Feasibility Of Hemodynamic Analysis Of Local Coronary Arteries And Effects On Plaques

Background:Atherosclerosis shows a predilection in regions of arterial trees withmorphological (geometrical) particularities, such as bends, bifurcations andtrifurcations. This suggests that hemodynamic factors such as static wall pressure,wall shear stress and flow velocity, may be responsible for the localization andprogression of atherosclerosis. Hemodynamic parameters cannot be directlymeasured in vivo, accordingly, computational fluid dynamic (CFD) analysis hasbeen established as an important method to study hemodynamics in coronaryarteries. Previous researches have been mainly based on ideal vascular models orsilicon models, under simplified presumptions. However, these researches cannotprovide realistic hemodynamic peculiarities of human arteries. With thedevelopment of CFD techniques, now we are able to acquire more accurate andvisualized patient-specific models based on CTA images, to investigate thehemodynamic mechanism of atherosclerosis formation and progression, and topredict possibilities of plaque rupture and thrombosis formation.Objective：To investigate the methods of establishing patient-specific hemodynamicmodels of coronary arteries based on computational fluid dynamics (CFD)technique, to simulate numerically the local hemodynamics in anatomicallyrealistic human coronary arteries in order to analyze the hemodynamic mechanismof coronary atherosclerosis formation and implications to plaque growth, ruptureand embolism formation.Methods:Two cases which underwent CTA examinations were selected, one was confirmed to be normal, and the other was diagnosed with stenosed LCA. DICOMformat computed tomography angiography (CTA) images were acquired andinput into Mimics software.3D realistic models of the left coronary artery werereconstructed. The models were surface-meshed and body-meshed by the CFDsoftwares. Simulation was performed in real geometry of the arteries with a finitevolume method by FLUENT software. Data results were imported into ANSYSsoftware for post-processing. Visualized pictures of parameter distributions wereacquired. The dominant hemodynamic parameters were analyzed in relation to theformation and progression of atherosclerosis.Results:Patient-specific vascular models were established and contours ofhemodynamic parameters were displayed, including streamlines of blood velocity,wall pressure(WP), and wall shear stress(WSS). Low blood flow velocity wasobserved at the outer walls of bifurcations. At the apices of the bifurcations, highWP, WSS were observed, while locally low WP, WSS appeared opposite to theflow dividers. High blood flow velocity with low WP, high WSS were observedin the regions of stenosed LAD, while distributions of low WSS, high WP, bloodturbulence were observed in the vicinity.Conclusions:CT image-based CFD is an effective method in reconstructing more realisticpatient-specific coronary artery models. Changes of flow velocity are related toatherosclerosis formation and progression. Low WP is related to atherosclerosisformation and further development of plaques. Low WSS is related toatherosclerosis formation and progression, as well as possibilities of plaquerupture and thrombosis formation. CFD is an effective way to elucidate in vivothe role of hemodynamic parameters in the formation and progression of coronaryartery atherosclerosis.