Myocardial velocity gradient assessed by a tissue Doppler imaging technique

Although tissue Doppler imaging (TDI) is a promising technique for quantitative regional left ventricular wall motion analysis, Doppler angle of incidence and translational motion of the heart influence the velocity measurement by TDI because, in principle, TDI detects the velocity against the transducer. Myocardial velocity gradient (MVG) is derived from TDI as the slope of the regression line for a transmural velocity profile across the myocardial wall, which reflects regional wall thickening and thinning dynamics. Thus, regional diastolic and systolic function may be quantified by using MVG. MVG is also validated to be independent of the translational motion both theoretically and clinically. MVG may therefore be used as an indicator of regional wall motion even under such a condition that the translational motion of the heart cannot be neglected. Our preliminary experience suggests that the quantitative and objective nature of MVG enhances the diagnostic power of stress echocardiography. Further development of the automated, real time processing system and the algorithm for the apical approaches should be awaited for the practical approaches of MVG to be applied to daily clinical practice.