scholarly journals A New Observation on the Stress Distribution in the Coronary Artery Wall

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Chong Wang ◽  
Xiaomei Guo ◽  
Ghassan S. Kassab
Keyword(s):  
Coronary Artery ◽  
Stress Distribution ◽  
Vascular Function ◽  
Stress Gradient ◽  
Circumferential Stress ◽  
Wall Stress ◽  
Opening Angle ◽  
Porcine Coronary Artery ◽  
Physiological Loading ◽  
Health And Disease

The stress distribution in the vessel wall has an important bearing on vascular function in health and disease. We studied the relationship between the transmural stress distribution and the opening angle (OA) to determine the stress gradient. The simulation of wall stress was based on transmural measurements of strain and material properties of coronary arteries in reference to the zero-stress state. A one-layer model with material constants of the intact vessel was used to calculate the circumferential stress distribution. A sensitivity analysis using both one- and two-layer models (intima-media and adventitia layers) was carried out to study the effect of the OA on the circumferential stress distribution and average circumferential stress. A larger OA always shifts the circumferential stress from the intima-media to the adventitia layer. We report a new observation that the circumferential stress at the adventitia may exceed that at the intima at physiological loading due to the larger OA in the porcine coronary artery. This has important implications for growth and remodeling, where an increase in opening angle may shift excessive stress from the inner layer to the outer layer.

scholarly journals Increase in Opening Angle in Hypertension Off-Loads the Intimal Stress: A Simulation Study

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Chong Wang ◽  
Ghassan S. Kassab
Keyword(s):  
Stress Distribution ◽  
Vascular Function ◽  
Vessel Wall ◽  
Circumferential Stress ◽  
Opening Angle ◽  
Protective Mechanism ◽  
Acute Hypertension ◽  
Physiological Loading ◽  
Intimal Layer ◽  
Large Opening

The stress distribution in the vessel wall has important bearing on vascular function including intima, media, and adventitia. The residual strain in the vessel wall has been thought to largely normalize the transmural stress distribution with slightly higher values at the intima. In hypertension, the compensatory increase in opening angle is thought to maintain a uniform stress distribution. We have recently shown that the circumferential stress at adventitia may exceed that at intima at physiological loading due to large opening angle (OA) in normal porcine coronary arteries. The objective of this study was to show that increases in opening angle subsequent hypertension can further shift the stress from the intima to the adventitia. The change in stress distribution during acute hypertension was calculated using available data on the changes in vessel geometry, material property, and internal pressure during hypertension. It was found that the increase in OA following acute hypertension off-loads the stress from intima to adventitia, therefore, relieving some of the stress increase in the intimal layer induced by the sudden pressure increase. This has important implications for hypertension where it may shift the excessive stress from the inner layer to the outer layer. This may be a protective mechanism for the intima layer in hypertension.

Mechanical Properties of the Porcine Coronary Artery

2009 ◽  
Author(s):  
Chantal N. van den Broek ◽  
Arjen van der Horst ◽  
Marcel C. N. Rutten ◽  
Frans N. van de Vosse
Keyword(s):  
Mechanical Properties ◽  
Coronary Artery ◽  
Vascular Function ◽  
Arterial Wall ◽  
Material Model ◽  
Porcine Coronary Artery ◽  
Balloon Catheters ◽  
General Parameter ◽  
Fiber Reinforced Material ◽  
Parameter Values

Knowledge of the mechanical properties of arteries is important to understand vascular function during disease and the effect of interventions, such as PTCA treatment. A mechanical model of the vascular tree would facilitate the improvement of (balloon-)catheters and stents. The aim of this research is to propose general parameter values for the fiber-reinforced material model as proposed by Driessen et al. (2005) that can describe the arterial wall behavior of the porcine left anterior descending coronary artery (LAD, fig. 1a) at physiological axial stretch.

