A diseased coronary artery has been modeled to study the implications of plaque morphology on the fluid dynamics. In our previous study, we have successfully classified the coronary plaques of 42 patients who underwent intravascular ultrasound (IVUS) into four-types (Type I, Type II, Type III, and Type IV) based on the plaque morphology. In this study, we demonstrate that, for the same degree of stenosis (height of the plaques), hemodynamics parameters are strongly dependent on the plaque shape. This study is the first one to clearly demonstrate that in addition to wall shear stress, presence of turbulence and location of transition from laminar to turbulence state are additional hemodynamics parameters to identify plaques vulnerable to rupture. 1. Introduction Coronary artery disease (CAD) is a progressive disease characterized by the accumulation of plaques on the artery walls. CAD is initiated by the deposition of fatty materials in the coronary artery resulting in the thickening and formation of streaks of plaque on the artery walls. During these early stages, the plaques are not of significant consequence to the flow dynamics, and the flow does not deviate from the laminar state present in a normal coronary artery [1–3]. As time progresses, these plaques start growing inwards into the lumen (channel in which the blood flows), resulting in the localized narrowing of the artery or stenosis of the artery lumen, and thus, playing a critical role in altering the flow characteristics. It is clear that once a stenosis is developed, the blood flow is further disturbed and hemodynamic parameters continue to play a crucial role as the stenosis progresses [4]. Hence, as the stenosis increases this alters the flow characteristics causing a laminar to turbulent transition in the blood flow. The evidence of turbulence in regions distal to a stenosis was first demonstrated based on detection of high frequency pressure signals for lesions with 23%–76% stenoses [5]. Based on clinical findings as murmurs [6], laboratory experiments [1, 7, 8], and medical imaging methods [9–11], it is now well established that stenosed coronary artery creates high levels of turbulence, thus significantly modifying the flow characteristics. As of today, the degree of stenosis has been a classical metric to define the extent of the disease for medical purposes. The stenoses are commonly assessed as a percentage of obstruction in the diameter of the lumen. It is a common practice to characterize the stenosis using the percentage obstruction or the height of the obstruction criterion.
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