Murray J G, Brown A L, Anagnostou E A, Senior R
Department of Radiology, Northwick Park Hospital, Harrow, Middlesex, London, England.
AJR Am J Roentgenol. 1995 May;164(5):1089-92. doi: 10.2214/ajr.164.5.7717208.
This study evaluated widening of the tracheal bifurcation (subcarinal and interbronchial) angle on posteroanterior chest radiographs as a sign of left atrial enlargement. The purpose was to determine the diagnostic sensitivity and specificity of the sign.
The chest radiographs and echocardiograms of 122 clinically stable patients were retrospectively reviewed. The mean interval between examinations was 10 days (range, 0-30 days). The left atrial dimension was measured on the two-dimensional echocardiograms. Sixty-five patients had a normal left atrial dimension (mean, 34 mm), and 45 patients had an enlarged atrium (mean, 47 mm) on echocardiography. Subcarinal and interbronchial angles were jointly measured by two observers who were unaware of the echocardiographic findings. Correlation analysis was used to determine which angle measurement best predicted the left atrial size. Discriminant analysis was used to derive a threshold angle that predicted left atrial enlargement.
The carina was inadequately seen on 14 radiographs. Left atrial size correlated poorly with both the interbronchial (r = .33) and the subcarinal (r = .25) angel values. An interbronchial angle of 76.4 degrees and a subcarinal angle of 65.4 degrees were the best discriminators between patients with normal and those with enlarged left atrial dimensions (sensitivities, 61% and 51%, respectively; specificities, 63% and 66%).
Our findings show that widening of the tracheal bifurcation angle on chest radiographs is an insensitive and nonspecific sign of left atrial enlargement. This sign is of little value in diagnosing left atrial enlargement.
本研究评估在后前位胸片上气管隆突（隆突下和支气管间）角增宽作为左心房扩大的征象。目的是确定该征象的诊断敏感性和特异性。
回顾性分析122例临床稳定患者的胸片和超声心动图。检查之间的平均间隔时间为10天（范围0 - 30天）。在二维超声心动图上测量左心房大小。65例患者左心房大小正常（平均34mm），45例患者超声心动图显示心房扩大（平均47mm）。由两名不知超声心动图检查结果的观察者共同测量隆突下和支气管间角。采用相关分析确定哪种角度测量最能预测左心房大小。采用判别分析得出预测左心房扩大的阈值角度。
14张胸片上隆突显示不清。左心房大小与支气管间角（r = 0.33）和隆突下角（r = 0.25）的相关性均较差。支气管间角76.4度和隆突下角65.4度是区分左心房大小正常和扩大患者的最佳指标（敏感性分别为61%和51%；特异性分别为63%和66%）。
我们的研究结果表明，胸片上气管隆突角增宽是左心房扩大的一个不敏感且非特异性的征象。该征象在诊断左心房扩大方面价值不大。
