Cross-Sectional Echocardiographic Localization of the Sites of Left Ventricular Outflow Tract Obstruction (LVOTO)
Real-time, motion studies of sagittal crosssectional anatomy were obtained by the multicrystal echo method (Bom) in 37 consecutive patients with LVOTO prior to their hemodynamic study. In each patient the echo findings allowed the prediction of the site of obstruction. Thus, in valve aortic stenosis (VAS) diagnostic findings included dilation of the ascending aorta, thickened cusp tissue, increased superior-inferior cusp excursion with poor lateral mobility (doming). The site of supravalvar aortic narrowing was observed readily although the echo findings often underestimated the degree of obstruction noted at catheterization. In patients with discrete subaortic stenosis (DSAS) the major finding was a localized thickening of the septum at its insertion into the anterior aortic wall. The combination of DSAS and VAS could be identified as well as mitral valve abnormalities associated with LVOTO. Asymmetric septal hypertrophy and mitral leaflet systolic anterior motion were noted in all patients with IHSS. Thus, this new echo approach allows the accurate localization of the site of LVOTO and the detection of associated malformations. The method has substantial merit as an initial test to establish diagnosis and allows more appropriate planning of subsequent hemodynamic study.