Factors predicting compensatory vascular remodelling of the carotid artery affected by atherosclerosis

Abstract

Objective: To investigate factors predicting the development of outward remodelling of the carotid artery in patients with atherosclerosis. Design: 130 patients with carotid artery stenosis (15-85% of the vessel diameter) were divided into two groups, based on the presence or absence of outward remodelling of the sclerotic carotid segment on high resolution ultrasonography. Logistic regression analysis was used to evaluate the contribution of haemodynamic, laboratory, and clinical measurements on the development of remodelling, including age, sex, type of stenosis, extent of plaque, per cent diameter stenosis, underlying disease, selected drug treatment, and plasma concentrations of total cholesterol, high density lipoprotein cholesterol, triglyceride, and uric acid. Results: 64 patients (49%) had outward remodelling. Multivariate regression analysis showed that hypertension, the type of plaque, the thickness of the plaque, and the extent of stenosis were independent factors predicting remodelling. The odds ratios of hypertension, unstable shape of plaque, thickness of plaque, and the extent of the stenosis were 6.70, 3.02, 2.04, and 1.05, respectively. Other measurements did not contribute significantly to the estimation of remodelling. Conclusions: Compensatory enlargement of the vessel occurs in about 50% of carotid artery segments with a diameter stenosis of 15-85%. Hypertension and the shape of the plaque are major determinants of the development of outward remodelling. I t has become apparent that blood vessels can enlarge to accommodate atheromatous plaques, forestalling encroachment on the lumen and hence preserving distal flow. Glagov and colleagues were the first to describe this process in the left main coronary artery in necropsy specimens.1 The findings were confirmed clinically in femoral 2 and coronary arteries, 3 using intravascular and epicardial ultrasonography, and in the carotid artery by body surface ultrasonography. This "outward remodelling" consists of a spectrum of structural changes whereby the vascular wall responds to alterations in its haemodynamic environment. Smoking, 4 aging, 5 and hypercholesterolaemia 6 are also thought to be involved in the development of outward vascular enlargement. However, although attempts have been made to investigate the factors participating in compensatory vascular reconstruction, the mechanism of this type of remodelling remains obscure. Our aim in this study was to determine the prevalence of vascular remodelling and to investigate the factors leading to outward remodelling in the atherosclerotic carotid artery, using high resolution cross sectional ultrasonography. METHODS SubjectsThe study population consisted of 165 consecutive patients with 15-85% diameter stenosis of the carotid artery system, determined by B mode ultrasonographic examination. Exclusion criteria were as follows: a major attack of coronary or cerebrovascular disease within one month of the investigation; overt congestive heart failure; cardiogenic shock; loss of consciousness; si...

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