Under normal conditions, the center of mass in the heart is in the LV, and the ventricular septum maintains its concave curvature towards the LV throughout the cardiac cycle. As such, the LV maintains its circular shape in the transgastric midpapillary view. However, as the RV hypertrophies, the center of mass shifts rightward, towards the septum itself (Figure 13–12). The septum begins to flatten, and the LV thus begins to assume a D shape. Furthermore, this septal deformation results in the loss of the normal triangular or crescent shape of the RV in the transgastric view and the RV assumes a more spherical shape. Indeed, from the transgastric, midpapillary view, the two ventricles may begin to appear as two similar cavities with a flat wall dividing them. However, because the deformity in septal configuration is due to elevations in pressure within the ventricular cavities, this flattening is greatest when the intracavitary pressures are greatest, that is, at end-systole.12–14