The Doppler modes were originally only used for characterizing blood flow velocity. Now they are for estimating the velocity of the tissue as well. In this mode, the roles of what is desired and not desired are reversed compared to traditional Doppler, and the velocity of the strong tissue signal is shown. 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 strain and strain rate 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.