Myocardial strain of the left ventricle in normal children

Abstract

Background: There have been few reports regarding cardiac strain in children. The present study was performed to determine the reference values for circumferential and radial strains of the left ventricle in normal children and discern the relative influence of aging and cardiac growth on these left ventricular functional indices.

Methods: The study population consisted of 180 children (aged 2 months to 21 years) who had normal cardiac function and normal cardiac load. None of the patients had symptoms, and none was receiving medical therapy. 2D cine-loop recordings of short-axis views at the papillary muscle level were stored for off-line analysis. Custom acoustic-tracking software was used to measure left ventricular strain. Continuous variables are reported as mean values ± standard deviation. The correlation coefficients were calculated to identify the relative influences of aging on the strains. Tukey's test was used to assess differences in strain among the six-myocardial segments. In all analyses, p<0.01 was taken to indicate statistical significance.

Results and conclusions: The strains of all segments could be analyzed in 136 of 180 children. There were no significant age-related changes in circumferential or radial strain in children, but regional heterogeneity in left ventricular strain. The circumferential and radial strains showed inverse distributions; the circumferential strain in the region with low radial strain was high, and that in the region with high radial strain was low. These observations indicated there are differences among the three-dimensional movements of the regions.