Atherosclerosis is preceded by a phase of changes ill the arterial wall tha
t could have functional consequences even before the appearance of atheroma
tous changes. We hypothesized that early alterations of the mechanical prop
erties of the arterial wall could precede clinical and echographic modifica
tions. We used an automatic, computerized, ultrasonic procedure to evaluate
geometric and mechanical characteristics of the common carotid artery (CCA
) in normotensive children with primary familial class IIA hypercholesterol
emia (FH; n=30; mean+/-SD age, 11+/-2: years old; mean+/-SD systolic/diasto
lic blood pressure, 109+/-9/55+/-7 mm Hg) These subjects were compared with
age-matched, nonobese control subjects (n=27; 11+/-3 :years old; 112+/-10/
55+/-7 mm Hg). Noninvasive ultrasonic measurements were performed by the sa
me investigator to measure the CCA luminal systolic and diastolic diameters
and intima-media thickness (IMT). The cross-sectional compliance, cross-se
ctional distensibility, and the incremental elastic modulus of the CCA wall
were then calculated. Fin:ally, we assessed the degree of reactive hyperem
ia in the brachial artery produced after distal cuff occlusion and release.
The changes in brachial arterial diameter in response to reactive hyperemi
a (endothelium-dependent dilation) and to glyceryltrinitrate (endothelium-i
ndependent dilation) were then measured. In patients with FH, we observed a
significant reduction of systodiastolic variations in diameter (by 20%, P<
0.001) without a significant difference in IMT. Cross-sectional compliance
and cross-sectional distensibility were significantly reduced in FH subject
s (by 15%, P<0.05 and 19%, P<0.01, respectively). In parallel, the incremen
tal elastic modulus was significantly increased (by 27%, P<0.01) in childre
n with FH. No correlation was evident between the carotid incremental modul
us and either IMT or plasma low density lipoprotein cholesterol level, Ther
e was no difference in diameter of the brachial artery at rest in control a
nd FH subjects (3.0+/-0.5 versus 3.0+/-0.4 mm). The reactive hyperemia and
glyceryltrinitrate dilation were also similar in the 2 groups. However, the
flow-mediated dilation of the brachial artery was smaller in the FH subjec
ts (4.2+/-2.9%) than in controls (9.0+/-3.1%, P<0.001). In FH, endothelium-
dependent dilation was negatively correlated with the plasma low density li
poprotein cholesterol level (P<0.04). These results indicate that increased
stiffness of the CCA wall in children with FH is independent of blood pres
sure and could be related to endothelial dysfunction. Thus, alterations in
CCA wall mechanics could be early and easily,measurable markers of atheroma
tous changes in the arterial wall.