ULTRASONOGRAPHY OF THE ARTERIAL-WALL - PR ECLINICAL DETECTION OF ATHEROSCLEROSIS

Ultrasonography of the arterial wall allows detection of structural (t hickening, plaque) and/or functional (rigidity, reactivity) changes as sociated with preclinical atherosclerosis. Thickening of the arterial wall may be observed by measuring the intima-media thickness of the po sterior wall of the common carotid or superficial femoral arteries. Hy pertension, hypercholesterolaemia, diabetes and cigarette smoking indu ce carotid (and femoral) intima-medial thickening, the atherogenic nat ure of which however has not been clearly demonstrated. An atheromatou s plaque results in a localised echogenic thickening which intrudes in to the lumen and which may be assessed qualitatively by its presence o r absence in peripheral arteries at risk of atherosclerosis (carotids, abdominal aorta, femorals). The number of these peripheral sites invo lved increases in parallel with the number of traditional risk factors in a given individual. The elasticity of the arterial walls may be ev aluated at carotid or femoral levels by measuring systolo-diastolic di stension by a technique known as ''echotracking'' The increased rigidi ty of the arterial wall observed in hypertension or diabetes Is a mark er of the slerotic component of atherosclerosis. Arterial reactivity, dependent on changes in blood flow, is assessed by pulsed Doppler at t he humeral and femoral arteries by changes in diameter induced by isch aemia/hyperaemia. Changes in arterial reactivity are observed in hyper cholesterolaemia even in the absence of atherosclerosis. Structural an d functional changes detected by arterial ultrasonography and associat ed with atherosclerosis have a prognostic value which may contribute t o a more accurate assessment of global vascular risk and may be useful in evaluating the efficacy of antihypertensive or lipid lowering ther apy.