Direct ultrasound measurement of longitudinal, circumferential, and radial strain using 2-dimensional strain imaging in normal adults.

Current noninvasive techniques used to evaluate left ventricular systolic function are limited by dependence on the angle of insonation (tissue Doppler imaging/TDI) or limited by availability (MRI tagging). We utilized 2-dimensional speckle strain (epsilon) imaging (1) to establish normal values for all three epsilon vectors; (2) to compare circumferential epsilon values with circumferential shortening (midwall fractional shortening (FS(mw)); (3) to examine the relationship between left ventricular epsilon and wall stress; and (4) to compare 2D echocardiographic characteristics by gender. Echocardiography was performed in 60 normal subjects (mean 39 +/- 15 years). Small, but significant regional heterogeneity was seen in circumferential epsilon, but not in radial or longitudinal epsilon. We found an inverse correlation between circumferential epsilon and stress (r =-0.29, p<0.05) as well as longitudinal epsilon and stress (r =-0.11, P < 0.05), though the relationships were not close. We also observed a linear relationship between mean circumferential epsilon and FS(mw) (r = 0.29, P < 0.05). In conclusion, (1) 2-dimensional epsilon imaging permits measurement of regional systolic epsilon values in the majority of normal individuals; (2) epsilon values furnished by this method obey expected stress-shortening relationships; (3) systolic epsilon displays minor regional heterogeneity in the circumferential direction; (4) for the first time, a close relationship between FS(mw) and mean circumferential epsilon was demonstrated; and (5) there are minor gender-related differences in LV geometry and function.