Growth of Cardiovascular Structures from the Fetus to the Young Adult

Accumulating Sedentary Time and Physical Activity From Childhood to Adolescence and Cardiac Function in Adolescence

BACKGROUND

Increased physical activity (PA) may mitigate the negative cardiovascular health effects of sedentary behavior in adolescents. However, the relationship of PA and sedentary time from childhood with cardiac function in adolescence remains underexplored. Therefore, we investigated the associations of cumulative sedentary time and PA from childhood to adolescence with cardiac function in adolescence.

METHODS AND RESULTS

Participants were 153 adolescents (69 girls) who were aged 6 to 8 years at baseline, 8 to 10 years at 2-year follow-up, and 15 to 17 years at 8-year follow-up. Cumulative sedentary time and PA exposure between baseline and 2-year follow-up and between baseline and 8-year follow-up were measured using a combined accelerometer and heart rate monitor. Cardiac function was assessed using impedance cardiography at 8-year follow-up. The data were analyzed using linear regression analyses adjusted for age and sex. Cumulative moderate to vigorous PA (standardized regression coefficient [β]=-0.323 [95% CI, -0.527 to -0.119]) and vigorous PA (β=-0.295 [95% CI, -0.508 to -0.083]) from baseline to 8-year follow-up were inversely associated with cardiac work at 8-year follow-up. Conversely, cumulative sedentary time had a positive association (β=0.245 [95% CI, 0.092-0.398]). Cumulative vigorous PA from baseline to 8-year follow-up was inversely associated with cardiac work index at 8-year follow-up (β=-0.218 [95% CI, -0.436 to 0.000]).

CONCLUSIONS

Higher levels of sedentary time and lower levels of PA during childhood were associated with higher cardiac work in adolescence, highlighting the importance of increasing PA and reducing sedentary time from childhood.

Effects of 6-month customized home-based exercise on motor development, bone strength, and parental stress in children with simple congenital heart disease: a single-blinded randomized clinical trial

BACKGROUND

New "noncardiac" problems in children with congenital heart disease (CHD), such as developmental delay or long-term neurodevelopmental impairments, have attracted considerable attention in recent years. It is hypothesized that exercise might attenuate CHD-associated neurodevelopmental impairments; however, this has not been thoroughly investigated. The objective of this prospective, single-blinded, randomized controlled experiment was to evaluate the impact of customized home-based exercise for children with CHD.

METHODS

Children aged 0-5 years with echocardiography-confirmed simple CHD subtypes who were scheduled to undergo cardiac catheterization were screened for enrolment. Among 420 screened CHD children, 192 were enrolled and randomly assigned at a 1:1 ratio to receive a 6-month intervention (30 min daily customized home-based exercise program with supervision for no less than 5 days per week, combined with home-based exercise education) or control treatment (home-based education). The primary outcome was motor development (gross motor quotient (GMQ), fine motor quotient (FMQ), and total motor quotient (TMQ)). The secondary outcomes were cardiac function and structure, bone quality, physical development, parental anxiety, caregiver burden, and quality of life. Children and their families were assessed before and 1, 3, and 6 months after catheterization; 183 (95.3%) children were included in the primary analysis.

RESULTS

After 6-month treatment, the intervention group significantly increased their motor quotient, which was consistently higher than that of the control group (GMQ p < 0.0001, FMQ p = 0.02, TMQ p < 0.001). The physical developments in height, weight, and circumferences of the upper-arm, chest, and head were also significantly improved by exercise (all p < 0.017). No significant improvements in the bone strength or the cardiac structure and function were found among patients in the intervention group (all p > 0.017). For parents, higher quality of life level (total score p = 0.016) was observed in the intervention group; while effects of exercise on the anxiety (rude score p = 0.159, standard score p = 0.159) or the Zarit caregiver burden scale score (p = 0.404) were non-significant. No adverse events occurred during the study period.

CONCLUSIONS

Customized home-based exercise improved motor development in children with CHD. While the long-term effects of parent training in home-based exercise are unknown, the study results suggest positive outcomes.

TRIAL REGISTRATION

A home-based exercise program in congenital heart disease children with cardiac catheterization: a randomized controlled trial. ( http://www.chictr.org.cn/ , ChiCTR-IOR-16007762, January 14, 2016).

