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Figure 1 Temporal Sequences of LV Twist During a Cardiac Cycle

The left ventricular (LV) rotation from apical and basal cross-sections of LV has been obtained by speckle tracking of B-mode cardiac ultrasound images (GE Healthcare, Milwaukee, Wisconsin) in a normal healthy subject. The difference between the 2 rotations provides an estimate of net LV twist angle (black line). During isovolumic contraction (phase 1), the apex shows a brief clockwise rotation and the base shows a brief counterclockwise rotation. During ejection (phase 2), the direction of rotation changes to counterclockwise at the LV apex and clockwise at the LV base, respectively. Torsional recoil occurs predominantly during the phase of isovolumic relaxation (phase 3) and early diastolic filling (phase 4).