• 제목/요약/키워드: stenosed artery

검색결과 32건 처리시간 0.022초

편심협착부가 있는 관상동맥내 카테터삽입에 따른 혈액유동특성 (Blood Flow Characteristics due to Catheter Insertion in the Eccentric Stenosed Coronary Artery)

  • 노형운;서상호;권혁문;이병권
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.707-708
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    • 2002
  • Catheters are used to measure translesional pressure gradients in the stenosed coronary arteries. Catheter insertions during coronary angioplasty cause flow obstructions. A narrowed flow cross section with catheter present effectively introduced a tighter stenosis than the enlarged residual stenoses after balloon angiplasty. In general, the form of stenoses are no uniform. Sometimes, these are occurred the irregularly eccentricity If the analyses are conducted for uniform stenosed artery, the results will be underestimated. Thus, in this study, three dimensional computer simulations are conducted to investigate the flow blockage effects due to the catheter insertion during the coronary angioplasty. The results for the eccentric stenosed artery are compared with those of the concentric stenosed artery.

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Hemodynamic Analysis of Coronary Artery Microcirculation Using a Pig's Morphometric Data

  • Shin Sehyun;Park Jungsu
    • Journal of Mechanical Science and Technology
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    • 제19권6호
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    • pp.1313-1320
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    • 2005
  • Stenosed coronary artery may play an important role in various coronary heart diseases. However, it has not been known how much stenosed coronary artery affects coronary circulation system, quantitatively. The present study developed a mathematical model for microcirculation in the left common coronary artery (LCCA) with adopting a previously measured morphological data and mechanical properties of the coronary vessels. We examine the effect of percent diameter stenosis on blood flow rate and shear stress for two cases. Case I comprised of one-stenosed element at $10^{th}$ order ($\%$ diameter stenosis are 10, 30, and 50, respectively). Case II consisted of completely occluded element at $10^{th}$ order (number of occluded elements are 0, 1, and 2 out of 8, respectively). As the level of stenosis becomes severe, the shear stress increases significantly but the flow rate reduction was relatively small. However, for the occluded case, there was linearly proportional reduction of flow rate according to number of occluded elements. Either such high shear stress associated with coronary artery stenosis or reduced flow rate due to occlusion may cause atherosclerosis and myocardial ischemia.

Effect of body acceleration on pulsatile flow of Casson fluid through a mild stenosed artery

  • Nagarani, P.;Sarojamma, G.
    • Korea-Australia Rheology Journal
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    • 제20권4호
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    • pp.189-196
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    • 2008
  • The pulsatile flow of blood through a stenosed artery under the influence of external periodic body acceleration is studied. The effect of non-Newtonian nature of blood in small blood vessels has been taken into account by modeling blood as a Casson fluid. The non-linear coupled equations governing the flow are solved using perturbation analysis assuming that the Womersley frequency parameter is small which is valid for physiological situations in small blood vessels. The effect of pulsatility, stenosis, body acceleration, yield stress of the fluid and pressure gradient on the yield plane locations, velocity distribution, flow rate, shear stress and frictional resistance are investigated. It is noticed that the effect of yield stress and stenosis is to reduce flow rate and increase flow resistance. The impact of body acceleration is to enhance the flow rate and reduces resistance to flow.

협착이 발생된 관상동맥내 시퀜셜 문합의 효과 (Sequential Bypass Effects in the Stenosed Coronary Artery)

  • 노형운;서상호;권혁문;이병권
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1919-1922
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    • 2003
  • Bypass anastomosis are frequently adopted for surgical treatments. After the bypass grafting, the bypass artery is often occluded due to restenosis and/or anastomotic neointimal fibrous hyperplasia phenomena. Optimal coronary bypass anastomosis should be investigated to improve the patency for the arterial bypass techniques. The objective of this study is to investigate the influence of bypass with sequential bypass effects in the stenosed coronary artery. Numerical analyses are focused on the understanding of the flow patterns for different sequential anastomosis techniques. Blood flow field is treated as two-dimensional incompressible laminar flow. The finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as the constitutive equation for blood. To find the optimal sequential bypass anastomotic configurations, the mass flow rates at the outlet of different models are compared quantitatively.

