Intravenous perfluoropropane-exposed sonicated dextrose albumin produces myocardial ultrasound contrast that correlates with coronary blood flow

If microbubble gas blood solubility and diffusivity are reduced, the persistence (and hence ultrasound reflectivity) of the microbubble in blood is prolonged. Recently we have sonicated a multifold dilution of human albumin with 5% dextrose while exposed to gases of low blood solubility and diffusivity and produced microbubbles that consistently opacify the myocardium after intravenous injection. The objective of this study was to test the hypothesis that a gas with very low diffusivity, perfluoropropane, when introduced into dextrose albumin during sonication, would produce visually evident myocardial ultrasound contrast after intravenous injection compared to sonicating with gases that have more rapid diffusivity. Second, we sought to determine whether the degree of contrast (peak myocardial videointensity) achieved with this agent would correlate with coronary blood flow. In eight open-chest dogs, intravenous injections of dextrose albumin sonicated with either room air, sulfur hexafluoride, or perfluoropropane (PESDA) were given under baseline conditions. PESDA injections were repeated when coronary flow was increased during low-dose dobutamine infusion. Left anterior descending coronary blood flow was monitored with a transit-time flow probe. Background-subtracted anterior myocardial peak videointensity was measured after each injection. Visible myocardial opacification was seen in 100% of the 0.04 to 0.08 ml/kg intravenous injections of PESDA. No significant myocardial contrast was observed with the same doses of intravenous room air- or sulfur hexafluoride-exposed sonicated dextrose albumin. There was a strong correlation between left anterior descending coronary artery flow (range 17 to 96 ml/min) and myocardial peak videointensity (r=0.75; p<0.0001) in all dogs. We conclude that intravenous injections of PESDA can safely produce consistent myocardial ultrasound contrast. The peak videointensity produced correlates with changes in coronary blood flow. Therefore this agent could be used to quantify coronary blood flow noninvasively.