Vascular Remodeling During Atherosclerotic Plaque Build Up Is Controlled by the Plaque Free Part of the Vessel Wall

Glagov et al. observed that positive, compensatory vascular remodeling during plaque build up prevents lumen narrowing until plaque burden, this is the relative plaque area to media bounded area, exceeds a threshold of 40% [1]. Until now it is not clear what mechanism controls the compensatory vascular remodeling during the atherosclerotic plaque build up and what determines absence or limits compensatory vascular remodeling. Plaque burden does not seem to reflect a parameter, which could serve as a limiting step in the known control process in the vascular system. For instance, healthy arteries control vascular remodeling by fluid flow induced shear stress via a number of endothelium dependent pathways [2]. The endothelium at the atherosclerotic plaque side is considered to be dysfunctional [2] and might thereby limit the remodeling process. Since plaques are mostly eccentric, we hypothesize that the healthy part of the artery (or plaque free wall) will respond to changes in shear stress and will determine the capacity of the arteries to remodel up till the moment of complete circumferential involvement of the disease. We investigated whether the size of the plaque free wall contributes to vascular remodeling over a 3 year period using serial intravascular ultrasound measurements by determining 1) the frequency of positive remodeling in segments with varying size of plaque free vessel wall 2) the degree of vascular remodeling for segments with varying size of plaque free vessel wall.