Abstract 15587: Diagnostic Ultrasound Induced Inertial Cavitation of Microbubbles Improves Microvascular Re-Flow Following Thrombotic Microembolization to a Greater Degree than Stable Cavitation
Background: Feedback cavitation detection (FCD), when combined with with guided therapeutic impulses (TI) from the same diagnostic transducer, may provide mechanistic information for determining how ultrasound and microbubbles restore microvascular flow following micro-thrombotic embolization in the absence of anticoagulation or fibrinolysis.
Hypothesis: We hypothesized that dominant inertial cavitation (IC) feedback during an intravenous (IV) microbubble infusion would be optimal for restoring microvascular flow following thrombotic occlusion.
Methods: Using a 1.7 MHz modified diagnostic ultrasound system capable of FCD (Philips S5-1), we measured cavitation responses within the microvasculature of a rat hindlimb in response to different mechanical indices (MI) ranging from 0.4 to 1.8 (all 20 usec pulse duration). Subsequent to this, thrombotic microvascular obstruction was created in the rat hindlimb muscle by injecting <200 micron diameter thrombi into the common iliac supplying the hindlimb. Microvascular occlusion was confirmed with low MI non-destructive imaging (NDI) at 0.2 MI during a continous IV Definity (Lantheus) microbubble infusion. After occlusion, rats were randomized to TI that produced dominant stable cavitation (SC) versus those that produced dominant inertial cavitation (IC) during the same microbubble infusion. All treatment times were 10 minutes, and all imaging and TI were applied through either a three or six centimeter tissue mimicking phantom (TMP) to simulate transthoracic attenuation. NDI alone (without TI) was used as a control group. Skeletal blood volume (SBV) was quantified using Q lab software before and after randomized treatments.
Results: A total of 20 rats were randomly assigned to the three treatment groups. The MI impulses that produced dominant IC produced the greatest recovery of SBV through both three and six centimeter TMP attenuation depths (p<0.0001 compared to both NDI and SC TI). Post-mortem histology confirmed no microvascular damage with any treatment group.
Conclusions: TI from a modified diagnostic transducer that induce dominant IC of microbubbles are essential in restoring microvascular reflow following thrombotic embolization.
Author Disclosures: F. Xie: None. J. Lof: None. E. Everbach: None. F. Vignon: None. W.T. Shi: None. J. Powers: None. S.J. Radio: None. T.R. Porter: Research Grant; Modest; GE Healthcare, Lantheus Medical Images. Research Grant; Significant; Philips Research North America, Astellas Pharma.
- © 2014 by American Heart Association, Inc.