NONINVASIVE DETECTION OF AN INCREASED VASCULAR MASS IN UNTREATED HYPERTENSIVE PATIENTS

Structural changes of the arterial vasculature are of major pathophysi ologic and prognostic significance in human hypertension. A high-resol ution ultrasonic echotracking device was used to measure internal diam eter and intima-media thickness of the radial artery, a medium-sized m uscular conduit artery, in 60 hypertensive patients and in 40 age-matc hed control subjects. Of the 60 hypertensives, 33 were never treated a nd 27 were well-controlled by antihypertensive therapy. Radial artery mass and thickness/radius ratio were used to describe the radial arter y structure. Radial artery mass was validated in vitro by comparing th e weight of arterial segments to the ultrasonographic determination of their mass, calculated as: rho L(pi R(e)(2) - pi R(i)(2)), where rho is the arterial wall density, L the length of the arterial segment, an d R(e) and R(i) the ultrasonic values of internal and external radii, respectively. Diastolic internal diameter did not differ among the thr ee groups, but wall thickness, radial artery mass, and thickness/radiu s ratio were significantly higher in the untreated hypertensive group than in the control group. In treated well-controlled hypertensive sub jects, radial artery mass and thickness/radius ratio were not differen t from that of control subjects. Among the population of untreated pat ients, significant univariate relations existed between radial artery mass and blood pressure and radial artery mass and age. In multivariat e analysis, radial artery mass was independently predicted by mean blo od pressure, age, and sex. Circumferential wall stress, calculated fro m diastolic internal diameter, wall thickness, and diastolic blood pre ssure, was not different in the three groups. These results suggest th at the increase in radial artery mass is a reaction to the high blood pressure according to the classic Laplace law. Long-term control of bl ood pressure might normalize radial artery wall thickness and radial a rtery mass. Longitudinal studies using this new approach are needed to evaluate the effects of antihypertensive therapy on vascular structur e.