NONINVASIVE IDENTIFICATION OF ACUTE MYOCARDIAL-ISCHEMIA AND REPERFUSION WITH CONTRAST ULTRASOUND USING INTRAVENOUS PERFLUOROPROPANE-EXPOSEDSONICATED DEXTROSE ALBUMIN

Objectives. The purpose of this study was to determine whether intrave nous dextrose albumin sonicated with a commonly used gas of low blood solubility and diffusivity (perfluoropropane) could identify acute myo cardial ischemia and reperfusion. Background. Recently, it has been de monstrated that dextrose albumin sonicated with gases that have low bl ood solubility and diffusivity results in microbubbles capable of cons istently producing myocardial ultrasound contrast after intravenous in jection. It remains to be determined, however, whether this contrast a gent can visually detect the myocardial blood how abnormalities seen w ith acute ischemia or stunned myocardium after reperfusion. Methods. W e gave intravenous injections (0.06 ml/kg body might) of perfluoroprop ane-exposed sonicated dextrose albumin to 10 open chest dogs. The meas ured degree of myocardial contrast (0+ to 2+) and background-subtracte d peak anterior myocardial videointensity produced from each injection were measured at three stages: 1) under baseline conditions, 2) durin g acute ischemia produced by a proximal left anterior descending coron ary artery ligation lasting 10 to 120 min, and 3) after reflow was est ablished. Coronary blood flow was monitored during all injections by u sing an ultrasound flow probe placed around the left anterior descendi ng artery. Results. Coronary blood how ranged from 0 to 137 ml/min, an d peak myocardial videointensity after intravenous administration of p erfluoropropane-exposed sonicated dextrose albumin ranged from 0 to 70 gray scale U. There ms consistent visual myocardial opacification in all dogs during baseline conditions and a visually evident decrease in myocardial contrast in the left anterior descending artery distributi on after ligation. A relative increase in contrast in this same distri bution after intravenous contrast agent administration occurred in 7 o f the 10 dogs during reflow. Quantitatively, there was an excellent co rrelation in individual dogs between peak myocardial videointensity an d coronary how at all stages (mean correlation coefficient 0.95 +/- 0. 04, range 0.87 to 0.99). Conclusions. Perfluoropropane-exposed sonicat ed dextrose albumin is an ultrasound contrast agent that can visually identify myocardial perfusion abnormalities from a peripheral venous i njection.