Researchers have developed a new tool and technique that uses “vortex ultrasound” — a sort of ultrasonic tornado — to break down blood clots in the brain. The new approach worked more quickly than existing techniques to eliminate clots formed in an in vitro model of cerebral venous sinus thrombosis (CVST).
“Our previous work looked at various techniques that use ultrasound to eliminate blood clots using what are essentially forward-facing waves,” says Xiaoning Jiang, co-corresponding author of a paper on the work. “Our new work uses vortex ultrasound, where the ultrasound waves have a helical wavefront.
“In other words, the ultrasound is swirling as it moves forward,” says Jiang, who is the Dean F. Duncan Professor of Mechanical and Aerospace Engineering at North Carolina State University. “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.”
The new tool consists of a single transducer that is specifically designed to produce the swirling, vortex effect. The transducer is small enough to be incorporated into a catheter, which is then fed through the circulatory system to the site of the blood clot.
For proof-of-concept in vitro testing, the researchers used cow blood in a 3D-printed model of the cerebral venous sinus.
“Based on available data, pharmaceutical interventions to dissolve CVST blood clots take at least 15 hours, and average around 29 hours,” Shi says. “During in vitro testing, we were able to dissolve an acute blood clot in well under half an hour.”
During any catheterization or surgical intervention there is a potential risk of harm, such as damaging the blood vessel itself. To address this issue, the researchers performed experiments applying vortex ultrasound to animal blood vein samples. Those tests found no damage to the walls of the blood vessels.
The researchers also conducted tests to determine whether the vortex ultrasound caused significant damage to red blood cells. They found that there was not substantial damage to red blood cells.
