Steady Flow and Wall Compression in Stenotic Arteries: A Three-Dimensional Thick-Wall Model With Fluid–Wall Interactions

Abstract

Severe stenosis may cause critical flow and wall mechanical conditions related to artery fatigue, artery compression, and plaque rupture, which leads directly to heart attack and stroke. The exact mechanism involved is not well understood. In this paper a nonlinear three-dimensional thick-wall model with fluid-wall interactions is introduced to simulate blood flow in carotid arteries with stenosis and to quantify physiological conditions under which wall compression or even collapse may occur. The mechanical properties of the tube wall were selected to match a thick-wall stenosis model made of PVA hydrogel. The experimentally measured nonlinear stress-strain relationship is implemented in the computational model using an incremental linear elasticity approach. The Navier-Stokes equations are used for the fluid model. An incremental boundary iteration method is used to handle the fluid-wall interactions. Our results indicate that severe stenosis causes considerable compressive stress in the tube wall and critical flow conditions such as negative pressure, high shear stress, and flow separation which may be related to artery compression, plaque cap rupture, platelet activation, and thrombus formation. The stress distribution has a very localized pattern and both maximum tensile stress (five times higher than normal average stress) and maximum compressive stress occur inside the stenotic section. Wall deformation, flow rates, and true severities of the stenosis under different pressure conditions are calculated and compared with experimental measurements and reasonable agreement is found.

Simulating cyclic artery compression using a 3D unsteady model with fluid–structure interactions

“…Better wall models and experimental data for tube material under compression are needed to get detailed stress/strain distributions in the tube wall which cannot be obtained from the current model [43,44].…”

“…where E is the Young's modulus of the tube determined from experiment [44], h w is wall thickness, m is Poisson ratio, r is the mean tube radius. Following the derivation in Flaherty's paper [10] with some adjustments, use the natural coordinates and neglecting the inertia force (<1% of tension forces) and the circumferential shear stress from the fluid, the equilibrium equations for the tube wall are given by…”

“…Flow velocity accelerates when passing through a stenosis (a constriction in blood vessels) which lowers flow pressure. If the stenosis is severe enough, blood pressure may become negative and cause artery compression or even collapse leading to serious clinical consequences such as stroke or heart attack [1,3,41,44]. The mechanism for the whole collapse process is not fully understood.…”

“…Various computational models (from 1D to 3D, with rigid or compliant tubes) have been used to quantify flow and wall mechanical behaviors [1,3,9,11,21,27,44,48]. It has been found that artery stiffness, stenosis geometry and severity and imposed pressure conditions are the dominating factors affecting blood flow and artery motion.…”

Evaluating the Effect of Magnetic Field, Impulse Flow and Gravity Acceleration on Different Femoral Bypass Angles in Order to Remove Lipid Accumulations in Atherosclerosis Disease by Simulation Method

“…Sankar and Lee mathematically modeled non-Newtonian fluid impulse flow in narrow arteries 11 . Tang et al assessed blood impulse flow in three axial symmetric narrow tube models and three asymmetric narrow tubes with various narrowness intensity 12 . According to these studies flow in the bypass accompanied artery is not considered and most of researchers considered blood as a Newtonian fluid and none has studied on magnetic field effect on bypass.…”