Insect-inspired swivel catheter for treating hard-to-reach aneurysms

The complexity of the brain, with its very narrow and delicate blood vessels, makes navigating the nooks and crannies of this organ one of the most difficult tasks. For this reason, there are limits to what existing catheters can achieve.

Fortunately, engineers and doctors have developed a unique ‘steerable’ catheter that will give neurosurgeons the ability to safely navigate arteries and blood vessels in the brain, opening up new possibilities for treating hard-to-reach aneurysms. . The device is inspired by nature, particularly the legs of insects and flagella (tail-like structures that allow microscopic organisms such as bacteria and sperm to swim).

The University of California (UC) San Diego The team describes the breakthrough in an article published on August 18, 2021 in the journal Scientific robotics.

The newly developed steerable catheter (right) and how it navigates a cerebral blood vessel (insert left). (Credit: UC San Diego)

An aneurysm is an abnormal swelling of a blood vessel caused by a weakness in the wall of the blood vessel. When blood passes through this weakened blood vessel, the blood pressure causes a small area to swell outward like a balloon.

Current methods of fighting aneurysms in the brain involve neurosurgeons inserting tiny wires into an artery near the groin, guiding a catheter through the aorta and into the brain. These wires include a curved tip which is used to navigate the many corners and junctions until the terrible aneurysm is found.

The problem with this method is that the guidewires then have to be removed so that the catheter can deliver platinum coils to block blood flow to the aneurysm and prevent the brain from bleeding. However, this recovery procedure often dislodges the catheter and changes its position; in other words, some types of aneurysms can be complicated to treat.

Among these is an unruptured intracranial aneurysm on the cerebral artery, a blister-like abrasions that can rupture and affects more than 160 million people worldwide. Unfortunately, about 25% of them cannot be treated because the aneurysm is too difficult to reach, leaving patients at risk of rupture, death and long-term disability.

Study author James Friend, professor of medical engineering at UC San Diego, explained:

Unfortunately, many of the most important blood vessels we have to deal with are some of the most tortuous and fragile in the body. While robotics meets the need to solve many medical problems, the deformable devices to the scale required for this type of surgery simply do not exist.

Therefore, to create these devices, Friend and his team examined the type of strain and micro-scale hydraulics observed in mating beetles, flagella, and insect legs. This inspired the team to develop a hydraulically actuated flexible robotic microcatheter to perform delicate neurosurgery.

The team started by placing concentric layers of silicone on top of each other, each with different levels of stiffness. This formed a silicone rubber catheter with interior cavities filled with harmless saline liquid via a handheld controller to improve hydraulic pressure, allowing it to be piloted like a “Nintendo for neurosurgeons”. The new technology has been demonstrated in the cerebral artery of a pig, with the “steerable” tip visible on x-rays. The device has been shown to be able to efficiently deploy the platinum coils.

Insect-inspired swivel catheter for treating hard-to-reach aneurysms
Scientists have demonstrated the new steerable catheter in the brain of a pig. (Credit: UC San Diego)

Dr Alexandre Khalessi, MD, chair of the neurosurgery department at UC San Diego Health, concluded:

As a neurosurgeon, one of the challenges we have is to direct the catheters to the delicate and deep recesses of the brain. Today’s results demonstrate proof of concept of a flexible, easily steerable catheter that would dramatically improve our ability to treat brain aneurysms and many other neurological conditions, and I look forward to advancing this innovation in care. to patients.

Then the researchers will build on these promising early results with a larger-scale animal and ultimately humans trial. The UC San Diego team talks about the technology in the video below.

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