Objectives: Measuring strain in multiple myocardial layers using 2-dimensional tissue Doppler imaging may provide valuable diagnostic information about non-transmural disease. However, its feasibility in humans has not been demonstrated previously, and optimal machine settings not defined.
Design: From parasternal short axis, zoomed tissue Doppler imaging of the left ventricular inferior wall was obtained in 23 young, healthy humans. Images were recorded with six different machine settings. Velocity, strain rate and strain were measured in two and three layers across the wall.
Result: For two-layer-measurements, all subendocardial values were significantly higher than the subepicardial ones (p<0.003 for all data sets). Minimal radial and maximal lateral averaging resulted in largest strain differences: 106.4+/-32.6% (mean+/-SD) subendocardially versus 54.2+/-20.1% subepicardially. By similar settings in three layers, strain was 105.7+/-34.5% subendocardially, 81.2+/-26.9% midmyocardially and 48.3+/-26.9% subepicardially (p <0.05).
Conclusion: We have demonstrated that it is feasible to measure radial velocity, strain rate and strain in up to three individual layers in young healthy humans, and the diagnostic potentials should be tested on patient groups.