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Towards the detection of vulnerable atherosclerotic plaques

University of British Columbia

Atherosclerosis is a deadly cardiovascular disease that is one of the leading causes of mortality in North America. It slowly progresses over the course of a person’s life starting as a streak of fatty cells on the endothelial lining of arteries into a fibrous capped atherosclerotic plaque with a highly thrombotic necrotic core. It is generally asymptomatic until the plaque ruptures causing acute potentially fatal events such as stroke or myocardial infarction. A plaque’s likelihood to rupture is based on an elaborate relationship between physiological, biomechanical and geometric factors. This thesis aims develope methods to study and understand the relationship between these factors and gain a better understanding of plaque rupture. A computational study was performed and published to study the effects of the viscoelastic properties of atherosclerotic plaque on rupture. Material models were chosen to reflect the viscoelastic nature of plaque. Realistic models were obtained from medical imaging, and idealized geometries were created using shapes typically formed by necrotic cores. The computational study showed that higher heart rates led to higher stresses in the plaques. Differing viscous properties affect the stress too, as lower viscous models generated higher stress, and so more prone to rupture. The study illuminated just how limited studies like this are, and how much more there is to know. In addition to computational simulations, physical tests can help close the gap in knowledge to better treat atherosclerosis and predict plaque rupture. Arterial phantoms developed here at the Heart Valve Performance Laboratory can be utilized as they mimic the material properties of arterial tissue. They can be injected with a lipid mixture to simulate atherosclerotic plaque. The missing element is a testbed to pressurize the phantoms between a max and min at different frequencies to simulate the heart. With this testbed, a large number of arteries can be pressurized until plaque rupture, helping gain insight into the events that precede plaque rupture. This testbed is designed, built, and tested, and ready to be used in further studies to learn about atherosclerosis. The computational study and the testbed are initial stepping stones to understanding plaque rupture. By investigating further, a plaque’s stability may eventually be measurable to an accuracy suitable for a clinical setting.

Text

2021-02-02

Attribution-NonCommercial-ShareAlike 4.0 International

http://hdl.handle.net/2429/77233

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-sa/4.0/