Mechanical properties of the common carotid artery in Williams syndrome

Objective-To determine whether arterial wall hypertrophy in elastic arteries was associated with alteration in their mechanical properties in young patients with Williams syndrome. Methods-Arterial pressure and intima-media thickness, cross sectional compliance, distensibility, circumferential wall stress, and incremental elastic modulus of the common carotid artery were measured non-invasively in 21 Williams patients (mean (SD) age 8.5 (4) years) and 21 children of similar age. Results-Systolic and diastolic blood pressures were higher in Williams patients (125/66 a 113/60 mm Hg, p < 0.05). The mean (SD) intima-media thickness was increased in Williams patients, at 0.6 (0.07) a 0.5 (0.03) mm (p < 0.001). Normotensive Williams patients had a lower circumferential wall stress (2.1 (0.5) er 3.0 (0.7) mm Hg, p < 0.01), a higher distensibility (1.1 (0.3) a 0.8 (0.3) mm Hg-1.10(-2), p < 0.01), similar cross sectional compliance (0.14 (0.04) v 0.15 (0.05) mm(2).mm Hg-1, p > 0.05), and lower incremental elastic modulus (7.4 (2.0) a 14.0 (5.0) mm Hg.10(2); p < 0.001). Conclusions-The compliance of the large elastic arteries is not modified in Williams syndrome, even though increased intima-media thickness and lower arterial stiffness are consistent features. Therefore systemic hypertension cannot be attributed to impaired compliance of the arterial tree in this condition.