Figure 1 Schematic illustration of how strain rate within a tissue segment (r) is estimated from the tissue velocity (). The dashed line indicates orientation of the ultrasound beam. The distance along the beam is denoted r. The strain rate is calculated by subtracting (r + r) from (r) over the distance (r) between these two points. Size of r is exaggerated for clarity. l= a given length; l = instantaneous change in length.
Figure 2 Representative strain (upper), strain rate (middle) and tissue velocity (lower) profiles obtained from identical sample point in the longitudinal axis before coronary angioplasty. All measurements were done from the same heartbeat.
Figure 3 Strain profiles from different segments in the same heartbeat during left anterior descending coronary artery (LAD) occlusion. The profile from basal septum (solid line) showing compression (normal deformation) and from the ischemic apical septum (dashed line) showing expansion (paradoxical motion).