Every heart beats differently. Each person’s heart is different in terms of size and form. Those who have heart illness may notice these variations to a greater extent since their hearts and main arteries must work harder to compensate for any decreased performance.

With a personalized robotic heart, MIT engineers want to assist physicians in adjusting therapies to individuals’ unique heart structures and functions. The group has created a method to 3D print a flexible and squishy duplicate of a patient’s heart. The activity of the replica may then be controlled to imitate the patient’s capacity to pump blood.

The method entails first creating a three-dimensional computer model using medical photographs of a patient’s heart so that the researchers may 3D print it. The end product is a soft, flexible shell that is precisely the form of the patient’s own heart. This method may also be used by the team to print a patient’s aorta, which is a significant artery that transports blood from the heart to the rest of the body.

The team has created sleeves that are akin to blood pressure cuffs that wrap over a printed heart and aorta in order to simulate the heart’s pumping function. Each sleeve’s inside has a design that is similar to bubble wrap. Researchers can adjust the outflowing air to rhythmically expand the bubbles in the sleeve and constrict the heart, simulating the pumping motion of the heart, when the sleeve is attached to a pneumatic system.

The researchers can also enclose a printed aorta in a separate sleeve that is inflated to tighten the artery. They claim that this restriction may be adjusted to resemble aortic stenosis, a disease in which the aortic valve narrows and the heart must pump blood more forcefully.

A synthetic valve that widens the native aortic valve is often surgically implanted as part of the treatment of aortic stenosis. The research team predicts that in the future, physicians may utilize their innovative method to print a patient’s heart and aorta first, then insert several valve designs to test which one fits and functions best for that specific patient. The medical device sector and research facilities may potentially employ the heart replicas as realistic testing grounds for different heart disease treatments.

“All hearts are different,” comments Luca Rosalia from MIT. “There are massive variations, especially when patients are sick. The advantage of our system is that we can recreate not just the form of a patient’s heart, but also its function in both physiology and disease.”

Rosalia and his colleagues published their findings in Science Robotics today.

Along with Benjamin Bonner of the Massachusetts General Hospital, James Weaver of Harvard University, Caglar Ozturk, Debkalpa Goswami, Jean Bonnemain, Sophie Wang, and Ellen Roche from MIT, as well as Christopher Nguyen, Rishi Puri, and Samir Kapadia from the Cleveland Clinic in Ohio, are co-authors on the paper.

In January 2020, members of a team led by mechanical engineering professor Ellen Roche created a “biorobotic hybrid heart” — a general replica of a beating heart made from synthetic muscle containing small, inflatable cylinders that could be controlled to mimic the contractions of a real beating heart.

The Covid-19 outbreak soon after those initiatives led Roche’s lab, along with the majority of others on campus, to temporarily shut. Rosalia didn’t let that stop her from making changes to the design at home.

“I recreated the whole system in my dorm room that March,” adds Rosalia.

After a few months, the lab reopened, and the team picked up where they left off, working to improve the control of the heart-pumping sleeve, which they tested on animals and in computer models. Then, they changed how they did things to make sleeves and copies of hearts that fit each patient. They used 3D printing for this.

As explained by Wang: “There is a lot of interest in the medical field in using 3D printing technology to accurately recreate patient anatomy for use in preprocedural planning and training.”

In the latest research, they used 3D printing to create customized copies of the hearts of real patients. Scientists used a polymer-based ink that, after printing and curing, can contract and expand much like a genuine beating heart.

The researchers utilized the medical scans of 15 individuals with aortic stenosis as their primary data. The scientists used each patient’s photos to create a three-dimensional computer model of the left ventricle and aorta, the heart’s primary pumping chamber. They used a 3D printer to create a soft, anatomically correct shell of the ventricle and vasculature using this model as input.

The group also created sleeves to go around the printed forms. They made each sleeve’s pockets so they could be individually calibrated to constrict and compress the printed models realistically when the sleeves were wrapped around their unique shapes and attached to a tiny air-pumping apparatus.

The researchers demonstrated that they could precisely reproduce the identical heart-pumping pressures and flows that had previously been observed in each unique patient for each model heart.

“Being able to match the patients’ flows and pressures was very encouraging,” Roche remarks. “We’re not only printing the heart’s anatomy, but also replicating its mechanics and physiology. That’s the part that we get excited about.”

In order to evaluate whether the printed heart and vascular behaved similarly to the procedures that a small number of the patients received, the researchers went one step further and attempted to duplicate some of those operations. Several individuals underwent valve implants that were meant to widen the aorta. Roche and her colleagues placed comparable valves in each patient’s printed aorta. They noticed that the implanted valve provided similarly better flows as in real patients after their surgical implantations when they turned on the printed heart to pump.

Lastly, the researchers compared implants of various sizes to see which would provide the greatest fit and flow. They hope that in the future, practitioners will be able to accomplish this for their patients.

“Patients would get their imaging done, which they do anyway, and we would use that to make this system, ideally within the day,” points out co-author Nyugen. “Once it’s up and running, clinicians could test different valve types and sizes and see which works best, then use that to implant.”

Finally, Roche claims that patient-specific replicas might aid in the development and identification of optimal medicines for people with unique and complex heart geometry.

According to Roche, designing inclusively for a broad variety of anatomies and evaluating treatments throughout this range may expand the target group that may be treated with minimally invasive procedures.

Source: 10.1126/scirobotics.ade2184

Image Credit: MELANIE GONICK, MIT