High-volume sports club participation and autonomic nervous system activity in children.

BACKGROUND: Sixty minutes of daily moderate-to-vigorous physical activity (PA) are recommended for children. This study investigated the additional impact of high-volume sports club participation on the autonomic nervous system in active children, while controlling for acute effects of short-term PA. MATERIALS AND METHODS: Forty-nine children (29 females) aged 10-13 years were investigated. Sports club participation was assessed with a validated questionnaire. Short-term PA and night-time autonomic tone (spectral power and nonlinear analysis of heart rate variability) were measured with an ambulatory device (Actiheart(®) ). Children were dichotomized into two groups, based on their individual weekly time spent in a sports club: low-volume group < 180 min/week (N = 26) and high-volume group ≥ 180 min/week (N = 23). RESULTS: Children in the high-volume group exhibited higher indices of vagal tone compared with the children in the low-volume group. Short-term moderate PA had a significant impact on the night course of autonomic activity. Boys showed a linear increase in vagal activity over the night course in relation to volumes of short-term moderate PA of the previous day. A similar but nonsignificant trend was observed for girls. CONCLUSIONS: In active children, higher volumes of sports club participation have an additional benefit on indices of autonomic tone.

Puberty and microvascular function in healthy children and adolescents.

OBJECTIVE: To determine the role of pubertal status on microvascular function in healthy children and adolescents. STUDY DESIGN: Children 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. RESULTS: Complete 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; ß = 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). CONCLUSION: Pubertal 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.

Evolution of cardiac autonomic nervous activity indices in patients presenting with transient left ventricular apical ballooning.

BACKGROUND: Transient left ventricular (LV) apical ballooning (AB) is characterized by a rapidly reversible, acute LV systolic dysfunction, triggered by physical or emotional stress. Despite observations strongly suggesting catecholamine-mediated myocardial stunning due to enhanced sympathetic activity, the early time course of heart rate variability (HRV) has not been described. METHODS: We prospectively enrolled 39 consecutive patients (median age = 68 years, range 35-85 years, 38 women) with LV AB. Indices of HRV were extracted from 24-hour ambulatory electrocardiograms on the day of hospital admission, on days 2 and 3, and 3 months after the hospitalization. RESULTS: Within 48 hours after hospital admission, the indices of HRV were markedly depressed (standard deviation of normal-to-normal [NN] intervals [SDNN] 89.6 +/- 19.9 ms; mean standard deviation of NN intervals for 5-minute segments [SDNNi] 37.8 +/- 6.2 ms; root mean square of consecutive difference of normal-to-normal intervals [rMSSD] 23.0 +/- 9 ms; standard deviation of the averages of NN intervals for all 5-minute segments [SDANN] 70.1 +/- 18.0 ms; geometric triangular index [TI] 23.7 +/- 5.9 ms), recovered in the subacute phase and had normalized at 3 months follow-up (SDNN 124.7 +/- 24 ms; SDNNi 47.1 +/- 5.7 ms; rMSSD 31.1 +/- 10.5 ms; SDANN 118.5 +/- 27 ms; TI 31.2 +/- 8 ms; all P < 0.05). Mean RR-interval increased from 845 +/- 121 ms on day 1, to 929 +/- 84 ms at 3 months (P=0.06). CONCLUSIONS: A marked depression of cardiac parasympathetic activity was observed in the acute phase of LV AB, followed by recovery of autonomic modulation between the subacute and the chronic phases. The rapid return of parasympathetic function may partially explain the favorable outcomes of patients presenting with LV AB.

Echocardiogram versus cardiac magnetic resonance imaging for assessing systolic function of subaortic right ventricle in adults with complete transposition of great arteries and previous atrial switch operation.

