Noninvasive identification of acute myocardial ischemia and reperfusion with contrast ultrasound using intravenous perfluoropropane-exposed sonicated dextrose albumin.

OBJECTIVES

The purpose of this study was to determine whether intravenous dextrose albumin sonicated with a commonly used gas of low blood solubility and diffusivity (perfluoropropane) could identify acute myocardial ischemia and reperfusion.

BACKGROUND

Recently, it has been demonstrated that dextrose albumin sonicated with gases that have low blood solubility and diffusivity results in microbubbles capable of consistently producing myocardial ultrasound contrast after intravenous injection. It remains to be determined, however, whether this contrast agent can visually detect the myocardial blood flow abnormalities seen with acute ischemia or stunned myocardium after reperfusion.

METHODS

We gave intravenous injections (0.06 ml/kg body weight) of perfluoropropane-exposed sonicated dextrose albumin to 10 open chest dogs. The measured degree of myocardial contrast (0+ to 2+) and background-subtracted peak anterior myocardial videointensity produced from each injection were measured at three stages: 1) under baseline conditions, 2) during acute ischemia produced by a proximal left anterior descending coronary artery ligation lasting 10 to 120 min, and 3) after reflow was established. Coronary blood flow was monitored during all injections by using an ultrasound flow probe placed around the left anterior descending artery.

RESULTS

Coronary blood flow ranged from 0 to 137 ml/min, and peak myocardial videointensity after intravenous administration of perfluoropropane-exposed sonicated dextrose albumin ranged from 0 to 70 gray scale U. There was consistent visual myocardial opacification in all dogs during baseline conditions and a visually evident decrease in myocardial contrast in the left anterior descending artery distribution after ligation. A relative increase in contrast in this same distribution after intravenous contrast agent administration occurred in 7 of the 10 dogs during reflow. Quantitatively, there was an excellent correlation in individual dogs between peak myocardial videointensity and coronary flow at all stages (mean correlation coefficient 0.95 +/- 0.04, range 0.87 to 0.99).

CONCLUSIONS

Perfluoropropane-exposed sonicated dextrose albumin is an ultrasound contrast agent that can visually identify myocardial perfusion abnormalities from a peripheral venous injection.