• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.485-490
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• 2003

In this paper, a nonlinear finite-element method was employed to analyze mechanical behaviors of the 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 studied using commercial FEM code, ANSYS. As a result, the pressure necessary to expand the stent up to a diameter of 3mm was 7.6atm, longitudinal recoil, radial recoil and foreshortening were -0.388%, 2.87% and 4.07% respectively. In conclusion, a finite element model used in this study could help in designing new stents or analyzing actual stents.

• 대한기계학회논문집A
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• 제28권7호
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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.

• 대한기계학회논문집A
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• 제29권1호
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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.

• Journal of Korean Neurosurgical Society
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• 제46권6호
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• pp.572-576
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• 2009

Detachable balloon-based endovascular fistula occlusion is a widely accepted treatment for traumatic carotid cavernous fistulas (CCF). However, more recently coils have been used to obliterate the lesion, especially in case detachable balloon is not available. We failed balloon-assisted coil embolization for CCF because of large fistulas and herniation of coil loops into the parent artery. The authors describe our experiences of balloon-expandable graft-stents to treat CCF, and place emphasis on arterial wall reconstruction. Three traumatic CCF patients were treated using a graft-stent with/without coils, and underwent angiographic follow-up to evaluate the patency of the internal carotid artery (ICA). In all cases, symptoms related to CCF regressed after stent deployment and did not recur during follow-up. Follow-up angiography revealed good patency of the ICA in all patients. Graft-stents should be considered as an alternative means of treating CCF and preserving the parent artery by arterial wall reconstruction especially in patients with a fistula that cannot be successfully occluded with detachable balloons or coils.

• Journal of Korean Neurosurgical Society
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• 제50권1호
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• pp.48-50
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• 2011

A 57-year-old man presented with a 2-day history of left oculomotor palsy. Digital subtraction angiography revealed a pseudoaneurysm of the left cavernous internal carotid artery (ICA) measuring $37{\times}32mm$. The pseudoaneurysm was treated with a balloon expandable graft-stent to occlude the aneurysmal neck and preserve the parent artery. A post-procedure angiogram confirmed normal patency of the ICA and complete sealing of the aneurysmal neck with no opacification of the sac. After the procedure, the oculomotor palsy improved gradually, and had completely resolved 3 months after the procedure. A graft-stent can be an effective treatment for a pseudoaneurysm of the cavernous ICA with preservation of the parent artery.

• Tuberculosis and Respiratory Diseases
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• 제39권4호
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• pp.318-324
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• 1992

기관지내 팽창성 금속 스텐트의 사용은, 아직은 외국의 경우에서도, 추적 관찰기간이 짧고 시술받은 환자의 수도 많지 않으며 장기간 삽입후의 변화에 대하여는 그 결과가 예측하기 힘들다는 점등을 생각할 때는 현재 이의 시행은 아직은 실험적 단계라 할 수 있다. 그러나 내과적 혹은 외과적인 문제로 수술적 기관지 보존술등을 시행받기 어려운 상태에 있는 기관지 협착환자에서는 단독으로, 혹은 laser therapy, electrocoagulation, cryotherapy, balloon dilatation 및 다른 tracheal devices (예(例): Montgomery T-tube)등 의 치료방법들과 같이 병행하여, 팽창성 금속 스텐트의 삽입은 기관기관지 협착증의 치료에 도움이 되리라 생각된다. 또 국내에서는 아직도 유병율이 높은 폐결핵환자에서 충분한 기간동안 약물치료후에도 일부 환자에서는 기관지 결핵에 의하여 기관지 협착이 발생하는데 이때 수술적 치료외에는 적절한 치료방법이 없는 실정이다. 이러한 환자에서 만약 협착부위가 한쪽 주 기관지에 부분적으로 국한 되어 있으며 그 이하의 폐실질파괴가 심하지 않다면 스텐트 삽입은 수술적 치료이전에 시도하여 볼 수 있으리라 사료된다.

• Journal of Chest Surgery
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• 제33권1호
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• pp.107-111
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• 2000

Although a tracheal stent can be an option for inoperable tracheal stenoses there still are some troublesome side effects including overgranulation from foreign body irritation restenosis and patient's discomfort associated with the procedure. We report a successful case of a retrievable stent made of self-expandable 'shape memory' metal and polyurethane in a 24 year old female patient with respiratory distress and tight stenosis in the trachea and left main bronchus, The stent was inserted following a balloon dilatation and was successfully removed on the 7th days after the procedure. She regained a normal active life without any repiratory symptoms and a follow-up of 8 months showed satisfactory results.

• Journal of Korean Neurosurgical Society
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• 제45권5호
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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 Korean Neurosurgical Society
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• 제50권4호
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• pp.322-326
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• 2011

Objective : Stenting of symptomatic intracranial stenosis has recently become an alternative treatment modality. However, urgent intracranial stenting in patients with intracranial stenosis following a transient ischemic attack (TIA) or minor stroke is open to dispute. We sought to assess the feasibility, safety, and effectiveness of urgent intracranial stenting for severe stenosis (>70%) in TIA or minor stroke patients. Methods : Between June 2009 and October 2010, stent-assisted angioplasty by using a balloon-expandable coronary stent for intracranial severe stenosis (>70%) was performed in 7 patients after TIA and 5 patients after minor stroke (14 stenotic lesions). Technical success rates, complications, angiographic findings, and clinical outcomes were retrospectively analyzed. Results : Stenting was successful in all 12 patients. The mean time from symptom onset to stenting was 2.1 days (1-8 days). Post-procedural angiography showed restoration to a normal luminal diameter in all patients. In-stent thrombosis occurred in one patient (n=1, 8.3%), and was lysed with abciximab. No device-related complications, such as perforations or dissections at the target arteries or intracranial hemorrhaging, occurred in any patient. The mortality rate was 0%. No patient had an ischemic event over the mean follow-up period of 12.5 months (range, 7-21 months), and follow-up angiography (n=7) revealed no significant in-stent restenosis (>50%). Conclusion : Urgent recanalization with stenting is feasible, safe, and effective in patients with TIA or acute minor stroke with intracranial stenosis of ${\geq}$ 70%.

• Journal of Chest Surgery
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• 제39권12호
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• pp.927-930
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• 2006

생후 13일, 체중 2.2 kg의 여아가 기능적 단심증으로 하이브리드 술식을 받았다. 환아의 진단은 '삼첨판 폐쇄, 완전 대혈관 전위, 심한 대동맥 축착 및 동맥관 의존형 전신 순환'이었으며, Norwood형의 수술을 시행하기에는 미숙아, 저체중, 괴사성 장염 등 위험인자가 너무 많아서 수술 범위를 최소화 하는 하이브리드 술식을 시행하기로 하고 수술장에서 정중흉골 절개 하에 양쪽 폐동맥 띠조임술, 동맥관 내 스텐트 삽입 및 역행성 Blalock-Taussig 단락술을 시행하였다. 수술 후 복부 팽만 및 유미복수 등 다소 어려운 경과를 보였지만 술 후 33일째 퇴원할 수 있었고 퇴원 후 4개월에는 성공적인 2차 수술을 시행하였다. 환아는 2차 수술 후 4개월째 외래 관찰 중이며 정상 발육을 보이고 있다.