Prosthetic heart valves, ventricular assist devices, and other cardiac implants go through an extensive research and development process, followed by testing on animals before human trials. There is no machine that simulates the function of the heart with any sufficient accuracy for comprehensive use by device designers, but researchers at MIT are trying to change that by modifying real hearts with synthetic muscle components that behave like the real thing.
The team developed a way to open up pig hearts and replace their muscles with a material consisting of tiny bubbles that, when inflated, pull in the same direction as the muscle fibers would have in the same location. This material looks much like packaging bubble wrap, only on a much smaller scale. The rest of the heart remains native, preserving much of its complex native structure.
A preserved heart muscle (1) is removed and replaced with a soft synthetic matrix (2). The two structures (inner cardiac tissue and synthetic matrix) (3) are bonded using a newly developed adhesive, TissueSil (4). The resulting piece is the biohybrid heart containing the preserved intracardiac structures and synthetic heart muscle (5).
All this required a great deal of novel artificial tissue development and the invention of a special adhesive that can bind the new material with the inner cardiac tissue of the pig heart.
By inflating and deflating the bubbles within the artificial muscle tissue in a synchronized fashion, the researchers were able to get the hybrid heart muscle to pump. So far, they have only reproduced the muscle of the left ventricle, but the concept should work the same for the rest of the heart. They even scanned their new device using MRI and ultrasound imaging, including while it was performing its pumping movements, and it looks remarkably like a real working heart ventricle.
Though cardiac device development and testing is an obvious use for the new hybrid heart, there are other intriguing possibilities. “Imagine that a patient before cardiac device implantation could have their heart scanned, and then clinicians could tune the device to perform optimally in the patient well before the surgery,” said Chris Nguyen, the co-lead author of the study appearing in Science Robotics. “Also, with further tissue engineering, we could potentially see the biorobotic hybrid heart be used as an artificial heart — a very needed potential solution given the global heart failure epidemic where millions of people are at the mercy of a competitive heart transplant list.”
Study in Science Robotics: An organosynthetic dynamic heart model with enhanced biomimicry guided by cardiac diffusion tensor imaging