Calculation of the myocardial velocity gradient

The peak negative myocardial velocity gradient (MVG) is obtained from tissue Doppler imaging (TDI). The endocardial and epicardial boundaries of the left ventricular (LV) posterior wall are manually traced from an M-mode image, and the velocity between the two lines is extracted from the corresponding color-coded image (left panel). At each point in time, indicated by the vertical line in early diastole, the velocity profile across the myocardial wall is obtained and provided for the least squares linear regression analysis (right panel). The slope of the regression line was determined as the instantaneous MVG; the MVG calculations are repeated at each point in time throughout the cardiac cycle, and peak negative MVG is determined.