[Mode of hypertrophy in hypertrophic cardiomyopathy based on the external shape of the left ventricle: a two-dimensional echocardiographic study].

To assess the mode of left ventricular hypertrophy in hypertrophic cardiomyopathy (HCM), two-dimensional echocardiography was performed in 15 patients with asymmetric septal hypertrophy and in 13 normal subjects. The long-axis diameter (LxD) was defined as the distance from the midpoint between the anterior annulus of the aortic valve and the posterior annulus of the mitral valve to the apex in the apical long-axis image. In the parasternal long-axis image, the long axis of the left ventricle (LV) was determined by overlaying the parasternal image on the apical image. The external diameter (ExD) and the internal diameter (InD) of the LV at chordal level were measured in the direction of the short axis. The anterior part (-a) and the posterior part (-p) of both ExD and InD, which were divided by the long axis, were also measured. LxD, ExD, ExD-a, ExD-p and InD-p in HCM were greater than those in the normal subjects. Thus, the interventricular septum (IVS) in HCM was thickened inwardly and outwardly. In contrast, the left ventricular posterior wall (PW) in HCM showed only outward deviation. Thickness of the IVS and PW, and the excursion of the PW in HCM were greater than those in the normals, but the excursion of the IVS in HCM was smaller than those in the normals. We concluded that outward expansion of the IVS and PW occurs in HCM and distinct narrowing of the LV occurs only on the septal side in HCM.(ABSTRACT TRUNCATED AT 250 WORDS)