Compensatory Enlargement in Coronary and Femoral Arteries Is Related to Neither the Extent of Plaque-Free Vessel Wall Nor Lesion Eccentricity

Abstract

Arteries may demonstrate compensatory enlargement in response to plaque accumulation. It has been proposed that enlargement is achieved by the expansion of the nondiseased (plaque-free) vessel wall. In this study, we assessed this hypothesis. Post mortem, 32 atherosclerotic coronary arteries (left anterior descending, n = 10; left circumflex, n = 11; and right coronary, n = 11) and 54 atherosclerotic femoral arteries were pressure fixed. Cross sections (coronary arteries, n = 537; femoral arteries, n = 1602) were obtained for analysis every 2.5 mm for the coronary arteries and every 5.0 mm for the femoral arteries. From these cross sections, we determined the degree of remodeling and an eccentricity index. Finally, we measured the extent of plaque-free vessel wall. The plaque-free vessel wall was defined as (1) no plaque present or (2) plaque thickness < 0.5 mm. A very weak, negative correlation was observed between the degree of remodeling and the extent of the plaque-free vessel wall (coronary arteries: no plaque r2 = .13, P < .01; < 0.5 mm plaque r2 = .15, P < .05; femoral arteries: no plaque r2 = .02, P < .01; < 0.5 mm plaque r2 = 0.04, P < .01). The degree of remodeling did not correlate with the eccentricity index (coronary arteries r2 = .002, P > .05 and femoral arteries r2 = .001, P > .05). Thus, compensatory enlarged segments did not reveal a larger circumference of plaque-free vessel wall compared with segments that failed to enlarge. This study provides no support for the hypothesis that nondiseased vessel-wall expansion is responsible for compensatory enlargement in atherosclerotic arteries.

Expansive Remodeling Is a Response of the Plaque-Related Vessel Wall in Aortic Roots of ApoE-Deficient Mice

“…dilatory response. This effect would be anticipated to be least pronounced in the plaque-related vessel wall because of endothelial dysfunction, thereby explaining the observation of some investigators, though not all, 25 that outward remodeling is more prominent in the setting of eccentric than concentric plaques. 4,10 Conversely, Glagov et al, 1 using detailed geometrical characterization of human coronary arteries, concluded that the dilatory response is mainly associated with outward bulging beneath plaques.…”

Positive remodeling at 3 year follow up is associated with plaque free coronary wall segment at baseline: A serial IVUS study

“…This cut-off value was based on earlier histological data [19] and IVUS study [20], that also used this criterion to discriminate between presence and absence of plaque. Plaque free wall (PFW) was defined as the arc of the vessel wall having a wall thickness<0.5 mm [19,20] expressed in degrees: PFW ¼ 360 means totally healthy, PFW ¼ 0 means disease with more than 0.5 mm wall thickness over the complete circumference. To determine the PFW on IVUS (IVUS-PFW), the circumference was subdivided into 32 equidistant angles and at each angle the wall thickness was evaluated.…”

Arterial Remodeling

“…It is perhaps because eccentric atherogenesis frequently originates at sites of low or turbulent flow that also impairs outward remodeling that postmortem studies have found no relationship between remodeling and lesion eccentricity or extent of disease-free arc. 41 …”