Young vascular systems adapt to obesity

By Eleanor McDermid, Senior medwireNews Reporter

Researchers have identified physiologic changes in the vascular systems of children that appear to be an adaptive response to obesity.

Obese children had improved indices of vascular function, relative to their healthy-weight peers, despite having increased heart rate and blood pressure, Marietta Charakida (Great Ormond Street Hospital for Children, London, UK) and team report in the Journal of the American College of Cardiology.

Although these findings are reassuring at face value, editorialist Stephen Daniels (University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, Canada) believes they have "ominous" long-term implications.

He says: "In the context of the anticipated large number of aortic and vascular expansions and stretching expected over a lifetime, the known relationships of these hemodynamic factors to vascular structural and functional changes, and the concomitant changes in insulin resistance, inflammation, and other vasoactive factors associated with obesity, these results suggest that these young subjects are on a path toward increasing vascular stiffness, increasing blood pressure, and concentric left ventricular hypertrophy as they grow into adulthood."

These changes potentially affect a large number of children. The findings are based on data from the Avon Longitudinal Study of Parents and Children, and one in 20 of the 6576 children in this cohort were overweight or obese at age 10 to 11 years (16% overweight; 4% obese), according to the age- and gender-specific International Obesity Taskforce definitions.

Overweight and obese children had higher heart rates than their healthy-weight peers, at an average of 72.4 and 74.6 versus 71.7 beats/min, respectively. The same was true for systolic blood pressure, at 106.3 and 108.0 versus 103.6 mmHg, respectively, and diastolic pressure, at 61.5 and 62.7 versus 59.9 mmHg.

But this was not associated with evidence of vascular damage. In fact, most measurements in overweight and obese children were significantly improved relative to those in healthy-weight children. Brachial artery diameter was larger, at 2.80 and 2.93 versus 2.64 mm, respectively; carotid-to-radial pulse wave velocity was lower, at 7.25 and 6.99 versus 7.65 m/s, indicating decreased arterial stiffness; and absolute flow-mediated dilation was increased, at 0.22 and 0.24 versus 0.21 mm.

Blood flow at rest and reactive blood flow were also significantly higher in overweight or obese children compared with those with a healthy weight.

However, a previous assessment of the children at age 9 years showed that those who were overweight or obese had significant increases in plasma markers of vascular risk, including lipid markers, inflammatory markers, and leptin, with decreased levels of adiponectin.

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