[Clinical use of ultrasonographic assessment of the gradient of luminal narrowing of the internal carotid artery in atherosclerotic lesion].

Objective: The study was aimed at investigating the clinical significance of the gradient of luminal narrowing of atherosclerotically altered internal carotid arteries as a risk factor for ischemic cerebral damage by means of ultrasonographic techniques and magnetic resonance imaging.

Patients and methods: The study enrolled a total of 20 patients, mean age 62.4±1.3 years. Based on the findings of cerebral magnetic resonance imaging, they were subdivided into two groups: those without ischemic cerebral damage (13 subjects) and with ischemic lesion (7 patients). The vessels of carotid basin were assessed by means of ultrasonographic techniques, calculating the gradient of narrowing of the lumen of atherosclerotically altered arteries using 2 methods: A - as the ratio of the percentage of the internal carotid artery stenosis to the distance between near-to-stenosis distal/proximal segment of the non-stenotic artery and the site of maximal narrowing; B - as the ratio of the difference of the cross-sectional areas of the internal carotid artery in the place of stenosis and the nearest maximal non-stenotic distal/proximal portion to the distance between them.

Results: In the group of confirmed foci of ischemic lesion of the brain as compared with the group having no ischemic lesions according to the A method, we revealed a statistically significant difference in the parameters of the gradient of luminal narrowing on the distal portion of the internal carotid artery, with no statistically significant differences in the examined parameters revealed on the proximal portion. There were no statistically significant differences in the gradient of luminal narrowing calculated according to the B method on either distal or proximal portion.

Conclusion: The gradient of narrowing of arterial lumen characterizes the degree of incrementing luminal narrowing from the 'normal' (without stenosis) proximal portion of the artery to the area of maximal stenosis and further to free distal lumen, which is an important diagnostic criterion for stenosis severity and prediction of ischemic cerebral lesion. There is yet no sufficient experience in using this index in clinical practice, since it was proposed relatively recently. However, this parameter appears to possess an advantage, primarily a prognostic one, as compared with the classical methods of measuring stenosis by the ECST and NASCET methods. The most preferable should be recognized calculation of the luminal narrowing according to the A method supposing measuring the ratio of the percentage of stenosis (according to the ECST method) of the internal carotid artery to the distance between the near-to-stenosis distal/proximal region without stenosis and the site of maximal narrowing.