The new technique improves success rates in the treatment of strokes and other clot -related diseases

When treating an ischemic stroke – where a clot prevents oxygen flow from the brain – each minute counts. The faster the doctors can remove the clot and restore blood flow, the more brain cells will survive and the more likely the patients have a good effect. But current technologies only successfully remove the clots in the first test about 50% of the time, and in about 15% of cases, they fail.

Stanford Engineering researchers have developed a new technique called Milli-Spinner thrombectomy that could significantly improve success rates in the treatment of strokes, as well as heart attacks, pulmonary embolism and other disease-related diseases. In a document published on June 4 at NatureResearchers have used both flow models and animal studies to show that Milli-Spinner significantly exceeds available therapies and offers a new approach to rapid, easy and complete removal of the thrombus.

For most cases, we double the effectiveness of current technology and the toughest clots – which we only remove about 11% of the time with current devices – we take the artery open to the first test 90% of the time. It is incredible. This is a marine change technology that will drastically improve our ability to help people. ”

Jeremy Hate, co-author, Head of Neuroimaging and Neurodexual Appeal to Stanford and Associate Professor of Radiology

Exploiting the tangles

Blood clots are held by confused fibrous, a hard, protein thread that traps red blood cells and other materials to form a sticky clump. Usually, doctors try to remove them by inserting a catheter into the artery and either by sweeping the thrombus or wire strike. But these methods do not always work and can break fibrous yarn, causing pieces of thrombus to break and deposit into new, more difficult to reach parts.

With existing technology, there is no way to reduce the size of the thrombus. They are based on the deformation and rupture of the thrombus to remove it. What is unique to Milli-Spinner is that it applies compression and shear powers to shrink the entire clot, dramatically reducing the volume without causing rupture. “

Renee Zhao, Assistant Professor of Mechanical Engineering and Senior Author in the Book

Milli-Spinner, who also reaches the thrombus through a catheter, consists of a long, hollow tube that can rotate quickly, with a series of fins and slits that help create a localized suction near the thrombus. This applies two forces – compression and shear – to roll the fibrous yarns into a tight ball without breaking them.

Imagine a loose ball of cotton fibers (or a handful of long hair pulled by a hair brush if you prefer). If you press it between your palms (compression) and rub your hands together in a cycle (shear), the fibers will become increasingly confused on a smaller, denser ball. Milli-Spinner is able to do this the same thing as fibrous yarns in a clot, using suction to compress the thrombus at the end of the tube and rotate quickly to create the necessary shear.

Zhao and her colleagues showed that Milli-Spinner could reduce a thrombus to just 5% of his original volume. The process shakes the red blood cells, which are normally moving through the body as soon as they are not trapped in the fiber and the now tiny fibrous sphere sucks the Milli-Spinner and outside the body.

“It works so well, for a wide range of compositions and clots,” Zhao said. “Even for fierce, rich in fibrous clots, which are impossible to deal with current technologies, their Milli-Spinner can handle them using this simple but powerful concept of engineering to thicken the fibrous network and shrink the thrombus.”

An amazing success

The Milli-Spinner design is an extension of Zhao’s work for Millirobots-microscopic robots based on the Origami made to swim through the body to distribute medicine or to help with diagnosis. The rotating concave structure with fins and slits was intended as a propulsion mechanism, but when the researchers realized that it was also creating local suction, they decided to see if they could have other uses.

“Initially, I wondered if this suction could help remove a blood clot,” Zhao said. “But when we tried the spinning in a thrombus, we noticed a striking change of thrombus color, from red to white, along with a dramatic volume decrease.

Interesting this unexpected and unprecedented thrombus reaction, the researchers wanted to reveal the underlying mechanism and then pass hundreds of design repetitions to make Milli-Spinner as effective and effective. But they have not forgotten about the possibilities of propulsion. Zhao and her colleagues are also working on a deadlock of the Milli-Spinner version that could swim freely through blood vessels to target and heal the clots.

While focused on the treatment of blood clots, there are many other possible uses for Milli-Spinner, Zhao said. She and her team are already working to use the local suction of the Milli-Spinner to capture and remove the kidney stone fragments.

“We are exploring other biomedical applications for the design of Milli-Spinner and even capabilities beyond medicine,” Zhao said. “There are some very exciting opportunities in front.”

Knowing the difference it could make for patients with a stroke and those with other diseases associated with blood clot, Zhao, Heit and their colleagues hope to obtain Milli-Spinner’s thrombosis approved for the use of patients as soon as possible. They have started a new company that allows Stanford technology to develop and bring it to the market, with clinical trials scheduled for the near future.

“What makes this technology really fascinating is its only mechanism to reshape actively and solid clots, rather than only extracted them,” Zhao said. “We are working to bring it to clinical arrangements, where it could significantly enhance the success rate of thrombometry procedures and save patients’ lives.”