(A) A single long-axis view of the heart shows labeling for the left ventricle (LV), left ventricular outflow tract (LVOT), anterior (AML) and posterior (PML) mitral leaflets, left atrium (LA), aortic valve (AoV) and the aorta (Ao). Anterior (AA) and posterior (PA) annular points have been marked. Note that in this orientation, the negative z-axis (for purposes or annular height calculations) extends towards the apex, and the positive z-axis extends towards the left atrium. (B) All mitral annular data points are shown. The anterior commissure (AC), posterior commissure (PC), aorta (Ao), and right atrium (RA) are labeled in this view. (MVO = mitral valve orifice.) (C) As illustrated in this view, in each of the septolateral measurement planes, between 5 and 40 individual points (depending on the septolateral diameter of the MV at the position of a given measurement plane) on the atrial surface of the MV are manually marked. The position of each point is recorded as anterior mitral leaflet (AML), coaptation point (CP), or posterior mitral leaflet (PML).