Alternative to body surface area as a solution to correct systematic bias in pediatric echocardiography Z scores

BACKGROUND

Z scores are the method of choice to report dimensions in pediatric echocardiography. Z scores based on body surface area (BSA) have been shown to cause systematic biases in overweight and obese children. Using aortic valve (AoV) diameters as a paradigm, the aims of this study were to assess the magnitude of Z score underestimation in children with increased body mass index Z score (BMI-Z) and to determine if a predicting model with height and weight as independent predictors would minimize this bias.

METHODS

In this multicenter, retrospective, cross-sectional study, 15,006 normal echocardiograms in healthy children 1-18 years old were analyzed. Residual associations with body size were assessed for previously published Z score. BSA-based and alternative prediction models based on height and weight were developed and validated in separate training and validation samples.

RESULTS

Existing BSA-based Z scores incompletely adjusted for weight, BSA and BMI-Z and led to an underestimation of >0.8 Z score units in subjects with higher BMI-Z, compared to lean subjects. BSA-based models led to overestimation of predicted AoV diameters with increasing weight or BMI-Z. Models using height and weight as independent predictors improved adjustment with body size, including in children with higher BMI-Z.

CONCLUSIONS

BSA-based models result in underestimation of Z scores in patients with high BMI-Z. Prediction models using height and weight as independent predictors minimize residual associations with body size and generate well-fitted predicted values that could apply to all children, including those with low or high BMI-Z.

Effect of fat mass index, fat free mass index and body mass index on childhood blood pressure: a cross-sectional study in south China

BACKGROUND

Evidence on how different body composition indexes, such as body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI), influence blood pressure (BP) in Chinese children and adolescents is sparse. The aim of this study is to assess the effect of different body composition on BP in participants aged 7-18 in south China.

METHODS

A cross-sectional study was conducted in 2013. A total of 1,609 children and adolescents from urban and rural areas in Hainan Province, South China, were selected using multi-stage stratified cluster sampling method. Each participant underwent anthropometric and BP tests. BMI, FMI and FFMI were calculated and analyzed as body composition indexes.

RESULTS

In the population level stratified by sex, FFMI had the highest r-value (Partial Spearman correlations) of correlation with systolic BP in boys (r_s=0.305, P<0.001) and girls (r_s=0.237, P<0.001). FMI was found to have the highest r-value of correlation with DBP in boys (r_s=0.154, P<0.001). The quantile regression model indicated that, within each age group, all body composition indexes was positively associated with systolic BP, and FFMI has the greatest value of regression coefficient (4.38, 95% CI: 3.81-4.95). But for diastolic BP, positive associations with BMI, FMI and FFMI were only observed in the 11-12 years group. Restrict cubic spline models showed that there were both linear and non-linear relations between BMI, FMI and BP, but for FFMI, there was only linear association with BP.

CONCLUSIONS

The relation between BP and FFMI was stronger than with BMI and FMI. Combined measurement of body composition should be considered to help health professionals interpret body mass data from children and adolescents with varied stature and age.

Are Body Composition Parameters Better than Conventional Anthropometric Measures in Predicting Pediatric Hypertension?

Body composition (BC) parameters are associated with cardiometabolic diseases in children; however, the importance of BC parameters for predicting pediatric hypertension is inconclusive. This cross-sectional study aimed to compare the difference in predictive values of BC parameters and conventional anthropometric measures for pediatric hypertension in school-aged children. A total of 340 children (177 girls and 163 boys) with a mean age of 8.8 ± 1.7 years and mean body mass index (BMI) z-score of 0.50 ± 1.24 were enrolled (102 hypertensive children and 238 normotensive children). Significantly higher values of anthropometric measures (BMI, BMI z-score, BMI percentile, waist-to-height ratio) and BC parameters (body-fat percentage, muscle weight, fat mass, fat-free mass) were observed among the hypertensive subgroup compared to their normotensive counterparts. A prediction model combining fat mass ≥ 3.65 kg and fat-free mass ≥ 34.65 kg (area under the receiver operating characteristic curve = 0.688; sensitivity = 66.7%; specificity = 89.9%) performed better than BMI alone (area under the receiver operating characteristic curve = 0.649; sensitivity = 55.9%; specificity = 73.9%) in predicting hypertension. In conclusion, BC parameters are better than anthropometric measures in predicting pediatric hypertension. BC measuring is a reasonable approach for risk stratification in pediatric hypertension.

