Bluestein Danny, Alemu Yared, Avrahami Idit, Gharib Morteza, Dumont Kris, Ricotta John J, Einav Shmuel
Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8181, USA.
J Biomech. 2008;41(5):1111-8. doi: 10.1016/j.jbiomech.2007.11.029. Epub 2008 Feb 7.
Sudden heart attacks remain one of the primary causes of premature death in the developed world. Asymptomatic vulnerable plaques that rupture are believed to prompt such fatal heart attacks and strokes. The role of microcalcifications in the vulnerable plaque rupture mechanics is still debated. Recent studies suggest the microcalcifications increase the plaque vulnerability. In this manuscript we present a numerical study of the role of microcalcifications in plaque vulnerability in an eccentric stenosis model using a transient fluid-structure interaction (FSI) analysis. Two cases are being compared (i) in the absence of a microcalcification (ii) with a microcalcification spot fully embedded in the fibrous cap. Critical plaque stress/strain conditions were affected considerably by the presence of a calcified spot, and were dependent on the timing (phase) during the flow cycle. The vulnerable plaque with the embedded calcification spot presented higher wall stress concentration region in the fibrous cap a bit upstream to the calcified spot, with stress propagating to the deformable parts of the structure around the calcified spot. Following previous studies, this finding supports the hypothesis that microcalcifications increase the plaque vulnerability. Further studies in which the effect of additional microcalcifications and parametric studies of critical plaque cap thickness based on plaque properties and thickness, will help to establish the mechanism by which microcalcifications weaken the plaque and may lead to its rupture.
在发达国家，突发性心脏病仍然是过早死亡的主要原因之一。据信，无症状的易损斑块破裂会引发此类致命的心脏病发作和中风。微钙化在易损斑块破裂机制中的作用仍存在争议。最近的研究表明，微钙化会增加斑块的易损性。在本论文中，我们使用瞬态流固耦合（FSI）分析，对偏心狭窄模型中微钙化在斑块易损性中的作用进行了数值研究。比较了两种情况：（i）不存在微钙化；（ii）有一个微钙化点完全嵌入纤维帽中。钙化点的存在对临界斑块应力/应变条件有显著影响，并且取决于血流周期中的时间（阶段）。带有嵌入钙化点的易损斑块在钙化点上游稍远处的纤维帽中呈现出更高的壁面应力集中区域，应力传播到钙化点周围结构的可变形部分。根据之前的研究，这一发现支持了微钙化会增加斑块易损性的假设。进一步研究额外微钙化的影响以及基于斑块特性和厚度对临界斑块帽厚度进行参数研究，将有助于确定微钙化削弱斑块并可能导致其破裂的机制。
