Quantitative assessment of myocardial acceleration in normal left ventricle with velocity vector imaging

Application of two-dimensional myocardial acceleration map derived from tissue Doppler imaging is limited by inherent angle dependency and substantial reader variability in the visualization of the origin of ventricular activation site. In this study we investigated the characteristics of myocardial acceleration in normal left ventricular (LV) walls with velocity vector imaging (VVI).

VVI was applied to the parasternal short-axis two-dimensional echocardiographic images at basal, mid, and apical levels of the LV in 30 normal volunteers. Peak acceleration during early systole (ACC(s)) and time to ACC(s) (TACC(s)) were calculated for each segment of the standard 16-segment model.

The time point of onset of active myocardial contraction corresponding to the QRS complex could not be determined in 409 (85.21%) of all 480 segments. No significant differences were found in TACC(s) among different LV levels and walls. In LV-free walls, there were no significant differences in ACC(s) among different LV levels and walls.

The time point of onset of myocardial active contraction during early systole cannot be determined in most of normal myocardial segments. Also, there is homogeneity of the time to early systolic peak acceleration in the whole normal LV walls. Myocardial acceleration seems to have limited potential in the assessments of the site of initial electrical stimulation and the sequence of ventricular depolarization.