The most frequent cause of stroke is Atrial fibrillation (AF), a cardiac arrhythmia consisting of irregular heartbeats. These strokes are the most devastating ones. Recent observations in stroke patients suggest that stroke can also cause AF. This Post-Stroke Atrial Fibrillation (PSAF), in turn, can produce more strokes.
Victoria Thorburn, a Master’s student at Lawson Health Research Institute and Western University’s Schulich School of Medicine & Dentistry in the department of Anatomy and Cell Biology, has been awarded with a Lawson Internal Research Fund (IRF) Studentship to develop the first rodent model of PSAF. The goal of the study is to gain more understanding of the relationship between stroke and PSAF.
The cause of PSAF is currently unknown but it is believed that strokes occurring in the insular cortex, a brain region responsible for monitoring heart rhythm, may trigger PSAF. When this brain region is damaged by stroke, the heart is left without regulation, resulting in chaotic heart rhythms. Previous studies have not been able to confidently diagnose PSAF, since approximately one third of AF cases are silent or asymptomatic.
“Without continuous monitoring of heart rhythm prior to stroke, it is difficult to determine if PSAF is in fact a newly developed arrhythmia occurring after stroke or whether it was actually a silent form of AF that already existed before stroke,” Thorburn says.
Thorburn will experimentally induce stroke in the rat insular cortex to determine whether PSAF or other types of irregular heartbeats occur as a result. The project will be supervised by Dr. Luciano Sposato, Lawson scientist, physician at London Health Sciences Centre and associate professor in the Department of Clinical Neurological Sciences at Schulich, and Dr. Shawn Whitehead, assistant professor at Schulich. They will monitor heartbeat before and after insular stroke then assess potential biological factors or structural changes in the brain or heart that may be associated with PSAF. Animals that developed PSAF will be compared to those without the condition.
Since the proposed cause of PSAF, the involvement of insular cortex damage, differs greatly from the traditional cause of AF, which is often a structural abnormality in the heart, there could also be a difference in treatment. The hope is that the knowledge of PSAF formation gained from the first rodent model will lead to the development of prevention and therapeutic strategies, minimizing the number of stroke patients affected by PSAF and ultimately reducing the recurrence of stroke.
“I wanted to become involved with research that was currently relevant and had the translational potential to improve public health. With the current aging population, the number of individuals directly affected by stroke and AF will continue to rise,” says Thorburn. “Thanks to funding opportunities like Lawson’s IRF, students like myself are able to train alongside accomplished researchers and participate in research that uniquely integrates both basic science and clinical perspectives.”
The IRF is designed to provide Lawson scientists and students the opportunity to obtain start-up funds for new projects with the potential to obtain larger funding, be published in a high-impact journal, or provide a clinical benefit to patients. Funding is provided by the clinical departments of London Health Sciences Centre and St. Joseph’s Health Care London, as well as the hospital foundations (London Health Sciences Foundation and St. Joseph's Health Care Foundation).
