The Left Ventricle

Abstract

The left ventricle forms the apex and the lower part of the left heart border. It is shaped like a cone (ellipsoid of revolution) with its long axis directed from the apex to the base. Real-time 3D TEE may depict the internal configuration of the ventricle by properly cutting the left ventricle through longitudinal planes. Sections parallel to the ventricular long axis reveal the ellipsoid geometry (Fig. 9.1), while short axis cross-sections, perpendicular to long axis, reveal a roughly circular geometry (Fig. 9.2). The endocardial surface is irregular compared to the epicardial surface owing to the presence of two groups of papillary muscles and trabeculations. Papillary muscles are left ventricular muscular protuberances that anchor the valvular chords to the left ventricular wall. The two groups are located beneath the commissures, occupying antero-lateral and postero-medial positions (Fig. 9.3). Papillary muscles are conceptualized as being directly continuous with the solid portion of the heart wall, the compact myocardium. But tomographic imaging has consistently shown that the bases of the papillary muscles are not solid. Instead, they are composed of muscular continuations from the trabeculations that line the ventricular cavity (Fig. 9.4).