Coronary Blood Flow and Coronary Vascular Reserve

The severity of coronary artery disease (CAD) has traditionally been evaluated by assessing coronary artery anatomy and left ventricular function during cardiac catheterization. The reduction in coronary artery blood flow caused by a particular stenosis has been inferred from its appearance on coronary arteriography.1 It is now well known that the visual estimation of coronary artery stenosis is inaccurate and poorly reproducible because of inter- and intraobserver variation. It also has been shown that the physiologic effects of the majority of coronary obstructions cannot be determined accurately by conventional angiographic appearance.2 Human coronary vascular reserve correlates poorly with percent diameter stenosis and geometry of the lesions.