Pierre Dupont is trying to solve a medical problem almost no one has ever heard of.
About 1,000 American children are born every year with an incomplete esophagus. Their mouth doesn’t connect to their stomach, so they can’t eat.
For the most difficult cases — about 50 children a year — the best current treatment is to put them to sleep for several weeks, while slowly stretching two stubs of tissue until they can be attached in the middle to make a complete esophagus.
But Dupont thinks a motorized device implanted under the child’s rib cage could do most of the work without putting the child in a coma. How he even got to solve this problem is, on its own, pretty unusual in medicine.
Dupont is a mechanical engineer whose circuitous route to helping severely ill young patients was born out of the frustration that physicians at Boston Children’s Hospital felt with the medical device industry.
Too often, these doctors found themselves working with terrible tools because manufacturers could not justify making equipment specifically for children, and there is little federal funding to support such tool development.
“Almost everything we use is designed for adults — we have to adapt it or fashion it in some way to use it in kids,” said Pedro del Nido, chief of cardiac surgery at Children’s.
So del Nido and his cardiac colleagues took the unorthodox step of hiring a device maker — Dupont.
A bioroboticist, Dupont was brought over from Boston University to start the Pediatric Cardiac Bioengineering Lab at Children’s. The nascent field of biorobotics does have an established foothold in medicine, largely in orthopedics. But del Nido said that, as far as he knows, Children’s has the only hospital cardiac department that employs someone like Dupont.
Having a lab right next to the hospital, rather than across town, makes him more effective, Dupont said.
“Without that direct connection to the hospital environment, it’s very easy for [engineers] to propose ridiculous solutions — to assume what the real problems are, to assume what an acceptable solution would be, and then just plunge forward,” Dupont said. “The benefit of being here at the hospital is that the clinicians will tell me to my face: ‘That’s a dumb idea, Pierre, don’t even think about it, and this is why.’ ”
In addition to reimagining esophagus surgery, Dupont has been working to make heart surgery less invasive and disruptive — performing it while the heart is beating, rather than while the patient is on a heart-lung machine.
The goal, he said, is to create robotic catheters and imaging systems that give doctors the same control and visualization they would have in an open surgery.
One specialized catheter used for valve repairs would have a “sensing skin,” allowing surgeons to feel how hard they are pushing along the length of the catheter instead of just at its tip. Dupont compared it to putting your arm under the hood of a car; you’d want to be able to feel if your elbow were touching a boiling hot part, something current tools don’t allow.
His team is also working on creating motors that can be used inside MRI scanners and are powered by the scanners themselves. Such technology would enable surgeons to drive needles for biopsies and implant robotics.
And he is dreaming about making millimeter-scale swimming robots that he can unleash in the spine and send into the brain, delivering a drug or telling doctors what’s going on in there.
Fixing esophaguses may not seem like it comes under the purview of the cardiac department, but the work will eventually help heart patients, del Nido said. Many of the procedures del Nido and other cardiac specialists do could benefit from the stretching techniques that Dupont is trying on the esophagus — for infants with missing aortas, absent ventricles, or incomplete blood vessels.
“For one technology development, you get many, many bangs for your buck,” del Nido said. “That’s what we were hoping would happen” when Children’s hired Dupont. “And it’s really happening now, so it’s very gratifying.”
Esophageal atresia, as the condition is known, is a birth defect that prevents infants from eating normally and often involves the breathing tube, which puts them at risk for drowning in saliva.
At birth, the infants start to choke when fed, turn a terrifying shade of blue, and need to be fed intravenously.
Some versions of atresia can be fixed by surgery that reknits the esophagus back into a single tube.
But the so-called long-gap type of defect, in which there is too much space between the two ends of the esophagus, is often fixed by an unusual technique that stretches the separate tissues so they grow toward each other.
Surgeons tie sutures to tissue at both ends of the esophagus and loop them around the baby’s ribs to get traction, Dupont explained. Then the sutures are fed out a hole in the baby’s back so they can be tightened each day to stimulate the tissues to grow toward each other.
The baby undergoes frequent X-rays to track progress, and the stretching has to be done while the child is asleep, or the stitches will get pulled out with daily activity.
Instead, Dupont has designed a robotic implant — a motorized device that, once installed, could do all the necessary pulling from the inside, powered by a tiny motor.
Rather than pulling against the ribs, the device uses one esophagus stub to pull against the other. It can sense how hard it is pulling and how much the ends have grown, removing the need for frequent, potentially damaging X-rays.
Best of all, the child would not need to remain asleep during the stretching process.
Dupont and postdoctoral students Dana Damian and Slava Arabagi have made a prototype implant that they will soon be testing in animals. Their research will also help them understand what happens when the pressure is applied — whether the tugging simply stretches the tissue or leads to new cell growth — and whether it is best to tighten the sutures once a day or continuously.
Such insights would not have happened if Dupont worked exclusively in academia, said Robert Howe, a professor of engineering at the Harvard School of Engineering and Applied Sciences who has collaborated with both Dupont and del Nido.
Innovation takes the face-to-face encounters in the hallway, Howe said, the mixing of graduate students and the “visionary” freedom to experiment that del Nido gave Dupont.
Dupont said he is grateful for the opportunity to put his engineering skills to good use, working with doctors and surgeons.
“I’m having fun,” he said.
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