Sedentary Behavior in Childhood, Lower Arterial Compliance and Decreased Endothelial Function-Cross Sectional Data From a German School Cohort.

BACKGROUND: Endothelial function by flow-mediated dilatation assesses early markers of atherosclerotic progression. Greater amounts of physical activity and physical fitness in children are associated with cardiovascular health benefits. We aimed to explore factors, influencing endothelial function and arterial compliance in a cohort of healthy school children. METHODS: The 94 participants (41 girls, 53 boys) in the study were young, healthy children from a German school cohort. Anthropometric data, body composition and blood pressure were assessed. Blood was drawn (8 h overnight fast), assessing total cholesterol, high density lipoprotein and low density lipoprotein and triglycerides. Endothelial function was diagnosed by flow-mediated dilatation with ultrasonography (ALOKA/Hitachi, Prosound alpha 6). Tracking gates were set on the intima in B-mode. The waveform of diameter changes over the cardiac cycle was displayed in real time using the FMD-mode of the eTRACKING system. Changes in arterial diameter at baseline, ischaemia and vasodilatation were measured. A symptom limited pulmonary exercise test on a bicycle ergometer was performed to test cardiorespiratory fitness. Physical activity was assessed using GT3x accelerometers (Actigraph, USA), over 4 days (including 1 week-end day), with a minimum wear-time duration of 10 h. RESULTS: The median age was 12.2 years (11.8-12.8). Children were normal weight, blood lipid profiles (cholesterol, high-density lipoprotein, low-density lipoprotein, triglyceride) were in normal range. Baseline measurements during the diagnostics of endothelial function revealed higher arterial compliance of the brachial artery in boys. Boys' cardiorespiratory fitness was higher than compared to girls. Boys met the recommendations of 60 min moderate to vigorous activity, whereas girls were significantly less active and did not meet current recommendations. More time spent in sedentary activity was the main predictor for lower arterial compliance (adjusted for age and sex), accounting for 14% of the variance. No significant model revealed, analyzing the influencing factors such as anthropometric data, blood lipids, physical activity and fitness on endothelial function. CONCLUSION: This is the first study on endothelial function in association to objectively measured physical activity and cardiorespiratory fitness in healthy school children in Germany. The study highlights the importance of reducing time spent being sedentary to maintain endothelial health.

Frequency and individual severity of arterial blood pressure changes in children and adolescents with attention-deficit/hyperactivity disorder treated with methylphenidate hydrochloride: a prospective non-interventional study.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a common behavioural disorder in childhood. The psychostimulant methylphenidate hydrochloride (MPH) is one of the major pharmacological options for ADHD. MPH is known to result, on average, in a small increase in arterial blood pressure (BP). However, there are few clinical data regarding the individual influences of MPH on BP among children and adolescents with ADHD. According to the European Union-wide standardised patient information sheet for MPH, BP changes >10 mm Hg compared with baseline values are 'common' (ie, ≥1% to <10%) in children and adolescents with ADHD during MPH therapy. AIM: To investigate the frequency and individual severity of BP changes in children and adolescents with ADHD during the first 6 months of new MPH therapy. METHODS: In this study, 44 (77% male) children and adolescents (mean age (SD) 9.13 (1.86) years) with a diagnosis of ADHD according to the International Classification of Diseases, tenth revision, underwent ambulatory BP monitoring before and during the first 6 months of routine MPH therapy. Exclusion criteria were pre-existing MPH therapy and other medications that potentially influence BP or interfere with MPH. The non-interventional study was conducted prospectively at 10 paediatric cardiology centres in Germany and Austria. RESULTS: After beginning MPH therapy, 34% of participants (99% CI 15.52% to 52.66%) had BP increases/decreases >10 mm Hg. The mean changes in systolic BP and diastolic BP were 0.87 mm Hg (95% CI -1.75 mm Hg to 3.48 mm Hg) and 1.96 mm Hg (95% CI 0.21 mm Hg to 3.7 mm Hg), respectively. The proportion of participants with initial prehypertension/hypertension was 54.55%. CONCLUSIONS: In our sample with a high baseline rate of prehypertension/hypertension, BP changes >10 mm Hg during MPH therapy were more frequent than those indicated by the patient information sheet. Moreover, individual BP changes, including increases and decreases >10 mm Hg, resulted in a small average BP increase in the sample, thus reflecting neither the severity nor the direction of individual BP changes. Therefore, the frequency and, due to the common use of the arithmetic mean, the individual severity of BP changes during MPH therapy may be underestimated. Further studies without averaging and with larger samples including patients in primary care settings are warranted.