Novel Z Scores to Correct Biases Due to Ventricular Volume Indexing to Body Surface Area in Adolescents and Young Adults

BACKGROUND

Reference values for cardiac magnetic resonance imaging (cMRI) in children and young adults are scarce. This leads to risk stratification of patients with congenital heart diseases being based on volumes indexed to body surface area (BSA). We aimed to produce cMRI Z score equations for ventricular volumes in children and young adults and to test whether indexing to BSA resulted in an incorrect assessment of ventricular dilation according to sex, body composition, and growth.

METHODS

We retrospectively included 372 subjects aged < 26 years with either normal hearts or conditions with no impact on ventricular volumes (reference group), and 205 subjects with repaired tetralogy of Fallot (TOF) aged < 26 years. We generated Z score equations by means of multivariable regression modelling. Right ventricular dilation was assessed with the use of Z scores and compared with indexing to BSA in TOF subjects.

RESULTS

Ventricular volume Z scores were independent from age, sex, and anthropometric measurements, although volumes indexed to BSA showed significant residual association with sex and body size. In TOF subjects, indexing overestimated dilation in growing children and underestimated dilation in female compared with male subjects, and in overweight compared with lean subjects.

CONCLUSIONS

Indexed ventricular volumes measured with cMRI did not completely adjust for body size and resulted in a differential error in the assessment of ventricular dilation according to sex and body size. Our proposed Z score equations solved this problem. Future studies should evaluate if ventricular volumes expressed as Z scores have a better prognostic value than volumes indexed to BSA.

Stimulus-effect relations for left ventricular growth obtained with a simple multi-scale model: the influence of hemodynamic feedback

Cardiac growth is an important mechanism for the human body to respond to changes in blood flow demand. Being able to predict the development of chronic growth is clinically relevant, but so far models to predict growth have not reached consensus on the stimulus–effect relation. In a previously published study, we modeled cardiac and hemodynamic function through a lumped parameter approach. We evaluated cardiac growth in response to valve disease using various stimulus–effect relations and observed an unphysiological decline pump function. Here we extend that model with a model of hemodynamic feedback that maintains mean arterial pressure and cardiac output through adaptation of peripheral resistance and circulatory unstressed volume. With the combined model, we obtain stable growth and restoration of pump function for most growth laws. We conclude that a mixed combination of stress and strain stimuli to drive cardiac growth is most promising since it (1) reproduces clinical observations on cardiac growth well, (2) requires only a small, clinically realistic adaptation of the properties of the circulatory system and (3) is robust in the sense that results were fairly insensitive to the exact choice of the chosen mechanics loading measure. This finding may be used to guide the choice of growth laws in more complex finite element models of cardiac growth, suitable for predicting the response to spatially varying changes in tissue load. Eventually, the current model may form a basis for a tool to predict patient-specific growth in response to spatially homogeneous changes in tissue load, since it is computationally inexpensive.

Sex- and Age-Related Reference Values in Cardiology, with Annotations and Guidelines for Interpretation

The definition of "abnormal" in clinical sciences is often based on so-called reference values which point to a range that experts by some sort of consensus consider as normal when looking at biological variables. Such a level is commonly calculated by taking (twice) the standard deviation from the mean, or considering certain percentiles. The suspicion or even confirmation of a disease is then established by demonstrating that the value measured exceeds the upper or lower reference value. As is often the case, the measurement accuracy may depend on the conditions and specific method employed to collect and analyze data. This implies that, for example, data assessed by 2D echocardiography possibly differ from those obtained by MRI and therefore require modality-specific reference values. In this review we summarize reference values for the electrocardiogram, cardiac compartmental volumes, and arterial vessel size in males and females for various age groups. These values may further depend on other variables such as body size, physical training status, and ethnicity. Additional variables relevant for cardiology such as those referring to the microcirculation and biomarkers are only mentioned with reference to the pertinent literature. In general, the sex- and age-specific differences observed are often remarkable and warrant consideration in clinical practice and basic biomedical sciences.