A Magnetic, Microrobotic Catheter to Treat Strokes

According to the American Heart Association, heart disease and stroke claim more lives every year in the U.S. than all forms of cancer and chronic lower respiratory disease combined.¹

In 2020, stroke accounted for about one of every 21 deaths in the U.S. This means someone died of a stroke every three minutes, 17 seconds. It ranks fifth among all causes of death in the U.S., causing 160,264 deaths in 2020. On the global scale, there were over 7 million deaths related to cerebrovascular disease worldwide. About half of those were from ischemic stroke.

If a blood clot in the brain can’t be removed by using drugs, emergency surgery is needed. It’s a tricky surgery—the surgeon must maneuver a catheter through an artery, past the heart and into the brain to clear away the disturbance of the blood supply.

The risk of sustaining long-term damage from a stroke is reduced the sooner and more quickly the procedure is carried out. Typically, surgeons will use a pull wire to manually navigate the catheter tip through the winding network of blood vessels. But since the tip can only be moved in two directions, the procedure takes quite some time and requires great skill and experience.

Enter ETH Zürich spinoff Nanoflex, which has built a new type of neurovascular catheter that’s steered by a remote control and computer using a magnetic field. The highly dexterous robotic device was engineered to navigate the dense, tortuous arterial structure of the brain. The device combines insertion and rotation by including a helical protrusion on the device’s outer surface. This protrusion is similar to a flexible screw, engaging with the vessel wall and pulling the device forward when rotated.

“Not only can the catheter tip be bent in any direction thanks to a magnetic head; it’s also smaller, more maneuverable, and safer due to the softness of the material,” explained ETH alumnus Christophe Chautems, one of three founders of Nanoflex.

The rotation occurs at the proximal end of the catheter and is transmitted to the distal end along its body, which transmits torque. The actuation principle, coupled with magnetic steering, provides the dexterity and navigability needed to access the difficult-to-reach locations in the vascular system.

Since the surgeon steers the magnetic catheter by remote control, they don’t have to be at the patient’s side during the thrombectomy. This shields doctors from X-ray radiation that lets them navigate inside the patient’s body.

The ETH team hopes the magnetic catheter’s precision steering will speed up and simplify procedures compared to neurovascular catheters currently in use.

“Even surgeons with less experience should be able to treat strokes with our system,” Chautems said.

The magnetically controlled catheter was invented by a collaboration of researchers, engineers, and neuroradiologists at the Multi-Scale Robotics Lab (MSRL) at ETH Zürich. The tech to generate and control electromagnetic fields for the endovascular device navigation was based on over two decades of research at the lab.

In 2021, Nanoflex took over the robotic system’s commercialization, then pocketed $12 billion of venture capital in February 2023 to commercialize it. Then in October last year, the company partnered with Brainomix, a developer of automated medical software for stroke image analysis and certain lung diseases. Nanoflex also received almost $1 million in financial backing from the U.K. and Switzerland to combine an AI-assisted magnetic navigation system and robotic surgical tools.

In February 2024, the Nanoflex team published successful endovascular navigation from the aorta to millimeter-sized cranial arteries in vivo on a pig test subject in the journal Science Robotics.² The researchers also reported successful navigation in models of human vasculature.

But it doesn’t end there: “With our system, it will be possible to carry out procedures from a distance by remote control and on a screen,” said Silvia Viviani, who studied robotics at ETH Zürich and has worked at Nanoflex since 2021. The Nanoflex team hopes to allow stroke patients to be operated on at the nearest local hospital by a specialist who doesn’t even have to be in the building, saving precious time.

The team also hopes their magnetic field generator can replace commercially available options because theirs is significantly lighter and has a wider application range. The team said it can be wheeled into the OR as needed and requires only power and water.

“Our goal was to generate a magnetic field within the smallest possible space to bring the size and weight of the equipment down. We finally cracked it by developing a new, now-patented cooling system for the electromagnet,” explained Chautems.

The Nanoflex founders’ vision is for every large hospital to have one of their magnetic navigation systems in the future. The recent success has propelled this vision, and the team hopes to obtain approval in the U.S. within the next year or two.

Should this come to pass, the team also believes the technology will lend itself to other fields, like heart and eye surgery, gastroscopy, and fetal surgery. 

References

1. bit.ly/4a0yMRt
2. bit.ly/49EeT2f