Experiment-Based 3-D Computational Studies of Blood Flow in Stenotic Carotid Arteries with Dynamic Wall Properties

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The principal investigator and his colleagues use anexperiment-based computational approach to model blood flow inlarge stenotic arteries and investigate critical flow and arterywall behaviors that may lead to artery compression, plaque caprupture, stroke and heart attack. Dynamic properties of thestenotic arteries with plaque stiffness and geometry variationsare determined experimentally using hydrogel tubes whosemechanical properties are close to those of bovine carotidarteries. This leads to a series of 3-D nonlinear computationalmodels with fluid-wall interactions based on the experimentalmeasurements. Arbitrary Lagrangian-Eulerian formulation is usedto deal with free moving boundaries. Implicit methods includingthe SIMPLER algorithm and fully coupled methods based onmesh-free generalized finite differences with staggered grids,upwind techniques, and a consistent physical interpolationtechnique are used to solve the fluid model. A sequence ofexperiment-based thin- and thick-wall models are introduced tomodel the dynamic nonlinear properties of the stenotic tube wallwith large strain, deformation, compression and collapse. Anincremental boundary iteration method and an under-relaxationtechnique are used to handle the fluid-wall interactions.Validated by experimental data, results obtained arephysiologically relevant and may provide information helpful forearly detection, diagnosis and prevention of relatedcardiovascular diseases. The models and numerical methodsdeveloped are applicable to a wide range of problems withfluid-structure interactions and can be extended to include masstransfer, structures of arteries and plaques, endothelialresponses, and arterial remodeling. Stenosis, a constriction in blood vessels, is one of theleading causes of death in the western world. The investigatorsand their colleagues couple experiments with computations tomodel blood flow in large stenotic arteries and investigatecritical flow and artery wall behaviors that may lead to arterycompression, plaque cap rupture, stroke and heart attack. Theproblem is difficult because of the high complexity of arterystructure and its nonlinear mechanical properties, strong bloodand artery interactions, and critical flow conditions caused bysevere stenosis. Dynamic properties of the stenotic arteries aredetermined experimentally using bovine carotid arteries andhydrogel tubes, whose properties are close to those of bovinecarotid arteries. A series of 3-D nonlinear computational modelswith fluid-wall interactions, based on the experimentalmeasurements, are solved by a novel numerical method to quantifyconditions under which artery compression and plaque cap rupturemay occur. Validated by experimental data, these results can behelpful for early detection, diagnosis and prevention of relatedcardiovascular diseases. The models and numerical methodsdeveloped are applicable to a wide range of problems withfluid-structure interactions and complex geometries. The modelscan be extended to include mass transfer, structures of arteriesand plaques, grafts and stents, endothelial responses andarterial remodeling. As applications of biotechnology, theresults obtained can be used to improve the design of medicaldevices such as grafts and stents.