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Assessing atherosclerotic plaque vulnerability based on limited in vivo patient data has been a major challenge in cardiovascular research and clinical practice. Considerable advances in medical imaging technology have been made in recent years to identify vulnerable atherosclerotic carotid plaques in vivo with information about plaque components including lipid-rich necrotic pools, calcification, intraplaque hemorrhage, loose matrix, thrombosis, and ulcers, subject to resolution limitations of current technology [1]. Image-based computational models have also been developed which combine mechanical analysis with image technology aiming for more accurate assessment of plaque vulnerability and better diagnostic and treatment decisions [2]. However, 3D models with fluid-structure interactions (FSI), cyclic bending and anisotropic properties based on in vivo IVUS images for human coronary atherosclerotic plaques are lacking in the current literature. In this paper, we introduce 3D FSI models based on in vivo IVUS images to perform mechanical analysis for human coronary plaques. Cyclic bending is included to represent deformation caused by cardiac motion. An anisotropic material model was used for the vessel so that the models would be more realistic for more accurate computational flow and stress/strain predictions.Copyright © 2009 by ASME

Arteries display highly nonlinear, anisotropic material behavior and can be considered to be a layered composite of fiber oriented materials composed of three layers: intima, media and adventitia. The intima does not affect the material properties of the artery. Thus, the mechanical properties of an artery result from the combined interaction of the media and adventitia with each layer displaying different material properties. It has been widely accepted that atherosclerosis changes the material properties of the arterial wall. However, little experimental data exists relating the properties of the media and adventitia of atherosclerotic vessels to the overall properties of the artery. Knowledge of the properties of human atherosclerotic tissues is essential for an improved understanding the effects of atherosclerosis and also for creating more accurate computational models for predicting the effects of the disease [1]. A prior study of bovine carotid arteries determined the properties of the adventitia and media using a deductive method [2]. This paper focuses on directly measuring and comparing the stiffness of paired samples of adventitia, media and full thickness specimens from human atherosclerotic carotid arteries.Copyright © 2009 by ASME

The abrupt closure of an artery by an occlusive thrombus is the main cause of myocardial infarcts and other thrombotic sequelae of atherosclerosis. This thrombosis is often associated with rupture of an atherosclerotic plaque [1,2]. Histology has shown that most rupture sites are also sites of increased mechanical stress [2]. It has been widely accepted that atherosclerosis leads to locally increased stresses in the region of lesions. However, validation of this hypothesis has been impeded by a lack of experimental data on the material strength of atherosclerotic tissues. Knowledge of mechanical properties of human atherosclerotic tissues is essential for understanding the rupture mechanism and also for creating more accurate computational models for predicting fatal cardiovascular events [3]. Moreover, an increased understanding of the mechanical properties of atherosclerotic tissue is important for developing greater insight into the pathophysiology of the cardiovascular system and as well as for predicting the outcome of interventional treatments such as balloon angioplasty.Copyright © 2009 by ASME

Atherosclerotic plaque vulnerability assessment and the ability to predict possible future rupture are of vital importance for early diagnosis, prevention and treatment of cardiovascular diseases related to atherosclerosis. It has been hypothesized that critical stress conditions in the plaque may be closely related to plaque rupture and can be combined with current image-based assessment techniques for more accurate plaque evaluation. A major challenge for all available plaque assessment schemes is the lack of gold standard based on in vivo patient data where both ruptured and non-ruptured plaques were compared and analyzed. In vivo patient image data showing rupture verified by histological information (current gold standard) provided by excised specimens data will help to establish in vivo benchmark for image-based and/or stress-based assessment schemes.Copyright © 2009 by ASME