EFFECTS OF FIBROUS CAP THICKNESS ON PEAK CIRCUMFERENTIAL STRESS IN MODEL ATHEROSCLEROTIC VESSELS
EFFECTS OF FIBROUS CAP THICKNESS ON PEAK CIRCUMFERENTIAL STRESS IN MODEL ATHEROSCLEROTIC VESSELS
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DOI：
10.1161/01.res.71.4.850
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发表时间：
1992-10-01
影响因子：
20.1
通讯作者：
LEE, RT
中科院分区：
文献类型：
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作者：
LOREE, HM;KAMM, RD;LEE, RT
很可能是狭窄严重程度以外的因素；使一些动脉粥样硬化斑块易于破裂。由于周向应力的局灶性增加可能是斑块破裂的重要机制，因此我们通过基于与血管内超声图像相似的病变血管的理想化二维横截面的有限元分析，检查了动脉粥样硬化病变的峰值周向应力。该研究旨在检验以下假设：内膜下斑块结构特征（例如纤维帽的厚度）是斑块应力分布中比狭窄严重程度更重要的因素。该分析结合了正常血管和患病血管的平衡生物力学参数，并确定了平均管腔内压为 110 mm Hg 时斑块内的应力分布。随着管腔面积持续减少 70%，归一化为管腔压力 (sigma(max)/P) 的最大周向应力 (sigma(max)) 从 6.0 增加到 24.8，因为脂质池的厚度从斑块厚度的 38% 增加到 54%，因为脂质池上的纤维帽更薄。当脂质池厚度恒定时，通过增加纤维帽厚度将狭窄严重程度从 70% 增加到 91%，使 sigma(max)/P 从 24.8 降低到 4.7。当不存在脂质池且狭窄严重程度从 70% 增加至 99% 时，sigma(max)/P 从 5.3 降至 4.7。因此，减少纤维帽厚度会显着增加斑块中的峰值周向应力，而增加狭窄严重程度实际上会降低斑块中的峰值应力。峰值周向应力对内膜下结构的关键依赖性可以解释为什么一些破裂并引起心肌梗塞的动脉粥样硬化斑块在血管造影上并不严重。
It is likely that factors other than stenosis severity; predispose some atherosclerotic plaques to rupture. Because focal increases in circumferential stress may be an important mechanism of plaque rupture, we examined peak circumferential stress of atherosclerotic lesions by using finite element analysis based on idealized two-dimensional cross sections of diseased vessels similar to intravascular ultrasound images. The study was designed to test the hypothesis that subintimal plaque structural features such as thickness of the fibrous cap are more important factors in the distribution of stress in the plaque than stenosis severity. The analysis incorporated equilibrium biomechanical parameters from normal and diseased vessels and determined the stress distribution within the plaque at a mean luminal internal pressure of 110 mm Hg. With a constant luminal area reduction of 70%, maximum circumferential stress (sigma(max)) normalized to luminal pressure (sigma(max)/P) increased from 6.0 to 24.8 as the thickness of the lipid pool was increased from 38% to 54% of the plaque thickness because of the thinner fibrous cap over the lipid pool. When the lipid pool thickness was constant, increasing the stenosis severity from 70% to 91% by increasing the fibrous cap thickness decreased sigma(max)/P from 24.8 to 4.7. When no lipid pool was present and the stenosis severity was increased from 70% to 99%, sigma(max)/P decreased from 5.3 to 4.7. Thus, reducing the fibrous cap thickness dramatically increases peak circumferential stress in the plaque, whereas increasing the stenosis severity actually decreases peak stress in the plaque. The critical dependence of peak circumferential stress on subintimal structure may explain why some atherosclerotic plaques that rupture and cause myocardial infarction are not angiographically severe.