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Changes of left ventricular isovolumic relaxation time with growth in children
Y Hayashi1, K Watanabe, K Kishida
1Department of Pediatrics, Shimane Medical University, Japan.
Insights
Left ventricular isovolumic relaxation time (LVIRT) prolongs with growth in children. Diastolic blood pressure and body weight significantly influence this cardiac function development, which also relates to sexual maturation in adolescents.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
- Developmental Biology
Background:
- Left ventricular isovolumic relaxation time (LVIRT) is a key indicator of diastolic function.
- Understanding LVIRT changes during childhood is crucial for assessing cardiac development.
- Previous studies have not fully elucidated the longitudinal changes and influencing factors of LVIRT in healthy children.
Purpose of the Study:
- To investigate the changes in left ventricular isovolumic relaxation time (LVIRT) throughout childhood.
- To identify factors influencing LVIRT, such as body size and blood pressure, during growth.
- To examine the relationship between LVIRT and sexual maturation in adolescents.
Main Methods:
- A 10-year follow-up study involving 187 healthy children (aged 6-15 years).
- Serial measurements of body height, body weight, lean body weight, heart rate, blood pressure, left ventricular muscle volume index (LVMVI), and LVIRT corrected by the R-R interval (IRT/R-R).
- Statistical analysis to determine correlations between IRT/R-R and various physiological parameters.
Main Results:
- IRT/R-R showed a consistent prolongation with growth in both boys and girls.
- Girls exhibited longer IRT/R-R than boys at ages 12 and 15.
- Significant positive correlations were found between IRT/R-R and diastolic blood pressure (0.31), body weight (0.28), and LVMVI (0.28).
Conclusions:
- Left ventricular diastolic function, as indicated by IRT/R-R, develops with increasing body size, particularly body weight.
- Diastolic blood pressure is a primary determinant of IRT/R-R in children.
- Early diastolic function in adolescents is associated with sexual maturation, highlighting its role in cardiac adaptation during puberty.
Abstract:
We investigated the changes of left ventricular isovolumic relaxation time (LVIRT) with growth and the factors influencing them during childhood, in a 10-year follow-up study. We measured the body height (BH), body weight (BW), lean body weight (LBW), heart rate (HR), blood pressure (BP), left ventricular muscle volume index (LVMVI), and LVIRT corrected by the preceding R-R interval (IRT/R-R), of 187 healthy children at 3-year intervals (6, 9, 12, 15 years old). IRT/R-R were prolonged with growth in boys and girls. At the ages of 12 and 15, the IRT/R-R of girls were longer than those of boys. Significant correlation coefficients for IRT/R-R on systolic and diastolic, BW, and LVMVI were 0.28, 0.31, 0.20, 0.28, respectively. These data suggest that (1) IRT/R-R is mainly determined by the diastolic BP, (2) left ventricular diastolic function of children develops with growth of body size, especially BW, and (3) left ventricular early diastolic function in adolescents is related to sexual maturation.