Comparison of Two Measurement Devices for Pulse Wave Velocity in Children: Which Tool Is Useful to Detect Vascular Alterations Caused by Overweight?

Vascular alterations may lead to manifest cardiovascular disease in future life. There is a tremendous time delay between the onset and obvious clinical appearance of vascular alterations. Pulse wave velocity (PWV) is one subclinical parameter to detect vascular alterations at a very early stage. Different techniques exist to measure PWV non-invasively as a vascular parameter-all with their own technique-inherent advantages, challenges, and pitfalls. The aim of this study was to compare two techniques to measure PWV, to assess their agreement, and interchangeability. In 780 (♀ = 49.4%) healthy children and adolescents (mean age: 11.61 ± 2.11 years), PWV was obtained with two different techniques. Ultrasound-measured local PWV (PWVß) at the carotid artery was graphically compared by a Bland-Altman plot with aortic PWV (aPWV), measured oscillometrically on the brachial artery. Reproducibility was assessed with the concordance correlation coefficient by Lin (ρc). Furthermore, participants were categorized by BMI as normal weight (N) or overweight/obese (O) to identify differences in PWVß and aPWV caused by an increased BMI. Mean PWVß was lower (4.01 ± 0.44 m/s) than mean aPWV (4.67 ± 0.34 m/s). The two methods differ by mean Δ0.66 ± 0.47 m/s (95% CI: 0.62 to 0.69 m/s; p < 0.001). Bland-Altman analysis indicated the 95% limits of agreement (-0.26 to 1.57) without any evidence of systemic difference. Lin's ρc represented a weak concordance between PWVß and aPWV (ρc = 0.122; 95% CI: 0.093-0.150). There was no difference in PWVß between N and O, whereas aPWV was higher in O: 4.81 ± 0.42 m/s than in N: 4.65 ± 0.32 m/s (p < 0.001). The difference, Δ0.16 m/s, 95% CI [-0.25; -0.08], was significant, t (121) = -3.76, p < 0.001, with a medium-sized effect. PWVß (ultrasound) and aPWV (oscillometry) show a level of disagreement that includes clinically important discrepancies. A discrimination between normal and altered vascular function was possible with aPWV but not with PWVß.

Controversies in the association of cardiorespiratory fitness and arterial stiffness in children and adolescents.

The relationship between cardiorespiratory fitness and arterial compliance in children and adolescents remains controversial. The aim of this study was to assess this association with a quantitative approach. A total of 646 healthy children and adolescents (316 females, age 13.9±2.1 years) were cross-sectionally investigated in seven school settings in and around Munich for their cardiorespiratory fitness and demographic, anthropometric and hemodynamic parameters. Surrogates of arterial stiffness, such as pulse wave velocity (PWV), Augmentation Index normalized to a heart rate of 75 (AI@75), and peripheral and central systolic blood pressures were measured in a supine position using the oscillometric Mobil-O-Graph. Cardiopulmonary fitness was measured by 6-min indoor run tests. After correction for age, sex, body weight, body height, heart rate and mean arterial pressure, controversial findings were produced. PWV increased with higher cardiorespiratory fitness (Beta=0.173; P<0.001), which represented an unfavorable relationship, whereas AI@75 declined with higher cardiorespiratory fitness (Beta=-0.106; P=0.025). Therefore, in contrast to PWV, higher cardiorespiratory fitness seems beneficial for AI@75. The third surrogate of arterial stiffness, central systolic blood pressure, showed no association with cardiorespiratory fitness (Beta=0.066; P=0.052). These controversial outcomes remain almost unchanged when the boys and girls were analyzed separately. Different surrogates of arterial stiffness have different relationships with cardiorespiratory fitness in children and adolescents after correcting for multiple confounders. More research is needed in this field to understand the functioning of the juvenile vessels, and measurements and methodological approaches should be reconsidered.

