EFFECT OF SIGNIFICANT 2-VESSEL VERSUS ONE-VESSEL CORONARY-ARTERY STENOSIS ON MYOCARDIAL CONTRAST DEFECTS OBSERVED WITH INTERMITTENT HARMONIC IMAGING AFTER INTRAVENOUS CONTRAST INJECTION DURING DOBUTAMINE STRESS ECHOCARDIOGRAPHY

Objectives. We sought to determine the effect of multivessel as oppose d to single-vessel coronary artery stenosis on myocardiail contrast de fects observed with intermittent harmonic imaging and intravenous perf luorocarbon-exposed sonicated dextrose albumin contrast injection. Bac kground. Intermittent harmonic imaging has permitted the detection of myocardial perfusion abnormalities with an intravenous ultrasound cont rast agent. The effect of multivessel disease on inducibility of these perfusion abnormalities is unknown. Methods. In 10 dogs, intravenous injections of contrast agent were given at rest and during dobutamine stress echocardiography when a single coronary artery stenosis was pre sent (greater than or equal to 50% diameter by quantitative angiograph y) and again when a second stenosis (range 44% to 92% diameter) was pr esent in the vessel supplying the adjacent perfusion bed. The peak myo cardial contrast was visually and quantitatively assessed in the mid a nd lateral regions of the perfusion bed of the first stenosis (origina l stenosis zone) in the presence of one-and two vessel stenosis. Resul ts. Peak myocardial contrast defects in both the mid and lateral segme nts of the original stenosis zone during dobutamine stress echocardiog raphy was significantly lower when two-vessel stenosis,vas present (p = 0.015), especially in the lateral segment. The spatial extent of the perfusion defect in the original stenosis zone risk area increased si gnificantly when two vessel stenosis was present, and correlated close ly with actual risk area (r = 0.99). Previous total occlusion followed by reperfusion of the vessel supplying the original stenosis zone sig nificantly increased the amount of collateral activity between perfusi on beds. Conclusions. Collateral how limits the spatial extent of indu cible ischemia within the risk area of single vessel stenosis. Restor ing blood how to one perfusion bed reduces the extent of a perfusion a bnormality that can be induced in an adjacent stenosed bed. (C) 1997 b y the American College of Cardiology.