Figure 2.

Principle of the calculation of apical traction. (A) To estimate the traction of the apex (AT_4CV) perpendicular to the longitudinal axis of the heart, two local displacement curves (dx_L, dx_R) (B) are obtained from both sides of the apex, e.g. by means of speckle tracking. (C) Then, the left-sided displacement curve (dx_L) is inverted, which allows averaging. (D) Apical traction is then measured as displacement of the apex (dx_averaged) during systole, i.e. between mitral valve closure (MVC) and aortic valve closure (AVC).