UCalgary team tackles abdominal aortic aneurysms — a condition affecting 20,000 Canadians

The aorta is the body’s largest blood vessel and is responsible for delivering blood from the heart to all areas of the body. It is normally strong and elastic with smooth walls, but any part of the aorta can develop bulges, known as aneurysms, when the walls of the vessel weaken.

Aneurysms in the abdominal aorta, which leads away from the heart through the abdomen delivering blood to the torso and legs, are the most common. According to the Canadian Task Force on Preventative Health Care, an estimated 20,000 Canadians are diagnosed with an abdominal aortic aneurysm (AAA) annually.

“AAAs are dangerous because they may rupture, and when that happens there is a 50 per cent mortality rate,” says Dr. Elena Di Martino, PhD, a professor and biomedical engineer in the Schulich School of Engineering at the University of Calgary. “If a patient doesn’t get to the hospital right away, there is really nothing that can be done.”

Dr. Scott McClure, MD, a Calgary-based cardiac surgeon and researcher at the Cumming School of Medicine (CSM), agrees.

A ruptured aorta is a serious as it gets. Without expeditious treatment, death is an absolute certainty.

About 1,200 Canadians die each year due to AAA, typically because the disorder is symptomless and remains undetected. In fact, AAAs are often discovered by chance during routine ultrasound or X-ray tests looking for other conditions.

Open surgery or endovascular stents are the only treatment for AAAs. But because aneurysms are often stable for some time, surgeons must carefully weigh the risk of a rupture against that of surgery. Currently, they determine timing based on measurements of the aneurysm.

But measurements aren’t always reliable because aneurysms may rupture before they reach the size that would trigger surgery, or enlarged but strong areas may function well after reaching a size that would trigger a repair, resulting in unnecessary interventions.

Patient death sparks 15-year journey of discovery

Dr. Randy Moore, MD, a vascular surgeon and associate professor at the Cumming School of Medicine, knows the unreliability of current methods of treating AAAs first-hand. In fact, it was the death of Moore’s patient due to a ruptured AAA that kicked off his 15-year journey to develop a more precise way of determining treatment strategies for individual patients and led to a partnership with Di Martino.

“This patient’s AAA was smaller than the cutoff for surgery, and although I followed the guidelines, he ruptured prematurely,” says Moore, noting the death, which occurred during emergency surgery, troubled him deeply.  

Following the loss, Moore, who has been a vascular surgeon for 25 years, spent five years scouring the scientific literature and looking for potential partners with an interest in this area. Serendipitously, Moore met Di Martino.

The two have worked together for 10 years.

CIHR grant to study aneurism patients

Di Martino and Moore recently received a $661,725 Canadian Institutes of Health Research grant to study aneurysm patients. The research team will also study tissues from patients selected for AAA surgery in their continued quest to find dependable, non-invasive ways, to measure risk of AAA rupture.

Researchers will use engineering methods, including special instruments to assess the performance of tissue samples, to test their hypothesis that aneurysm growth can be predicted and look at ways to deepen their understanding of why the aorta weakens. They hope to find ways to better predict when to intervene using simple diagnostic tests to assess the strength of an individual’s aortic walls, such as blood pressure measurements and CT scans.

“The idea is really understanding how to treat the right patients in the right way at the right time,” says Di Martino.

Moore agrees. “Patients don’t care how the other 100 people with AAAs are doing, they want to know how their own aorta is doing,” he says. 

Predictive software 'absolute game changer'

Moore and Di Martino are making headway. They are preparing to launch software that will revolutionize the treatment of AAAs, called Virtual Touch Aortic Aneurysm (ViTAA), by predicting an individual’s risk of aortic growth that can lead to rupture.

The software analyzes data from either the patient’s CT scans or MRIs, both common imaging tests, using a proprietary computer algorithm. ViTAA then provides images and a functional map that will help the clinician to decide when surgery is required.

“For the first time ever, we can tell you if your AAA is weak,” says Moore. “It’s an absolute game changer.”

Moore has been using the dynamic CT scans that are used in ViTAA analysis in his surgical practice for five years and is excited about the potential lives that may be saved globally.

McClure is also optimistic. He says if the research comes to fruition, it will have a “colossal” impact. “It would completely transform our approach to aortic disease,” he says. “We would finally have definitive evidence to guide us as to who is really at risk and in need of aggressive interventions.”