Sonothrombolysis of intra-catheter aged venous thrombi using microbubble enhancement and guided three-dimensional ultrasound pulses

Background: Central venous and arterial catheters are a major source of thromboembolic disease in children. The investigators hypothesized that guided high-mechanical index (MI) impulses from diagnostic three-dimensional (3D) ultrasound during an intravenous microbubble infusion could dissolve these thrombi. Methods: An in vitro system simulating intracatheter thrombi was created and then treated with guided high-MI impulses from 3D ultrasound, using low-MI microbubble sensitive imaging pulse sequence schemes to detect the microbubbles. Ten aged thrombi >24 hours old were tested using 3D ultrasound coupled with a continuous diluted microbubble infusion (group A) and 10 with 3D ultrasound alone (group B). Results: The mean thrombus age was 28.6 hours (range, 26.6-30.3 hours). Group A exhibited a 55 ± 19% reduction in venous thrombus size compared with 31 ± 10% in group B (P = .008). Feasibility testing was performed in four pigs, establishing an in vivo model to investigate further the efficacy of this approach. Conclusions: Sonothrombolysis of aged intracatheter venous thrombi can be achieved with commercially available microbubbles and guided high-MI ultrasound from a diagnostic 3D transducer.