Digital radiographic assessment of coronary flow reserve

Abstract

Although the accurate measurement of coronary blood flow by electromagnetic flow meter [1] and myocardial perfusion by radionuclide tagged particles [2] are relatively easy techniques to perform under experimental conditions, the clinical assessment of these important physiologic parameters is both considerably more difficult and inaccurate. Current methods for measuring human coronary blood flow or myocardial perfusion include thermodilution coronary sinus flow [3], inert gas washout [4], thallium-201 scintigraphy [5], doppler catheter [6] and coronary videodensitometry [7, 8]. In general, these techniques usually employ exercise, cardiac pacing, or hyperemic stimuli to provide additional information on the ability of the coronary circulation to respond to increased myocardial oxygen demands. Thallium scintigraphy has been the most widely used technique and has provided the clinician with a relatively simple, non-invasive tool for visualizing myocardial perfusion. The accuracy of this test has usually been judged using coronary arteriography as the standard [9], although the latter measures coronary anatomy rather than physiology. This fact underscores the continued use of selective coronary arteriography as the definitive standard for the assessment of human coronary disease. Much of this dependence is based upon experimental data showing a close correspondence between percent luminal narrowing and alterations in coronary flow reserve [10, 11].