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A very small magnetic steerable catheter will allow surgeons to perform complex movements inside the body with a lower risk of injury to the patient.

For patients with cardiac arrhythmia, surgeons routinely perform a minimally invasive procedure to ablate the sections of the heart that cause unwanted electrical impulses.

The physician inserts a catheter through a vein into the heart that locally generates heat to ablate the relevant sections. To navigate the catheter tip through the blood vessels with a high level of precision, the surgeon can bend the tip manually using a pull wire inside the catheter. But it can be moved in only two directions: to the left and to the right.

Now, rather than being steered manually, the new magnetic catheter is operated from a computer via an external magnetic field. This allows the front part of the catheter to be bent in any direction with the highest level of precision, researchers say.

Tight curves

“As a result, the new catheter can be steered through more complex blood vessels better than a conventional catheter,” says Christophe Chautems, a doctoral student working with Brad Nelson, professor of robotics and intelligent systems at ETH Zurich.

Since the magnetic device doesn’t require a pull wire, it can be made much thinner, resulting in the smallest ever steerable catheter.

With the new catheter, surgeons can adjust the stiffness of the front part too, thanks to a low melting point alloy placed in three of its sections. With power supplied through fine copper wires inside the catheter, the sections can heat up and become flexible.

If the front part of the catheter is relatively rigid, applying an external magnetic field lets it bend only slightly. In contrast, a soft catheter allows for bends in very tight curves. This allows surgeons to navigate through blood vessels with much greater precision, and also reduces the risk of accidentally injuring vessels from the inside.

Less radiation

For surgeons to work with these magnetic catheters, patients must lie on a magnetic navigation system, an apparatus used to produce directed magnetic fields. Researchers have already developed such devices. Today, commercial providers also offer these devices, which are currently in use at some 100 hospitals around the world.

Magnetic catheter navigation has another advantage: in contrast to manual navigation, the surgeon is not next to the patient, but in a control room next door.

This provides better protection from the radiation of the X-ray machine used to generate images for navigating inside the patient’s body. It’s also possible to remotely perform the operation from a distance. There are even efforts underway to automate such procedures completely in the medium term.

For their proof of concept, the researchers focused on using the catheter to treat cardiac arrhythmia. They’ve gotten a patent on the system and are looking for partners from industry to further develop the catheter and bring it to market. They are also working on catheter applications in eye and gastrointestinal surgery.

Source: ETH Zurich