• Journal of Chest Surgery
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• v.33 no.1
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• pp.99-102
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• 2000

The usual treatment for aortic aneurysms is surgical replacement with a prosthetic graft; however the associated morbidity and mortality rates must be considered. Endovascular placement of self-expandable stent-graft is a safe noninvasive treatment that can be an alternative to the surgical repair, the postoperative course of the 2 cases of thoracoabdominal aortic aneurysms was uneventful and no complication has been associated with the stent-graft during the 17 months and 5 months follow-up studies,.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.223-224
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• 2006

• Journal of Korean Neurosurgical Society
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• v.53 no.6
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• pp.360-363
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• 2013

We recently experienced self-detachment of the Solitaire stent during mechanical thrombectomy of acute ischemic stroke. Then, we tried to remove the detached stent and to recanalize the occlusion, but failed with endovascular means. The following diffusion weighted image MRI revealed no significant increase in infarction size, therefore, we performed surgical removal of the stent to rescue the patient and to elucidate the reason why the self-detachment occurred. Based upon the operative findings, the stent grabbed the main thrombi but inadvertently detached at a severely tortuous, acutely angled, and circumferentially calcified segment of the internal carotid artery. Postoperative angiography demonstrated complete recanalization of the internal carotid artery. The patient's neurological deficits gradually improved, and the modified Rankin scale score was 2 at three months after surgery. In the retrospective case review, bone window images of the baseline computed tomography (CT) scan corresponded to the operative findings. According to this finding, we hypothesized that bone window images of a baseline CT scan can play a role in terms of anticipating difficult stent retrieval before the procedure.

• Journal of Biomedical Engineering Research
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• v.24 no.1
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• pp.37-44
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• 2003

This experimental study is aimed at evaluating the hydrodynamic performance of newly designed self-expandable graft stents under steady flow condition. Two graft stents with different coating materials and a bare TiNi metallic stent for comparison test were used in the experiment. Pressure variation and velocity distribution at the upstream and downstream of the stents were measured at flow rates of 5, 10, and 15 l/min, respectively. Pressure loss due to insertion of the stent increased with increasing flow rate exponentially as expected. At a flow rate of 15 l/min, pressure loss of Polyure-thane(PU)-coated graft stent was 6 times higher than that of TiNi metallic stent, while the pressure loss of a porous Polytetrafluoroethylene(PTFE)-coated graft stent was comparable to a bare TiNi metallic stent. Velocity profiles of the porous PTFE-coated graft stent were similar to those of a bare TiNi metallic stent regardless of flow rate. Furthermore, the velocity profile of PU-coated graft stent revealed an asymmetrical and relatively low central velocity at a higher flow rate than 10 1/min, expecially, where the effects resulted in increases of wall shear stress and normal stress. The worse hydrodynamic behavior of PU-coated graft stent than the other two stents might be attributed to formation of folds due to poor flexibility of coated material when inserting the graft stent into the pipe with a more smaller size, which later gave rise non-symmetry of flow area, increase of surface roughness and jet flow via the crevice between the stent and cylinder wall.

• Korean Journal of Bronchoesophagology
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• v.10 no.2
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• pp.17-21
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• 2004

Background Insertion of tracheal stent in the treatment of benign tracheal & bronchial disease has increased since the introduction of expandable metallic stent. Material & Methods : Between Jan, 1995 and Feb. 2004, eight patients who had benign tracheo-bronchial disease underwent insertion of expandable metallic tracheal stent. We retrospectively analyzed stent insertion indications, complications, and following the result. Results : Surgical indications were post-intubation tracheal stenosis (1 case), tracheal stenosis following tracheal surgery (2 cases), tracheo-esophageal fistula (2 cases), broncho-pleural fistula(1 case), left main bronchus stenosis following bronchoplasty (1 case), and left main bronchus stenosis due to mediastinal repositioning (1 case). Expandable metallic tracheal stent was inserted in five patients to resolve dyspnea caused by airway obstruction, and to prevent recurrent pneumonia in three patients. The complication developed in 6 patients $75\%$; 3 cases of distal stenosis due to growth of granulation tissue, and one case each of tearing of posterior membrane, aggravation of tracheo-esophageal fistula, and airway partial obstruction due to stent migration. The stent was removed in 5 patients and tracheal surgery (tracheal resection and end to end anastomosis with primary repair of esophagus, pericardial patch tracheo-bronchoplasty, tracheal repair and omental wrapping) was performed in 3 patients. Conclusion Insertion of self expandable metallic stent in benign tracheo-bronchial disease is an effective means of relieving dyspnea for only a short period, and it did not increase the long term survival. Better means of treatment of benign tracheo-bronchial stenosis in necessary.

• Journal of the Korean Ceramic Society
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• v.44 no.7
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• pp.362-367
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• 2007

Stent is a tiny structure made with either ceramic coating and/or bare metal. Being approximately $1{\sim}2 mm$ in diameter, it consists of holes, slots, or void space and is designed to cover entire medical lesions. Stent implantation into patients' arteries has been practiced for a little more than a decade in order to widen the blocked artery. The adoption of the stent has significantly improved the efficacy when compared with the previous medical practice by balloon angioplasty alone. Yet better biomedical performance of the stent is being demanded in order to eliminate the still existing problem of artery restenosis, which means the artery becomes narrowed again. Recent literature survey shows researches on ceramic coatings onto the stent surface, or material design to improve the mechanical response of the stent. This study focuses more on the material design and mechanical analysis. The results showed that the void configuration within the stent affects the mechanical response significantly. The rectangular shape was found to yield expansion at a relatively lower pressure than the elliptical slot for a slotted tube stent. The present results, when combined with research on coating at the stent surface, may provide stents with improved bio-medical performance.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.439-445
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• 2020

The purpose of this study was to investigate the feasibility of stent placement and the evaluation of tissue hyperplasia caused by bare metallic stent placement in a mouse colon model. In a pilot study, C57BL/6 mouse were used to verify diameter of colon. Mean diameter size was 4.05 mm. Twenty C57BL/6 mice were divided into two groups to assess differing stent diameters (Group A, 5 mm diameter; Group B. Group B, 4 mm diameter). Follow-up, 1-week fluoroscopic imaging, 4-week endoscopic imaging were obtained. Mice were sacrificed 4-week after stent placement. Microscopic findings were evaluated. Stent placement was technically successful except one mouse in Group A. Data from the mouse was omitted. During follow-up, five mice in Group A died within 7 days after stent placement, and one stent in Group B was migrated into the rectum. The incidence of stent-related complication was 60% and 10% between group A and Group B, respectively. Gross and Endoscopic findings showed tissue hyperplasia through the mesh, and all the stents had become incorporated into the wall of the colon. Microscopic findings were no statistically significant difference. colonic stent placement was technically feasible, and stent-induced tissue hyperplasia was evident in a mouse model. With stent large size, there was the highest incidence of colon perforation.

• 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.