Acoustic Activation Imaging With Intravenous Perfluoropropane Nanodroplets Results in Selective Bioactivation of the Risk Area.

Abstract

BACKGROUND: Acoustically activatable perfluoropropane droplets (PD) can be formulated from commercially available microbubble preparations. Diagnostic transthoracic ultrasound frequencies have resulted in acoustic activation (AA) predominately within myocardial infarct zones (IZ). OBJECTIVE: We hypothesized that the AA area following acute coronary ischemia/reperfusion (I/R) would selectively enhance the developing scar zone, and target bioeffects specifically to this region. METHODS: We administered intravenous PD in 36 rats and 20 pigs at various stages of myocardial scar formation (30&#x2009;minutes, 1&#x2009;day, and 7&#x2009;days post I/R) to determine what effect infarct age had on the AA within the IZ. This was correlated with histology, myeloperoxidase activity, and tissue nitrite activity. RESULTS: The degree of AA within the IZ in rats was not associated with collagen content, neutrophil infiltration, or infarct age. AA within 24&#x2009;hours of I/R was associated with increased nitric oxide utilization selectively within the IZ (P&#x2009;<&#x2009;.05 compared with remote zone). The spatial extent of AA in pigs correlated with infarct size only when performed before sacrifice at 7&#x2009;days (r&#x2009;=&#x2009;.74, P&#x2009;<&#x2009;.01). CONCLUSIONS: Acoustic activation of intravenous PD enhances the developing scar zone following I/R, and results in selective tissue nitric oxide utilization.