Fig. 1

The method used to measure interventricular septal curvature. (a, d) Short-axis images of the heart at the level of left ventricular papillary muscles were acquired at end systole. (b, e) Three different points at the posterior (a: Xa, Ya), middle (b: Xb, Yb), and anterior (c: Xc, Yc) positions on the endocardial surface of the interventricular septum were marked. The X and Y coordinates were read. A circle that passed through the three points on the septum (circle shown partially) was used to calculate radius of curvature of the septum. (c) A rightward (physiologic) curvature was denoted as a positive value and (f) a leftward curvature as a negative value