Determination of coronary flow reserve by digital angiography: validation of a practical method not requiring power injection or electrocardiographic gating.

Although coronary flow reserve is a well established measure of the physiologic significance of atherosclerotic stenosis, cumbersome methodology has prevented its widespread clinical application. This study evaluated a new simplified method of measuring coronary flow reserve based on indicator-dilution analysis of hand-injected digital coronary arteriograms. In five dogs, the circumflex artery was instrumented with an angiographic catheter, an electromagnetic flow probe and a pneumatic occluder. For each of 18 stenoses of varying severity, arteriograms were obtained under basal conditions and during papaverine-induced hyperemia. A pair of background-corrected arterial time-density curves was generated for each stenosis by off-line computer analysis of the circumflex artery arteriograms. Coronary flow reserve was calculated from the measured areas of the time-density curves and the known volume of contrast medium used to produce each curve. Angiographic flow reserve ranged from 0.9 to 6.1 (mean 2.99), whereas electromagnetic flow reserve ranged from 0.7 to 6.9 (mean 3.02). Angiographic and electromagnetic measurements of coronary flow reserve correlated well (r = 0.86). This study establishes that indicator-dilution analysis of 30 frames/s digital coronary arteriography permits the accurate determination of coronary flow reserve. The technique described employs hand injection of small doses of radiographic contrast medium using conventional catheters, and should be readily applicable to the study of human coronary artery disease.