for anastomotic leaks when using a benign fully covered SEMS with an anchoring thread and thick silicone covering the membrane to prevent stent embedding and migration. We retrospectively reviewed the data of 14 consecutive patients with gastric cancer and anastomotic leaks after total gastrectomy treated from January 2009 to December 2016. Results: The technical success rate of endoscopic stent replacement was 100%, and the rate of complete leaks closure was 85.7% (n=12). The mean size of leaks was 13.1 mm (range, 3-30 mm). The time interval from operation to stent replacement was 10.7 days (range, 3-35 days) and the interval from stent replacement to extraction was 32.3 days (range, 18-49 days). The complication rate was 14.1%, and included a single jejunal ulcer and delayed stricture at the site of leakage. No embedded stent or migration occurred. Two patients died due to progression of pneumonia and septic shock 2 weeks after stent replacement. Conclusions: A benign fully covered SEMS with an anchoring thread and thick membrane is an effective and safe stent in patients with anastomotic leaks after total gastrectomy. The novelty of this stent is that it provides complete prevention of stent migration and embedding, compared with conventional fully covered SEMS.

• Journal of Chest Surgery
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• v.48 no.5
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• pp.368-370
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• 2015

Stent entrapment is a very rare complication of percutaneous coronary intervention. The interventional approach could be a treatment strategy. However, if it does not work, surgical treatment should be considered. Here, we report a case of surgical treatment of stent entrapment in the left coronary sinus of a 53-year-old male patient.