703-2 Detection of Regional Perfusion Abnormalities During Adenosine Stress Echocardiography Using Intravenous Perfluoropropane-enhanced Sonicated Dextrose Albumin

Altering sonicated dextrose albumin microbubble gas diffusivity and solubility with perfluoropropane results in microbubbles which produce myocardial contrast (MC) following an intravenous injection. It is unknown whether the intensity of MC produced will accurately identify flow abnormalities due to coronary ischemia. Accordingly, we measured peak myocardial videointensity (PMVI) from the left anterior descending (LAD) and left circumflex (LCX) perfusion beds following intravenous 0.06ml/kg injections of perfluoropropane enhanced sonicated dextrose albumin (PESDA). The same injection was given under resting conditions, and during peak adenosine stress (ADS) (140μ/kg/min) in 6 open-chest dogs who had either no stenosis or an angiographically significant stenosis in the proximal LCX coronary artery (using quantitative angiography). PMVI from the LCX perfusion beds during ADS was compared with actual flows measured with a Transonic Doppler cuff around the LCX, and quantitative angiographic (QA) severity. Wall thickening (WT) responses were also measured as the difference in LCX perfusion bed end-diastolic and end-systolic wall thickness.Injections of PESDA were given during 10 different stenosis severities in the six dogs (range 0-87% diameter). There was a strong correlation between PMVI in the LCX bed and actual LCX flow by Doppler (r=0.75, p<0.001). In the absence of a >50% stenosis, the PVI ratio in the LCX perfusion bed during ADS compared to baseline PVI ranged from 1.8 to 2.1, while the Doppler flow ratios in the LCX ranged from 2.0 to 4.2. When a greater than 70% diameter stenosis was present in the LCX, the PVI ratio during ADS compared to baseline ranged from 0.8 to 1.4 (P=0.02; compared to PVI ratio without >70% stenosis), while the simultaneous Doppler ratios also decreased to a range of 0.5 to 2.8. There was a close correlation between Doppler flow ratios in the LCX and PMVI ratios during ADS (r=0.75; p<0.05). WT increased during ADS by 20% or greater in three of the six dogs despite a greater than 70% diameter stenosis. These data indicate that the background-subtracted PMVI produced with intravenous PESDA can identify abnormalities in coronary perfusion during ADS. This ultrasound contrast agent, therefore, could be a non-invasive method of determining myocardial perfusion abnormalities during adenosine stress echocardiography in humans