Vortex Ultrasound Busts Brain Blood Clots Better

A new tool and technique for breaking down blood clots in the brain uses “vortex ultrasound,” a sort of ultrasonic tornado. According to a new study, the method eliminated clots formed in an in vitro model of cerebral venous sinus thrombosis (CVST) faster than existing techniques.

“Our previous work looked at various techniques that use ultrasound to eliminate blood clots using what are essentially forward-facing waves,”

said co-corresponding author Xiaoning Jiang, The new research employs vortex ultrasound, which produces ultrasound waves with a helical wavefront. In other words, as it moves forward, the ultrasound is swirling.

“Based on our in vitro testing, this approach eliminates blood clots more quickly than existing techniques, largely because of the shear stress induced by the vortex wave,”

said Jiang, professor of mechanical and aerospace engineering at North Carolina State University.

Cerebral Venous Sinus Thrombosis Increasing

Because CVST clots increase pressure on blood vessels in the brain, the fact that this new technique works quickly is critical. The increased pressure raises the risk of a hemorrhage in the brain, which can be catastrophic for patients.

“Existing techniques rely in large part on interventions that dissolve the blood clot. But this is a time-consuming process. Our approach has the potential to address these clots more quickly, reducing risk for patients,”

said Chengzhi Shi, co-corresponding author and an assistant professor of mechanical engineering at Georgia Institute of Technology.

Cerebral venous sinus thrombosis happens when a blood clot forms in the veins that drain blood from the brain. CVST incidence rates in the United States were between 2 and 3 per 100,000 in 2018 and 2019, and the rate appears to be increasing.

Jiang noted that current CVST treatments fail in 20-40% of cases.

Ultrasound Faster Than Drug Treatments

vortex ultrasound catheter
The schematic view of the sonothrombolysis process with a vortex ultrasound transducer. The vortex ultrasound transducer is installed in a 9-Fr catheter and inserted into the blood vessel with a blood clot. The microbubble cavitation agents are injected through a drug delivery lumen of the catheter. The blood clot breaks up under the shear stress and cavitation effects of vortex ultrasound. Credit: Research (2023). DOI: 10.34133/research.0048

The new device is made up of a single transducer that is specifically designed to create the swirling, vortex effect. The transducer is small enough to fit into a catheter, which is then passed through the circulatory system to the location of the blood clot.

The researchers used cow blood in a 3D-printed model of the cerebral venous sinus for proof-of-concept in vitro testing.

“Based on available data, pharmaceutical interventions to dissolve CVST blood clots take at least 15 hours, and average around 29 hours. During in vitro testing, we were able to dissolve an acute blood clot in well under half an hour,”

Shi said.

Next Steps

There is a risk of harm during any catheterization or surgical intervention, such as damaging the blood vessel itself.

To address this issue, the researchers conducted experiments on animal blood vein samples using vortex ultrasound. These tests revealed no damage to the blood vessel walls.

The researchers also tested to see if the vortex ultrasound caused any significant damage to red blood cells. They discovered that there was no significant damage to red blood cells.

“The next step is for us to perform tests using an animal model to better establish the viability of this technique for CVST treatment. If those tests are successful, we hope to pursue clinical trials,”

Jiang said.

“And if the vortex ultrasound ever becomes a clinical application, it would likely be comparable in cost to other interventions used to treat CVST,”

added Shi.

The research was supported by the National Institutes of Health and the National Science Foundation.

Reference:
  1. Bohua Zhang, Huaiyu Wu, Howak Kim, et al. A Model of High-Speed Endovascular Sonothrombolysis with Vortex Ultrasound-Induced Shear Stress to Treat Cerebral Venous Sinus Thrombosis. Research, 11 Jan 2023, DOI: 10.34133/research.0048

 

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