Tissue Doppler Techniques:
Tissue Doppler uses essentially the same methodology as standard Doppler which looks at blood flow, except that rather than measuring the high velocity low signal traces from the blood pool it measures low velocity high signal traces from the myocardium. At present the techniques are a research tool, but awareness of normative data in the newborn population is increasing.
Basic tissue Doppler measures calculate the simple velocity of myocardial motion.
However by measuring velocity at two adjacent points in the myocardium the relative velocity between the two can be used to assess strain rate (rate of shortening) in a portion of the myocardium. By integrating strain rate against time the % strain can also be calculated.
These techniques are sensitive to image quality, artefact and angle of insonation, but they provide significant scope for the future.