Lang R M, Cholley B P, Korcarz C, Marcus R H, Shroff S G
University of Chicago Hospitals, Department of Medicine, Ill.
Circulation. 1994 Oct;90(4):1875-82. doi: 10.1161/01.cir.90.4.1875.
Evaluation of regional aortic elastic properties in humans has been hampered by the need for invasive techniques to access instantaneous aortic pressure, wall thickness, and cross-sectional area or diameter. In this study, a new noninvasive method is presented for quantification of regional aortic elastic properties.
Twenty-five patients were studied during transesophageal echocardiographic procedures. Measurements of instantaneous aortic cross-sectional area were obtained with an automated border detection algorithm applied to short-axis transesophageal two-dimensional echocardiographic images of the proximal descending thoracic aorta. Instantaneous aortic wall thickness was derived from combined two-dimensional targeted M-mode end-diastolic wall thickness and instantaneous aortic area measurements. Instantaneous aortic pressures were estimated from calibrated subclavian pulse tracings recorded simultaneously. Data were digitized to generate aortic area-pressure loops. Regional aortic mechanical properties were quantified in terms of compliance per unit length (C is the slope of the area-pressure regression), aortic midwall radius (Rm), and incremental elastic modulus of the aortic wall (Einc). To assess the independent effect of age, Rm and Einc values were compared at a common level of aortic midwall stress (0.666 x 10(6) dynes/cm2). Mean values (+/- SD) for C, Rm, and Einc were 0.01 +/- 0.004 cm2/mm Hg, 1.14 +/- 0.17 cm, and 7.059 +/- 4.091 x 10(6) dynes/cm2, respectively. An inverse linear correlation was found between aortic compliance per unit length and age (r = -.68, P < .0007). Incremental elastic modulus was related to age (r = +.80, P < .00003) in a nonlinear fashion such that it increased sharply after the age of 60 years. Finally, midwall radius was less tightly correlated with age (r = +.45, P < .05). Values for C, Rm, and Einc as well as the age dependency of these properties are similar to those reported previously when invasive techniques were used.
This methodology constitutes a new tool to improve the clinical evaluation of regional aortic elastic properties in multiple disease states.
评估人体主动脉局部弹性特性一直受到限制，因为需要采用侵入性技术来获取主动脉瞬时压力、壁厚度以及横截面积或直径。在本研究中，提出了一种用于量化主动脉局部弹性特性的新型非侵入性方法。
对25例患者在经食管超声心动图检查过程中进行了研究。应用自动边界检测算法，对胸降主动脉近端短轴经食管二维超声心动图图像进行测量，获取主动脉瞬时横截面积。主动脉瞬时壁厚度由二维靶向M型舒张末期壁厚度和主动脉瞬时面积测量值联合得出。通过同时记录的校准锁骨下脉搏描记图估算主动脉瞬时压力。将数据数字化以生成主动脉面积 - 压力环。根据每单位长度的顺应性（C为面积 - 压力回归斜率）、主动脉中膜半径（Rm）和主动脉壁的增量弹性模量（Einc）对主动脉局部力学特性进行量化。为评估年龄的独立影响，在主动脉中膜应力的共同水平（0.666×10⁶达因/cm²）下比较Rm和Einc值。C、Rm和Einc的平均值（±标准差）分别为0.01±0.004 cm²/mm Hg、1.14±0.17 cm和7.059±4.091×10⁶达因/cm²。发现主动脉每单位长度的顺应性与年龄呈负线性相关（r = -0.68，P < 0.0007）。增量弹性模量与年龄呈非线性相关（r = +0.80，P < 0.00003），在60岁以后急剧增加。最后，中膜半径与年龄的相关性较弱（r = +0.45，P < 0.05）。C、Rm和Einc的值以及这些特性的年龄依赖性与先前使用侵入性技术时报告的结果相似。
该方法构成了一种新工具，可改善多种疾病状态下主动脉局部弹性特性的临床评估。
