A team of researchers at Case Western Reserve University, Cleveland, OH, have received a $1.3 million grant from the National Institutes of Health for its project to perfect the technology to steer a robotic catheter through the heart’s beating chambers using the push and pull of magnetic fields while the patient lies inside a magnetic resonance imager (MRI).
The project aims to improve treatment of arterial fibrillation—an irregular beat due to electrical conductivity problems in the heart. To treat the problem, surgeons thread a catheter through a vein in the thigh into the heart and use an electrode tip to ablate the tissues involved in the short-circuiting, allowing the heart’s electrical currents to work smoothly.
But, a beating heart moves the target, flowing blood creates turbulence, and the 2D view produced through fluoroscopy imaging is often grainy or blurry. The result is surgeons sometimes burn more tissue than necessary, or not enough to eliminate the problem.
In the Case Western project, doctors will still hand-feed the catheter from thigh to heart. But once there, robotics will take over, they said. To make a catheter robotic, the researchers have wrapped the inch behind the tip in tiny copper coils. By passing an electrical current through them, the coils create a magnetic field.
When this magnetic field is paired with the magnetic field created inside the MRI to produce images, the catheter has the ability to move. In order to control the movement, Cavusoglu’s lab is now developing software to use the fields like a pair of deftly controlled bar magnets.
A doctor using a joystick or touch screen will guide the catheter inside the patient. In the heart, to turn the catheter to the left or right, a current will be applied to coils in either direction.
The magnetic fields can produce the same effect as aiming two like poles of magnets at each other: they repel. Or aiming two unlike poles at each other: they attract. But, because the MRI field is much stronger, it’s the catheter that moves. And, because the fields encircle the catheter, it can move up and down, not just side to side.
To maintain a steady aim and contact with target tissues inside the beating heart, they have already developed algorithms that automatically compensate for the contracting and expanding muscles and the pulsing blood.