A Study on the Compliance of a Right Coronary Artery and Its Impact on Wall Shear Stress

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Dehong Zeng ◽  
Evangelos Boutsianis ◽  
Marc Ammann ◽  
Kevin Boomsma ◽  
Simon Wildermuth ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Right Coronary Artery ◽  
Imaging Techniques ◽  
Time History ◽  
Distal Region ◽  
Proximal Region ◽  
Phase Changes ◽  
Wall Shear

A computational model incorporating physiological motion and uniform transient wall deformation of a branchless right coronary artery (RCA) was developed to assess the influence of artery compliance on wall shear stress (WSS). Arterial geometry and deformation were derived from modern medical imaging techniques, whereas the blood flow was solved numerically employing a moving-grid approach using a well-validated in-house finite element code. The simulation results indicate that artery compliance affects the WSS in the RCA heterogeneously, with the distal region mostly experiencing these effects. Under physiological inflow conditions, coronary compliance contributed to phase changes in the WSS time history, without affecting the temporal gradient of the local WSS nor the bounds of the WSS magnitude. Compliance does not cause considerable changes to the topology of WSS vector patterns nor to the localization of WSS minima along the RCA. We conclude that compliance is not an important factor affecting local hemodynamics in the proximal region of the RCA while the influence of compliance in the distal region needs to be evaluated in conjunction with the outflow to the myocardium through the major branches of the RCA.

Velocity and Wall Shear Stress Patterns in the Human Right Coronary Artery

1999 ◽  
Vol 121 (4) ◽  
pp. 370-375 ◽  
Author(s):  
A. Kirpalani ◽  
H. Park ◽  
J. Butany ◽  
K. W. Johnston ◽  
M. Ojha
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Right Coronary Artery ◽  
Proximal Region ◽  
Proximal Segment ◽  
Shear Stresses ◽  
Human Right ◽  
Wall Shear ◽  
Stress Patterns

Blood flow dynamics in the human right coronary artery have not been adequately quantified despite the clinical significance of coronary atherosclerosis. In this study, a technique was developed to construct a rigid flow model from a cast of a human right coronary artery. A laser photochromic method was used to characterize the velocity and wall shear stress patterns. The flow conditions include steady flow at Reynolds numbers of 500 and 1000 as well as unsteady flow with Womersley parameter and peak Reynolds number of 1.82 and 750, respectively. Characterization of the three-dimensional geometry of the artery revealed that the largest spatial variation in curvature occurred within the almost branch-free proximal region, with the greatest curvature existing along the acute margin of the heart. In the proximal segment, high shear stresses were observed on the outer wall and lower, but not negative, stresses along the inner wall. Low shear stress on the inner wall may be related to the preferential localization of atherosclerosis in the proximal segment of the right coronary artery. However, it is possible that the large difference between the outer and inner wall shear stresses may also be involved.

scholarly journals Intimal Thickness Is not Associated With Wall Shear Stress Patterns in the Human Right Coronary Artery

2004 ◽  
Vol 24 (12) ◽  
pp. 2408-2413 ◽  
Author(s):  
Anil K. Joshi ◽  
Richard L. Leask ◽  
Jerry G. Myers ◽  
Matadial Ojha ◽  
Jagdish Butany ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Right Coronary Artery ◽  
Human Right ◽  
Intimal Thickness ◽  
Wall Shear ◽  
Stress Patterns

scholarly journals Numerical Simulation of Dispersed Particle-Blood Flow in the Stenosed Coronary Arteries

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mongkol Kaewbumrung ◽  
Somsak Orankitjaroen ◽  
Pichit Boonkrong ◽  
Buraskorn Nuntadilok ◽  
Benchawan Wiwatanapataphee
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Stokes Equations ◽  
Spherical Shape ◽  
Shear Stresses ◽  
Wall Shear

A mathematical model of dispersed bioparticle-blood flow through the stenosed coronary artery under the pulsatile boundary conditions is proposed. Blood is assumed to be an incompressible non-Newtonian fluid and its flow is considered as turbulence described by the Reynolds-averaged Navier-Stokes equations. Bioparticles are assumed to be spherical shape with the same density as blood, and their translation and rotational motions are governed by Newtonian equations. Impact of particle movement on the blood velocity, the pressure distribution, and the wall shear stress distribution in three different severity degrees of stenosis including 25%, 50%, and 75% are investigated through the numerical simulation using ANSYS 18.2. Increasing degree of stenosis severity results in higher values of the pressure drop and wall shear stresses. The higher level of bioparticle motion directly varies with the pressure drop and wall shear stress. The area of coronary artery with higher density of bioparticles also presents the higher wall shear stress.

