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Thesis Format

Integrated Article


Master of Science


Medical Biophysics


Goldman, Daniel

2nd Supervisor

McIntyre, Christopher W



Background: Atrial fibrillation (AF) is a prevalent cardiac disease which has been associated with increased risk of dementia and cognitive decline. We hypothesize that atrial fibrillation leads to regional transient hypoperfusion events in the brain, and that geometric variations in the arterial structure called the Circle of Willis (CoW) play a role in these events.

Methods: A computational model was developed to simulate cerebral blood flow in six common variations of the CoW. Risk was assessed based on frequency of beat-wise regional hypoperfusion events during AF, and sensitivity analysis was performed with respect to this model output.

Results: A key artery in the CoW, called the A1 segment, was found to play the most important role in cerebral perfusion. Intrinsic heart rate was also found to influence the frequency of hypoperfusion events.

Conclusions: Our results suggest that heart rate and CoW geometry play important roles influencing cerebral hemodynamics during AF.

Summary for Lay Audience

Atrial fibrillation is a common cardiac illness characterized by irregular and dysfunctional beating of the heart. We know that patients suffering from atrial fibrillation often have an increased risk of early cognitive decline, however the mechanism underlying this risk is not well understood. We hypothesize that atrial fibrillation reduces blood supply to the brain, which means the brain receives less than normal amounts of food and oxygen. To help our future experiments and clinical trials, this study developed a computer model that could test our hypothesis. It is designed to help us better understand how atrial fibrillation affects blood supply to the brain. The model can also help the study of varying shapes and sizes of large arteries in the brain. The results of these simulations show that atrial fibrillation leads to adverse low blood flow events in the brain. Moreover, it was found that the heart rate has a large impact on how often these events occur. A lower heart rate resulted in fewer harmful events. Finally, it was found that geometric configuration of cerebral arteries plays an important role in the severity of low blood flow events caused by atrial fibrillation, and patients with a “missing A1” configuration are at highest risk for these adverse events.

Creative Commons License

Creative Commons Attribution-Share Alike 4.0 License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.