Custom, 3D-printed heart replicas look and pump just like the real thing
The soft robotic models are patient-specific and could help clinicians
zero in on the best implant for an individual.

Date:
February 22, 2023
Source:
Massachusetts Institute of Technology
Summary:
Engineers developed a procedure to 3D print a soft and flexible
replica of a patient's heart. These models could help doctors
tailor treatments, such as aortic valves, to an individual patient.


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FULL STORY ==========================================================================
No two hearts beat alike. The size and shape of the the heart can vary
from one person to the next. These differences can be particularly
pronounced for people living with heart disease, as their hearts and
major vessels work harder to overcome any compromised function.


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MIT engineers are hoping to help doctors tailor treatments to patients' specific heart form and function, with a custom robotic heart. The team
has developed a procedure to 3D print a soft and flexible replica of
a patient's heart. They can then control the replica's action to mimic
that patient's blood-pumping ability.

The procedure involves first converting medical images of a patient's
heart into a three-dimensional computer model, which the researchers can
then 3D print using a polymer-based ink. The result is a soft, flexible
shell in the exact shape of the patient's own heart. The team can also
use this approach to print a patient's aorta -- the major artery that
carries blood out of the heart to the rest of the body.

To mimic the heart's pumping action, the team has fabricated sleeves
similar to blood pressure cuffs that wrap around a printed heart and
aorta. The underside of each sleeve resembles precisely patterned bubble
wrap. When the sleeve is connected to a pneumatic system, researchers
can tune the outflowing air to rhythmically inflate the sleeve's bubbles
and contract the heart, mimicking its pumping action.

The researchers can also inflate a separate sleeve surrounding a printed
aorta to constrict the vessel. This constriction, they say, can be tuned
to mimic aortic stenosis -- a condition in which the aortic valve narrows, causing the heart to work harder to force blood through the body.

Doctors commonly treat aortic stenosis by surgically implanting a
synthetic valve designed to widen the aorta's natural valve. In the
future, the team says that doctors could potentially use their new
procedure to first print a patient's heart and aorta, then implant a
variety of valves into the printed model to see which design results
in the best function and fit for that particular patient. The heart
replicas could also be used by research labs and the medical device
industry as realistic platforms for testing therapies for various types
of heart disease.

"All hearts are different," says Luca Rosalia, a graduate student in
the MIT- Harvard Program in Health Sciences and Technology. "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 report their results in a study appearing today in Science Robotics.MIT co-authors include Caglar Ozturk, Debkalpa Goswami, Jean Bonnemain, Sophie Wang, and Ellen Roche, along with Benjamin Bonner
of Massachusetts General Hospital, James Weaver of Harvard University,
and Christopher Nguyen, Rishi Puri, and Samir Kapadia at the Cleveland
Clinic in Ohio.

Print and pump In January 2020, team members, led by mechanical
engineering professor Ellen Roche, developed a "biorobotic hybrid heart"
-- a general replica of a heart, made from synthetic muscle containing
small, inflatable cylinders, which they could control to mimic the
contractions of a real beating heart.

Shortly after those efforts, the Covid-19 pandemic forced Roche's lab,
along with most others on campus, to temporarily close. Undeterred,
Rosalia continued tweaking the heart-pumping design at home.

"I recreated the whole system in my dorm room that March," Rosalia
recalls.

Months later, the lab reopened, and the team continued where it left off, working to improve the control of the heart-pumping sleeve, which they
tested in animal and computational models. They then expanded their
approach to develop sleeves and heart replicas that are specific to
individual patients.

For this, they turned to 3D printing.

"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," notes Wang, who is a vascular surgery resident
at Beth Israel Deaconess Medical Center in Boston.

An inclusive design In the new study, the team took advantage of 3D
printing to produce custom replicas of actual patients' hearts. They
used a polymer-based ink that, once printed and cured, can squeeze and
stretch, similarly to a real beating heart.

As their source material, the researchers used medical scans of 15
patients diagnosed with aortic stenosis. The team converted each patient's images into a three-dimensional computer model of the patient's left
ventricle (the main pumping chamber of the heart) and aorta. They fed
this model into a 3D printer to generate a soft, anatomically accurate
shell of both the ventricle and vessel.

The team also fabricated sleeves to wrap around the printed forms. They tailored each sleeve's pockets such that, when wrapped around their
respective forms and connected to a small air pumping system, the sleeves
could be tuned separately to realistically contract and constrict the
printed models.

The researchers showed that for each model heart, they could accurately recreate the same heart-pumping pressures and flows that were previously measured in each respective patient.

"Being able to match the patients' flows and pressures was very
encouraging," Roche says. "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." Going a step further, the team aimed to replicate
some of the interventions that a handful of the patients underwent, to
see whether the printed heart and vessel responded in the same way. Some patients had received valve implants designed to widen the aorta. Roche
and her colleagues implanted similar valves in the printed aortas modeled
after each patient. When they activated the printed heart to pump, they observed that the implanted valve produced similarly improved flows as
in actual patients following their surgical implants.

Finally, the team used an actuated printed heart to compare implants of different sizes, to see which would result in the best fit and flow -
- something they envision clinicians could potentially do for their
patients in the future.

"Patients would get their imaging done, which they do anyway, and we would
use that to make this system, ideally within the day," says 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." Ultimately, Roche says the patient-specific replicas could help develop
and identify ideal treatments for individuals with unique and challenging cardiac geometries.

"Designing inclusively for a large range of anatomies, and testing interventions across this range, may increase the addressable target
population for minimally invasive procedures," Roche says.

This research was supported, in part, by the National Science Foundation,
the National Institutes of Health, and the National Heart Lung Blood
Institute.

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========================================================================== Story Source: Materials provided by
Massachusetts_Institute_of_Technology. Original written by Jennifer
Chu. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Luca Rosalia, Caglar Ozturk, Debkalpa Goswami, Jean Bonnemain,
Sophie X.

Wang, Benjamin Bonner, James C. Weaver, Rishi Puri, Samir
Kapadia, Christopher T. Nguyen, Ellen T. Roche. Soft robotic
patient-specific hydrodynamic model of aortic stenosis and
ventricular remodeling. Science Robotics, 2023; 8 (75) DOI:
10.1126/scirobotics.ade2184 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230222141222.htm

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