Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that can present without cardiovascular disease (lone AF). Frequent high-intensity endurance exercise is a risk factor for lone AF, and the pathophysiology of AF induced by intense endurance exercise is unknown. We found that after 6 weeks of intense swimming and running, mice were far more susceptible to AF, but not ventricular arrhythmias. Exercise induced atrial fibrosis, inflammation and slowed conduction without detectible changes in ventricles. Since AF is associated with stretch and since a tumor necrosis factor-α (TNFα) is a mechanosensitive inflammatory factor, mice were treated with the TNFα inhibitor etanercept. Etanercept treatment blocked inflammation, fibrosis, and AF vulnerability in the exercised mice. Consistent with these findings, we found that exercise caused large elevations in atrial pressures. Our findings support the conclusion that mechanical loading of atria during exercise induces TNFα release, leading to structural remodeling and enhanced AF vulnerability.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/35120 |
| Date | 18 March 2013 |
| Creators | Izaddoustdar, Farzad |
| Contributors | Backx, Peter |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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