This robot can help keep pig hearts beating by gently squeezing them

Thursday, 23 November 2017, 04:48:56 AM. It could one day save the lives of people with heart failure

Scientists have created a new robotic device that can keep a failing heart beating by gently squeezing half of it. The device has only been tested in pigs for now, but it holds the potential to one day save the lives of people with heart failure.

The robot is made of three parts: a rigid, half-moon frame that hugs one side of the heart, an “anchor” that goes inside the heart, and a soft, muscle-like band that twists and contracts, squeezing the heart to keep the blood flowing. The researchers successfully tested the device in pigs that were given different types of heart failure in the lab — allowing their hearts to keep pumping blood the way they were supposed to, according to a study published today in the journal Science Robotics.

The device. Image: Payne et al., Sci. Robot. 2, eaan6736 (2017)

Around the world, at least 26 million people suffer from heart failure. Many of these are children, who are born with congenital diseases that don’t allow their hearts to pump enough blood, says study co-author Nikolay Vasilyev, a researcher for Boston Children's Hospital and assistant professor of surgery at Harvard Medical School. Heart transplantation is the best option, but there’s a shortage of donor organs. As people await transplantation, their hearts are put on so-called ventricular assist devices, or VADs. These devices use artificial tubes to reroute blood from the heart to the vessels going in and out, but they can cause serious problems: blood can clot in the tubes, putting people at risk of stroke. To avoid that, patients with VADs are given blood thinners, but that can cause dangerous bleeding.

So researchers are looking for better options. Earlier this year, researchers at Harvard created a soft robot that functioned as a silicone “sleeve” around the heart, squeezing the organ so it could pump blood again. (That device was also tested in pigs.) The device described in today’s study, created by some of the same Harvard researchers, also squeezes the heart to restore blood flow, but with a different mechanism.

The latest device doesn’t target the whole heart, but only half of it. The human heart is divided into two lower chambers, called ventricles: the right ventricle pumps blood to the lungs, while the left one pumps blood to the rest of the body. When people have heart failure, sometimes it’s because only one of the two ventricles isn’t working. So the new device is meant to target only the malfunctioning ventricle, not both, like the soft robot described earlier this year.

A schematic of how the device works, in this case on the diseased right ventricle. Image: Payne et al., Sci. Robot. 2, eaan6736 (2017)

To do this, the new device has a rigid “anchor” that braces the sturdy muscle wall separating the two ventricles. That way, when compressed air is pumped into the device to twist the elastic bands on one side of the heart, only one ventricle is squeezed to eject blood, leaving the healthy ventricle alone. The device — which is placed through a small cut — also syncs up its squeezing with the heart’s existing rhythm, so it can function autonomously. Unlike existing VADs, this device doesn’t reroute blood through artificial tubes, says Vasilyev. That means that patients could receive much less blood thinning medication, avoiding complications like bleeding and stroke. “It’s a completely different concept,” Vasilyev tells The Verge.

The device isn’t perfect: it’s connected through wires to an outside air pumping and control box that’s a little bigger than a DVD player. The researchers also tested the device only on pigs, for about an hour. Before it could actually be used in people, longer-term animal studies and clinical trials need to show it’s safe and effective. In the future, the air pumping box could be made more portable, Vasilyev says, so that people with the device could technically be discharged from hospitals. But that’s a long way away: Vasilyev hopes that the device will become available in a few years, allowing patients — especially children — waiting for heart transplants to survive longer and with fewer complications.

“I truly hope that our device will help those children,” Vasilyev says.

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