Residual Stress and Circumferential Stress Distribution in a Finite Element Model of the Arterial Wall

Volume 2 ◽  
2004 ◽  
Author(s):  
Nooshin Haghighipour ◽  
Mohammad Tafazzoli Shadpour ◽  
Albert Avolio
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Arterial Wall ◽  
Stress Component ◽  
Circumferential Stress ◽  
Opening Angle ◽  
Human Aorta ◽  
Endothelial Lining

Stress distribution of the arterial wall is an important factor in biomechanics of arteries. It has been suggested that excessive stress leads to arterial degeneration and lesion formation. In addition to circumferential tensile stress caused by luminal pressure, arterial wall contains circumferential residual stress with compressive and tensile components with maximum values on intima and adventitia respectively. The compressive residual stress component compensates part of maximum tensile stress, and therefore decreases severity of tension on endothelial lining. If an arterial ring is cut in radial direction it opens. The degree of opening angle is a determinant of circumferential residual stress. In this investigation, Finite element modeling was used to evaluate circumferential residual stress in a typical model of cross section of human aorta with differing opening angle and Young’s modulus of elasticity. Results show that residual stress values are influenced by structural and mechanical parameters. Elevation of the opening angle and stiffening of the arterial wall resulted in increase of residual stress level.

Non-Euclidean Stress-Free Configuration of Arteries Accounting for Curl of Axial Strips Sectioned From Vessels

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Keiichi Takamizawa ◽  
Yasuhide Nakayama
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Riemannian Geometry ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Arterial Walls ◽  
Physiological Loading ◽  
Residual Strains

It is well known that arteries are subject to residual stress. In earlier studies, the residual stress in the arterial ring relieved by a radial cut was considered in stress analysis. However, it has been found that axial strips sectioned from arteries also curled into arcs, showing that the axial residual stresses were relieved from the arterial walls. The combined relief of circumferential and axial residual stresses must be considered to accurately analyze stress and strain distributions under physiological loading conditions. In the present study, a mathematical model of a stress-free configuration of artery was proposed using Riemannian geometry. Stress analysis for arterial walls under unloaded and physiologically loaded conditions was performed using exponential strain energy functions for porcine and human common carotid arteries. In the porcine artery, the circumferential stress distribution under physiological loading became uniform compared with that without axial residual strain, whereas a gradient of axial stress distribution increased through the wall thickness. This behavior showed almost the same pattern that was observed in a recent study in which approximate analysis accounting for circumferential and axial residual strains was performed, whereas the circumferential and axial stresses increased from the inner surface to the outer surface under a physiological condition in the human common carotid artery of a two-layer model based on data of other recent studies. In both analyses, Riemannian geometry was appropriate to define the stress-free configurations of the arterial walls with both circumferential and axial residual strains.

Biaxial incremental homeostatic elastic moduli of coronary artery: two-layer model

2004 ◽  
Vol 287 (4) ◽  
pp. H1663-H1669 ◽  
Author(s):  
Xiao Lu ◽  
Aditya Pandit ◽  
Ghassan S. Kassab
Keyword(s):  
Coronary Artery ◽  
Axial Direction ◽  
Circumferential Direction ◽  
Small Perturbations ◽  
Porcine Coronary Artery ◽  
Physiological Relevance ◽  
Health And Disease ◽  
The Media

The detailed mechanical properties of various layers of the coronary artery are important for understanding the function of the vessel. The present article is focused on the determination of the incremental modulus in different layers and directions in the neighborhood of the in vivo state. The incremental modulus can be defined for any material subjected to a large deformation if small perturbations in strain lead to small perturbations of stresses in a linear fashion. This analysis was applied to the porcine coronary artery, which was treated as a two-layered structure consisting of an inner intima-media layer and an outer adventitia layer. We adopted a theory based on small-perturbation experiments at homeostatic conditions for determination of incremental moduli in circumferential, axial, and cross directions in the two layers. The experiments were based on inflation and axial stretch. We demonstrate that under homeostatic conditions the incremental moduli are layer- and direction dependent. The incremental modulus is highest in the circumferential direction. Furthermore, in the circumferential direction, the media is stiffer than the whole wall, which is stiffer than the adventitia. In the axial direction, the adventitia is stiffer than the intact wall, which is stiffer than the media. Hence, the coronary artery must be treated as a composite, nonisotropic body. The data acquire physiological relevance in relation to coronary artery health and disease.

