Normal Values and Growth-Related Changes of Left Ventricular Volumes, Stress, and Strain in Healthy Children Measured by 3-Dimensional Echocardiography.

Normal pediatric values of three-dimensional (3D) left ventricular (LV) volumes and strain are not well established; moreover, no reports exist of the stress-strain relation and the heart rate-corrected velocity of circumferential fiber shortening (VCFc) based upon 3D imaging in children. Three-dimensional LV datasets were obtained in pediatric patients (≤18 years of age) with structurally normal hearts. Ventricular volumes and strain components (longitudinal, GLS; circumferential, GCS; and 3D strain, 3DS) were analyzed using a commercial 3D speckle-tracking analysis package. LV mid-wall global average end-systolic fiber stress was calculated from 3D LV volumes. A total of 238 patients were included in the analysis with a median age of 13.1 years (range 0.4 to 17.9 years). Regression equations were derived for 3D volume parameters, permitting body surface area-based Z score calculation. Overall, 3DS values were more negative than GLS and GCS (mean ± SD = -33.8 ± 2.8; -27.8 ± 2.9; and -21.7 ± 3.1, respectively); only GLS varied significantly with age (r = 0.22; p <0.001). Both global average end-systolic fiber stress and 3D VCFc increased significantly with age (p <0.001 for both). Stress-adjusted 3DS and VCFc both varied with age (p <0.001 for both), consistent with increased contractility. In conclusion, 3D echocardiography may be used to calculate LV stress, strain, and volumes in pediatric patients with strong reproducibility. Among strain parameters, significant age-related changes were seen only in GLS. Both indexes of contractility investigated (3DS and VCFc indexed to wall stress) improved with age. Future studies of the 3D echocardiography stress-strain relation may yield new insights into maturational changes in myocardial contractility.