Are changes in conduit artery function associated with intima-medial thickness in young subjects?

BACKGROUND: Impaired brachial artery endothelial function, assessed by flow-mediated dilation (FMD), provides a strong prognostic index of cardiovascular events in asymptomatic adults and those with cardiovascular disease. However, the relationship between FMD and carotid intima-medial thickness (cIMT) in young people is unknown. We hypothesized that impaired FMD, and decreased FMD over time, would predict cIMT. DESIGN AND METHODS: FMD and cIMT were assessed using high-resolution Doppler ultrasound in 53 children (18 boys) aged 10.3 ± 0.3 years. FMD was assessed at baseline and 4-month and 30-month follow up. cIMT was assessed at 30-months. RESULTS: There was no significant relationship between FMD measured at baseline (10.7 ± 4.3) and cIMT at 30 months. FMD was depressed at 4 months (7.2 ± 3.5, p < 0.05) and 30 months (8.2 ± 3.3, p = 0.51). However, there was no correlation between changes in FMD and cIMT. CONCLUSION: Changes in arterial function occurred in young subjects across a 30-month time frame; however, these changes were unrelated to individual differences in cIMT in this cohort. These data contrast with findings in adults and indicate that longer periods of functional impairment may be necessary before atherosclerotic wall thickening becomes apparent in young people, suggesting there is a 'window of opportunity' for preventative intervention strategies.

Conduit diameter and wall remodeling in elite athletes and spinal cord injury.

PURPOSE: This study aimed to investigate localized and systemic effects of chronic exercise and inactivity on conduit artery remodeling in humans. METHODS: We recruited elite athletes engaged in predominantly lower limb (LL runners/cyclists, n = 10) or upper limb (UL canoe paddlers, n = 12) exercise and matched able-bodied, recreationally active, controls (C, n = 16). We also studied wheelchair controls (spinal cord injury, n = 9) and athletes (spinal cord injury, n = 1; spina bifida, n = 4). Carotid, brachial, and superficial femoral (SF) artery diameter and wall thickness were assessed using high-resolution ultrasound. RESULTS: Brachial diameters were significantly larger in UL and wheelchair users (athletes and controls) compared with C (both P < 0.05). SF artery diameter in wheelchair controls was significantly smaller compared with the other groups, with LL athletes having significantly greater lumen diameter than controls (both P < 0.05). In all arteries, a lower wall thickness was found in able-bodied athletes compared with C, including wheelchair athletes compared with wheelchair controls (P < 0.001). In the SF artery, wall-to-lumen-ratio was significantly lower in able-bodied athletes and higher in wheelchair controls compared with able-bodied controls (P < 0.001). In the brachial and carotid arteries, able-bodied and wheelchair athletes demonstrated lower wall-to-lumen-ratio than less active wheelchair controls and able-bodied controls (P < 0.001). CONCLUSIONS: These findings suggest that remodeling of the arterial wall occurs systemically in response to exercise training and is unrelated to exercise type in humans. Conversely, localized effects are evident with respect to the effect of exercise on arterial diameter. These findings have implications for our understanding of the effects of exercise on arterial structure and function in humans.

Resistance training and diastolic myocardial tissue velocities in obese children.

PURPOSE: The primary purpose of this study was to determine the effects of resistance exercise training on early diastolic myocardial velocities (E') in an obese pediatric population. METHODS: Twenty-three obese adolescents were selected to participate in either a resistance-based training program (RT; n = 13, 12.2 +/- 0.4 yr, body mass index [BMI] = 32.5 +/- 1.9 kg m(-2)) or a nonexercise control intervention (n = 10, 13.6 +/- 0.7 yr, BMI = 30.2 +/- 2.6 kg m(-2)) for 8 wk. All subjects had repeated echocardiographic assessments to determine left ventricular (LV) geometry, early transmitral flow velocity (E), and E'. RESULTS: LV mass and wall thicknesses did not significantly change with training or in controls. RT improved E' (11.9 +/- 0.5 to 13.3 +/- 0.5 cm s(-1), P< 0.01) in the presence of a decrease in E/E' (8.17 +/- 0.39 to 7.06 +/- 0.30 cm s(-1), P < 0.01), a marker of left atrial pressure. No changes were evident in the inactive control subjects. CONCLUSIONS: A supervised 8-wk RT exercise program improved early diastolic tissue velocity in obese children, independent of changes in LV morphology.

Impact of obesity on diastolic function in subjects < or = 16 years of age.

The aim of this study was to investigate the impact of obesity on diastolic function in children and adolescents. Echocardiographic measurements were compared in 28 obese subjects (14 males, 14 females) and 15 age- and gender-matched lean controls (8 males, 7 females). Two-dimensional ultrasound imaging, M-mode imaging, and pulse-wave conventional and tissue Doppler measurements were used to assess cardiac structure and function at rest. No differences were evident between lean and obese subjects in age (13.3 +/- 0.5 vs 12.4 +/- 0.4 years), height (163 +/- 4 vs 159 +/- 2 cm), or systolic blood pressure (119 +/- 3 vs 123 +/- 2 mm Hg). Body mass (54.6 +/- 4.0 vs 85.8 +/- 3.6 kg, p < 0.0001) and body mass index (20.5 +/- 0.7 vs 33.3 +/- 1.0 kg/m2, p < 0.00001) were significantly greater in the obese subjects, whereas measurements of wall thickness (interventricular septal wall 0.86 +/- 0.04 vs 0.89 +/- 0.02 cm, posterior wall 0.83 +/- 0.04 vs 0.91 +/- 0.02 cm) and fractional shortening (38.6 +/- 1.2% vs 38.8 +/- 1.2%) did not significantly differ. The E/E' ratio (6.86 +/- 0.20 vs 8.30 +/- 0.32, p < 0.01), E' (13.93 +/- 0.38 vs 12.29 +/- 0.44 cm/s, p < 0.05), the E'/A' ratio (2.49 +/- 0.17 vs 2.05 +/- 0.09, p < 0.05), and the deceleration time of early transmitral blood flow velocity (125.3 +/- 7.7 vs 154.5 +/- 6.8 ms, p < 0.01) were significantly different between the groups, suggesting reduced diastolic function in the obese subjects. In conclusion, these data suggest that indexes of diastolic function, including tissue Doppler measures, are significantly impaired in obese young subjects.