The Doppler modes were originally only used for characterizing the speed of blood flow. But lately they have been used to find the speed of tissue as well. In the later years, an imaging method has been developped that switches the roles of what is desired and not desired, and shows the speed of the strong tissue signal. This method (Tissue Velocity Imaging) can show the movements of the walls of the heart better than the B-mode image. 
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In a dynamically changing muscle such as the heart, there is valuable information to be found in the elasticity and rate of elasticity in the tissue as it says something about deformation, not only movement. Deformation says something about whether the heart muscle as a whole works actively or if parts of it are inactive due to infarction.