Experimental Validation of Quantitative Coronary Arteriography for Determining Pressure-Flow Characteristics of Coronary Stenosis

SUMMARY The applicability of classic fluid dynamic equations to tapering stenoses in vasoactive, flexible coronary arteries in vivo and the validity of quantitative coronary arteriography was tested by comparing experimentally measured and x-ray-predicted pressure gradients at equal flows for left circum-flex stenoses in five dogs chronically instrumented with a balloon. occluder, flow probe, and proximal and distal catheters for.injection of contrast media or recording distal coronary pressure. Arterial borders on cut-film orthogonal arteriograms were digitized and computer processed into a three-dimensional recon-struction of the stenosis. The total pressure gradient was calculated from stenosis dimensions using classic fluid dynamic equations. Over the full range offlow, the correlation of x-ray-predicted and experimentally measured pressure gradient for 51 separate stenoses was y = 1.11x + 0.75, r = 0.95, p < 0.001, with a standard deviation about the regression line of 9.4 mm Hg and with 95 % of x-ray-predicted values falling within ± 18.5 mm Hg of the experimentally measured values (95. % confidence limits). Mean experimentally measured and x-ray-predicted pressure gradients were 10.1 7.7 mm Hg ( ± SD) and 10.9 + 5.6 mmn Hg at low flow and 48.2 ± 23.1 mm Hg and 55.8 ± 28.8 mm Hg at high flow, respectively. The mean difference was 3.9 ± 4.3 mm Hg at rest flow and 11.9 ± 10.5 mm Hg at high flow. For all data over the entire range of flows, the frequency distribution of differences between x-ray-predicted and experimentall