GEOMETRY OF THE CAROTID ARTERIES AND TILT-UP HYPOTENSION IN SUBJECTS WITH ESSENTIAL ARTERIAL-HYPERTENSION

Dysfunction of the baroreceptor structures located in the carotid bulb is considered responsible for hypotensive responses to orthostatic po sture in hypertensive subjects. Because of a recurrent vascular impair ment in essential hypertensives, the authors hypothesized that in thes e cases the baroreceptive dysfunction could be related to some peculia r vascular disarrangement of the carotid arteries, at the level of the bulb. To test this, they compared two groups of mild essential hypert ensives, divided into group A-15 subjects considered hyporeacting beca use of a decrease in mean blood pressure greater than or equal to 10 m mHg at the first minute of a passive orthostatic stress-and group B-15 subjects considered normoreacting because of an increase in mean bloo d pressure greater than or equal to 5 mmHg. They evaluated by high def inition echo Doppler ultrasonography: (1) an arterial compliance index , (2) the volume of the carotid bulb, and (3) a score expressing the d egree of arteriopathy at the level of the carotid arteries. In group A , results demonstrated a significant impairment of the carotid artery structure, expressed by an increase in volume of the carotid bulb (389 .4 +/- 134.7 vs 233.2 +/- 116.5 mm(3), P < 0.05) and a higher vascular score (2.7 vs 1, P < 0.001), while the index of arterial compliance w as similar in the two groups. In conclusion, in mild essential hyperte nsion a baroreceptor dysfunction could be strictly linked To a derange ment of the carotid artery structure, while arterial, compliance does not seem to involve the baroreceptor function.