PULLMAN, Wash. – Washington State University researchers have developed a 3D-printed model of the left side of the heart that contracts and beats, offering the chance for surgeons and medical students to rehearse important heart surgeries on a model that acts like the real thing.
The WSU researchers, in fact, did a valve repair on their heart model, using ultrasound imaging and customized sensors attached to the model to show a successful repair. They report on their work in the journal, Advanced Materials Technologies .
"It's very useful for doctors and surgeons to practice when the heart is still beating, especially for minimally invasive surgery," said Kaiyan Qiu, Berry Family Assistant Professor, School of Mechanical and Materials Engineering, and corresponding author on the paper. "In our case, this model is the first fully synthetic model that, without any assistance of animal models, mimics the complete left side of the heart. We were able to incorporate both the anatomic features and the dynamic functions."
Heart disease is the leading cause of death in the U.S., and about 800,000 people undergo heart surgery annually. In addition to major surgeries, doctors often perform minimally invasive procedures to treat heart diseases, such as valve fixes. Training for the procedures often requires practice on animals or cadavers, which aren't patient-specific or reusable. They can also practice on a computer, viewing the procedure.
"There have been other, synthetic models that are mostly mold-casted, and one of the main limitations there is that they cannot do some of the more complex curvatures that you see in the heart," said Alejandro Guilllen Obando, first author and a PhD candidate in the School of Mechanical and Materials Engineering.
In their work, the researchers used a scan of a real heart to 3D print a replica of the left side of the heart. The left side of the heart experiences the highest pressures and performs the heart's most vital functions, pumping oxygenated blood throughout the body. As people age, the mitral valve between the two left heart chambers often gets leaky, so that blood flows backward, or regurgitates, and reduces the heart's efficiency.
The heart model the researchers made includes the atrium, ventricle and mitral valve and has a soft texture similar a real heart. It also has multiple tiny pneumatic actuators that pump the model and string-like material similar to a real heart that manage the mitral valve movement. As imitation blood is pumped through the model, sensors on the model can monitor "blood pressure."
"Our layer-by-layer approach in 3D printing allows us to add more curvature and make the chambers simulate a real heart," said Guillen Obando.
After creating their model, the researchers printed a defective mitral valve and then repaired it. They created a repair device similar to commercially available devices and inserted it into the mitral valve. Sensors on the model showed increased blood pressure in the left ventricle, indicating that the valve was fully closing. They also could see with ultrasound imaging that their imitation blood was not regurgitating into the heart chamber.
The researchers have filed a provisional patent with the Office of Innovation and Entrepreneurship and are now working to develop a complete heart model with all four chambers and four valves. They also plan to work with medical professionals and students in the future to conduct more patient-specific, pre-surgical rehearsals on the model for different valve diseases.
The work was funded by the National Science Foundation as well as by WSU's Cougar Cage Funds and Commercialization Special Project Fund.
