دانلود رایگان مقاله تراکم ناپذیری آترواسکلروز عروق کرونر از طریق ارتباط تصویر دیجیتال

Abstract

So far there is no study to measure the Poisson’s ratio of the human coronary arteries in order to verify their incompressibility regardless of being healthy or atherosclerosis. It has been reported that atherosclerosis alters the elastin content of the arterial wall which is responsible for the elastic behavior of the arterial wall and helps tissue to reserve its initial shape after contracting or stretching. It is believed that the arterial walls are almost incompressible with nonlinear anisotropic mechanical response under axial or circumferential loading. Although the elastic modulus and Poisson’s ratios were both originally stemmed from the linear solid mechanics, they can be employed to address the linear elastic mechanical properties of the arterial wall under small deformation/strain. To date, many studies assumed the arterial wall as an incompressible material whether via a direct mechanical measurement or a fluid simulation study in the arterial wall, despite there is no enough supporting evidence. The present study was planned to discover this issue in detail using Digital Image Correlation (DIC) technique to lively measure the induced strains of 9 healthy and 8 atherosclerotic human coronary arteries at two different longitudinal strain rates, i.e., 5 and 20 mm/min. The Poisson’s ratio of the arterial walls, thereafter, were measured as a value of transverse strain with respect to the longitudinal strain. The results revealed the mean Poisson’s ratio of 0.49098 and 0.49330 for the healthy and atherosclerotic arterial walls, respectively, under the strain rate of 5 mm/min. Furthermore, the Poisson’s ratio of 0.49156 and 0.49702 were seen in the healthy and atherosclerotic arterial walls, respectively, under the strain rate of 20 mm/min. The results well verified the incompressibility of the coronary arterial walls regardless of being healthy or atherosclerotic under the both strain rates.

Conclusions

So far there are a large amount of literatures on the supposition of the coronary arterial wall’s incompressibility, however, there is still a lack of experimental verification on that. In addition, there is no study up to now to perform a comparative study on the Poisson’s ratio of the healthy and atherosclerotic human coronary arteries under different strain rates. This study was aimed to employ the Digital Image Correlation (DIC) technique to measure the transverse strain versus longitudinal strain of the healthy and atherosclerotic human coronary arteries, in the other words Poisson’s ration, under two different strain rates, namely 5 and 20 mm/min. The results well indicated the incompressibility of the coronary arterial walls not only under various strain rates but also in two different healthy and atherosclerotic conditions. The results revealed that the Poisson’s ratio of the atherosclerotic arteries are insignifi- cantly higher than that of the healthy ones. This might be related to the weakness of the elastin and collagen content of the atherosclerotic arterial walls which provide whether a large strain in the transverse direction or small strain in the longitudinal directions. Although in this study a combination of mechanical measurement and DIC technique were used to measure the Poisson’s ratio of the healthy and atherosclerotic of the human coronary arteries, the authors believe that their results are still promising and further research are required to consider more factors in the measurements, such as mean angle of collagen fibers, more number of markers, and biaxial mechanical testing.