Left Atrial Volumes and Strain in Healthy Children Measured by Three-Dimensional Echocardiography: Normal Values and Maturational Changes.

BACKGROUND: Assessment of left atrial (LA) size and function is important in a number of pediatric cardiac conditions including those affecting the diastolic performance of the left ventricle. Measurements of LA volume and strain by two-dimensional echocardiography rely upon inaccurate geometric assumptions and are hampered by out-of-plane motion. The objective of this study was to characterize LA volumes and strain by three-dimensional echocardiography in healthy children.

METHODS: LA volumes and strain were retrospectively measured by three-dimensional echocardiography in healthy children with no known structural or functional heart disease using a commercial speckle-tracking package applied to the LA to compute maximum volume (Vmax ), minimum volume (Vmin ), ejection volume (LAEV), ejection fraction (LAEF), and the following components of global strain: 3D principal (3DS), longitudinal (GLS), and circumferential (GCS).

RESULTS: The study population included 196 normal subjects (median age, 12 years; range, 4 days to 20.9 years). Vmax , Vmin , and LAEV increased with age and body surface area. Significant age-related declines were present in all measured functional indices including LAEF, 3DS, GLS, and GCS. Analysis of a subset of 50 subjects showed excellent agreement between Vmax derived by three-dimensional and two-dimensional biplane area-length method. Regression equations with standard deviations were generated to enable calculation of Z scores.

CONCLUSIONS: LA volume and functional indices can be reliably calculated using a commercial three-dimensional analysis software. All components of LA strain decline modestly with age. Normative data generated in this study have the potential to greatly enhance the utility of three-dimensional echocardiography-derived measurements in a wide range of cardiac pathologies.