Quantitative assessment of myocardial perfusion during graded coronary artery stenoses by intravenous myocardial contrast echocardiography

OBJECTIVES The purpose of this study was to examine whether coronary stenos es of variable severity could be quantitatively assessed by analysis of myo cardial perfusion as determined by intravenous (IV) myocardial contrast ech ocardiography. BACKGROUND Recently, new contrast agents and imaging technology have been d eveloped that may enable improved assessment of myocardial perfusion by IV contrast injection. METHODS Variable obstruction of the left anterior descending (LAD) coronary artery in dogs was produced by a screw occluder. Coronary artery flow was measured with a transit time flowmeter during baseline, pharmacological vas odilation, a non-flow-limiting stensosi at rest in conjunction with vasodil ation, a flow-limiting stenosis, and total occlusion. Myocardial contrast e chocardiography was performed after IV injection of the contrast agent NC 1 00100 . Time-intensity curves were obtained off-line for the LAD risk area and the adjacent left circumflex (LCx) territory, and peak background-subtr acted video intensity was determined. Fluorescent microspheres were injecte d at each intervention for determination of regional myocardial blood flow. RESULTS During non-flow-limiting stenosis, flow limiting stenosis and total occlusion, LAD/LCx ratios of peak myocardial videointensity and blood flow decreased proportionately. Both LAD/LCx ratios of video intensity and bloo d flow identified the non-flow-limiting and the flow-limiting stenoses as w ell as total occlusion of the LAD artery. A significant correlation between LAD/LCx video intensity and blood flow ratios was observed (r = 0.83, p < 0.0001). CONCLUSIONS The degree of blood flow mismatch between ischemic and normal m yocardial regions during graded coronary stenoses can be estimated in the d og by quantitative assessment of myocardial perfusion produced by IV myocar dial contrast echocardiography. (C) 2001 by the American College of cardiol ogy.