Strain rate imaging from a normal subject. Top, still frames from systole showing yellow to red colours of negative strain rate (shortening), and early diastole showing blue to cyan colours of positive strain rate (lengthening). Periods of no strain are shown in green. The colour legend is reproduced to the left. A curved M-mode is placed in the septum. Below is shown the resulting M-mode from the same cine-loop of one heart cycle. The numbers to the left refers to the numbers on the 2D images, and are for orientation only. Systole (S) starts more or less simultaneous in all levels of the ventricle, while early filling (E) and atrial systole (A) can be seen as waves of stretching propagating from the base to the apex. The principle of propagation velocity measurement as the slope of ΔL/Δt is shown The ECG is shown at the bottom for reference.