Assessment of regional right ventricular velocities, strain, and displacement in normal children using velocity vector imaging

Background: Velocity vector imaging (VVI) is a novel technique to assess regional myocardial mechanics. We evaluated the utility of VVI in the assessment of right ventricular (RV) function in normal children. Methods: RV images (apical 4-chamber view, high frame rate capture) from 30 normal children (mean 8.7 years; range 1.1-18) were selected. Longitudinal myocardial velocities, peak systolic strain (PSS), maximal longitudinal displacement (LD), and times to peak for these parameters were obtained from six RV segments. Simultaneous Doppler tissue imaging (DTI) derived peak systolic and early diastolic velocities were obtained from the free tricuspid annulus. Measurements were made independently by two observers. Results: Qualitative analysis shows dominant longitudinal systolic and diastolic myocardial motion, particularly at the basal segments. Velocities and LD were greatest at the basal segments and decreased from base to apex. PSS values were less consistent between segments and observers, with the greatest PSS generally found in the apical segments. LD and time to peak displacement (TPD) were the most reproducible. TPD in the basal segments were strikingly similar in each patient and correlated with R-R intervals. Peak diastolic velocities in the right base did correlate with corresponding annular DTI velocities; DTI velocities were consistently higher than VVI velocities. Conclusions: RV segmental velocities and LD are reliably obtained by VVI. PSS is less reproducible. LD is a reproducible measure of systolic function and TPD appears to be useful in the assessment of synchrony. Correlation of these findings with children who have known RV pathology is an important next step.