[Arterial rigidity and endothelial dysfunction in obese children]

Obesity is a cardiovascular risk factor in adults. Poorly is known about effect of obesity on cardiovascular system in children. Mechanical properties of a great elastic trunk, the common carotid artery (CCA) and endothelium function of the brachial artery were studied in 130 obese children (age: 12 +/- 3 years, body mass index (BMI): 29 +/- 5.5 kg/m2, without hypertension (115 +/- 19/58 +/- 8 mmHg). These patients had a vascular high resolution echographical analysis. Cross sectional compliance (CSC), cross sectional distensibility (CSD) and incremental elastic modulus (Einc) were analysed at the CCA site. The brachial artery dilation was measured after hyperthemia (flow mediated dilation, FMD), an endothelium dependent function and after sublingually glyceryl trinitrate (GTNMD), an independent endothelium function. Fat mass composition and distribution were assessed by dual-energy X-ray absorptiometry in 70 patients. In 50 obese patients an oral glucose tolerance test was done to determine insulin resistance. The obese children had significantly lower CSC and CSD than the healthy controls (respectively 0.12 +/- 0.04 vs 0.14 +/- 0.05 mm2.mmHg-1; p < 0.05 and 0.5 +/- 0.2 vs 0.8 +/- 0.4 mmHg(-1).10(-2); p < 0.001). Obese children had higher value than the controls for Einc (2.4 +/- 0.4 vs 1 +/- 0.24 mmHg.10(3); p < 0.001) that correlated poorly with fasting insulin concentrations (r = 0.34; p < 0.06) and BMI (r = 0.34; p < 0.01). FMD was significantly lower in obese children than in controls (6 +/- 3 vs 8 +/- 4%, p < 0.01) without modification of GTNMD (17 +/- 6 vs 18 +/- 7%, NS). These two parameters were respectively correlated with the android fat distribution (r = 0.36; p < 0.01; r = 0.49; p < 0.001). The CCA stiffness of obese children is linked to the amount of the overweight and to insulin resistance. The android fat distribution is related to endothelium dysfunction.