One of the most common congenital heart defects, coarctation of the aorta (CoA) is a narrowing of the main artery transporting blood from the heart to the rest of the body. It affects more than 1,600 newborns each year in the United States, and can lead to health issues such as hypertension, premature coronary artery disease, aneurysms, stroke and cardiac failure.
To better understand risk factors for people with CoA, a large team of researchers, including a former Lawrence Fellow and her mentor at Lawrence Livermore National Laboratory (LLNL), have combined machine learning, 3D printing and high performance computing simulations to accurately model blood flow in the aorta. Using the models, validated on 3D-printed vasculature, the team was able to predict the impact of physiological factors such as exertion, elevation and even pregnancy on CoA, which forces the heart to pump harder to get blood to the body. The work was published in the journal Scientific Reports.
Proposed as an Institutional Computing Grand Challenge project at LLNL by then-Lawrence Fellow Amanda Randles (now the Mordecai assistant professor of biomedical sciences at Duke University) and her mentor, LLNL computer scientist Erik Draeger, the work represents the largest simulation study to date of CoA, involving more than 70 million compute hours of 3D simulations done on LLNL’s Blue Gene/Q Vulcan supercomputer.
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“You can take these simulations and really understand the realistic range of effects on people with this condition, beyond the factors present when the patient is sitting at rest in a doctor’s office,” Draeger said. “It also describes a protocol where, although you still need to do simulations, you don’t need to do all the configurations there are. One of the things that’s really interesting about this type of study is that, until you can do this level of simulation, you have to go by average results. Whereas with this, you can take an image of the aorta of that specific person and model the stress on the aortic walls.”
On Vulcan, Draeger, Randles and their team ran simulations of the aorta with stenosis — a narrowing in the left side of the heart that creates a pressure gradient through the aorta and on to the rest of the body. The simulations used a fluid dynamics software called HARVEY, developed by Randles to model blood flow, run on 3D geometries of the aorta derived from computed tomography and MRI scans. Because the aorta is so large and has a very chaotic flow, Randles — who has a background in biomedical simulation and HPC — rewrote the HARVEY code to maximize it for Vulcan so the team could run the enormous amount of simulations necessary to accurately model it.