RELATIONSHIP BETWEEN ULTRASOUND ASSESSMENT OF ARTERIAL-WALL PROPERTIES AND BLOOD-PRESSURE

Physical properties of an artery can be described in terms of stiffnes s, distensibility, and compliance. Changes in these properties can pre dict atherosclerosis disease, but it is necessary to identify an index that is independent of changes in blood pressure. We measured common carotid artery diameter and pulsatile change with an ultrasonic phase- locked, echo-tracking system, in 7 subjects whose mean brachial blood pressure had varied 15 mm Hg or more within a month. Patients taking a ntihypertensive agents were excluded from the study. We measured chang es in arterial diameter (n=41) at least four times during the study pe riod and calculated the pressure-strain elastic modulus (Ep), distensi bility coefficient (DC), cross-sectional compliance (CC) and stiffness parameter (beta) from inner diameter, its pulsatile change, and blood pressure. The correlation coefficients of mean blood pressure with ea ch index are as follows: Ep, 0.53; DC, 0.58; CC, 0.63; beta, 0.21. Whe n mean blood pressure increased 1 mm Hg, the change in each index at 1 00 mm Hg was as follows: Ep, 1.48 +/-1.30%; DC, -1.05 +/-0.97%; CC, -0 .69 +/-0.90%; beta, 0.45 +/-1.11%. Among the four indices that measure the properties of the arterial walls, stiffness parameter beta was th e least dependent on blood pressure. Thus, it appears to have usefulne ss as an index of arterial wall sclerosis.