The artificial cavity can be adjusted to mimic healthy and diseased states. The team manipulated the model to simulate conditions of right ventricular dysfunction, including pulmonary hypertension and myocardial infarction. They also used the model to test cardiac devices. For example, the team implanted a mechanical valve to repair a faulty natural valve, then observed how the chamber's pumping action changed in response.
They claim that the new robotic right cavity, or RRV, can be used as a realistic platform to study right cavity disorders and test devices and therapies intended to treat those disorders.
"The right heart chamber is particularly susceptible to dysfunction in intensive care unit settings, especially in mechanically ventilated patients," says Manisha Singh, a postdoctoral researcher at the MIT Institute for Medical Engineering and Science (IMES). "The RRV simulator can be used in the future to study the effects of mechanical ventilation on the right heart chamber and develop strategies to prevent right heart failure in these vulnerable patients.".
Singh and his colleagues report details of the new design in a paper appearing today in Nature Cardiovascular Research. Their co-authors include Associate Professor Ellen Roche, a senior fellow at IMES and associate chief of research in the Department of Mechanical Engineering at MIT, along with Jean Bonnemain, Caglar Ozturk, Clara Park, Diego Quevedo-Moreno, Meagan Rowlett, and Yiling Fan of MIT, Brian Ayers of Massachusetts General Hospital, Christopher Nguyen of the Cleveland Clinic, and Mossab Saeed of Boston Children's Hospital.
A ballet of heartbeats
The right chamber is one of the four chambers of the heart, along with the left chamber and the left and right atria. Of the four chambers, the left chamber is the most important, as its thick, conical musculature is designed to pump blood throughout the body. The right chamber, according to Roche, is a "dancer" in comparison, as it handles a lighter but no less crucial workload.
"The right heart chamber pumps deoxygenated blood to the lungs, so it doesn't have to pump as hard," Roche points out. "It's a thinner muscle, with a more complex architecture and movement.".
This anatomical complexity has made it difficult for doctors to accurately observe and assess right-sided heart function in patients with heart disease.
"Conventional tools often fail to capture the intricate mechanisms and dynamics of the right cavity, leading to potential misdiagnoses and inadequate treatment strategies," says Singh.
To improve understanding of the lesser-known chamber and accelerate the development of cardiac devices to treat its dysfunction, the team designed a realistic, functional model of the right chamber that captures both its intricate anatomies and its pumping function.
The model includes real heart tissue, which the team chose to incorporate because it preserves natural structures that are too complex to reproduce synthetically.
"There are thin cords and small valve leaflets with different material properties that all move in unison with the cavity muscle. Trying to melt or print these very delicate structures is quite challenging," Roche explains.
The lifespan of a heart
In the new study, the team reports that they removed the right heart chamber from a pig, which they treated to carefully preserve its internal structures. They then placed a silicone lining around it, which acted as a soft, synthetic myocardium. Within this lining, the team embedded several long, balloon-like tubes, surrounding the actual heart tissue, in positions that the team determined through computer modeling to be optimal for reproducing the chamber's contractions. The researchers connected each tube to a control system, which they configured to inflate and deflate each tube at rates that mimicked the heart's actual rhythm and movement.
To test its pumping capacity, the team infused the model with a blood-like viscosity fluid. This particular fluid was also transparent, allowing engineers to observe with an internal camera how the internal valves and structures responded as the cavity pumped fluid.
They discovered that the pumping power of the artificial chamber and the function of its internal structures were similar to what they had previously observed in healthy, living animals, demonstrating that the model can realistically simulate the action and anatomy of the right heart chamber. The researchers were also able to adjust the frequency and power of the pumping tubes to mimic various cardiac conditions, such as irregular heartbeat, muscle weakness, and hypertension.
"We are 'reviving' the heart, in a sense, and in a way that allows us to study and potentially treat its dysfunction," Roche says.
To demonstrate that the artificial cavity can be used to test cardiac devices
