Tissue Doppler echocardiography: principles and applications.

Tissue velocity imaging is an important development in the field of cardiac ultrasound that provides quantitative information for analysis of myocardial motion independent of the quality of gray-scale 2-D echocardiography data. It holds promise to reduce inter- and intraobserver variability in regional wall motion interpretation and is likely to improve the accuracy and reproducibility of stress echocardiography and myocardial viability assessment. It also enables regional diastolic function assessment independent of the loading conditions and offers a practical clinical tool to differentiate pathologic from physiologic myocardial hypertrophy, restrictive cardiomyopathy from constrictive pericarditis and for monitoring and selecting therapies in patients with advanced heart failure. The use of tissue velocity data for myocardial strain and strain rate imaging is likely to circumvent the limitations of tissue velocity in differentiating active and passive motion of a myocardial segment. However, its incremental utility and exact role in improving the diagnostic yield and clinical outcome needs to be addressed in future studies.