Vascular remodeling in coronary artery disease

Traditionally, the diagnosis of significant coronary atherosclerotic disease has relied on angiographic techniques. Both histologic analyses and, more recently, intravascular ultrasonography techniques have revealed that a significant atherosclerotic plaque load may be present in epicardial coronary arteries without significant luminal narrowing, consistent with compensatory vessel enlargement or remodeling. In patients with coronary atherosclerosis, more limited structural changes are present in the smaller resistance arterioles, whereas a decrease in luminal area with an increase in wall thickness and perivascular fibrosis are the characteristic structural changes observed in resistance arteries in the presence of systemic hypertension. Further, functional changes, such as impairment of endothelium-mediated vasodilation, are present in epicardial and resistance vessels of patients with coronary atherosclerosis and may influence the progression of this disease and development of ischemic syndromes. The introduction of two-dimensional intravascular and Doppler ultrasonography enables us to study in vivo these morphologic and functional changes. In this article, the knowledge acquired in humans on the mechanisms and clinical relevance of vascular remodeling with the use of these two ultrasonography-based techniques is reviewed. The possibility of using pharmacologic interventions to improve or normalize the vascular response to endothelium-dependent and independent vascular interventions is discussed, with special attention to the efficacy of the inhibition of the angiotensin-converting enzyme.