The National Institutes of Health has awarded Professor Pierre Dupont (AME) a five-year, $5 million Bioengineering Research Partnership grant to develop minimally invasive surgical instruments to fight disease and repair defects inside the human heart. Children’s Hospital of Boston and Microfabrica, Inc., a California-based microdevice manufacturer, will collaborate with Dupont on the grant.
The goal, Dupont said, is to develop surgical instruments that will eliminate many of the current limitations of minimally invasive surgery.
“To perform repairs inside the heart, there are two approaches – open heart surgery and catheter interventions. With catheters, you don’t have to place the patient on a heart-lung machine or cut the chest and heart open,” Dupont said. “But in comparison with open heart surgery, what you can actually do with a catheter is limited. We’re trying to incorporate the best of both approaches. We want to produce instruments that are as minimally invasive as catheters, but which provide the precision and control of open-heart surgery.”
The instruments Dupont envisions would enter the chest and heart wall through needle-sized incisions and snake their way under surgeon control through the chambers of the heart to the surgical site. Once the location of the repair is reached, tools would be deployed from the instrument tip to perform the repair. A surgeon would guide the instrument using a joystick controller. A variety of medical imaging techniques, such as ultrasound, would enable the surgeon to observe the instrument inside the beating heart.
In his lab, Dupont is developing the robotics technology needed to perform these tasks. The instrument body is a slender, needle-like robot arm that can extend telescopically along a curved path and manipulate tools at its tip. Dupont is partnering with Microfabrica to develop a toolbox of millimeter-scale tools.
“Surgery inside the heart is a lot like plumbing repairs,” Dupont said. “You need two types of tools – one set is for removing blockages from pipes and valves. The second is for patching leaks.”
The tools will be made from biocompatible metal alloys using a micro-electro-mechanical systems (MEMS) process. Despite their miniature size, each tool can be designed using familiar mechanical components, such as gears and bearings, but is built pre-assembled. Because the instruments will be made out of metal, Dupont thinks this approach will produce sturdy tools despite their small size.
“Some reviewers said, ‘These tools won’t be strong enough to cut anything. They’ll break,’” Dupont said. “So we made a video showing a prototype shaving plaster, which is similar to the calcium deposits in the tissue of diseased hearts.”
Dupont believes that the device will eliminate many of the problems and limitations that exist in both minimally invasive and open heart surgery.
“Catheters are made to be very flexible so that they can passively slide along vessels walls. This limits their positioning accuracy and the forces you can apply with a catheter tip. Since our devices can be steered through the heart, they can be made stiffer than a catheter giving greater control of the tip-mounted tools. And while open heart surgery is performed every day, and done well, there are still there are many side effects that come along with such a traumatic procedure.”
According to Dupont, the biggest benefit may be the technology’s potential to help all age groups: adults, children and even fetuses.
“Working with our clinical partners at Children’s Hospital, we’re developing different instruments for each of these groups,” he said. “Fetal surgery is especially exciting since, in certain cases, repairing a heart defect before birth can greatly improve the chances for the heart to develop normally.”