In an animal model of cardiac valve repair, the international team - including bioengineers at Boston Children's Hospital - programmed a robotic catheter to find its way along the walls of a beating, blood-filled heart to a leaky valve. The work is reported in Science Robotics.
Informed by a map of cardiac anatomy and preoperative scans, the team's robotic catheter navigated using an optical touch sensor that was developed in the lab of senior investigator Pierre Dupont, PhD, chief of Paediatric Cardiac Bioengineering at Boston Children's Hospital. Using AI and image processing algorithms, the touch sensor enabled the catheter to ascertain its location in the heart and where it needed to go.
For the demonstration, the team performed a paravalvular aortic leak closure, a challenging procedure that repairs replacement heart valves that have begun leaking around the edges. Once the robotic catheter reached the leak location, a cardiac surgeon took control and inserted a plug to close the leak.
In repeated trials, the robotic catheter navigated to heart valve leaks in roughly the same amount of time as a surgeon using a hand tool or a joystick-controlled robot, which have been used by surgeons for over a decade.
Through a navigational technique called "wall following," the robotic catheter's optical touch sensor sampled its environment at regular intervals. The sensor told the catheter whether it was touching blood, the heart wall or a valve - through images from a tip-mounted camera - and how hard it was pressing.
Data from preoperative imaging and machine learning algorithms helped the catheter interpret visual features. In this way, the robotic catheter advanced by itself from the base of the heart, along the wall of the left ventricle and around the leaky valve until it reached the location of the leak.
"The algorithms help the catheter figure out what type of tissue it's touching, where it is in the heart, and how it should choose its next motion to get where we want it to go," Dupont said.
Though the autonomous medical robot took slightly longer than the surgeon to reach the leaky valve, its wall-following technique meant that it took the longest path.
"The navigation time was statistically equivalent for all, which we think is pretty impressive given that you're inside the blood-filled beating heart and trying to reach a millimetre-scale target on a specific valve," said Dupont.
He added that the robot's ability to visualise and sense its environment could eliminate the need for fluoroscopic imaging, which is typically used during the operation and exposes patients to ionising radiation.
As the US Food and Drug Administration begins to develop a regulatory framework for AI-enabled devices, Dupont foresees the global potential of autonomous surgical robots pooling their data to continuously improve performance.
"This would not only level the playing field, it would raise it," said Dupont. "Every clinician in the world would be operating at a level of skill and experience equivalent to the best in their field. This has always been the promise of medical robots. Autonomy may be what gets us there."