Aim of the study was to investigate short and long lasting actions of shear stress changes on vascular diameter of brachial artery in patients with arterial hypertension.
57 patients with arterial hypertension (mean age±SD, 51.26±1.94; 30 men and 27 women) and 17 healthy controls (mean age±SD, 51±5.41 ; 9 men and 8 women) were included in the study. All the subjects underwent to the investigation of vascular characteristics via high resolution vascular dopplerechography and clinical blood pressure investigations. Patients with cardiovascular, peripheral and cerebrovascular diseases, diabetes mellitus, smokers, pregnant, obese as well as those with secondary forms of hypertension, ischemic heart disease and heart failure were excluded from the study.
Compared with normotensive control subjects, initial vascular diameter (D0), was higher in hypertensive subjects (3.76±0.28vs. 4.32±0.14, P<0.01). Initial shear stress was not significantly different between the two groups. Therefore, after reactive hyperemia test (RHtest) shear stress as well as changes of shear stress were higher in hypertensive population compared with healthy control subjects (5.86±0.32vs. 5.15±0.32, P<0.05 and -0.35±0.09vs. -0.71±0.09; P<0.001). Initial vascular diameter was in a negative correlation with initial shear stress, as well as with after RHtest shear stress, but there was appeared positive correlation between initial vascular diameter and changes of it.
Arterial hypertension is associated with permanent changes of vascular wall diameter via neuro-humoral factors. Therefore, obtained results confirm an opinion that different from the short action of the changes of shear stress, vascular diameter of conduit arteries increases in response to the chronic increase of the shear stress.
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