LV outflow tract area in discrete subaortic stenosis and hypertrophic obstructive cardiomyopathy: a real-time 3-dimensional transesophageal echocardiography study.

PRECISE ANATOMICAL ANALYSIS OF STENOTIC LESIONS OF THE LEFT VENTRICULAR outflow tract (LVOT) in discrete subaortic membranous stenosis (DSS) and hypertrophic obstructive cardiomyopathy (HOCM) is challenging due to their complex nature (1,2). In the present study, we clarified the difference of the geometry and dynamic change of LVOT area using en face views of the LVOT in 6 patients with DSS and 6 patients with HOCM by real-time 3-dimensional transesophageal echocardiography. There was a conspicuous difference in LVOT velocity (Fig. 1) and geometry between DSS and HOCM: the LVOT shape was almost oval or flat in DSS, whereas there was a V shape or 2 separate open spaces in HOCM (Figs. 2 and 3, Online Videos 1 and 2). The magnitude of area change of the LVOT was less in DSS than in HOCM. The LVOT area was minimal in late systole in both DSS and HOCM in spite of the presence of an early peak in LVOT flow velocities in DSS versus a late peak in HOCM (Fig. 4).