中文摘要：

目的：心室辅助是晚期心衰最有效的治疗方法之一。但是，心室辅助装置产生的高流体切应力会对红细胞造成损伤。目前，大多数研究仅利用心室辅助装置造成的溶血值评价其对血液的损伤程度，却忽略了对还未破裂的红细胞受到损伤的关注。本文重点探究流体切应力所造成的红细胞形态的变化。方法首先，利用数值计算软件FLUENT，采用拉格朗日离散模型计算出心室辅助装置在一个心动周期内作用于红细胞的流体切应力曲线；然后，根据数值计算得出的切应力范围，对不同切应力下和不同暴露时间下的血液样本进行实验，并设立无受力对照组减小实验误差；最后，以实验后血样的游离血红蛋白含量作为判断血样溶血情况参数，并以血涂片中非常态红细胞的数量占总体的百分比作为衡量红细胞受损伤但未破裂状态的参数。结果非常态红细胞数目和切应力的相关系数是0.725，P =0.027（＆lt;0.05）。实验结果显示，血泵产生切应力会导致非常态红细胞出现，并且暴露时间一定，非常态红细胞数目随着切应力增大而增大。结论在心室辅助下，血泵流场除了会产生溶血这一极端现象，同时也会导致非常态红细胞数量的增多，降低血液质量，影响人体血液功能。

英文摘要：

Objective Ventricular assist device（ VAD）implanted in human body causes damage for erythrocytes because of the production of different levels of shear stress,due to mechanical structure. While most studies of VAD use hemolysis value to estimate the damage to blood,we may neglect the group of erythrocytes subjected to damage without bursting under low shear stress. The alm of this study is to focus on the morphological changes of erythrocytes caused by VADs,and to find an economical and effective way to evaluate the low shear stress damage to erythrocytes. Methods First,the maximum shear stress（ 450 dynes/cm^2 ）and the average level of shear stress（200 dynes/cm^2 ）acted on erythrocytes in one cardiac cycle（0. 8s） produced by VAD is calculated by FLUENT. Then,the calculated levels of shear stress is equivalent to a series of shear stress and exposure time,which are input into a hemodynamic shearing device（ thermo electron corporation）. Thus,erythrocytes are uniformly exposed to flow shear amount to shear stress produced by VAD. Finally,free hemoglobin of plasma is measured in groups, and blood smears are respectively made to count the number of abnormal erythrocytes. Results The correlation coefficient of the percent of abnormal erythrocytes（ PAE）＆amp;nbsp;and shear stress is 0. 725,and the significant value is 0. 027（ 〈0. 05）. The results show that after blood shearing experiments,the number of abnormal erythrocytes increases with shear stress under constant exposure time,and both shear stress and exposure time contribute to morphological changes in erythrocytes. Low shear stress damage of erythrocytes may be an important factor in the application of VAD. Conclusions Under the VAD,the flow field of blood pump not only will result in hemolysis which is the extreme phenomenon,but also will increase the number of abnormal erythrocytes.