Abstract 16143: Left Ventricular Rotational Mechanics Before and After Exercise in Normal Children
Introduction: Helical arrangement of left ventricular (LV) myofibers results in twisting motion of LV, which can be measured by speckle-tracking imaging. Moreover, by plotting twist vs radial displacement, a characteristic loop (T-D loop) is inscribed, with a linear systolic limb. Slope of this limb may serve as an index of systolic function. Little is known about LV rotational mechanics in children at rest and after exercise.
Hypothesis: We hypothesized that LV twist, untwist along with slope and area enclosed by T-D loops will increase after exercise in normal children.
Methods: Twenty patients (age:12-18 years) with normal hearts were imaged at rest and after moderate exercise, performed by repeated leg-raising in supine position. LV rotation, twist (T),radial displacement (D) and T-D loop were evaluated at rest and after exercise. LV torsion, recoil and untwist were also calculated.
Results: View Table 1. Fig.1 shows twist curve obtained from apical and basal rotations. Fig. 2 shows T-D loops at rest and exercise. They have “figure-of-8” appearances, with linear systolic limbs. Slope of systolic limb increases after exercise.
Conclusions: In normal children apical rotation, systolic twist and diastolic untwist increase significantly after exercise, except for peak basal rotation. This may be because basal rotation undergoes maturational change from infancy to adult pattern. T-D loop becomes “plumper” and its systolic limb remains very linear, while its slope increases significantly after exercise. This is the first study to describe LV rotational mechanics in children before and after exercise. It may serve as a foundation for studying disease states in children in future.
- © 2012 by American Heart Association, Inc.