Abstract 13249: Effect of Underlying Coronary Atherosclerosis on the Effectiveness of Three Dimensional Guided High Mechanical Index Impulses and Intravenous Microbubbles in Treating Acute Coronary Thromboses
Although animal models have demonstrated that guided high mechanical index (MI) impulses from a diagnostic transducer improve microvascular recanalization in acute ST segment elevation myocardial infarction (STEMI), the effect of underlying coronary atherosclerosis on the success of diagnostic ultrasound and microbubble mediated thrombus dissolution is unknown. The purpose of this study was to compare microvascular flow and epicardial recanalization (ER) rates with guided high MI impulses in normal versus atherosclerotic pigs having a STEMI.
Methods: In 14 normal pigs (Group I), an acute left anterior descending (LAD) thrombotic coronary occlusion was created. Pigs subsequently received aspirin, heparin and ½ dose fibrinolytic agent (Tenecteplase; Genetech), followed by randomization to either: 1) no additional treatment (control) or 2) a continuous infusion of non-targeted microbubbles (MRX 801; NuvOx Pharma). High MI impulses from a three dimensional transducer (3D/MB) were applied whenever low MI imaging indicated contrast from microbubbles within the risk area. ER rates, ST segment resolution, and changes in myocardial blood volume (MBV) fraction with contrast echo were compared. In a set of six atherosclerotic pigs on a high fat diet with underlying 10–50% intimal plaque in the LAD (Group II), the same LAD thormbosis was created to test the effectiveness of 3D/MB in this setting. The same doses of aspirin, heparin, and TNK were given to Group II pigs as in Group I pigs.
Results: 3D/MB treatment did not improve the ER rates in Group I pigs (29%) but did improve MBV fraction in both the central and peripheral portions of the risk area (p=0.03 compared to control) independent of ER. In Group II pigs, fasting cholesterol levels were 353 ± 90 mg/dl (p<0.01 compared to Group I). In this group, 3D/MB treatment resulted in ER in all six pigs (p=0.02 compared to Group I), and myocardial contrast defect size at the plateau intensity decreased from 1.62±0.56 cm2 to 0.44±0.42 cm2 following therapy (p=0.0005).
Conclusions: In atherosclerotic pigs, guided high MI impulses from a three dimensional diagnostic transducer during non-targeted microbubble infusion improves epicardial and microvascular revascularization to a greater degree than in normal pigs.
- © 2010 by American Heart Association, Inc.