Abstract 19072: Left Ventricular Apical Rotation, but not Basal Rotation Enhanced during Exercise in Normal Subjects. -Evaluation by a Automated Three-Dimensional-Wall Motion Tracking Technique-
Background: A newly developed three-dimensional-wall motion tracking (3D-T) system enabled us to evaluate left ventricular(LV) rotation and twist without through-plane phenomenon. Although the enhancement of LV twist contribute to the augmentation of LV contractility during exercise, the behavior of regional rotation were unknown.
Methods: Three-dimensional volume data sets were acquired from apex (Artida, Toshiba Medical Systems) in 18 healthy subjects at rest and during supine bicycle exercise (25W x 5min and 50W x 5min). Thirty-five short axis (SAX) planes which were parallel to basal SAX plane and 36 tracking points at 10 degree intervals around each SAX were defined in the endocardium. Total 1261 points (35 planes with 36 points per plane plus the apex) were tracked during a cardiac cycle, and then, LV was divided 16 segments (4-apical, 6-mid, 6-basal). The rotational angle in each segment was obtained and averaged in each apical, mid, and basal segment. LV twist was defined as a difference between the apical and basal rotation. LV ejection fraction (EF) was evaluated by 3D volume data.
Results: LVEF significantly increased during exercise (63+5 vs 68+7.5%, p<0.01). LV twist enhanced during exercise (11.1± 4.2 vs 14.9 ±5.0, p<0.01). Apical rotation significantly increased, in contrast, basal rotation unchanged before and during exercise (Figure).
Conclusion: The 3D-T revealed that increase in the apical rotation represented the dominant contribution to the augmentation of LV contractility during exercise in healthy subjects.
- © 2010 by American Heart Association, Inc.