Background and Objective

Recently, transplant of bypass vein is employed to charge blood fluid inside vein after stenosis position. Because, bypass vein can compensate consequences of stenosis in reducing blood flow within vessels. Therefore, analyses of shear stress for anemia, normal, and hypertensive individuals can prepare a valuable understanding in mechanical geometry which is applicable to design of transplantation especially for critical condition of shear stress. In this work, the transplantation of vessels is simulated in Fluent software, and user-defined function is used to indicate the blood properties as a non-Newtonian fluid based on Carreau fluid model.

Methods

Generally, shear stress profiles are studied for three cases of anemia, normal, and hypertensive individuals. Also, stenosis with the severity of 30% is simulated before the junction of host and grafted vessels. Finally, the results of shear stress on the walls (WSS) are reported with respect to three divided sections. Section one related to the distance from the stenosis position to the joining position of veins. Section two is the complete distance of the transplantation of veins, which blood flows are mixed. Section three is related to the distance after transplantation of host and grafted vessels.

Results

It was reported that flow separation causes the velocity of blood flow increases, which enhances shear stress. Moreover, increasing velocity in a hypertensive individual can exacerbate the shear stress. Maximum shear stress is as much as 105 Pa, 125 Pa, and 220 Pa in order of anemia, normal, and hypertensive individuals with abbreviations of LHD, NHD, and HHD, orderly.

Conclusions

A comparison of maximum shear stress values in the Heel and Toe section showed that transplantation of veins can be a critical position of failure, which is introduced potentially as a sensible position for medical treatment and related surgeries.

中文翻译：

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深入了解狭窄的冠状动脉与旁路静脉相连的狭窄内血流的重要性：贫血，正常和高血压患者。

背景与目的

近来，在狭窄位置之后，采用旁路静脉移植来向静脉内充入血液。因为，旁路静脉可以补偿狭窄的后果，减少血管内的血流。因此，对贫血，正常人和高血压个体的剪应力进行分析可以为机械几何学提供有价值的理解，这适用于移植设计，尤其是在剪应力的临界条件下。在这项工作中，在Fluent软件中模拟了血管移植，并根据Carreau流体模型，使用用户定义的函数将血液属性指示为非牛顿流体。

方法

通常，针对三种贫血，正常和高血压个体研究切应力曲线。同样，在宿主和移植血管交界之前，模拟了严重程度为30％的狭窄。最后，报告了墙体（WSS）上的剪应力结果，该结果涉及三个部分。第一节涉及从狭窄位置到静脉连接位置的距离。第二部分是静脉移植的完整距离，其中血液流动是混合的。第三部分与宿主和移植血管移植后的距离有关。

结果

据报道，流分离导致血流速度增加，这增加了剪切应力。此外，高血压个体的速度增加会加剧切应力。按贫血，正常人和高血压患者（LHD，NHD和HHD缩写）的顺序，最大剪切应力高达105 Pa，125 Pa和220 Pa。

结论

对脚后跟和脚趾部分的最大剪切应力值的比较表明，静脉移植可能是失败的关键部位，潜在地将其引入作为医疗和相关手术的明智部位。