Impact of Sex and Obesity on Echocardiographic Parameters in Children and Adolescents

Abstract

Subclinical alterations in left ventricular structure and function are detectable in adolescents with hypertension or obesity. However, data on early echocardiographic abnormalities in seemingly healthy children are lacking. Sex differences in cardiac structure and function have been previously reported, but sex-specific reference values are not available. Specifically, the potential interaction of sex and overweight has not been addressed at all. Anthropometric data, blood pressure and exercise tests were obtained in 356 healthy children. Echocardiographic parameters comprised peak early (E) and late (A) mitral inflow Doppler velocities, E/A ratio, tissue Doppler peak velocities of early (e') and late diastolic (a') excursion of mitral/septal annulus and isovolumetric relaxation time (IVRT). Left ventricular mass index (LVMI) and LVMI z-score were calculated. Interaction terms between BMI and sex and stratification by sex were used for analysis. We provide values for echocardiographic parameters for children of two age groups separated by BMI. Overweight/obese children had a significant higher LVMI, lower E/A ratio, higher E/e' ratios and a longer IVRT. For a given BMI in the upper ranges we demonstrated a higher LVMI in girls than in boys, the IVRT extended significantly more in girls than in boys with increasing BMI. There are sex differences in structural and functional echocardiographic parameters in children and adolescents. Our data not only confirms the importance of overweight and obesity, but demonstrates important interactions between sex and overweight. The greater susceptibility of overweight girls toward echocardiographic changes associated with potential long-term functional impairment needs further exploration and follow-up.Trial registration number DRKS00012371; Date 18.08.2017.

Keywords: Children; Echocardiography; Obesity; Reference values; Sex differences.

Fig. 1

Echocardiographic parameters in conjunction with increasing BMIz. a Higher BMIz was associated with higher left ventricular mass/height ^2.16. 7.22% of the overweight and obese children, but only 0.81% of those with BMIz < 1.04 had left ventricular hypertrophy (p < 0.001). The dotted line delineates 45 g/m^2.16 as the upper normal limit for LVMI. b Using the current reference values from Eidem et al., 19.6% of the overweight or obese, but only 5.6% of the children with a BMIz < 1.04 had a mitral valve E/A ratio below the lower limit. c Using the current reference values from Eidem et al., 34.3% of the overweight or obese, but only 18% of the children with a BMIz < 1.04 had a septal annular E/e′ ratio above the upper limit. d Using the current reference values from Eidem et al., 3.9% of the overweight or obese, but only 2.8% of the children with a BMIz < 1.04 had an isovolumetric relaxation time (IVRT) above the upper limit. BMIz body mass index z-score, E peak early diastolic inflow Doppler velocity, e early diastolic annular myocardial velocity, IVRT isovolumetric relaxation time, LVMI left ventricular mass index, TDI tissue Doppler imaging

Fig. 2

Left ventricular mass index (LVMI) and left ventricular mass index z-score (LVMIz) stratified according to children’s BMI z-score (BMIz). a Non-overweight children (BMIz < 1.04) had a significant lower LVMI than children overweight/obese (BMIz ≥ 1.04). b Children with BMIz < 1.04 had a significant lower LVMIz than children with a BMIz ≥ 1.04. BMI body mass index, BMIz body mass index z-score, LVMI left ventricular mass index, LVMIz left ventricular mass index z-score

Fig. 3

Left ventricular mass demonstrated for boys and girls separated according to children’s BMIz. a Significant difference in LVMI between boys and girls with a BMIz < 1.04. b The difference of LVMI between boys and girls was no longer found in children with a BMIz ≥ 1.04. c There is a sex-specific difference between the slopes for LVMI with increasing BMIz. BMIz body mass index z-score, LVMI left ventricular mass index

Fig. 4

a Sex-specific difference between the slopes for a isovolumetric relaxation time (IVRT) with increasing BMIz and b for diastolic pulmonary venous flow (PV d-wave) with increasing BMIz. BMIz body mass index z-score, IVRT isovolumetric relaxation time, PVd pulmonary venous flow velocity diastolic