Abstract 2336: The Impact Of Age On The Measurement Of Left Ventricular Torsion, Radial And Circumferential Strain And Strain Rate By Two-dimensional Echocardiographic Speckle Tracking
Background: Left ventricular (LV) torsion (LVtor) and strain (S) are important components of LV performance. However, there is a little information on the affect of age on these measurements.
Methods: 106 normal subjects (59 children, 55 adults, aged 0 to 41 years, (divided into 5 groups by age) mean 19.3 years) had LV rotation (LVrot) and LVrot velocity, circumferential (cirS) and radial (radS) strain and strain rate (SR) measured by speckle tracking imaging (STI) with customized software. Angular displacement of the LV in each slice was defined as LVrot and the difference between apical and basal LV slices as torsion (LVtor). Counter-clockwise rotation at the apex was defined as positive.
Changes during systole: Although LVtor increased with age due to augmentation of the apical LVrot (P<0.01), this disappeared when normalized by LV length: Normalized LVtor velocity increased due to augmentation of apical rotation (p<0.05). A unique positive LVrot and LVrot velocity during early systole at the base were larger in younger controls (p<0.005) and more pronounced when normalized by length (p<0.0005).
Changes during diastole: Maximum untwisting velocity was seen in the adolescent group (p<0.001) and disappeared when normalized by length. The recoiling velocity of the apical slice was larger (p<0.05) and occurred earlier (p<0.005) in younger controls. The maximum amount of untwisting and recoiling of the apical slice and circumferential lengthening during early diastole were seen in the pre-adolescent group and decreased with age (p<0.005).
Strain and strain rate: At the base cirS was larger in the younger group (p<0.005). At both the basal and apical slices in systole and diastole, peak cirSR were larger in the younger group (p<0.005)
Timing of peak values: Peak values occurred in late systole and early diastole, in the order from apical LVrot, LVtor, apical cirS, basal LVrot, basal cirS, apical radS, basal radS (p<0.0001). This order was preserved in all age groups.
Conclusion: The heart maintains a constant LVtor and LVrot profile when normalized by length and cardiac cycle. Younger hearts tend to twist, untwist, contract and lengthen faster than in our older controls. These novel profiles provide new insight into the LV systolic and diastolic function.