目的 探究不同的左前降支(left anterior descending, LAD)狭窄程度和分叉血管曲率对血流动力学的影响。方法 建立不同分叉血管曲率半径和 LAD 分支狭窄率的理想模型,使用流固耦合( fluid-structure interaction, FSI)方法评估不同曲率半径和不同狭窄率情况下对血流和壁面剪切力相关指标的影响。 结果 LAD 发生狭窄后,高震荡剪切指数(oscillatory shear index, OSI)和高相对滞留时间(relative residence time, RRT)区域主要分布于 LAD 分叉脊对侧、弯曲外侧狭窄位置下游近端和弯曲内侧下游远端,并且随着狭窄程度的增加会扩大其区域与程度;由于曲率半径减小,弯曲内侧中的高 OSI 和 RRT 会向 LAD 下游远端分布,高 RRT 区域面积相对整个血管面积平均降幅能够达到 35. 68% 。 结论 LAD 狭窄的存在会增加狭窄位置下游和 LAD 分叉脊对侧发生继发性狭窄的风险。 曲率降低会促进弯曲内侧斑块的形成与发展,但从整个血管来看,又会细微地降低斑块形成概率。 研究结果可为治疗 LAD 病变与预防继发性狭窄提供方案设计与优化的理论参考。

Objective To investigate the effects of different degrees of left anterior descending (LAD) stenosis and bifurcation vessel curvature on hemodynamics. Methods An ideal model with different bifurcation radii of curvature and stenosis rates of LAD branches was developed. The effects from different radii of curvature and different stenosis rates on blood flow and wall shear stress (WSS)-related parameters were evaluated using the fluid-structure interaction (FSI) method. Results After stenosis occurred at the LAD, the regions of high oscillatory shear index (OSI) and high relative residence time (RRT) were mainly distributed on contralateral sides of the LAD bifurcation ridge, proximal downstream of the stenosis location at lateral sides of the bend, and distal downstream at medial sides of the bend. And with the increase of the degree of stenosis, such areas and degrees would be expanded. As the radius of curvature decreased, high OSI and RRT in medial side of the bend were distributed distally at downstream of the LAD, and the average decrease of high RRT area relative to the whole vascular area could reach 35.68%. With the increase of the stenosis degree Conclusions The presence of LAD stenosis increases the risks of secondary stenosis at downstream of the stenosis location and contralateral side of the LAD bifurcation ridge. The decrease in curvature promotes the formation and development of plaque at medial side of the bend. Still, it will decrease the probability of plaque formation for the entire vessel. The results may provide the theoretical reference for protocol design and optimization for treating LAD lesions and preventing secondary stenosis.

河北省自然科学基金项目(A2020202015, A2021202014) ,国家自然科学基金项目(12102123)