Carotid diameter and blood flow velocities in cerebral circulation in hypertensive patients

The recent development of noninvasive techniques for the evaluation of the carotid arteries has focused attention on the study of arterial wall thickness to identify early lesions of vessels in patients at high risk for atherosclerosis, such as those with hypercholesterolemia, diabetes mellitus, and hypertension.

In a sample of 70 hypertensive patients without clinical evidence of target organ damage, we showed a thickening of the intimal plus medial layers compared with age- and sex-matched normotensive control subjects. In this sample we also studied the diameter of the carotid arteries by ultrasound imaging, and we studied flow velocities in common carotid, internal carotid, and middle cerebral arteries by Doppler technique. Pulsatility and resistance indexes were calculated.

Absolute values of the carotid diameter were similar in the two groups (6.3 +/- 0.7 versus 6.0 +/- 0.8 mm); however, the ratio of diameter to blood pressure was significantly reduced in hypertensive compared with normotensive subjects (5.3 +/- 0.7 versus 6.5 +/- 0.8; P < .001 for mean blood pressure). Parietal stress was increased in the hypertensive subgroup and significantly correlated with arterial diameter in the normotensive group but not in the hypertensive group. No significant differences between the two groups were observed in blood flow velocities, with the exception of a slight significant increase of mean velocity in the internal carotid artery in hypertensive patients (37.5 +/- 9.1 versus 32.7 +/- 3.0 cm/s; P < .02).

These results indicate that in addition to the degenerative changes of the common carotid wall, the diameter of the carotid artery and the relation to parietal stress show an early impairment in patients with uncomplicated hypertension.