Chironi Gilles N, Simon Alain, Bokov Plamen, Levenson Jaime
AP-HP, Hôpital Européen Georges Pompidou, Service de Cardiologie Préventive, Paris, France.
J Clin Ultrasound. 2009 Jun;37(5):270-5. doi: 10.1002/jcu.20578.
Early artery wall-thickening detected by ultrasound-assessed increased carotid intima-media thickness (IMT) may reflect atherosclerosis or represent an adaptive response to keep homeostasis tensile stress that is related inversely to wall thickness by Laplace's equation. We attempted to discriminate between both mechanisms by correcting IMT for its inverse association with tensile stress.
Common carotid IMT and lumen diameter (D) where determined in 40 healthy controls and 119 never-treated asymptomatic patients with >or=1 traditional cardiovascular risk factor. The cross-sectional area (CSA) was calculated as pi x IMT x (IMT + D). Tensile stress was approximated by [mean blood pressure x (D/2 x IMT)], and wall shear stress by [(blood viscosity) x 4 x (mean blood velocity/D)]. Inverse regression line relating IMT and tensile stress in controls (p < 0.001) was used as a reference to determine in an individual at-risk patient the IMT deviation, defining DeltaIMT from the regression line of controls at the measured patient's tensile stress.
DeltaIMT correlated positively with age (p < 0.05), body mass index (p < 0.05), blood pressure (p < 0.001), and glucose (p < 0.001). In multivariate analysis, DeltaIMT was independently associated with age (p < 0.01), male gender (p < 0.001), and blood pressure (p < 0.001). IMT showed positive association with age (p < 0.001) but not with other risk factors. Also, DeltaIMT, like CSA, correlated positively with tensile stress (p < 0.001) and negatively with wall shear stress (p < 0.05, p < 0.01), whereas IMT correlated negatively with tensile stress (p < 0.001) but not with wall shear stress.
Correcting IMT for adaptive association with tensile stress may give more strength to carotid evaluation for assessing cardiovascular risk.
通过超声评估发现的早期动脉壁增厚表现为颈动脉内膜中层厚度（IMT）增加，这可能反映动脉粥样硬化，或者代表一种适应性反应，以维持内稳态拉伸应力，根据拉普拉斯方程，该应力与管壁厚度呈负相关。我们试图通过校正IMT与拉伸应力的负相关关系来区分这两种机制。
测定了40名健康对照者和119名未经治疗的无症状患者（具有≥1个传统心血管危险因素）的颈总动脉IMT和管腔直径（D）。横截面积（CSA）计算为π×IMT×（IMT + D）。拉伸应力近似为[平均血压×（D / 2×IMT）]，壁面剪应力近似为[（血液粘度）×4×（平均血流速度 / D）]。将对照组中IMT与拉伸应力的反向回归线（p < 0.001）用作参考，以确定个体高危患者的IMT偏差，即根据测量的患者拉伸应力，从对照组回归线定义ΔIMT。
ΔIMT与年龄（p < 0.05）、体重指数（p < 0.05）、血压（p < 0.001）和血糖（p < 0.001）呈正相关。在多变量分析中，ΔIMT与年龄（p < 0.01）、男性（p < 0.001）和血压（p < 0.001）独立相关。IMT与年龄呈正相关（p < 0.001），但与其他危险因素无关。此外，ΔIMT与CSA一样，与拉伸应力呈正相关（p < 0.001），与壁面剪应力呈负相关（p < 0.05，p < 0.01），而IMT与拉伸应力呈负相关（p < 0.001），但与壁面剪应力无关。
校正IMT与拉伸应力的适应性关联可能会增强颈动脉评估在评估心血管风险方面的作用。