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협착이 발생된 관상동맥에 대한 이식우회로술의 효과분석 (Analysis of Bypass Grafting Effects in Stenosed Coronary Arteries)

  • 김형호;서상호;이정상
    • 대한기계학회논문집B
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    • 제36권2호
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    • pp.153-159
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    • 2012
  • 협착이 발생된 관상동맥의 치료를 위해 외과적인 수술방법으로는 이식우회로술이 많이 사용된다. 이식우회로술 시술 시 개존율 향상을 위해서는 최적의 혈관 문합 시술에 대한 연구가 필요하다. 본 연구의 목적은 Y-grafting bypass 와 T-grafting bypass 시술의 효과와 분지각도 및 문합각도 변화에 따른 문합효과를 분석하였다. 이를 위해 기하학적 형상을 최적화하고 각각의 기하학적 형상에 대해 혈류역학적 특성을 비교분석하였다. 이식혈관의 분지각도와 문합각도가 각각 $30^{\circ}$$15^{\circ}$일 경우에 LAD 와 LCX 쪽 모두 혈류량이 고르게 분배됨을 확인하였다.

Numerical study of the effects of periodic body acceleration (PGZ) and bifurcation angle in the stenosed artery bifurcation

  • Ro, Kyoung-Chul;Ryou, Hong-Sun
    • Korea-Australia Rheology Journal
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    • 제21권3호
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    • pp.175-183
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    • 2009
  • This article describes the numerical investigation of blood flow in the stenosed artery bifurcation with acceleration of the human body. Using the commercial software FLUENT, three-dimensional analyses were performed for six simulation cases with different body accelerations and bifurcation angles. The blood flow was considered to be pulsation flow, and the blood was considered to be a non-Newtonian fluid based on the Carreau viscosity model. In order to consider periodic body acceleration, a modified, time-dependent, gravitational-force term was used in the momentum equation. As a result, flow variables, such as flow rate and wall shear stress, increase with body acceleration and decrease with bifurcation angle. High values of body acceleration generate back flow during the diastolic period, which increases flow fluctuation and the oscillatory shear index at the stenosis.

관상동맥 협착부에 각이진 스텐트 시술시 혈류역학적 특성변화 (Changes of Hemodynamic Characteristics during Angulated Stenting in the Stenosed Coronary)

  • 서상호;조민태;권혁문;이병권
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.717-720
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    • 2002
  • The present study is to evaluate the performances of flow velocity and wall shear stress in the stenosed coronary artery using human in vivo hemodynamic Parameters and computer simulation. Initial and follow-up coronary angiographics in the patients with angulated coronary stenosis are performed. Follow-up coronary angiogram demonstrated significant difference in the percent of diameter in the stenosed coronary between two groups ($Group\;1:\;40.3{\%},\;Group\;2:\;25.5{\%}$). Flow-velocity wave obtained from in vivo intracoronary Doppler ultrasound data is used for the boundary condition for the computer simulation. Spatial and temporal variations of flow velocity vector and recirculation area are drawn throughout the selected segment of coronary models. The WSS of pre- and post-intracoronary stenting are calculated from three-dimensional computer simulation. Then negative shear stresses area on 3D simulation we noted on the inner wall of the post-stenotic area before stenting. The negative WSS is disappeared after stenting. High spatial and temporal WSS before stenting fell into within physiologic WSS after stenting. This finding was prominent in Model 2. The present study suggest that hemodynamic forces exerted by pulsatile coronary circulation termed WSS might affect on the evolution of atherosclerosis within the angulated vascular curvature. The local recirculation area which has low or negative WSS, might lead to progression of atherosclerosis.

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협착이 발생된 관상동맥내 혈류특성에 관한 연구 (Study on the Blood Flow Characteristics in the Stenosed Coronary Artery)

  • 노형운;서상호;유상신;권혁문;김동수
    • 대한의용생체공학회:학술대회논문집
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    • 대한의용생체공학회 1997년도 춘계학술대회
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    • pp.111-115
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    • 1997
  • The objective of present study is to obtain information about stenosis effects on the blood flow in the coronary artery bifurcation. The three dimensional steady of blood in the coronary artery bifurcation with stenosis and without stenosis are simulated using the finite volume method. Apparent viscosity of blood is represented as a function of shear rate by the Carreau models. Velocities vectors and wall shear stresses along the branch tubes with stenosis are compared with those of without stenosis for steady flows. Flow phenomena in the stenosed branch tubes are discussed extensively.

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