• Korea-Australia Rheology Journal
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• 제21권1호
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• pp.39-46
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• 2009

Atherosclerosis is a disease that narrows, thickens, hardens, and restructures a blood vessel due to substantial plaque deposit. The geometric models of the considered stenotic blood flow are three different types of constriction of cross-sectional area of blood vessel; 25%, 50%, and 75% of constriction. The computational model with the fluid-structure interaction is introduced to investigate the wall shear stresses, blood flow field and recirculation zone in the stenotic vessels. The velocity profile in a compliant stenotic artery with various constrictions is subjected to prescribed physiologic waveform. The computational simulations were performed, in which the physiological flow through a compliant axisymmetric stenotic blood vessel was solved using commercial software ADINA 8.4 developed by finite element method. We demonstrated comparisons of the wall shear stress with or without the fluid-structure interaction and their velocity profiles under the physiological flow condition in the compliant stenotic artery. The present results enhance our understanding of the hemodynamic characteristics in a compliant stenotic artery.

• 대한기계학회논문집B
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• 제32권11호
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• pp.891-896
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• 2008

In the present computational study, simple stenotic artery models using pulsatile flow condition were investigated. A 1 Hz non-reversing sinusoidal velocity for pulsatile flow was imposed at the flow inlet and the corresponding Womersley number based on the vessel radius is 2.75. The simple stenotic geometries have been used that consist of 25%, 50% and 75% semicircular constriction in a cylindrical tube. In this paper, numerical solutions are presented for a first harmonic oscillatory flow using commercial software ADINA 8.4. As stenosis and Reynolds number increase, the maximum wall shear stress(WSS) increases while the minimum WSS decreases. As the stenotic rate increases, the pressure drop at the throat severely decreases to collapse the artery and plaque. It is found that the fluid mechanical disturbances due to the constriction were highly sensitive with rate of stenosis and Reynolds number. When Reynolds number and stenosis increase, the larger recirculation region exists. In this recirculation region the possibility of plaque attachment is increasingly higher. The present results enhance our understanding of the hemodynamics of a stenotic artery.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.529-532
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• 2001

The purposes of the present study are to investigate hemodynamic characteristics and to define shear-sensitive remodeling in the stenosed coronary models. Two models for the compensatory remodelling used for this research are a pre-stenotic dilation and a post-stenotic dilation models for the computer simulation. The peak wall shear stress on the post-stenotic model is higher than that of the pre-stenotic model. Two recirculation zones are generated in the pre-stenotic model, and the zones in the pre-stenotic model are smaller than those in the post-stenotic model. Variation of the wall shear stress in the pre-stenotic model is lower than that in the post-stenotic model. In computer simulation with the post-stenotic model, higher temporal and spatial shear fluctuation and stress suggested shear-sensitive remodeling. Shear-sensitive remodeling may be associated with the increased risk of plaque rupture, the underlying cause of acute coronary syndromes, and sudden cardiac death.

• Journal of Korean Neurosurgical Society
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• 제41권3호
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• pp.200-203
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• 2007

We describe a case that showed augmention of the superficial temporal artery [STA] pedicle's patency 15 months after extracranial to intracranial [EC-IC] bypass surgery for a carotid artery occlusion with contralateral intracranial internal carotid artery stenosis. It is rare that meager patency of the STA pedicle in the early postoperative angiogram can be become well augmented with time where most branches of the middle cerebral artery [MCA] are robustly filled with blood from the STA. A 28-year-old woman with a history of a previous left hemispheric stroke presented with slurred speech after several bouts of seizure. Magnetic resonance imaging showed a new infarct on the right hemisphere in addition to an old infarct on the left hemisphere. Carotid angiography revealed stenosis of the right carotid siphon and occlusion of the left carotid artery. The patient underwent EC-IC bypass on the right side. Even though the early postoperative angiogram showed meager filling of MCA with no significant stenotic lesion change, a subsequent angiogram taken 15 months later, demonstrated a widely patent STA pedicle with occlusion of the previous intracranial stenotic lesion. Selected cases with an inaccessible intracranial stenotic lesion can benefit from EC-IC bypass surgery; however, its clear indication should first be established.

