Atherosclerosis, a buildup of plaque, can lead to heart disease, artery disease, and chronic kidney disease and is traditionally treated by inserting and inflating a balloon to expand the artery. Other treatments based on lasers can remove blockages rather than simply compressing them but are used infrequently, because they have a high risk of complication and low efficacy. Now, researchers have developed a method that combines a low-power laser with ultrasound to remove arterial plaque safely and efficiently.

High-power laser treatments direct thermal energy to vaporize water in the artery and create a vapor bubble, which expands and collapses to break the plaque. Similarly, the technology, pioneered by researchers at the University of Kansas (Lawrence, KS, USA) uses a low-power nanosecond pulsed laser to produce microbubbles. The addition of irradiation from ultrasound causes the microbubbles to expand, collapse, and disrupt the plaque. Because it destroys rather than compresses the plaque, the combination technique will have a lower restenosis rate, or re-narrowing of the artery, compared to balloon angioplasty or stenting. The control provided by the ultrasound and the low-power laser will lower the risk of dissection and perforation in arteries.

The team performed ex vivo experiments on carotid artery plaque samples and pork belly samples, and they are currently planning to perform in vivo experiments. Both the laser and ultrasound techniques are commonly used by clinicians and should be easy to teach and implement following the in vivo studies. Combining low-power lasers and ultrasound techniques is not limited to atherosclerosis treatments. The researchers are also using the methodology for photo-mediated ultrasound therapy and ultrasound-assisted endovascular laser thrombolysis. The former can be used to remove abnormal microvessels in the eye to prevent blindness, while the latter can dissolve blood clots in veins.

"In conventional laser angioplasty, a high laser power is required for the entire cavitation process, whereas in our technology, a lower laser power is only required for initiating the cavitation process," said Rohit Singh of the University of Kansas. "Overall, the combination of ultrasound and laser reduces the need for laser power and improves the efficiency of atherosclerotic plaque removal."

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