دانلود رایگان مقاله اثرات توزیع و کنتراست ضریب نرم کانونی آئورت با خصوصیات سیلیکونی

Abstract

Examining the change in regional stiffness of the arterial wall may prove as a reliable method for detecting various cardiovascular diseases. As suggested by MoenseKorteweg relationship, the pulse wave velocity (PWV) along the arteries has been shown to correlate to the stiffness of the arterial wall; the higher the stiffness, the higher the PWV. The current primary clinical practice of obtaining an average PWV between remote sites such as femoral and carotid arteries is not as clinically effective, since various cardiovascular diseases are shown to be accompanied by focal changes in stiffness. Therefore, methods to examine the PWVs focally are warranted. Extending on the findings of previous studies, pulse wave propagations along aortas with wall focal softening were addressed in this study using two-way coupled fluidestructure interaction (FSI) simulations of arterial pulsatile motions. Spatiotemporal maps of the wall displacement were used to evaluate the regional pulse wave propagations and velocities. In particular, soft wall inclusions of different number, size, and modulus were examined. The findings showed that the qualitative markers on the pattern of the wave propagations such as the existence of forward, reflected, and standing waves, as well as the quantitative markers such as PWV, linear coefficient of the propagating waves, and the width of the standing waves, provide a reliable tool to distinguish between the natures of the wall focal softening. Future studies are needed to include physiologically-relevant wall inhomogeneity in order to further implicate on the clinical potentials of the inverse problem for noninvasive diagnosis.

Discussions and conclusion

Currently, the aortic PWV is measured globally by estimating an average velocity with measurements at two locations: the carotid and femoral arteries.11,16 This accuracy of such global-PWV-based methods can be deteriorated due to the lack of knowledge of the arterial precise geometry, assuming that it is of a single longitudinal flow, and the absence of obtaining a regional PWV along a vascular branch.11,19 Furthermore, majority of cardiovascular diseases have shown to entail focal arterial wall degradations,21e23 which may not be detected based on a global-PWV-based method. Feasibility of using numerical methods such as FSI simulations to generate pulse wave propagations in simple geometry modeled arteries and determine local PWVs has been established.35 Furthermore, studies to determine the effects of various hard inclusions on the arterial wall and its outcome on the wave propagation in order to establish quantitatively and qualitatively markers to capture these differences have been found.36 The aim of this study is to examine the effects of various soft inclusions on the pulse propagation in order to further establish confirmation that qualitative and quantitative markers can be used to characterize properties such as number of inclusions, inclusion size, and modulus.