Subaortic obstruction by a membrane or systolic anterior motion of the mitral valve leaflets is usually suspected in young patients, especially if the anatomy of the aortic valve is not clearly stenotic and unexplained left ventricular hypertrophy exists in the context of high transaortic gradients. In certain circumstances, some patients show both aortic and subaortic stenotic lesions of variable severity. Doppler echocardiography can help in grading severity in the case of single-level obstruction but not in patients with multilevel obstruction where the continuity equation is of no value. Three-dimensional (3D) echocardiography allows "en-face" visualization of each level of the aortic valve and subaortic tract; in addition, direct planimetry of the areas can be done using multiplanar reformatting. Accordingly, 3D echocardiography plays a crucial role in the assessment in patients with multilevel left ventricular outflow tract obstruction as it can accurately delineate the location and size, and severity of the stenosis.

中文翻译：

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复杂多级左心室流出道梗阻：3D 超声心动图能增加什么？

年轻患者通常怀疑由膜或二尖瓣小叶的收缩期前运动引起的主动脉下阻塞，特别是如果主动脉瓣的解剖结构没有明显狭窄，并且在高经主动脉梯度的情况下存在无法解释的左心室肥大。在某些情况下，一些患者会出现严重程度不同的主动脉和主动脉下狭窄病变。多普勒超声心动图有助于对单节段梗阻的严重程度进行分级，但对于连续性方程没有价值的多节段梗阻患者则无济于事。三维 (3D) 超声心动图可以“正面”显示主动脉瓣和主动脉下束的每个水平；此外，可以使用多平面重新格式化来完成区域的直接平面测量。因此，