A stroke occurs as a result of some part of the brain failing to receive oxygen, usually because a blood vessel has a clot or has ruptured. Strokes are the fifth most common cause of death in the United States, and are one of the leading causes of disability. If a blood clot can be cleared soon after the stroke occurs, the chances of the patient surviving without severe disabilities are dramatically improved. To that end, researchers from MIT have developed robotic thread that is thin enough to navigate through the brain’s blood vessels in order to clear a clot.
Similar endovascular procedures are already commonly used to clear blood clots today. Those procedures are done using a thin wire that a surgeon manually guides from an entry point at a major artery, such as the groin. The wire is then fed through the artery until it reaches the brain and the clot can be cleared. The problem is that it’s difficult to successfully guide that wire through the winding blood vessels of the brain, and the procedure requires radioactive fluoroscopy to capture images of the brain that are used to navigate those blood vessels.
Fluoroscopy relies on X-rays, which don’t emit enough radiation to harm a patient in a single procedure. They can, however, expose the surgeon to significant amounts of radiation over time. This robotic thread makes it easier for surgeons to reach a blood clot, and it keeps them away from the radiation of fluoroscopy X-rays.
The thread is made up of a core of springy nickel-titanium alloy called nitinol. That is then coated in a layer of paste embedded with magnetic particles. Finally, a layer of hydrogel is bonded over the top of the magnetic covering. The hydrogel reduces friction and makes it easily to slide the robotic thread through tight blood vessels. During the procedure, a surgeon working in a separate room can use a large magnet to guide the thread through to the clot and clear it. In tests with a silicone replica of a brain’s blood vessels, the robotic thread performed well. In the future, this could improve the survival rate of strokes, while also protecting surgeons from repeated radiation exposure.
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Author: Cameron Coward