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Figure 6 Velocity Vector Imaging

The upper panels display radial and rotational mechanics of the left ventricle (LV) by Velocity Vector Imaging (VVI). (A) Depiction of radial velocity vectors (yellow arrows) in end-systole with the direction of the arrows pointing to a counter-clockwise rotation of the apex. Velocities that are orthogonal to these radial velocities are rotational velocities (red arrows). These velocities are automatically calculated at each location of the arrows around the LV circumference. (B and C) Depiction of visual representation of the rotational motion at the base (B) of the LV and at the apex (C). The lower panels show the magnitude of the rotational motion at the apex and base (degrees of rotation). The apical rotation in this example is –7°, the minus sign depicting counterclockwise rotation. The basal rotation in the clockwise direction is 4°. Thus, the LV twist is 11°, and LV torsion is derived by dividing LV twist by the distance between the base and the apex in centimeters.