[Ultrasonographic study of the arterial walls: application to the detection of preclinical atherosclerosis].

: Ultrasonography of the arterial wall allows detection of structural (thickening, plaque) and/or functional (rigidity, reactivity) changes associated with preclinical atherosclerosis. Thickening of the arterial wall may be observed by measuring the intima-media thickness of the posterior wall of the common carotid or superficial femoral arteries. Hypertension, hypercholesterolaemia, diabetes and cigarette smoking induce carotid (and femoral) intima-medial thickening, the atherogenic nature of which however has not been clearly demonstrated. An atheromatous plaque results in a localised echogenic thickening which intrudes into the lumen and which may be assessed qualitatively by its presence or absence in peripheral arteries at risk of atherosclerosis (carotids, abdominal aorta, femorals). The number of these peripheral sites involved increases in parallel with the number of traditional risk factors in a given individual. The elasticity of the arterial walls may be evaluated at carotid or femoral levels by measuring systolo-diastolic distension by a technique known as "echotracking". The increased rigidity of the arterial wall observed in hypertension or diabetes is a marker of the sclerotic component of atherosclerosis. Arterial reactivity, dependent on changes in blood flow, is assessed by pulsed Doppler at the humeral and femoral arteries by changes in diameter induced by ischaemia/hyperameia. Changes in arterial reactivity are observed in hypercholesterolaemia even in the absence of atherosclerosis. Structural and functional changes detected by arterial ultrasonography and associated with atherosclerosis have a prognostic value which may contribute to a more accurate assessment of global vascular risk and may be useful in evaluating the efficacy of antihypertensive or lipid lowering therapy.