• Journal of Chest Surgery
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• 제25권12호
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• pp.1487-1491
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• 1992

The renovascular hypertension is a rare disease in which obstructive lesion of renal artery results in hypertension and it is the most common surgically curable form of hypertension. Recently, we experienced two cases of renovascular hypertension treated successfully with resection of the stenotic segment and end-to-side reanastomosis of the renal artery to the aorta in one case, and with resection of the stenotic segment and saphenous vein bypass graft in the other case at the Thoracic & Cardiovascular Surgery, Chungnam National University Hospital. Pathologic examinations revealed fibromuscular dysplasia of the medial layer of the renal artery in both cases

• 한국전산유체공학회지
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• 제22권1호
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• pp.15-25
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• 2017

Swirl flow is often found in proximal coronary arteries, because the aortic valves can induce swirl flows in the coronary artery due to vortex formation. In addition, the curvature and tortuosity of arterial configurations can also produce swirl flows. The present study was performed to investigate fractional flow reserve alterations in a post-stenotic distal part due to the presence of pre-stenotic swirl flow by computational fluid dynamics analysis for virtual stenotic models by quantifying fractional flow reserve(FFR). Simplified stenotic coronary models were divided into those with and without pre-stenotic swirl flow. Various degrees of virtual stenosis were grouped into three grades: mild, moderate, and severe, with degree of stenosis of 0 ~ 40%, 50 ~ 60%, and 70 ~ 90%, respectively. In this study, three-dimensional computational hemodynamic simulations were performed under hyperemic conditions in virtual stenotic coronary models by coupling with a zero-dimensional lumped parameter model. The results showed that the influence of pre-stenotic swirl inflow is dominant on FFR alteration in mild stenosis, whereas stenosis is dominant on FFR alteration in moderate/severe stenosis. The decrease in FFR caused by swirl flow is more significant in mild stenosis than moderate/severe stenosis. Biomechanical modeling is useful for clinicians to provide insight for medical intervention strategies. This hemodynamic-based parameter study could play a critical role in the development of a non-invasive imaging-based strategy-support system for percutaneous transluminal angioplasty in cases of mild/moderate stenosis.

• Journal of Chest Surgery
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• 제13권2호
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• pp.125-129
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• 1980

A patient with anomalous coronary artery crossing right ventricular outflow tract in association with Tetralogy of Fallot underwent total correction. The left anterior descending coronary artery was originated from right coronary artery anterior to the pulmonary valve ring. The incision from outflow tract to pulmonary artery tunneled underneath the aberrant artery and patch graft across the pulmonary valve ring to enlarge outflow of right ventricle and stenotic pulmonary valve ring.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• 제26권2호
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• pp.130-140
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• 2024

Objective: To assess whether local anesthetic infiltration could minimize the carotid baroreceptor reflex (CBR) which has an incidence after carotid artery stenting (CAS) that varies from 29% to 51%. Methods: This retrospective single-center study included 51 patients (mean age, 70.47 years) who underwent CAS for carotid stenosis. The groups included patients who underwent CAS for asymptomatic ischemic stroke (n=41) or symptomatic disease (n=10). Preprocedural percutaneous lidocaine injections (PPLIs) were administered to 70.6% and 5.9% of patients who underwent elective CAS and emergency CAS, respectively. Results: Among patients who received PPLIs, the mean degree of stenosis was 80.5% (95% confidence interval [CI]: ±10.74, 51-98%). The mean distance from the common carotid artery bifurcation to the most stenotic lesion (CSD) was 8.3 mm (95% CI: ±0.97, 6.3-10.2 mm); the mean angle between the internal carotid artery and common carotid artery (CCA) trunk (IAG) was 65.6° (95% CI: ±2.39, 61-70°). Among patients who did not receive PPLIs, the mean degree of stenosis was 84.0% (95% CI: ±8.96, 70-99%). The mean CSD was 5.9 mm (95% CI: ±1.83, 1.9-9.9 mm); the mean IAG was 60.4° (95% CI: ±4.41, 51-70°). The procedure time was longer in the PPLI group than in the no PPLI group (28.19 [n=39] vs. 18.88 [n=12] days) (P=0.057); the length of intensive care unit stay was shorter in the PPLI group (20.01 [n=36] vs. 28.10 [n=5] days) (P=0.132). Conclusions: Targeted PPLI administration to the carotid bulb decreased aberrant heart rates and blood pressure changes induced by carotid stent deployment and balloon inflation. As CBR sensitivity increases with decreasing distance to the stenotic lesion from the CCA bifurcation, PPLIs may help stabilize patients during procedures for stenotic lesions closer to the CCA.