Body Weight and Not Exercise Capacity Determines Central Systolic Blood Pressure, a Surrogate for Arterial Stiffness, in Children and Adolescents.

Cardiopulmonary fitness benefits cardiovascular health. Various studies have shown a strong negative correlation between exercise capacity and arterial stiffness in adults. However, evidence for this connection in children and adolescents is scarce. About 320 healthy children and adolescents (252 male, 14.0±2.1 years) were evaluated with regard to their demographic, anthropometric and hemodynamic parameters, and their peak oxygen uptake. Peripheral and central systolic blood pressures were measured with patients in a supine position using an oscillometric device. Peak oxygen uptake was assessed by cardiopulmonary exercise testing. In multivariate regression, only peripheral systolic blood pressure (ß=0.653, P<.001) and body weight (ß=0.284, P<.001) emerged as independent determinants for central systolic blood pressure. Body weight therefore determines central systolic blood pressure in children and adolescents rather than measures of cardiorespiratory fitness. The prevention of overweight in childhood is necessary to reduce stiffening of the arteries and delay the onset of cardiovascular disease.

Increased intima-media thickness is not associated with stiffer arteries in children.

OBJECTIVE: Subclinical atherosclerosis can be assessed via sonographic measurement of intima-media thickness and carotid artery distensibility, both may already be pathologically altered in childhood. Therefore, the purpose of this study was to provide reference percentiles and investigate possible associations between alterations of intima-media thickness and distensibility. METHODS: Carotid intima-media thickness and distensibility was measured via B- and M-mode ultrasound. Distensibility was defined by arterial compliance, elastic modulus, stiffness parameter ß, and local pulse wave velocity ß. Age- and height-dependent reference values were calculated separately for boys and girls among 690 (intima-media thickness) and 870 (distensibility) non-obese children aged 7-17 years. RESULTS: Intima-media thickness and distensibility did not increase significantly with age or differ between boys and girls. Systolic blood pressure and body mass index were independent predictors of intima-media thickness, while an increased systolic blood pressure or pulse pressure was associated with stiffer arteries. Increased intima-media thickness was accompanied by higher arterial compliance and lower stiffness. CONCLUSION: Using this healthy cohort, we describe a functional and non-pathological arterial adaptation wherein an increase in intima-media thickness is not associated with stiffer arteries.

Percentiles for central blood pressure and pulse wave velocity in children and adolescents recorded with an oscillometric device.

OBJECTIVE: In adults with arterial hypertension, measuring arterial stiffness by pulse wave velocity (PWV) can determine the extent of cardiovascular subclinical organ damage. PWV has independent predictive value for cardiovascular events, but there are currently no recommendations for measuring PWV in children. In addition, central systolic blood pressure (cSBP) strongly reflects vascular changes. The aim of this study was to establish percentiles for cSBP and PWV in children and adolescents to evaluate and classify altered vascular function in youths. METHODS AND RESULTS: We measured PWV and cSBP with an oscillometric device with inbuilt ARCSolver-algorithm (estimated by using the brachial waveform) and calculated smoothed reference percentiles for 1445 children and young adults (49.5% female; 13.41 ± 2.80 years, range 8-22 years; PWV 4.67 ± 0.34 m/s; cSBP 100.7 ± 8.9 mmHg) using the LMS-method based on age and height. PWV and cSBP increased with age and height, but slightly differently for girls and boys, possibly reflecting different growth patterns. Between 8 and 21 years, PWV increased from 4.29 ± 0.32 to 4.98 ± 0.33 m/s in girls and from 4.27 ± 0.18 to 5.22 ± 0.46 m/s in boys. While girls showed a minor increase in cSBP (91.2 ± 7.5 to 109.1 ± 8.6 mmHg), the cSBP in boys ranged from 90.0 ± 5.8 to 110.5 ± 9.6 mmHg with a more pronounced increase between 14 and 17 years. CONCLUSION: These percentiles for PWV and cSBP can help define arterial stiffness in youths and contribute to risk stratification for cardiovascular disease. For example, in children with prehypertension or isolated systolic hypertension, PWV and cSBP can provide additional information about the function of the vascular system, thereby strengthening intervention strategies.

