University Department of Radiology, University of Cambridge, UK.
Atherosclerosis. 2012 Aug;223(2):321-6. doi: 10.1016/j.atherosclerosis.2012.06.015. Epub 2012 Jun 21.
Intraplaque hemorrhage is an increasingly recognized contributor to plaque instability. Neovascularization of plaque is believed to facilitate the entry of inflammatory and red blood cells (RBC). Under physiological conditions, neovessels are subject to mechanical loading from the deformation of atherosclerotic plaque by blood pressure and flow. Local mechanical environments around neovessels and their relevant pathophysiologic significance have not yet been examined.
Four carotid plaque samples removed at endarcterectomy were collected for histopathological examination. Neovessels and other components were manually segmented to build numerical models for mechanical analysis. Each component was assumed to be non-linear isotropic, piecewise homogeneous and incompressible. The results indicated that local maximum principal stress and stretch and their variations during one cardiac cycle were greatest around neovessels. Neovessels surrounded by RBC underwent a much larger stretch during systole than those without RBCs present nearby (median [inter quartile range]; 1.089 [1.056, 1.131] vs. 1.034 [1.020, 1.067]; p<0.0001) and much larger stress (5.3kPa [3.4, 8.3] vs. 3.1kPa [1.6, 5.5]; p<0.0001) and stretch (0.0282 [0.0190, 0.0427] vs. 0.0087 [0.0045, 0.0185]; p<0.0001) variations during the cardiac cycle.
Local critical mechanical conditions may lead to the rupture of neovessels resulting in the formation and expansion of intraplaque hemorrhage.
斑块内出血是斑块不稳定的一个日益被认识到的促成因素。斑块的新生血管化被认为有利于炎症细胞和红细胞（RBC）的进入。在生理条件下，新血管会受到血压和血流使动脉粥样硬化斑块变形产生的机械负荷的影响。新血管周围的局部机械环境及其相关的病理生理意义尚未被研究。
共收集了 4 个颈动脉斑块样本，这些样本是在血管内膜切除术时切除的，用于组织病理学检查。手动分割新血管和其他成分，以建立机械分析的数值模型。假设每个成分是非线性各向同性的、分段均匀的和不可压缩的。结果表明，局部最大主应力和拉伸及其在一个心动周期内的变化在新血管周围最大。在收缩期，被 RBC 包围的新血管比附近没有 RBC 的新血管经历更大的拉伸（中位数[四分位数范围]；1.089[1.056，1.131]比 1.034[1.020，1.067]；p<0.0001），并且在心动周期内经历更大的应力（5.3kPa[3.4，8.3]比 3.1kPa[1.6，5.5]；p<0.0001）和拉伸（0.0282[0.0190，0.0427]比 0.0087[0.0045，0.0185]；p<0.0001）变化。
局部临界机械条件可能导致新血管破裂，导致斑块内出血的形成和扩大。
