Before operating on someone, it would be very helpful if cardiac surgeons could examine a physical model of that specific individual’s heart. Well, they should soon be able to do so – and the model will actually pump liquid, just like the patient’s real heart pumps blood.
Building upon previous research, an MIT/Harvard University team has developed a process that begins with multiple medical images of a patient’s heart being converted into a 3D computer model. That model is then used to guide a 3D printer as it produces a soft, stretchable polymer replica of the heart.
Next, pneumatic sleeves (similar to those used to measure blood pressure) are wrapped around the model. When air is pumped in and out of those sleeves, small bubbles on their undersides expand and contract. This causes the heart model to do likewise, except in reverse – it contracts when the bubbles expand and press in on it, then expands back to its original state when they contract. In this manner, the model can pump a liquid used as a stand-in for actual blood.
It’s additionally possible to place another sleeve on the aorta of the model, and then inflate that sleeve to simulate aortic stenosis – a condition in which the aortic valve narrows.
Doctors can then experiment with different types of the synthetic valves which are currently used to open the natural valve back up. In practice, when they went to perform the actual valve-implantation surgery, the best-performing synthetic valve would already be on hand and ready to go.
The scientists have so far used medical scans to 3D-print models of the aorta and left ventricle of 15 patients with aortic stenosis. Not only did those models accurately replicate the blood pressure and flow measured in the patients’ actual hearts, but they also responded in the same manner when fitted with synthetic valves similar to those which some of the patients received.
“Patients would get their imaging done, which they do anyway, and we would use that to make this system, ideally within the day,” said Harvard’s Asst. Prof. Christopher Nguyen, co-author of the study. “Once it’s up and running, clinicians could test different valve types and sizes and see which works best, then use that to implant.”
A paper on the research, was is being led by MIT’s Assoc. Prof. Ellen Roche, was recently published in the journal Science Robotics. Some of the heart models can be seen in action, in the video below.
Patient-specific, 3D-printed, soft-robotic hearts
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