Thomas Radtke

Puberty and Microvascular Function in Healthy Children and Adolescents

OBJECTIVEnTo determine the role of pubertal status on microvascular function in healthy children and adolescents.nnnSTUDY DESIGNnChildren and adolescents (n = 112; age 10-16 years) were investigated in 2 separate prospective cross-sectional studies. The main outcome measure was microvascular function, assessed by peripheral arterial tonometry to determine the reactive hyperemic index (RHI). Physical activity was assessed using 7-day recall in one study and accelerometry in the other study. Subjects were grouped based on their self-assessed pubertal status according to Tanner stage: group 1 (prepuberty, Tanner I), group 2 (mid-puberty, Tanner II/III), and group 3 (late puberty, Tanner IV/V). Stepwise multiple regression analysis was performed to identify independent predictors of the RHI.nnnRESULTSnComplete data were available for 94 subjects (55 females) with a median (IQR) age of 14 (3.0) years and a mean body mass index of 19.0 ± 3.63 kg·m(-2). Significant correlations with RHI were observed for Tanner stage (r = 0.569; P < .001), age (r = 0.567; P < .001), stature (r = 0.553; P < .001), systolic blood pressure (r = 0.494; P < .001), and body mass index (r = 0.309; P = .001), but not for sex and moderate-to-vigorous physical activity. In stepwise regression analysis, pubertal status was the only independent predictor of microvascular function (R(2) = 0.242; β = 0.492; P < .001). Prepubertal children (group 1) had a significantly lower RHI [1.14 (0.24)] compared with group 2 [1.65 (0.57)] and group 3 [1.70 (0.75)] (all P < .001).nnnCONCLUSIONnPubertal status was the main predictor of microvascular function in healthy children and adolescents. Future studies investigating microvascular function in this age group should assess and control for pubertal maturation.

Methodological considerations and practical recommendations for the application of peripheral arterial tonometry in children and adolescents

Endothelial dysfunction is recognized as the primum movens in the development of atherosclerosis. Its crucial role in both cardiovascular morbidity and mortality has been confirmed. In the past, research was hampered by the invasive character of endothelial function assessment. The development of non-invasive and feasible techniques to measure endothelial function has facilitated and promoted research in various adult and paediatric subpopulations. To avoid user dependence of flow-mediated dilation (FMD), which evaluates nitric oxide dependent vasodilation in large vessels, a semi-automated, method to assess peripheral microvascular function, called peripheral arterial tonometry (Endo-PAT(®)), was recently introduced. The number of studies using this technique in children and adolescents is rapidly increasing, yet there is no consensus with regard to either measuring protocol or data analysis of peripheral arterial tonometry in children and adolescents. Most paediatric studies simply applied measuring and analysing methodology established in adults, a simplification that may not be appropriate. This paper provides a detailed description of endothelial function assessment using the Endo-PAT for researchers and clinicians. We discuss clinical and methodological considerations and point out the differences between children, adolescents and adults. Finally, the main aim of this paper is to provide recommendations for a standardised application of Endo-PAT in children and adolescents, as well as for population-specific data analysis methodology.

Acute effects of Finnish sauna and cold-water immersion on haemodynamic variables and autonomic nervous system activity in patients with heart failure.

Background The haemodynamic response to Finnish sauna and subsequent cold-water immersion in heart failure patients is unknown. Methods Haemodynamic response to two consecutive Finnish sauna (80℃) exposures, followed by a final head-out cold-water immersion (12℃) was measured in 37 male participants: chronic heart failure (nu2009=u200912, 61.8u2009±u20099.2 years), coronary artery disease (nu2009=u200913, 61.2u2009±u200910.6 years) and control subjects (nu2009=u200912, 60.9u2009±u20098.9 years). Cardiac output was measured non-invasively with an inert gas rebreathing method prior to and immediately after the first sauna exposure and after cold-water immersion, respectively. Blood pressure was measured before, twice during and after sauna. The autonomic nervous system was assessed by power spectral analysis of heart rate variability. Total power, low-frequency and high-frequency components were evaluated. The low frequency/high frequency ratio was used as a marker of sympathovagal balance. Sauna and cold-water immersion were well tolerated by all subjects. Results Cardiac output and heart rate significantly increased in all groups after sauna and cold-water immersion (pu2009<u20090.05), except for coronary artery disease patients after sauna exposure. Systolic blood pressure during sauna decreased significantly in all groups with a nadir after 6u2009min (all pu2009<u20090.05). Cold-water immersion significantly increased systolic blood pressure in all groups (pu2009<u20090.05). No change in the low/high frequency ratio was found in chronic heart failure patients. In coronary artery disease patients and controls a prolonged increase in low frequency/high frequency ratio was observed after the first sauna exposure. Conclusions Acute exposure to Finnish sauna and cold-water immersion causes haemodynamic alterations in chronic heart failure patients similarly to control subjects and in particular did not provoke an excessive increase in adrenergic activity or complex arrhythmias.

Physical activity intensity and surrogate markers for cardiovascular health in adolescents

We examined the impact of physical activity (PA) on surrogate markers of cardiovascular health in adolescents. 52 healthy students (28 females, mean age 14.5xa0±xa00.7xa0years) were investigated. Microvascular endothelial function was assessed by peripheral arterial tonometry to determine reactive hyperemic index (RHI). Vagal activity was measured using 24xa0h analysis of heart rate variability [root mean square of successive normal-to-normal intervals (rMSSD)]. Exercise testing was performed to determine peak oxygen uptake (

Ultra-endurance sports have no negative impact on indices of arterial stiffness.

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Reproducibility of peripheral arterial tonometry measurements in male cardiovascular patients

) and maximum power output. PA was assessed by accelerometry. Linear regression models were performed and adjusted for age, sex, skinfolds, and pubertal status. The cohort was dichotomized into two equally sized activity groups (low vs. high) based on the daily time spent in moderate-to-vigorous PA (MVPA, 3,000–5,200 counts.min−1, model 1) and vigorous PA (VPA, >5,200 counts.min−1, model 2). MVPA was an independent predictor for rMSSD (βxa0=xa00.448, Pxa0=xa00.010), and VPA was associated with maximum power output (βxa0=xa00.248, Pxa0=xa00.016). In model 1, the high MVPA group exhibited a higher vagal tone (rMSSD 49.2xa0±xa013.6 vs. 38.1xa0±xa011.7xa0ms, Pxa0=xa00.006) and a lower systolic blood pressure (107.3xa0±xa09.9 vs. 112.9xa0±xa08.1xa0mmHg, Pxa0=xa00.046). In model 2, the high VPA group had higher maximum power output values (3.9xa0±xa00.5 vs. 3.4xa0±xa00.5 Wxa0kg−1, Pxa0=xa00.012). In both models, no significant differences were observed for RHI and

Adolescent blood pressure hyperreactors have a higher reactive hyperemic index at the fingertip

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