[Tissue Doppler: the physical principles, representational and analytical modalities and clinical applications]

Tissue Doppler imaging or myocardial velocity imaging is a variation of conventional Doppler. This modality allows the quantification of the Doppler shift within the range of myocardial tissue motion. The velocity of motion at a variety of myocardial sites can be determined and distinguished very rapidly using Doppler techniques. The velocity of moving tissue can be studied with pulsed wave tissue Doppler sampling, which displays the velocity of a selected myocardial region against time, with high temporal resolution. In addition, the velocities can be calculated with time velocity maps and displayed as color coded velocity maps in either M-mode or two-dimensional format. This review will focus on the technical aspects and the different methods of tissue Doppler for regional systolic and diastolic left ventricular function analysis. While pulsed wave tissue Doppler allows us to measure the velocities of a selected myocardial region, color tissue Doppler gives the best overall view of cardiac dynamics because the whole scanned color data are displayed simultaneously. However, there is an increasing need for objective evaluation of tissue Doppler information. Digital images and data post-processing allow for quantitative off-line analysis, and the different approaches and parameters proposed from different centers are discussed. In recent years, tissue Doppler imaging has been applied for accurate evaluation of diastolic function, quantifying regional function particularly during stress, pre-excitation syndrome, and left ventricular hypertrophy. The results of these experiences indicate that tissue Doppler imaging is a promising technique for quantifying the response of the myocardium and endocardium during both normal and abnormal function. Again, there is a significant learning curve concerning its application, but with experience it will be a useful and reproducible technique.