Example of longitudinal strain-rate graph (Doppler derived). Longitudinal strain-rate using the region of interest of figure 3. Y-axis represents strain-rate (s-1), X-axis represents time (one cardiac cycle). Note the negative SR during systole when the ε becomes more negative (myocardial shortening) in figure 3 and the positive SR during the upstroke of the strain-curve during the E and A-wave. The SR is zero when no deformation occurs.