G Ital Cardiol. 1996 May;26(5):503-17.
Despite general acceptance of the normal limits for M-mode echocardiographic measurements established in the U.S.A. in the late seventies, several studies have shown that those limits of normality have some limitations which restrict their use in clinical practice, and that these limits should be specific for the population that should be studied. To date, however, there is no reference method to calculate normal limits of M-mode echocardiographic measurements in the Italian population.
627 healthy volunteers (382 males, 245 females) ranging in age from 4 to 89 years, were prospectively examined, using two-dimensionally directed M-mode echocardiography, in 13 echocardiographic laboratories. End-diastolic and-systolic left ventricular diameters, interventricular septum and posterior wall thickness, end-diastolic aortic dimension and end-systolic left atrial diameter were measured following the recommendations of the American Society of Echocardiography. Age, gender, weight, height, heart rate and blood pressure were used as determinants of the echocardiographic measurements. The specificity of the resulting normal limits of echocardiographic measurements was then tested on an independent population of 145 normal subjects (92 males, 53 females) who were prospectively examined after the development of the model.
Gender, age and weight were significant and independent determinants in nearly all the echocardiographic measurements performed. After logarithmic transformation of all the variables, we developed sex specific regression models which allow calculation of 95% prediction intervals for the cardiac chamber size and wall thickness, using an exponential multivariate regression model. Ninety-one percent of the echocardiographic measurements performed on the control population (range 84.6-94.1%) were correctly identified as normal using our model. Conversely, the specificity of the existing reference models developed in the U.S.A. or in the Netherlands identified, respectively, only 77% (range 53.1-92.4%) and 74% (range 53.8-87.6%) of those measurements as normal (p < 0.0001 vs our model for both). Differences in specificity between our models and the U.S. one also persisted after correcting the U.S. model for the Italian population (82.8% versus 91.3%, respectively; p = 0.003). Conversely, differences in specificity between our models and the Dutch ones were no longer detectable after correcting the Dutch models (which has a statistical approach very similar to ours) for the Italian population (91.3 versus 94.7%, respectively; p = NS).
Our study provides reliable mathematical model based on exponential growth (allometric) equations to calculate upper and lower normal limits of M-mole echocardiographic measurements obtained from Italian subjects given their gender, height, weight, heart rate, age and blood pressure.
尽管美国在20世纪70年代末建立的M型超声心动图测量正常范围已被广泛接受，但多项研究表明，这些正常范围存在一些局限性，限制了它们在临床实践中的应用，而且这些范围应该针对所研究的人群具有特异性。然而，迄今为止，尚无计算意大利人群M型超声心动图测量正常范围的参考方法。
对627名年龄在4至89岁之间的健康志愿者（382名男性，245名女性）进行前瞻性检查，在13个超声心动图实验室使用二维导向M型超声心动图。按照美国超声心动图学会的建议测量舒张末期和收缩末期左心室直径、室间隔和后壁厚度、舒张末期主动脉内径和收缩末期左心房直径。年龄､性别､体重､身高､心率和血压被用作超声心动图测量的决定因素。然后在145名正常受试者（92名男性，53名女性）的独立人群中测试所得超声心动图测量正常范围的特异性，这些受试者在模型建立后进行前瞻性检查。
在几乎所有进行的超声心动图测量中，性别、年龄和体重都是显著且独立的决定因素。对所有变量进行对数转换后，我们开发了性别特异性回归模型，该模型使用指数多元回归模型来计算心腔大小和壁厚度的95%预测区间。使用我们的模型，在对照组人群中进行的91%的超声心动图测量（范围84.6 - 94.1%）被正确识别为正常。相反，美国或荷兰开发的现有参考模型的特异性分别仅将这些测量中的77%（范围53.1 - 92.4%）和74%（范围53.8 - 87.6%）识别为正常（与我们的模型相比，两者p < 0.0001）。在对美国模型针对意大利人群进行校正后，我们的模型与美国模型之间的特异性差异仍然存在（分别为82.8%对91.3%；p = 0.003）。相反，在对荷兰模型（其统计方法与我们的非常相似）针对意大利人群进行校正后，我们的模型与荷兰模型之间的特异性差异不再可检测到（分别为91.3%对94.7%；p = 无显著性差异）。
我们的研究提供了基于指数增长（异速生长）方程的可靠数学模型，以根据意大利受试者的性别、身高、体重、心率、年龄和血压计算M型超声心动图测量的正常上限和下限。
