ABSTRACT
Intravascular ultrasound (IVUS) is a tomographic technique with the ability to provide a direct and comprehensive visualization of atherosclerotic plaque and residual coronary lumen in vivo.1-4 In addition, the echogenic characteristics of the plaque may be used as a surrogate to determine its underlying histology.3 This information has represented a major advancement in our understanding of coronary artery disease, a disease of the vessel wall.1-4 Until very recently, selective coronary angiography was the only available technique to study coronary anatomy in patients. Lumen stenoses are readily detected by angiography, a technique well suited for depicting the coronary lumen silhouette as a shadowgram image.1-5 Comparing the minimal lumen diameter of the target lesion with the adjacent angiographically normal reference segment provides a valid measurement of relative lumen narrowing. This, in turn, has been classically considered a valid surrogate of stenosis severity. Angiography provides a rough estimation of the physiologic implications of coronary lesions, but fails to provide critical anatomic insights to predict lesion-related flow limitations.5-8 However, nowadays the limitations of conventional angiography are well known.5-7 In addition, despite complete and exhaustive angiographic examination, we often encounter lesions that elude accurate characterization. The paradigm of considering coronary angiography as the ‘gold standard’ for the diagnosis of coronary artery disease has been critically challenged.1-7 This is relevant because our previous preoccupation with ‘coronary luminology’5 has recently turned into concerns on how to gauge precise physiologic insights, a critical issue in decisions concerning coronary interventions.8
