Apr 25 2019
At Boston Children’s Hospital, bioengineers have reported the first demonstration of a robot that has the potential to autonomously navigate within the body.
The researchers programmed a robotic catheter in an animal model of cardiac valve repair to navigate its way along the walls of a blood-filled, beating heart to a leaky valve without any guidance from a surgeon. The scientists have recently reported their study in Science Robotics.
For more than 10 years, surgeons have utilized joystick-operated robots, and now the researchers have demonstrated that small robots can be guided through the body by means of external forces, for example, magnetism. Nevertheless, according to Pierre Dupont, senior investigator, PhD, and chief of Pediatric Cardiac Bioengineering at Boston Children’s Hospital, this is the first study of the equivalent of an autonomous car finding its way to a preferred location within the body.
Dupont believes that autonomous robots can help surgeons in challenging operations, can reduce their fatigue and thus give them more time to concentrate on the most complicated maneuvers, enhancing outcomes.
The right way to think about this is through the analogy of a fighter pilot and a fighter plane. The fighter plane takes on the routine tasks like flying the plane, so the pilot can focus on the higher-level tasks of the mission.
Pierre Dupont, Senior Investigator, PhD, and Chief, Pediatric Cardiac Bioengineering Laboratory, Boston Children’s Hospital
Touch-guided vision, informed by AI
The robotic catheter developed by the team steered with the help of an optical touch sensor created in Dupont’s laboratory, informed by preoperative scans and the cardiac anatomy map. Using image processing algorithms and artificial intelligence (AI), the touch sensor allows the catheter to understand its exact position in the heart and where it has to go.
For the demonstration, the researchers carried out a highly technically complex procedure called paravalvular aortic leak closure, in which the replacement heart valves that have started to leak around the edges are repaired. (For the experiments, the researchers built their own valves). As soon as the robotic catheter reached the location of the leak, a skilled cardiac surgeon took charge and implanted a plug to seal the leak.
In recurrent trials, the new robotic catheter effectively steered to the heart valve leaks in about the same period of time as the cardiac surgeon (utilizing either a joystick-controlled robot or a hand tool).
Biologically inspired navigation
Via a navigational method known as “wall following,” the optical touch sensor of the robotic catheter sampled its environment at fixed intervals, just like how the whiskers of rodents or the antennae of insects sample their environments to construct mental maps of dark and unfamiliar surroundings. The catheter is instructed by the sensor as to whether it was touching a valve, blood, or the heart wall (via images from a tip-mounted camera) and how firmly it was pressing (so that it does not injure the beating heart).
Data from machine learning algorithms as well as preoperative imaging assisted the robotic catheter to understand visual aspects. In this manner, the catheter moved by itself from the heart base, along the left ventricle wall, and then around the leaky heart valve until it arrived at the site 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,” explained Dupont.
Compared to the surgeon’s technique, the autonomous robot took slightly longer to reach the leaky valve but its wall-following method meant that it took the lengthiest 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 millimeter-scale target on a specific valve.
Pierre Dupont, Senior Investigator, PhD, and Chief, Pediatric Cardiac Bioengineering Laboratory, Boston Children’s Hospital
Dupont added that the potential of the robot to view and perceive its environment can possibly remove the necessity for fluoroscopic imaging, which is often utilized in this operation and subjects patients to ionizing radiation.
A vision of the future?
To date, the project was the most challenging of his career, stated Dupont. The cardiac surgical fellow, who carried out the operations on swine, was able to relax whilst the robot identified the valve leaks, but for Dupont’s engineering fellows, the project was quite demanding because at times, they had to reprogram the robot in the middle of the operation as they further improved the technology.
I remember times when the engineers on our team walked out of the OR completely exhausted, but we managed to pull it off. Now that we've demonstrated autonomous navigation, much more is possible.
Pierre Dupont, Senior Investigator, PhD, and Chief, Pediatric Cardiac Bioengineering Laboratory, Boston Children’s Hospital
Certain cardiac interventionalists who know about Dupont’s work believe that apart from navigation, robots can also be used for carrying out routine heart-mapping tasks, for instance. Some also believe that this technology can provide directions during especially challenging or extraordinary cases, or helping in operations in various parts of the globe where highly experienced surgeons are scarce.
As the Food and Drug Administration starts to prepare a regulatory framework for devices enabled by AI, Dupont envisages the prospects of autonomous surgical robots throughout the world combining their data to constantly enhance performance over time—in much the same way autonomous vehicles in the field convey their information back to Tesla to improve its algorithms.
This would not only level the playing field, it would raise it. 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.
Pierre Dupont, Senior Investigator, PhD, and Chief, Pediatric Cardiac Bioengineering Laboratory, Boston Children’s Hospital
First author on the paper is Georgios Fagogenis, PhD, of Boston Children’s Hospital. Coauthors were Margherita Mencattelli, PhD, Zurab Machaidze, MD, Karl Price, MaSC, Viktoria Weixler, MD, Mossab Saeed, MB, BS, and John Mayer, MD of Boston Children’s Hospital; Benoit Rosa, PhD, of ICube, Universite de Strasbourg (Strasbourg, France); and Fei-Yi Wu, MD, of Taipei Veterans General Hospital, Taipei, Taiwan.
The research was funded by the National Institutes of Health (R01HL124020), with partial support from the ANR/Investissement d’avenir program. Dupont and a number of his coauthors are inventors on U.S. patent application held by Boston Children’s Hospital that covers the optical imaging method.