Good Receives AHA Award to Improve Stroke Treatment
One of every six deaths from cardiovascular disease in the United States is due to stroke. Of those, nearly 87% are ischemic strokes, in which a blood clot starves part of the brain of oxygen. If not treated within hours of the blockage, stroke can lead to cognitive disability, partial paralysis, and even death.
To treat ischemic stroke, surgeons use X-rays to position clot-removal tools in the brain, but they cannot keep the X-rays on during the procedure. Instead, they must wait until the tools have been withdrawn and check by X-ray to see if blood flow was restored by the first pass (attempt). If the clot remains, surgeons reposition the tools and try again.
“Each of these passes could take 15 to 20 minutes,” said Bryan Good, an assistant professor in the Department of Mechanical, Aerospace and Biomedical Engineering (MABE) who studies the pressure, flow, and other mechanical properties of blood (hemodynamics) in diseases like ischemic stroke. “Anything we can do to shave even a few minutes off a stroke treatment is critical for the patient.”
This spring, Good received a three-year, $231,000 American Heart Association (AHA) Career Development Award to create the first models of ischemic stroke that incorporate patient-accurate hemodynamics downstream of the blood clot.
Under the mentorship of MABE Associate Professor Caleb Rucker and Vanderbilt University Medical Center (VUMC) neurosurgeon Michael Froehler, Good will create the world’s most detailed computational model of ischemic stroke, validate the model with experimental data, and test new methods of blood clot removal.
“We’re going to be studying why some strokes are easier to treat than others,” Good said. “To do that, we need accurate models of the anatomy of the brain.”
Engineering Reveals the Invisible
Hemodynamics is well understood in healthy brains, but measurements in stroke patients after blood clots lodge in their arteries are essentially impossible to gather. After diagnosis, surgeons are racing to save a patient’s life; any unnecessary delay is out of the question.
“You can image the brain before you treat a clot and you can image it after, but you can’t see a stroke treatment in real time,” Good said.
Nonetheless, recent clinical data have shown that stroke patients with strong collateral blood flow—blood flowing from other vessels to brain regions downstream of the clot—have better recovery outcomes.
Good believes understanding the role of collateral blood flow will allow clinicians to treat more ischemic stroke patients on the first pass.
“The forces and flow mechanics happening on the other side of a blood clot have been something of a black box,” Good said. “As engineers, we can build models to better understand what’s happening in the brain throughout a stroke and its treatment. That’s what really piqued my interest; it’s where I think we can make some real improvements.”
A Silicone Stroke Patient
Neurosurgeons like Froehler take computed tomography (CT) scans to diagnose ischemic stroke and evaluate patient recovery. Those CT scans can be converted into 3D models showing the real state of a patient’s brain before and after treatment.
After securing his AHA award, Good will purchase a three-foot-tall silicone model of an average ischemic stroke patient’s vascular system from the heart to the brain. Good and his students will pump liquid through this model, gathering baseline data and noting how blood flows and pressures change when clots are introduced in various vessels.
The model is made of soft silicone, so the tubes inside can flex like real blood vessels as an electronic heart ‘pumps’ the fluid through it.
“With this model, we will really be able to understand how the collateral blood flow patterns change during a stroke and how this affects blood pressures around the clot,” Good said.
Using the experimental data from the silicone vasculature, Good and his students will build a computational model of ischemic stroke, then apply it to scans of Froehler’s stroke patients from the VUMC. Eventually, the team will use their computational model to investigate new procedures and medical devices that could improve clot removal.
“We can mimic different patient cases and investigate why one case was easier to treat than another, for example,” Good said. “Hopefully, through this award, we’re able to get a lot of good results that we can turn into larger, patient-driven studies and improve overall stroke patient outcomes.”
Contact
Izzie Gall (865-974-7203, egall4@utk.edu)