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Changes to the heart’s tissue and to its electrical signals most often cause atrial fibrillation. To understand atrial fibrillation, it helps to know how the heart works. When the heart’s tissue or signaling is damaged, the regular pumping of the heart muscle becomes fast and irregular. Most often, damage to the heart is the result of other conditions such as high blood pressure and ischemic heart disease. Other factors can also raise your risk of atrial fibrillation.
Usually the cells of the heart fire and contract together. However, when aging, heart disease, infection, genetic , or other factors change heart tissue, that pattern breaks down. This can happen because of fibrosis , inflammation , a thinning or thickening of the heart walls, lack of blood flow to the heart, or an abnormal buildup of proteins, cells, or minerals in heart tissue.
Usually, a trigger heartbeat sets off atrial fibrillation. Electrical signals from this trigger may then cause the heart to beat slower or faster than usual because of changes in heart tissue. Sometimes, the signals create an atypical loop, telling the heart to contract over and over. This can create the fast, chaotic beating that defines atrial fibrillation.
Variations in the heart’s electrical signaling can be due to differences in heart anatomy, premature or extra heartbeats, normal heart rate adjustments, patches of faster or slower tissue, and repeated stimulation of certain tissue patches.