Effect of aging on twist-displacement loop by 2-dimensional speckle tracking imaging

Background: Newly developed 2-dimensional (2D) speckle tracking imaging provides simultaneous information on both cardiac rotation and radial displacement throughout the cardiac cycle, thus, providing the opportunity to noninvasively construct twist-displacement loops. The aim of this study was to examine the effect of aging on twist-displacement loops. Methods: Basal and apical 2D left ventricular (LV) short-axis images with high frame rates were acquired in' 59 asymptomatic healthy volunteers. Using commercially available software, LV rotation and radial displacement were obtained at each plane by 2D speckle tracking analysis. LV twist was defined as apical LV rotation relative to the base. To adjust intersubject differences in heart rate, the time sequence was normalized to the percentage of systolic and diastolic duration. Volunteers were divided into 3 groups according to age. Results: Twist-displacement loops were characterized by a figure of 8 configuration. There was a linear relation between twist and displacement during systole (r = 0.97), with its slope being significantly larger in the older group compared with the young group. During early diastole, a substantial degree of untwisting developed despite a relatively small reversal of systolic radial displacement, resulting in a much steeper twist-displacement relationship observed in all groups. Subsequent diastolic expansion occurred with more gradual additional untwisting. Conclusion: We found that 2D speckle tracking imaging successfully provides twist-displacement loop, noninvasively. Aging affects the systolic component of the twist-displacement loop. The assessment of twist-displacement loop may be useful for evaluating LV function.