ASE: Ultrasound therapy may dissolve intravascular thrombi

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Intravenous microbubble contrast and high-pulse ultrasound may provide a non-invasive method for treating catheter-related blood clots in pediatric patients who need long term IV use, according to a study presented this week at the American Society of Echocardiography (ASE) 21st annual scientific sessions in San Diego.

Current methods of prescribing blood thinning medication and/or removing and replacing catheters to treat blood clots can be dangerous and painful, especially in children, according to the researchers.

“We traditionally dissolve blood clots by administering a very potent blood thinning medication, but giving this medication to a small child is extremely risky,” said lead author Shelby Kutty, MD, of the University of Nebraska and Creighton University in Omaha. “Blood thinning medications could cause a stroke or lead to excessive bleeding in small patients.”

Researchers developed an in vitro system simulating intra-catheter thrombi and treated the clots with guided high mechanical index impulses emitted by diagnostic ultrasound during microbubble infusion therapy.

The study used low microbubble sensitive imaging pulse sequence schemes to detect the microbubbles. Venous thrombi were prepared from healthy pigs and aged for more than 24 hours within a silastic tubing. A blood sample was introduced into tubing center to facilitate red blood cell deposition on its rough surface and serum formation above it. Tubing was connected to an in vitro flow system. Ten samples (group A) were tested using 3D ultrasound paired with continuous infusion diluted Definity contrast agent (Perflutren Lipid Microsphere, Lantheus Medical Imaging). Another 10 samples (group B) were tested with 3D ultrasound alone.

After treatment, Kutty and colleagues found that the mean thrombus weight of group A was 19.1 +/- 8 mg and 29 +/- 5.6 in group B. Ten minutes of ultrasound and microbubble treatment resulted in a 55 +/- 19 percent reduction in venous thrombus size.

The study demonstrates that cardiac ultrasound can serve as a therapeutic tool, said Kutty. [“This study] will broaden the thinking of scientists looking for less invasive treatments of other conditions,” predicted Kutty.