Mar 8, 2018 | By Benedict
Physicians and biomedical engineers at Ohio State University have been 3D printing patient aortas in flexible materials using CT scan data. These 3D printed aorta models can be tested in heart simulators to determine the best course of treatment for a patient.
Testing a 3D printed aorta in a heart simulator
There are many reasons why a patient might need an aortic valve replacement. One of the most common reasons, however, is aortic stenosis, a narrowing of the valve opening. This stenosis can occur when valve “leaflets” become stiff from calcification, which prevents the left ventricle from pumping a sufficient amount of blood into the aorta.
Once the valve is diseased in this way, doctors need to decide on the appropriate course of action, which is generally one of two things: either they replace the diseased valve entirely with risky open heart surgery (which requires opening up the chest) or they use the safer transcatheter method to deploy a bioprosthetic tissue valve through a blood vessel in the leg.
But which method to choose? For doctors at Ohio State’s Wexner Medical Center, a 3D printing trick is helping them make that difficult decision in a more informed way.
A 3D printed aorta in a heart simulator with artificial blood
It involves obtaining a 3D image of a patient’s aorta with a CT scanner, before 3D printing a replica aorta in a kind of flexible 3D printing filament. These 3D printed aortic valves can then be fitted to a physical heart simulator, which gives insight into how a patient might respond to either a new aortic valve or a transcatheter procedure.
“For most patients, available valves work comparably,” says Dr. Scott Lilly, interventional cardiologist and co-director of the structural heart program at Ohio State Ross Heart Hospital. “However, in some cases the anatomy of the patient may create additional considerations. For example, the patient may have calcified nodules on the valve leaflets, or coronary arteries that arise in close proximity to the valve. The ability to reconstruct the areas where the valve is going to rest is important.”
Lilly works with a team led by Lakshmi Prasad Dasi, an associate professor of biomedical engineering and surgery in Ohio State’s Davis Heart and Lung Research Institute, to obtain these 3D printed models, which are then loaded into the heart simulator and pumped with fake “blood,” which is, surprisingly, totally transparent!
Dr. Scott Lilly performing transcatheter aortic valve replacement
(Images: Ohio State University)
With this heart simulator rigged up, the medical team can then use a laser and high-speed camera to measure blood flow velocity and vortex patterns both with and without a replacement valve.
“We can model various therapies, positions, and types of valves to better understand problems such as leakage, clotting, or coronary obstruction,” Dasi says. “We can observe how different valves not only relieve the stenosis but also minimize the likelihood of blood clots forming on the leaflets, which is the goal of the treatment.”
Computer models are also used to analyze blood flow, as well as interaction between a transcatheter valve and the patient’s anatomy.
“Using 3D modeling we can determine whether or not to protect…blood vessels during deployment, or even whether to proceed with valve replacement at all,” explains Lilly. “These discussions have directly informed how we approach many valve replacement procedures.”
Dasi’s team now plans to improve its own bioprosthetic valves, which currently have limited durability. Future synthetic versions could be enhanced with biomolecules, making future transcatheter heart valves cheaper and more durable.
Posted in 3D Printing Applications
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