Doddamani Sanjay, Bello Ricardo, Friedman Mark A, Banerjee Anita, Bowers James H, Kim Bette, Vennalaganti Prashant R, Ostfeld Robert J, Gordon Garet M, Malhotra Divya, Spevack Daniel M
Department of Medicine, Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10461, USA.
Echocardiography. 2007 Sep;24(8):860-6. doi: 10.1111/j.1540-8175.2007.00479.x.
Determination of the left ventricular outflow tract cross-sectional area (ALVOT) is necessary for calculating aortic valve area (AVA) by echocardiography using the continuity equation (CE). In the commonly applied form of CE, pir(2) is used to estimate ALVOT utilizing the assumptions that LVOT is round and the parasternal long axis (PLAX) plane bisects LVOT. Imaging LVOT using real time 3D echocardiography (RT3DE) eliminates the need for these assumptions. We tested the hypothesis that LVOT is round based on a formula for eccentricity.
In 53 patients, 2D echocardiography (2DE) and RT3DE were acquired. ALVOT was calculated by 2DE using pir(2) (ALVOT-2D). Using RT3DE, ALVOT planimetry was performed immediately beneath the aortic valve (ALVOT-3Dplan). Eccentricity Index (EI) was calculated using the shortest and longest LVOT diameters. The long axis was measured to be larger by 0.53 cm +/- 0.36 (P < 0.005). The median EI was 0.20 (0.00-0.54), indicating that half the subjects had at least a 20% difference between the major and minor diameters. ALVOT-3Dplan was larger than ALVOT-2D (3.73 +/- 0.95 cm(2) vs. 3.18 +/- 0.73 cm(2); P < 0.001) by paired analysis. Using the equation of an ellipse (piab), ALVOT-3Dellip was 3.57 +/- 0.95 resulting in improved agreement with ALVOT-3Dplan.
In our small patient sample with normal aortic valves, we showed the LVOT shape is usually not round and frequently, elliptical. Incorrectly assuming a round LVOT underestimated the ALVOT-3Dplan and consequently the AVA by 15%. Investigating the LVOT in aortic stenosis is warranted to evaluate whether RT3DE may improve measurement of AVA.
通过超声心动图使用连续性方程（CE）计算主动脉瓣面积（AVA）时，确定左心室流出道横截面积（ALVOT）是必要的。在常用的CE形式中，利用左心室流出道是圆形且胸骨旁长轴（PLAX）平面平分左心室流出道的假设，使用πr²来估计ALVOT。使用实时三维超声心动图（RT3DE）对左心室流出道成像消除了这些假设的必要性。我们基于一个偏心率公式检验了左心室流出道是圆形的假设。
对53例患者进行了二维超声心动图（2DE）和RT3DE检查。通过2DE使用πr²计算ALVOT（ALVOT-2D）。使用RT3DE，在主动脉瓣正下方进行ALVOT面积测量（ALVOT-3Dplan）。使用左心室流出道最短和最长直径计算偏心率指数（EI）。长轴测量值大0.53 cm±0.36（P<0.005）。EI中位数为0.20（0.00 - 0.54），表明一半受试者的长径和短径至少相差20%。配对分析显示ALVOT-3Dplan大于ALVOT-2D（3.73±0.95 cm²对3.18±0.73 cm²；P<0.001）。使用椭圆方程（πab），ALVOT-3Dellip为3.57±0.95，与ALVOT-3Dplan的一致性得到改善。
在我们患有正常主动脉瓣的小样本患者中，我们发现左心室流出道形状通常不是圆形，而是经常为椭圆形。错误地假设左心室流出道是圆形会低估ALVOT-3Dplan，进而使AVA低估15%。有必要对主动脉瓣狭窄患者的左心室流出道进行研究，以评估RT3DE是否可以改善AVA测量。