In adults with congenital heart disease and a systemic right ventricle, subaortic ventricular systolic dysfunction is common. Echocardiographic assessment of systolic right ventricular (RV) function in these patients is important but challenging. The aim of the present study was to assess the reliability of conventional echocardiographic RV functional parameters to quantify the systolic performance of a subaortic right ventricle. We compared 56 contemporary echocardiograms and cardiac magnetic resonance studies in 37 adults, aged 26.9 ± 7.4 years, with complete transposition and a subaortic right ventricle. The fractional area change (FAC), lateral tricuspid annular plane systolic excursion, lateral RV systolic motion velocities by tissue Doppler, RV myocardial performance index, and the rate of systolic RV pressure increase (dp/dt) measured across the tricuspid regurgitant jet were assessed by echocardiography and correlated with the cardiac magnetic resonance-derived RV ejection fraction (EF). The mean RVEF was 48.0 ± 7.8%. FAC (r(2) = 0.206, p = 0.001) and dp/dt (r(2) = 0.173, p = 0.009) significantly correlated with RVEF, and the other nongeometric echocardiographic parameters failed to show a significant correlation with RVEF by linear regression analysis. FAC <33% and dp/dt <1,000 mm Hg/s identified a RVEF of <50% with a sensitivity of 77% and 69% and a specificity of 58% and 87%, respectively. In conclusion, in patients with a systemic right ventricle, routine nongeometric echocardiographic parameters of RV function correlated weakly with cardiac magnetic resonance-derived EF. RV FAC and the measurement of the rate of systolic RV pressure increase (dp/dt) should be preferentially used to assess systemic systolic function in adult patients with a subaortic right ventricle.

Distensibility and diameter of ascending aorta assessed by cardiac magnetic resonance imaging in adults with tetralogy of fallot or complete transposition.

Structural abnormalities of the medial aorta have been described for conotruncal defects (e.g., tetralogy of Fallot [TOF] and complete transposition of the great arteries (dextrotransposition [d]-TGA). In TOF, progressive aortic dilation is a frequent finding. In patients with d-TGA with an atrial switch, this problem is less often described. The aim of the present study was to compare the extent of dilative aortopathy and aortic distensibility in adults with an atrial switch procedure (n = 39) to that in adults with repaired TOF (n = 39) and controls (n = 39), using cardiac magnetic resonance imaging. The groups were matched for age and gender. Diameters of the aorta indexed to the body surface area were significantly increased in the patients with d-TGA and TOF compared to that of the controls at the aortic sinus up to the level of the right pulmonary artery. On multivariate testing, the diagnosis of a conotruncal defect (ß = 0.260; p = 0.003) and aortic regurgitant fraction (ß = 0.405; p <0.001) were independent predictors of an increased aortic sinus diameter. Ascending aorta distensibility was significantly reduced in those with d-TGA and TOF compared to controls: 3.6 (interquartile range 1.5 to 4.4) versus 2.8 (interquartile range 2.0 to 3.7) versus 5.5 (interquartile range 4.8 to 6.9) ×10(-3) mm Hg(-1) (p <0.001). The independent predictors of ascending aorta distensibility were the diagnosis of a conotruncal defect (p <0.001) and age (p = 0.028). In conclusion, intrinsic aortopathy, manifested as increased ascending aortic diameters and reduced ascending aortic distensibility, is not only evident in adults with TOF, but also in adults with d-TGA and an atrial switch procedure. Long-term follow-up is needed to monitor the aortic size in both patient groups.

Iyengar yoga increases cardiac parasympathetic nervous modulation among healthy yoga practitioners.

Relaxation techniques are established in managing of cardiac patients during rehabilitation aiming to reduce future adverse cardiac events. It has been hypothesized that relaxation-training programs may significantly improve cardiac autonomic nervous tone. However, this has not been proven for all available relaxation techniques. We tested this assumption by investigating cardiac vagal modulation during yoga.We examined 11 healthy yoga practitioners (7 women and 4 men, mean age: 43 +/- 11; range: 26-58 years). Each individual was subjected to training units of 90 min once a week over five successive weeks. During two sessions, they practiced a yoga program developed for cardiac patients by B.K.S. Iyengar. On three sessions, they practiced a placebo program of relaxation. On each training day they underwent ambulatory 24 h Holter monitoring. The group of yoga practitioners was compared to a matched group of healthy individuals not practicing any relaxation techniques. Parameters of heart rate variability (HRV) were determined hourly by a blinded observer. Mean RR interval (interval between two R-waves of the ECG) was significantly higher during the time of yoga intervention compared to placebo and to control (P < 0.001 for both). The increase in HRV parameters was significantly higher during yoga exercise than during placebo and control especially for the parameters associated with vagal tone, i.e. mean standard deviation of NN (Normal Beat to Normal Beat of the ECG) intervals for all 5-min intervals (SDNNi, P < 0.001 for both) and root mean square successive difference (rMSSD, P < 0.01 for both). In conclusion, relaxation by yoga training is associated with a significant increase of cardiac vagal modulation. Since this method is easy to apply with no side effects, it could be a suitable intervention in cardiac rehabilitation programs.