DETERMINATION OF SENSITIVITY OF BRACHIAL- ARTERY TO SHEAR-STRESS ON ENDOTHELIUM BY HIGH-RESOLUTION ULTRASOUND AS A METHOD OF ASSESSMENT OF ENDOTHELIUM-DEPENDENT VASODILATATION IN PATIENTS WITH HYPERTENSION

The aim of the study was to evaluate vasoregulating function of endoth elium in hypertension and hypercholesterolemia by means of assessment of brachial artery sensitivity to changes in shear stress. High resolu tion ultrasound (7 MHz) was used for determination of brachial artery diameter and blood flow velocity at rest and during reactive hyperemia in 12 patients with hypertension, 10 persons with hypercholesterolemi a and 10 healthy volunteers without cardiovascular risk factors. Chang es of shear stress and of artery diameter during reactive hyperemia an d sensitivity of brachial artery to shear stress were calculated for e valuation of endothelial-dependent vasodilatation. Sensitivity of brac hial artery to shear stress was significantly (p<0,05) lower in subjec ts with hypertension (0,041+0,008) and hypercholesterolemia (0,036+0,0 12) compared to control group (0,079+0,012), There were no significant differences between groups in endothelium-independent vasodilatation to nitroglycerin (17,6+/-1,3, 14,0+/-1,5 and 16,5+/-2,1% in control gr oup, subjects with hypertension and hypercholesterolemia, respectively ). These results confirm the presence of disturbances of endothelium-d ependent vasodilation in hypertension and hypercholesterolemia.