• Journal of Chest Surgery
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• 제37권1호
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• pp.35-42
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• 2004

배경: 허혈성 좌주간 관동맥 협착병변은 돌연사의 위험성이 높아 조속한 재관류를 요한다. 본 교실에서는 단독 좌주간 관동맥 협착병변으로 좌측 내흉동맥에 요골동맥이나 우위대망동맥을 Y모양으로 연결하여 관상동맥우회로 조성술을 시행했던 경우를 분석함으로써 내흉동맥만으로 심근의 혈액요구량을 충분하게 감당할 수 있는지의 여부와 경계부 협착을 보이는 좌주간 관동맥 협착병변에서 경쟁혈류에 의한 우회혈관의 재구성이 초래되는가를 알아보았다. 대상 및 방법: 2000년 3월부터 2003년 4월까지 관상동맥우회로 조성술을 시행받은 247명의 환자 중 단독 좌주간 관동맥 협착병변으로 진단되어 동맥이식편만을 이용한 관상동맥우회로 조성술을 시행받은 12명(4.8%)의 환자를 대상으로 하여 의무기록과 본 교실의 database를 기초로 역행성 연구를 시행하였다. 결과: 좌전하행지 문합은 전예에서 인공심폐기를 사용하지 않고 시행하였으나 둔각변연분지 문합 중 2예에서는 인공심폐기 가동 후 심박동하에서 문합하였다. 직경이 1 mm 이상되는 좌회선분지가 없어 문합을 시행하지 못한 1예를 제외한 11예에서 Y-도관을 이용한 완전재관류를 시행하였으며 환자 1인당 문합 수는 평균 2.0개이었다. 좌주간동맥의 협착이 75% 이하이었던 경우에서는 좌전하행지 문합 중 1예에서 좌내흉동맥에 string sign을 보였으며 좌회선분지 문합 7예 중 완전히 막힌 경우 2예, slender sign 1예가 있었으며 문합 원위부 관상동맥 혈류 형태가 도관의존성인 경우는 없었다. 그러나 이와는 반대로 90% 이상의 협착 병변에서는 문합된 관상동맥 모두에서 도관의존성의 원위부 혈류 형태를 보였다. 결론: 90% 이상의 협착을 보인 좌주간동맥 협착병변에서는 동맥이식편을 V-도관으로 만들어 TAR를 시행하더라도 심근의 혈류요구량을 충분하게 감당할 수 있을 것으로 판단된다. 그러나 경계부 협착을 가진 환자의 경우에는 고정된 치료방침을 택하기보다는 면밀한 진단을 통하여 정맥도관이나 동맥도관의 대동맥에 직접 문합 또는 경피적 관동맥중재술과의 보완 치료 등 좀 더 유연하고 신중한 치료방침의 결정이 필요할 것으로 생각된다.

• Journal of Chest Surgery
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• 제27권2호
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• pp.170-173
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• 1994

Isolated stenotic lesion located at the ostium of the left main coronary artery associated with Takayasu`s aortitis is quite rare. This report herein described a case of 25 year old woman with isolated ostial stenosis of the left main coronary artery underwent pericardial patch [fixed with 0.6 % glutaraldehyde] angioplasty. An anterior approach was used and postoperative coronary angiogram of the patient showed normal coronary ostial contour with normal runoff.