Reduction of exercise capacity in children from summer to winter is associated with lower sporting activity: a serial study.

BACKGROUND: Declining activity in children over the past decades is thought to be one of the main risk factors for an early development of exercise intolerance and obesity. Taking this background into account, this prospective study investigated the seasonal change of children's physical activity and its association with objective measures of exercise capacity. METHODS: A total of 96 children from two schools in Munich (42 girls, age 12.4 ± 0.8 y) underwent a cardiopulmonary exercise test (CPET) and an assessment of their daily activities (school sport, club sport, leisure sport) twice. Baseline testing was conducted in summer 2011. Follow-up examination was performed during winter 2012. RESULTS: From summer to winter, self-reported sporting activity decreased from 10.6 ± 4.1 to 8.5 ± 4.3 h/wk (P < 0.001) as school sport (P < 0.001) and leisure sport activities (P = 0.002) decreased, but the activity associated with club sport did not (P = 0.700). In parallel, peak oxygen uptake (VO2) declined from 102.0 ± 17.5 to 96.9 ± 17.9 % of predicted (P < 0.001). This decline in VO2 was associated with a reduction in overall sporting activity (r = 0.234; P < 0.032). CONCLUSION: Enhancing sporting activity in children during winter might be important to maintaining their exercise capacity.

The Munich Triathlon Heart Study: ventricular function, myocardial velocities, and two-dimensional strain in healthy children before and after endurance stress.

Intense exercise has been shown to have negative effects on systolic and diastolic ventricular function in adults. Very little is known about the normal reaction of the growing heart to endurance stress. For this study, 26 healthy children (18 males) with a mean age of 12.61 years (range, 7.92-16.42 years) took part in an age-adapted triathlon circuit. The athletes were investigated by two-dimensional (2D) echocardiographic/speckle tracking, M-mode, pulse-wave Doppler, color Doppler, and color-coded tissue Doppler at 2-4 weeks before and immediately after the race. After the competition, cardiac output increased, mediated by an increase in heart rate and not by an elevated preload, according the Frank-Starling mechanism. Two-dimensional speckle tracking showed a reduced longitudinal strain in the right and left ventricles and additionally reduced circumferential strain in the left ventricle. The late diastolic inflow velocities were increased in both ventricles, indicating reduced diastolic function due to an impairment of myocardial relaxation. Immediately after endurance exercise, systolic and diastolic functions were attenuated in children and adolescents. In contrast to adult studies, this study could show a heart rate-mediated increase in cardiac output. The sequelae of these alterations are unclear, and the growing heart especially may be more susceptible to myocardial damage caused by intense endurance stress.

Fetal color-coded tissue Doppler echocardiography: experiences with the "tracking method" in normal fetuses.

OBJECTIVE: Ultrasound-based tissue Doppler imaging has opened new perspectives for non-invasive quantification of global, as well as regional, myocardial function. We therefore studied fetal hearts using the "tracking method" in order to assess its feasibility and changes of fetal myocardial velocities throughout gestation. STUDY DESIGN: In 89 healthy fetuses color-coded tissue Doppler echocardiography (TDE) was prospectively conducted for further offline-analysis of global and regional myocardial function of the basal segment. Maximum tissue velocities at systole (S), in the early filling phase of diastole (E) and during atrial contraction (A) were estimated from three consecutive cardiac cycles. RESULTS: Within a selected time limit of 15 min, raw data acquisition was possible in 60 of the 89 fetuses (67%). From the stored samples, velocities of S, E and A-wave could be obtained in 76% with good reproducibility for septal and right wall velocities. During gestation all velocities increased but to a greater extent at the right and left ventricular wall compared to the interventricular septum. The A-wave velocity was higher than E-wave velocity in all basal segments. Throughout gestation, the increase in E-wave was higher, resulting in an increase of the E-wave/A-wave ratio. CONCLUSION: Tissue Doppler echocardiography using the tracking method in fetal hearts is practical during routine clinical examination, but it is time consuming and requires highly experienced observers The knowledge of myocardial velocities in normal pregnancies is essential in detecting pathologies.