Preliminary Near Wall Hemodynamic Evaluation of a Coronary Artery Bypass Graft Model With a Flow Streamlining Implant

2002 ◽  
Author(s):  
Pedro D. Pedroso ◽  
Andreas S. Anayiotos ◽  
Brad L. Hershey ◽  
Evangelos Eleftheriou ◽  
William L. Holman
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Coronary Artery Bypass Graft ◽  
Coronary Artery Bypass ◽  
Saphenous Vein ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Artery Bypass Graft ◽  
Wall Shear

Coronary artery disease (CAD) is the leading cause of death in the world today. According to the American Heart Association 529,659 people in 1999 died as a result of CAD [1]. Starting in the 1960’s, surgeons have used Coronary Artery Bypass Graft (CABG) techniques in order to reestablish blood flow to the heart. Today, the procedure remains the same, using autologous grafts, such as the mammary artery and the saphenous vein. An unresolved problem, is that a significant number of CABGs reocclude months to years postoperatively. In the case of Saphenous Vein Grafts (SVGs) typically 50% of these bypasses are totally occluded months to years after the procedure, the remaining half being more than 50% occluded [2]. The re-occlusion of CABGs is due to a process labeled intimal hyperplasia (IH). Investigators have shown that IH, believed by some to be a remodeling process, occurs at branch sites, regions of curvature, and anastomotic junctions [3,4]. At these sites there are low residence times, slow secondary structures, disturbed flow, and areas of recirculation, therefore the onset of IH is believed to be hemodynamically linked. Most recently, floor IH has been attributed to four variables: time averaged wall shear stress (WSS), oscillating shear index (OSI), spatial wall shear stress gradients (WSSG), and temporal WSSG [5]. Adverse values of these parameters, in the case of SVGs, are believed to be caused by impedance mismatch at the anastomosis site. Over time this characteristic causes a bulge at the sinus. Such a morphology additionally contributes to disturbed flows which tend to propagate down the CABG and are believed to play a major role in the development of IH and the eventual failure of the graft.

Plaque Progression in a Human Coronary Artery is Associated With Low Wall Shear Stress and Extended Particle Residence Time

2010 ◽  
Author(s):  
Jin Suo ◽  
Michael McDaniel ◽  
Parham Eshtehardi ◽  
Saurabh Dhawan ◽  
Ravi Prasad Avati Nanjundappa ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Residence Time ◽  
Vigorous Physical Activity ◽  
Region Of Interest ◽  
Reconstruction Technique ◽  
Plaque Progression ◽  
Human Coronary Artery ◽  
Wall Shear

Intravascular ultrasound (IVUS) evaluation was performed in the coronary arteries of a 45-year-old patient with stable angina during vigorous physical activity. Concurrent angiography demonstrated a mild plaque in the proximal left anterior descending artery (LAD), with obvious lumen dilatation immediately distal to the plaque. Blood velocity was measured by a catheter Doppler transducer at proximal and distal segments of the left coronary artery, and the left main artery (LM) and LAD were reconstructed using a 3D-IVUS reconstruction technique based on biplanar angiography and IVUS images, enabling simulation of the flow field in the artery employing computational fluid dynamics (CFD). Wall shear stress (WSS) and particle path lines were determined from the CFD studies. The patient returned for a follow up evaluation after 6 months, and plaque progression during this period was evaluated from the IVUS data. Results showed that low WSS, less than 5 dynes/cm2, which occurs in the region immediately distal to the plaque, correlates with localized progression of the lesion over the 6 month interval. The path line tracking computations showed that particles near the vessel surface where plaque progression was observed resided near the artery wall longer than one complete cardiac cycle, whereas in other areas particles were flushed through the region of interest rapidly. These observations in a specific individual are consistent with the hypothesis that plaque progression is related to low WSS and relatively long residence time of atherogenic blood-borne substances.

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