左冠状动脉主干分叉角度与非钙化斑块相关性及流体力学研究

Correlation between left main coronary artery bifurcation angle and non-calcified plaque and its hydrodynamics

目的探讨左冠状动脉主干分叉角度与非钙化斑块形成及分布的相关性及其流体力学理论基础。方法回顾性分析2014年1月至2016年6月临床疑诊为冠心病，并行冠状动脉CT血管成像（CCTA）的患者55例，在CCTA图像上测量左冠状动脉主干分叉角度、斑块分布象限、斑块中心距分叉参考平面的距离、斑块部位最小管腔面积及血管外弹力膜横截面积，并计算斑块负荷。将左冠状动脉主干分叉病变分为有斑块组和无斑块组，组间角度的比较采用t检验；将左冠状动脉主干分叉角度分为≥70°和〈70°两组，组间斑块的比较采用χ2检验，斑块所属象限的比较采用Fisher检验；分叉角度与斑块距离采用Pearson相关性分析。将无斑块组DICOM格式的冠状动脉CT数据导入MIMICS、3-MATIC及abaqus CFD软件，得到流体力学模型，进而分析不同角度下压力及速度的变化情况。结果有斑块组25例，分叉角度为（70.55±21.34）°；无斑块组30例，分叉角度为（55.95±14.77）°，有、无斑块组之间角度差异有统计学意义（t=2.893，P=0.006）；≥70°、〈70°组之间斑块例数差异有统计学意义（χ2=6.175，P=0.013）；斑块分布距离与分叉角度呈负相关（r=－0.773，P〈0.001）。随着分叉角度增大，靠近分叉处血管壁位置高压力区及低速区域范围越来越大；在与分支开口内侧红色区域相对的血管外侧壁出现绿色低壁面压力区，呈不规则分布，且这一区域附近壁面压力变化梯度较大。结论随着左冠状动脉主干分叉角度增大，形成斑块的可能性增大，斑块与分叉处距离增大；斑块易出现在血分叉下游外侧壁。

Objective To investigate the correlation between the angle and distribution of non-calcified plaque of left main coronary bifurcation and its hydrodynamic theory. MethodsRetrospective analysis of 55 patients suspected of coronary heart disease who had undergone coronary computed tomographic angiography from January 2014 to June 2016. Angle, quadrant distribution, distance from bifurcation reference plane, minimal lumen area and extravascular elastic membrane cross section area of left main coronary bifurcation were measured. Then we calculated the plaque burden. The left main coronary bifurcation lesions were divided into plaque group and non-plaque group. Student＇s t test was used to compare the two groups.The left main coronary bifurcation lesions were divided into ≥70° group and〈70° group, Chi-square test and Fisher exact test were used to compared the two groups. Pearson correlation analysis was used to analyse the bifurcation angle and plaque distance. The data of non-plaque group was imported into the MIMICS,3-MATIC and abaqus CFD software to establish the hydrodynamic model, which was used to analyze the changes of pressure and velocity at different angles.ResultsPlaque group has 25 patients whose average value of the bifurcation angle was （55.95±14.77）°;non-plaque group has 30 patients whose average value of the bifurcation angle was（55.95±14.77）°.Angle difference was statistically significant between plaque and non-plaque group（t=2.893, P=0.006）;Plaque difference was statistically significant between ≥70° and〈70° groups. The distance was negatively correlated with bifurcation angle（r=-0.773, P〈0.001）. Following the increase of bifurcation angle, the vascular wall area of high pressure and low speed region growed The green region of low-wall pressure with irregular distribution appeared in the lateral wall of the vessel that opposite to the red region of the bifurcation, and this region had lager gradient variability of wall pressure.ConclusionWith the increase of coronary bifurcation angle, the possibility of plaque formation increases, the distance from plaque to bifurcation increases,the plaques tend to appear in the lateral wall of the blood vessels.