Mechanical Properties of the Porcine Coronary Artery

2008 ◽  
Author(s):  
Chantal N. van den Broek ◽  
Marcel M. Rutten ◽  
Frans N. van de Vosse
Keyword(s):  
Mechanical Properties ◽  
Coronary Artery ◽  
Mechanical Model ◽  
Vascular Function ◽  
Vascular Tree ◽  
Porcine Coronary Artery ◽  
Balloon Catheters

Knowledge of mechanical properties of living arteries is important to understand vascular function during health, disease and intervention. A mechanical model of the vascular tree would facilitate the development of (balloon-)catheters and stents.

Effect of Residual Stress and Heterogeneity on Circumferential Stress in the Arterial Wall

2000 ◽  
Vol 122 (4) ◽  
pp. 454-456 ◽  
Author(s):  
S. J. Peterson ◽  
R. J. Okamoto
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Material Properties ◽  
Arterial Wall ◽  
Circumferential Stress ◽  
Single Species ◽  
Opening Angle ◽  
Layer Model ◽  
Multiple Sources ◽  
The Media

Quantifying the stress distribution through the arterial wall is essential to studies of arterial growth and disease. Previous studies have shown that both residual stress, as measured by opening angle, and differing material properties for the media-intima and the adventitial layers affect the transmural circumferential stress σθ distribution. Because a lack of comprehensive data on a single species and artery has led to combinations from multiple sources, this study determined the sensitivity of σθ to published variations in both opening angle and layer thickness data. We fit material properties to previously published experimental data for pressure–diameter relations and opening angles of rabbit carotid artery, and predicted σθ through the arterial wall at physiologic conditions. Using a one-layer model, the ratio of σθ at the internal wall to the mean σθ decreased from 2.34 to 0.98 as the opening angle increased from 60 to 130 deg. In a two-layer model using a 95 deg opening angle, mean σθ in the adventitia increased (112 percent for 25 percent adventitia) and mean σθ in the media decreased (47 percent for 25 percent adventitia). These results suggest that both residual stress and wall layers have important effects on transmural stress distribution. Thus, experimental measurements of loading curves, opening angles, and wall composition from the same species and artery are needed to accurately predict the transmural stress distribution in the arterial wall. [S0148-0731(00)02204-4]

Characterization of Thromboxane A2/Prostaglandin H2 Receptors in Porcine Coronary Artery -The Inhibitory Effect of a Novel Dibenzoxepin Derivative, KW-3635

1992 ◽  
Vol 67 (05) ◽  
pp. 582-584 ◽  
Author(s):  
Ichiro Miki ◽  
Akio Ishii
Keyword(s):  
Coronary Artery ◽  
Binding Sites ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Scatchard Analysis ◽  
Single Class ◽  
Porcine Coronary Artery ◽  
Equilibrium Binding ◽  
H2 Receptors

SummaryWe characterized the thromboxane A2/prostaglandin H2 receptors in porcine coronary artery. The binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to coronary arterial membranes was saturable and displaceable. Scatchard analysis of equilibrium binding showed a single class of high affinity binding sites with a dissociation constant of 18.5 ±1.0 nM and the maximum binding of 80.7 ± 5.2 fmol/mg protein. [3H]SQ 29,548 binding was concentration-dependently inhibited by thromboxane A2 antagonists such as SQ 29,548, BM13505 and BM13177 or the thromboxane A2 agonists such as U46619 and U44069. KW-3635, a novel dibenzoxepin derivative, concentration-dependently inhibited the [3H]SQ 29,548 binding to thromboxane A2/prosta-glandin H2 receptors in coronary artery with an inhibition constant of 6.0 ± 0.69 nM (mean ± S.E.M.).

Sign in / Sign up

Export Citation Format

Share Document