与多普勒超声相结合的人体二尖瓣狭窄下游湍流剪应力二维有限元分析

A STUDY ON TSS DOWNSTREAM OF MITRAL STENOSIS WITH A FINITE ELEMENT MODEL OF TWO DIMENSIONS COMBINED WITH DOPPLER ECHOCARDIOGRAPHY IN HUMAN BEINGS

目的探讨一种与多普勒超声相结合的人体二尖瓣狭窄下游湍流剪应力二维有限元分析方法。方法采用多普勒超声无创检测技术,将体内实时采集到的左心腔二维超声图像和左房、左室壁平均运动速度作为边界条件,对一组二尖瓣狭窄病人随访期间二尖瓣下游湍流剪应力(turbulentshearstress,TSS)进行计算机数值模拟、二维有限元分析。结果有限元分析显示:TSS在两次随访前后均存在显著性差异(P<0.05),与瓣膜病变Wilkins评分呈明显正相关(r:0.80～0.82);无论病变和狭窄程度怎样,跨瓣血流核心区位点TSS始终低于边界各位点,其最大值<80N/m2,结果同以往研究结论一致。结论二尖瓣狭窄下游所产生的TSS与瓣膜病变进展密切相关。有限元法对局部瓣区和整个流场中TSS和速度大小与分布的描述较为完整而详细,因此它与多普勒超声技术相结合,使心瓣流场中TSS的体内定量研究既全面而又准确。

Objective:To conduct such a study on TSS downstream of mitral stenosis using a finite element model of two dimensions combined with Doppler echocardiography in human beings.Method:Non-invasive Doppler echocar-diography was used to pick up in real-time way two dimensional images of left cardiac cavity and average ve-locities of left atrium and left ven tricle as boundary conditions,we conducted a computational study of TSS downstream of mitral valve in a group of patients with mitral stenosis during their follow-up using the finite el-ement method.Result:There was a significant difference with respect of TSS and Wilkins grade of valvular le-sion between the twice of follow-up(P<0.05),and the two items correlated with each other(r:0.80-0.82).Be-sides,however the extent of valvular lesion and stenosis is,TSS in the centerline locations is lower than that in the boundary locations.The maximul number of the former is less than80N/m 2 .Our results showed coincident with those of previous re searches.Conclusion:There is an obvious relationship between TSS downstream of mi tral stenosis and the aggravation of valvular lesion.The description of TSS and velocity in the local and total flow field of valve with finite element method is quite detailed and intact.So the combination of the two methods makes the quantitative study of TSS in the flow field of cardiac valve to be comprehensive and accurate.