Department of Pharmacology and INSERM U970, Hôpital Européen Georges Pompidou, Paris, France.
JACC Cardiovasc Imaging. 2011 May;4(5):468-77. doi: 10.1016/j.jcmg.2011.01.017.
The purpose of this study was to correlate the arterial mechanics of carotid atherosclerotic plaques assessed from echotracking with their composition by high-resolution magnetic resonance imaging (HR-MRI).
Analysis of the relationship between mechanical parameters and structure of the plaque allows better understanding of the mechanisms leading to mechanical fatigue of plaque material, plaque rupture, and ischemic events. A specific longitudinal gradient of strain (reduced strain, i.e., lower radial strain at the plaque level than at the adjacent segment) has been shown in atherosclerotic plaques on the common carotid artery (CCA) in patients with hypertension, dyslipidemia, or type 2 diabetes mellitus. The structural abnormalities underlying this functional behavior have not been determined.
Forty-six carotid plaques from 27 patients were evaluated; plaques were present at the site of the carotid bifurcation and extended to the CCA. Among the 27 patients, 9 had previous ischemic stroke ipsilateral to carotid stenosis (symptomatic) and 18 had not (asymptomatic). Mechanical parameters were measured at 128 sites on a 4-cm long CCA segment by noninvasive echotracking system, and strain gradient was calculated. Plaque composition was noninvasively determined by HR-MRI.
Complex plaques at HR-MRI (i.e., American Heart Association [AHA] stages IV to VIII) more often displayed a reduced strain than the simple plaques (i.e., AHA stages I to III; p = 0.046). HR-MRI verified complex plaques were associated with an outer remodeling upon echotracking, and had a lower distensibility than adjacent CCA (17.0 ± 5.0 MPa⁻¹ vs. 21.7 ± 7.3 MPa⁻¹; p = 0.007). An outer remodeling was observed in plaques with a lipid core at HR-MRI and was more frequent in symptomatic carotids.
These findings indicate that the longitudinal mechanics of "complex" plaques follows a specific pattern of reduced strain. They also suggest that reduced strain, associated with an outer remodeling, may be a feature of high-risk plaques.
本研究旨在将超声跟踪技术评估的颈动脉粥样硬化斑块的动脉力学与高分辨率磁共振成像（HR-MRI）评估的斑块组成相关联。
分析力学参数与斑块结构之间的关系有助于更好地理解导致斑块材料机械疲劳、斑块破裂和缺血性事件的机制。在高血压、血脂异常或 2 型糖尿病患者的颈总动脉（CCA）的粥样硬化斑块上，已经显示出特定的纵向应变梯度（应变减小，即在斑块水平的径向应变低于相邻节段）。导致这种功能行为的结构异常尚未确定。
评估了 27 例患者的 46 个颈动脉斑块；斑块位于颈动脉分叉处并延伸至 CCA。在 27 例患者中，9 例有同侧颈动脉狭窄引起的缺血性脑卒中（症状性），18 例无（无症状性）。通过非侵入性超声跟踪系统在 4cm 长的 CCA 节段的 128 个部位测量力学参数，并计算应变梯度。通过 HR-MRI 无创性确定斑块组成。
HR-MRI 显示复杂斑块（即美国心脏协会[ AHA ] IV 至 VIII 期）比简单斑块（即 AHA I 至 III 期）更常出现应变减小（p = 0.046）。HR-MRI 证实复杂斑块在超声跟踪时有外重塑，且弹性较相邻 CCA 降低（17.0 ± 5.0 MPa ⁻¹ 比 21.7 ± 7.3 MPa ⁻¹ ；p = 0.007）。在 HR-MRI 显示有脂质核心的斑块中观察到外重塑，并且在症状性颈动脉中更为常见。
这些发现表明“复杂”斑块的纵向力学遵循特定的应变减小模式。它们还表明，与外重塑相关的应变减小可能是高危斑块的特征。
