ABSTRACT
Introduction In the human heart, the ability of the resistance vessels to dilate or to constrict can only be assessed indirectly from measurement of coronary blood flow. The presence of epicardial coronary disease contributes additional resistance to blood flow and, with progressive obstruction, the ability of the vasodilated resistive vessels to accommodate this at times of hyperaemic stress is reduced.1 The anatomical significance of epicardial coronary artery disease may be documented by analysis of coronary arteriograms. However, large intra-and inter-observer variability exist with visual inspection of arteriograms, and despite the use of computer-assisted edge-detection methods,2 to reduce the error and inaccuracy of visual assessment,1,3 poor correlations still exist with post-mortem evaluation of coronary stenoses.4 Furthermore, there is a poor correlation between anatomical estimate of the severity of a coronary stenosis and any physiological measurement of the functional significance of the stenosis,5,6
particularly with lesions in the range of diameter stenoses 50-90%, that is those of most interest in determining functional significance.1
